Predatory plants will probably not trot over to attack us as we amble to our cars any time soon, John Wyndham's classic sci-fi novel Day of the Triffids notwithstanding. And yet, truth may well turn out to be stranger than fiction, if we only wait. In the case of plants coming out of genetic engineering labs that wait might perhaps be 10 years - or less. In the case of mother nature, radically new tricks might require waits of 10 million or 100 million years - or more.
Spore Storm. Anthrax bacteria can kill quickly, overwhelming an animal's natural defenses by multiplying and secreting toxins. The toxins build up in the body and they, not the organisms themselves, are what ultimately cause death. Once dead, the animal host is no longer a suitable source of food, shelter, and oxygen for the anthrax. Now something interesting happens. Some of the anthrax bacteria succeed in growing, inside their bodies, a tough cover encapsulating their genes and certain other cell components. This is called an endospore, and is capable of withstanding environmental conditions for long periods of time - several decades has been documented. When conditions finally become favorable (e.g. it is eaten by a host animal), it comes back to life, attempts to grow and divide, infects the new host, and the cycle begins anew.
Many terms derived from "spore" exist, from aeciospores to zygospores, and endospores are just one kind. Some plants reproduce via spores, ferns for example. Spores do nothing until conditions for growth are promising. Then they spring into action. Plant spores sprout into baby plants called sporelings (spores become sporelings, like seeds become seedlings). The sporelings eventually become full grown plants if all goes well. However, many familiar plants produce seeds, not spores. Seeds are much bigger and carry much more nutrition, used to give a baby plant a good start, or perhaps sustain an animal that eats it. Spores, on the other hand, are microscopic.
Oaks produce acorns, which are large seeds, not microscopic spores. But even the mightiest oak, like a tiny blade of grass, is missing a big opportunity. That is the opportunity for each cell in each leaf to create an endospore, instead of uselessly falling to the ground to rot when the leaf gets old or winter approaches. In the future, by natural accident or human design, some plant may become the first to grab that opportunity, and things may never be the same again. Instead of dropping their leaves, these plants will release a dust storm as each leaf transforms into millions upon millions of endospores, blowing in the wind. These endospores will eventually land and try to start a new plant, in the spring in temperate climates or any time in warmer conditions. Such spore-producing plants could continue to also produce seeds as they always have, but rather than waste their spent leaves along with an additional opportunity to propagate, they will instead much more efficient convert those leaves into quantities of endospores. This will give them an advantage over traditional plants, out-competing them and eventually dominating the earth, just as flowering plants have come to dominate since they first evolved at least 140 million years ago. Let us hope these superplants make useful crops. That way their domination will be useful to us.
When beans take over the world. Beans use a biological strategy that may be only beginning to play out. This strategy may ultimately change the biosphere radically, enabling considerably more living biomass and thus increasing the profusion and exuberance of life. The strategy is nitrogen fixation, which is the ability of a few plants (notably beans) to get their nitrogen directly from the air. The vast majority of plant life relies for nitrogen on decaying vegetable matter, lightning strikes whose concentrated heat forces nitrogen in the air to combine with oxygen to put it into bioavailable form, and other processes not under the plant's control. In the ocean, however, some species of cyanobacteria ("blue bacteria," commonly if problematically called "blue-green algae" since algae are plants, and cyanobacteria are technically not) can fix nitrogen from the air. Beans (more generally, legumes) do not actually fix nitrogen themselves but instead rely on bacteria that they shelter in root nodules.
Once the idea of fixing one's own nitrogen directly from the air takes hold in the plant kingdom, nitrogen need never be a bottleneck again. Then the Earth will be able to support a thicker, heavier, and more diverse blanket of vegetation. Since the animal kingdom ultimately depends on plants, the Earth will also then support more animal life (and potentially human life) as well. Fertilizer manufacturers may have one less component to worry about including in their products, but on the other hand might find less demand for their products. You might not have thought of beans as the vanguard of a new paradigm of domination among plants. But beans and many thousands of species of their descendants might take over the plant world analogously to how flowering plants began their ascendancy starting more than 100 million years ago.
At least they'll taste good. The idea of beans as masters of the Earth may be tough to swallow if you're not crazy about bean dishes. But maybe genetic engineering will change your mind and those of future generations. Genetically engineered crops will become increasingly important, accepted and desired, because there is little chance of stemming the coming tide of crop plants engineered to produce new and delicious foods at reasonable cost. Flavorings are metabolically cheap for plants to produce compared to soil fertility-draining and solar energy-intensive metabolic products like oils, proteins, and carbohydrates. Thus, there is no downside to major changes and improvements in plant product flavors. And it is relatively easy to do compared to some of the genetic engineering goals mentioned earlier. Even old-fashioned selective breeding, the "low tech" approach to genetic engineering, has produced such familiar taste-enhanced foods as sweet corn that is much sweeter than the corn eaten a couple of generations ago. Take beans, for instance (please don't tire of my discussing them - as future monarchs of the plant kingdom, they are entitled to some respect!). They are already a nutritious protein source, like meat but with less fat. Yet they don't taste as good as meat to many people. There is no reason they can't be engineered to taste like small chicken nuggets. Processed fungus mycelium (i.e., roots), sold in grocery stores, taste like chicken already. Try it if you don't believe it. Yum!. We could make chickpeas that taste like chicken, and rename them "chickenpeas." But why stop there? Potatoes with small hamburgers in the middle sound good (let's call them "hamburgatoes"), and there is no reason they can't be grown once genetic engineering gets a little further along. Carrots are crunchy, as are potato chips. So why not grow carrots that taste like potato chips? Or like Cheetos or other crunchy, cheese-flavored snacks. Kids would want to eat more veggies, and carrot sales would skyrocket.
Speaking of cheese flavor, consider the pits of avocados. They are so large that it seems a waste to just throw them out, as we do now. Avocados already contain lots of fats in the edible part, as cheeses do, so genetic engineering to put more fats in the pit would help make them edible and even taste like a hard cheese, say romano or parmesan. Then grate the pit it on food to taste! Avocado pits are a specialty item of course, but just a start.
Giant seeds taste better. Ever eat pumpkin or other winter squash seeds? They are both delicious and nutritious, roasted or just placed raw into foods before cooking. You can buy pumpkin seeds in small snack bags. The problem for many people is the coverings, which are challenging to bite off because there are so many of them, as the seeds may seem relatively small. Genetic engineering to increase the seed size could solve that problem, since genetic engineering of size is probably easier than a lot of other generic engineering goals. Instead of a pumpkin with a couple hundred or so small seeds, it could grow 5-10 large seeds. Or just one, as big as an avocado seed but a lot better tasting... delicious. Speaking of seed size as a critical factor, sunflower seeds present a similar situation. You can get packages of them in the supermarket as a snack, but the ones with the seeds still in their shells seem less popular because they are harder to eat. You have to tediously bite off the shells to get to the seed inside. They taste good once you get them out though. And you get a lot of hand and mouth activity per seed, slowing down the intake of calories and making them a nutritious and satisfying snack for dieters. Yet the sunflower seed market would almost certainly grow dramatically if the seeds were 10x larger or more. Imagine eating an enormous sunflower seed the size of an egg...hefting its weight in the palm of your hand...cracking off its shell to reveal the rich, tasty meat within...and finally sinking your teeth into it to savor its nutritious and distinctive flavor! Hmm. A future sunflower could produce a seed like that, if it wasn't spending its energy growing dozens and dozens of smaller seeds instead, like current sunflowers.
Fruits form a ready target for genetic engineers. Fruit is healthy and has near-universal appeal. Even people who have never eaten fruit in their lives rapidly develop a taste for it (who are these people, you ask? "Babies are puzzled by fruit... . But within a day or two practically all of them decide they love it." - Baby and child care icon Dr. Spock). To plant the seeds of some ideas for such babies and others who will become the next generation of genetic engineers, consider the following possibilities.
Black salad grows faster, looks funny. Most plants are green, and everyone can appreciate the healthy green glow of a vigorous plant. Would you say that plants like green light? Not so - green plants are green because they reflect green light, while absorbing red and blue. Consequently the green light goes into the eyes of the viewers, who thus see plants as green. By reflecting green light, plants are rejecting it. They use light that they absorb as solar energy, powering a process that sucks carbon dioxide out of the air and converts it, ultimately, into plant contents using a process known a photosynthesis. Perhaps weirdly, it now appears that photosynthesis, the biological process that terraformed the Earth in the distant past, creating and now maintaining at 21% the oxygen in the atmosphere so necessary for human life, uses the esoteric physics phenomenon known as quantum entanglement to do its work. A green color may be a sign of health, but it is also a sign of inefficiency. If the could only absorb and use green light better, it would be using solar energy more effectively and could grow faster, for either its own or human purposes. If a plant absorbed and used all light falling upon it, it would be black, not green, because black is what we see when all colors are absorbed and not reflected into our eyes.
If black plants would be better, then what are the prospects for mountains, plains, and rolling hills of deep black instead of striking green? Plants absorb light using special pigments which begin the solar energy harvesting process. Well-known and prevalent pigments are chlorophyll, of which there are several varieties named chlorophyll a, b, c, c1, c2, and others. Different chlorophylls (chloro- from a Greek word for green, -phyll from the Greek for leaf) are of varying shade depending on the type. However there are also other pigments useful for photosynthesis. Various xanthophylls (xantho- from the Greek for yellow) are also used. Carotenes, which make carrots orange, are another. There are hundreds of them. Opsins (ops- from the Greek for sight, as in 'optical,' and -in which indicates a biochemical substance) are not only used for sight in the human eye (namely rhodopsin, rhodo- for rose-colored, also named "visual purple"), but for photosynthesis (using bacteriorhodopsin, a misnomer since the organisms using it are archaea, not bacteria). Bacteriorhodopsin preferentially absorbs green light and reflects red and blue, thus appearing reddish-blue (that is, "purple"). Bacteriochlorophylls are related to chlorophylls and can be greenish or purplish. Phycobilins are used in photosynthesis in certain microorganisms and come in a variety of colors, from red to blue. Phycocyanins are another category of pigment used in photosynthesis (cyan meaning blue-green). Phycoerythrins too, which are red (-eryth from Greek and meaning red, as in erythrocytes - red blood cells).
Even invisible light is important. The water-dwelling microorganism Acaryochloris marina contains chlorophyll d, which is particularly good at absorbing infrared light for photosynthesis. On the other hand, some plants reflect infrared light. But they could reflect more, enough to actually change the world's climate significantly. It seems that leaf hairs can help reflect infrared while allowing visible light through for photosynthesis. By breeding plants with leaves that are quite hairy, more infrared could be reflected back into space, with a cooling effect on the climate. Extra hairy soy varieties have already been bred such that if they and other crops similarly bred were grown extensively enough in temperate regions, the average temperature of those regions would decrease by about 2 degrees F. It is a tough call which would be better, crops with pigments that use infrared light for photosynthesis, or crops that reflect as much of it as possible away from the Earth.
Be that as it may, a plethora of pigments exist to support photosynthesis and there seems no intrinsic reason why a plant could not eventually evolve naturally or be genetically engineered to mix and match the pigments so as to absorb and use nearly all light. Such plants would potentially have an evolutionary advantage over other plants that waste resources by taking the trouble to grow leaves and then not use all the light that falls upon them. Thus future plants that solve this problem would tend to take over, both in nature and in agriculture. Though the real action would be at the biomolecular level, visually such plants would be near-black, not green. Would black salad taste better than green? Only a future taste test will resolve this important question!
Alternamorphs: plants with options. All organisms are at least a little "alternamorphic": their form depends on the environment they grew in. A plant may be bigger under optimal conditions, smaller or even stunted under poor ones. A single cell may be bigger after a meal. A human may be darker or lighter depending on degree of sun exposure. Perhaps more interestingly, some kinds of grasshoppers, when crowded, change strikingly in appearance, becoming...locusts which gather in huge, hungry, migrating clowds, leaving devastated farmland in their paths. These are the locust swarms of biblical fame.
If properly endowed by natural evolution or genetic engineering, plants could turn the concept of alternamorphism to their advantage in many interesting ways. For example, consider the humble corn (zea mays) plant. It is a staple of the world food supply but is not particularly easy to grow successfully in one's garden, as many an inexperienced gardener can attest. Now imagine a new kind of corn plant that, after bearing its ear of corn, alternamorphically either dies or sinks a taproot that lasts the winter and then, in its second spring, sends up a new shoot that grows more slowly than before, but more sturdily. That grows, in fact, without producing any ear of corn that year but rather is built to last the following winter, so that it can build on that growth with further development in its third spring - eventually turning into a large corn tree that produces dozens of ears every year, and with far less work than farming an equivalently productive corn patch.
But what would determine which alternative the corn plant chooses, dying off as happens now, or beginning the process of turning into a corn tree? A reasonable genetic code for this would be to opt for the tree strategy if the ear is destroyed early in its development or fails to develop properly for whatever reason. In that case it makes sense for the corn plant to devote its energy to something else, such as trying to grow into a tree. Indeed, any excess of vitality would be a good reason to pursue the tree strategy, even if the initial ear is growing well. Perhaps the corn plant is simply experiencing highly favorable growth conditions and has the werewithal to both produce an ear, and grow the required large taproot. Similarly, any annual crop or other plant could potentially alternamorphically become a tree. Farmers and gardeners would be delighted. On the other hand, hundred foot ragweed trees would be bad news for many an allergy sufferer. Alternamorphic trees are just a start. The reader may enjoy dreaming up other kinds of alternamorphisms. In a number of years it may be possible to actually create these in a do-it-yourself basement bio lab.
A return to roots. The sun moves around in the sky, in many places casting its life-giving rays on different spots throughout the day. A plant that could move to the nearest sunny spot would have an advantage over ordinary plants that are stuck in one place. But plants have it rough. Unlike people, they can't pull up roots and relocate somewhere else.
Ambulatory plants that simply walk over to the nearest sunny spot would outcomplete regular plants, eventually becoming rulers of the plant kingdom. Unfortunately, it all seems a bit unlikely. Except for some interesting exceptions like species of Tillandsia (the so-called "air plants," which are discussed below), plants need their roots. And roots are, well, rooted in place. However, while the vast majority of plants do need roots, they don't need them every minute. As everyone who has experienced the concept of cut flowers in a vase of water knows, plants can go for quite some time without roots. And roots can do fine without the rest of the plant for a considerable time as well - just check your fridge, pantry, or grocery store for an assortment of potatos, carrots, etc., which do just that. In nature, in fact, many plants over-winter with just the underground roots alive all winter long, then grow new above-ground parts come Spring. The trick, then, is to build a plant that can separate temporarily at the base. The above-ground part then wanders off in search of maximum sunlight. As evening approaches, the plant literally returns to its roots, reattaches, and spends the night with its above-ground and below-ground sections in metabolic union.
It is unclear if such a plant variety would ever evolve spontaneously. However, genetic engineering should be able to do it at some point. Moving short distances would be feasible for plants based on their current capabilities - many plants can and do change in shape fast enough over the course of a day already. Flowers open and close, leaves move around, etc. For example the immature flower heads of the sunflower face the sun, tracking it as it crosses the sky over the course of the day. Engineering a plant that can detach at the base, walk off looking for sun, return in the evening and reattach until morning presents a number of varied challenges, all of which must be solved before it can work, including a detachment and reattachment mechanism, a slow but real walking capability, and the sensory capacity to find its way back to its roots. Yet there seems no fundamental reason why it could not be done.
Once such plants are on the march, additional genetic changes will be possible. Plants need not return to their own roots, but could instead return to the roots of another plant, perhaps even of a different species. Animals looking for a nutritious drink might try to suck juice from the exposed detachment point of the roots after the top of the plant has wandered off for the day in search of sun. Plants could evolve or be further engineered to allow animals to suck for juice only if they fertilize the plant as a down payment, by urinating at the base! Plants that can walk around would be strongly motivated (in an evolutionary sense) to develop better sensory systems and faster movements to compete with other plants. Such capabilities are normally associated with animals, not plants, so these plants of the future, as they evolve, would tend to increasingly blur the line between plants and animals. A world with walking plants would be different indeed!
Another strategy for adding walking plants to the biosphere would start with plants like Tillandsia, the air plants, which either do not have roots at all or have small ones used only to hold them in place. The genetic engineering complexities of a detachment/reattachment mechanism and a homing mechanism for finding roots earlier left behind would be unnecessary, simplifying the problem greatly. However as for soil-rooted plants. creating the capacity for locomotion would still be a challenge. Tillandsia plants absorb water and nutrients through their leaves, so an ambulatory version would have considerable advantages. They could walk around (and climb around, since they typically live on trees), looking for sun, taking a dip when thirsty, and loading up on compost (or, predator-like, trimming leaves off of other plants) to absorb nutrients from. Perhaps ambulatory descendants of the Tillandsia genus will one day rule the Earth.
Plants with mirror molecules. Suppose you had two identical dice with sides numbered 1 to 6 as usual. Typically one corner will have three sides numbered 1, 2, and 3 going around the corner in that order clockwise, with a 6 on the side opposite the 1 (because opposite sides add up to 7 on normal dice). Now take one of the dice and change it slightly. Paint a 6 over the 1, and a 1 over the 6. Now the sides numbered 1, 2 and 3 meet at a different corner and, what is more, they are arranged going around the corner counterclockwise instead of clockwise. Although both dice still function identically and may appear identical to a casual glance, in fact they are different: they are now mirror images of each other. In fact you don't need 6 faces for this mirror image situation. It can also occur with 4-sided tetrahedrons (tetra- means 4), which look like 3-sided pyramids. The 4th side is the triangular base and the top corners of the 3 triangular sides meet at the apex. Similarly, some organic molecules consist of a carbon atom in the middle with 4 different atoms or atom groups sprouting outward. These four branches are like the sides of the tetrahedron: if you switched any two of them you would get a different molecule, a mirror image of what it was, and no amount of rotating it or otherwise moving it around will erase that difference. Mirror image molecules are technically called "enantiomers," enantio- from the Greek for 'opposite,' and -mer meaning member of a group (from the Greek for 'part'). They relate to plants as follows.
1. Proteins are necessary for all living things, including plants, to make, have, and use. While the earliest life on planet Earth might not have contained proteins (the "RNA world" conjecture), every known life form today contains numerous kinds of protein as a major component.
2. Every protein molecule is made from building blocks, called amino acid molecules, which are connected together end-to-end like beads on a string.
3. There are 20 different kinds of amino acids heavily used in building proteins, of which all except glycine have a central carbon atom with four different branches.
4. Thus 19 of the 20 common amino acids have two enantiomers, called L (for "levorotatory," levo- from the Greek for 'left' because of the direction its solutions rotate polarized light), and D (for "dextrorotatory," dextro- from the Greek for 'right').
5. Organisms generally contain only the L versions of these amino acids. No one knows why. Organisms based on D amino acids could exist, but we don't see either plants or animals that do. (D forms have been observed in a few microorganisms.)
6. If we engineered plants to be based on D-amino acids, their nutritional value to pests (and humans) would be much lower, because animals can't build their own proteins from D-amino acids.
7. Such plants would therefore be pest resistant, hence agriculturally valuable - as long as we're talking about plants grown for purposes other than edible protein, such as vegetable oils, wood, etc. Pest resistance is an incentive that suggests that humans will, in fact, eventually create and grow such plants.
The pest resistance of D-amino acid based plants will give them a selective advantage over normal plants, and they could therefore come to significantly displace normal plants. Call them frankenplants if you like, but the world risks becoming significantly different, a planet overrun with plants that resist being eaten, and therefore, able to feed fewer animals of all kinds, from insects to humans.
Manufacturing plants. There is green manufacturing, and there is green manufacturing: an ordinary factory can be made more green, but it will never be as environmentally friendly as a real, growing green plant. Green plants have manufactured things for us since the dawn of our species. Green plants manufacture the oxygen we need to breathe and live, from the carbon dioxide they remove from the atmosphere. Indeed without plants, the oxygen in the air would dwindle away and humans (and other oxygen-breathing animals) could no longer survive on Earth. Plants also manufacture food, from grain to veggies to oils to mouth-watering fruits, nuts and spices; wood, from Douglas-fir for construction to beautiful furniture wood to light balsa wood to heavy ebony for piano keys; drugs, from traditional cures to modern pharmaceuticals to intoxicants like tobacco, opium, magic mint, and lactarium; and chemicals of endless variety. Green plants are manufacturing devices - they perform green manufacturing in every sense.
On the other hand, one often hears that such-and-such does not grow on trees. Money, for example, does not grow on trees. Yet numerous solid objects found in everyday life would be relatively simple to genetically engineer trees to produce. A chair for example merely needs a sapling (let's call it a "front left leg") to reach the height of a seat, then send out two horizontal branches at right angles. When they grow about two feet long, they send shoots straight down to the ground where they take root. They also send shoots out horizontally at right angles to their current direction, which meet to form the last corner of the seat, whereupon they send down the 4th leg. Similarly, extra branches can grow into a back, as well as arms and various bracing bars if desired. The banyan tree is an example of a plant whose branches send down shoots that turn into extra trunks already, so that part of the general concept is clearly feasible. The chair still needs a seat, which could grow from a network of tough, viny stems that give enough when sat upon to be comfortable. Or add a cushion if you like. Of course, you still have to pull it out of your garden, but that is no more trouble (probably less, actually) than a trip to the furniture store. The entire chair is one piece without fastened joints that could loosen with age or otherwise require maintenance, so it could be long-lasting and strong. How strong? That depends on how long you grow it...for stouter legs and other parts, a chair tree farm would just let the chair tree grow a couple years longer before harvesting to let the trunks and branches thicken.
Various other useful items could grow on trees in your yard or in tree farms, or the seeds might get loose and grow in vacant lots or in the wild. Tables might need a flat top to be added later. Ladders would be a natural. Railings (just turn a ladder on its side!). Marbles already grow on bushes (they're called "marble seeds") and plants could be engineered to grow many other small solid toy and light household items as well, from checkers and chess pieces to knobs and knick-knacks.
Here's another kind of thing that "doesn't grow on trees." Gold and silver. But no doubt they could and hopefully they will. Roots are chemical factories. Solar powered chemical factories. They extract raw materials from dirt, using energy captured by leaves from sunlight to convert the raw materials into useful chemicals. Mother nature has caused plants to make chemicals useful to the plant, but humans are increasingly causing them to make chemicals useful to humans. For example resveratrol is a chemical found in red grapes, peanuts, Japanese knotweed and some other plants. Some experiments suggest it increases the life spans of certain animals (and thus, perhaps humans). It can be produced not only by the roots of entire peanut plants, but by the peanut plant root system alone without benefit of light, leaves, or stems - the trick is to keep the peanut root systems properly bathed in a clear nutrient solution in a glass laboratory flask.
Back to gold and silver. Plants could be genetically "programmed" so their roots extract metal compounds as desired from the soil, transport molecules containing those metals within the plant, and concentrate and deposit them where they could be - literally - harvested. Already genetic engineering has been shown to enable plants to extract certain heavy metals like cadmium, lead, and copper from the soil for storage in the plant's tissues (for de-polluting soils, this is termed "phytoremediation," meaning, literally, "plant remedy").
Large trees are clearly a good kind of plant for this. Their root systems are extensive and access a large volume of soil and, hence, a lot of whatever metal compounds might be present in the soil. A good place for trees to concentrate and deposit the metal compounds is the bark, because the bark is relatively straightforward for humans to collect as it gradually flakes off, which occurs slowly, giving plenty of opportunity to concentrate its metal content as it grows. It would also be easier to genetically engineer bark deposition than many other options. The bark thus becomes metal ore from which the desired metal can be extracted. Almost any metal desired could be programmed into the tree's genetic code. Valuable metals like copper, silver, or even a longish list of various unusual and valuable metals could be mined this way. The platinum, rhodium, or other specific metals could be extracted from the valuable mixture later, or the biochemical pathway needed for extracting any given specific metal could be engineered. Gold might present special challenges because, when present in richer quantities, it tends to be in the form of pure metal particles. Roots would need special genetic engineering to dissolve and uptake the free metal. Yet some gold atoms are everywhere (even seawater, suggesting use of seaweed as an alternative to trees) and could be absorbed without the extra level of genetic engineering needed to dissolve the metal first.
Metal-enriched bark is nice, but even better are actual lumps of pure silver, gold, copper, even platinum or anything else. Another level or few of genetic engineering would be required, because now the metal not only needs to be uptaken by the roots and transported within the plant, it also needs to be deposited in a specific spot (the nugget), biochemically converted to metallic form, and provided with a covering of special-purpose plant tissue responsible for conversion, deposition, and protection. Each of these requires a fair amount of new genetic machinery. But what a result! For every tree, a "berry" containing a nugget of shining and perhaps precious metal, there for the plucking. For rare metals barely present in the soil the berry would be small. For common but useful metals (aluminum, for example) the berry would be larger, more like a pear if not a golden pear. Multiple aluminum pears might be more convenient than one massive aluminum "watermelon"!
But why stop there? No one really needs bumpy aluminum pears except to sell on the metals market. Nor do we need amorphous lumps of alloys like stainless steel, bronze or brass (after all, specific alloys instead of elemental metals are just a few more genetic tweaks away once we've gotten this far). But we do need stainless steel silverware, cups, bowls and colanders; beautiful brass doorknobs and other ornamental pieces; steel nails, hammer heads, screws, screwdrivers, bolts, nuts, plyer parts, wingnuts, washers, door hinges; aluminum and iron frying pans; plumbing fittings, and many other specially-shaped lumps of metal. Once we've got metal berries and pears growing on trees, another level of genetic programming or two and they'll no longer look like lumpy fruit but like anything from forks to frying pans, screws to screwdrivers, washers to wingnuts. Think silver spoons and copper wire will never grow on trees? Think again. And coins...let's not forget them, since who wouldn't want money to grow on trees.
Power plants. Trees could do a lot, as we have seen - and they're solar powered, too. Once trees can suck metals from the soil and grow useful, shaped objects like copper wire, a few more levels of genetic engineering could enable the tree to use this copper wire to deliver electricity. Since a tree is already, now, a solar energy converter, we can build on that by having the tree grow tissues that convert energy into electricity. Electric eels can already do that, producing enough of a jolt to be lethal to humans. Even ordinary fish produce small amounts of electricity to create electric fields in the water around them. Any object nearby disrupts the field, enabling the fish to tell that something is near, even in total darkness. We may never be able to plug something into a swimming fish but we can already make batteries out of potatoes. So why not trees that grow into electricity providers all by themselves? It would be great to be able to plug your electrical devices into a tree (or at least a socket in your house that is connected to the tree). Then you would no longer need to connect to the grid, purchase solar panels, or install a windmill. You would, however, need to keep your trees healthy and vigorous! Tree care specialists would become a highly employable occupation.
Greening the desert. The Sahara and various other less notorious but still very dry deserts around the world have plenty of sand and rocks. But they don't have much greenery. The main problem is lack of water. Vast swaths of the Sahara, for example, are plant free. It's just too dry. However this problem is solvable! Cacti and other desert plants could potentially extract water from the air. Plants already extract carbon dioxide molecules from the air. Even very dry air contains considerable water vapor, so why not extract water molecules too. Indeed, plants already transport water molecules in the ground into their roots, so is it really such a big step to do the same from the air? Tillandsia (air plant) species can already pull in water with their leaves, but it has to be rain or other liquid water. Creating plants that can extract gaseous water vapor from the air in a harsh desert environment would require sophisticated genetic engineering, or a leap for mother nature, but it is still only the first step. Plants get nutrients out of the soil by absorbing fluid that has dissolved them, so dry soil would be a problem even for a plant that contained plenty of water pulled from the air. Another level of genetic engineering or natural evolution would be required to enable them to secrete fluid out of their roots to moisten chunks of soil to dissolve its minerals, and reabsorb the now nutritious, mineral-laden liquid back into their roots.
Once this difficult task is accomplished, whether by natural evolution in the distant future or genetic engineering sooner, things will be different in the desert. Canopies of vegetation that hide the ground will be possible. Thus shaded and sheltered, the ground will be able to support a much richer ecosystem of creatures and maybe even humans than is currently the case in deserts. One of Earth's harshest environments would be tamed.
Phyto-terraforming. To terraform means to transform a place into an Earth-like state (terra is Latin for Earth). Mars for example is a desert wasteland, but it once ran with rivers, and it would be great if the Martian surface was made habitable - in other words, terraformed. Venus might be made habitable if we could only get rid of its dense blanket of carbon dioxide, which causes such a severe greenhouse effect that its surface is over 800 degrees Fahrenheit, toasty indeed. And why not consider terraforming inhospitable terrain right here on earth, like the Sahara desert, or Antarctica. Phyto-terraforming is terraforming using plants. Actually plants are so favored for this task that when people discuss terraforming, they usually mean phyto-terraforming. Long ago, plants did in fact terraform the Earth, converting a hostile atmosphere with no oxygen but plenty of carbon dioxide into a friendly one with enough oxygen that we can comfortably exist. Plants worked on Earth, and might work on Mars or even Venus, but not on the moon. The reason is that plants need carbon dioxide and water. Venus has these (and reasonable temperatures) high in the atmosphere, suggesting airborne algae cells. Mars is a more likely bet as it has water (as ice) available to surface-dwelling plants at least in places.
If Mars is the most likely candidate for phyto-terraforming, what efforts have been made to move in that direction? A first step has been to splice genes into ordinary plants from an organism that lives in hot water associated with deep ocean thermal vents. This organism is named Pyrococcus furiosus (Pyro- means fire in Greek, coccus refers to ball-shaped bacteria, hence "fireball"). Pyrococcus is most comfortable living at about the boiling point of water and can grow furiously, double its population in 37 minutes. It has evolved genes for destroying free radicals that work better than those naturally present in plants. Free radicals are produced by certain stressors in plants (and humans), cause cell damage, and can even lead to death of the organism. By splicing such genes into the plant Arabidopsis thaliana, the experimental mouse of plant research, this small and nondescript-looking plant can be made much more resistant to heat and lack of water. These genes have also been spliced into tomatoes, which could help feed future colonists. Of course Mars requires cold, not heat tolerance, but the lack of water part is a good start. The heat and drought parts might be useful for building plants to terraform deserts here on Earth, bringing terraforming of Earth deserts a couple of steps closer. With several additional levels of genetic modification, we might eventually terraform Mars yet.
Recommendations
When the advances described here are likely to happen would be good to know. Will they occur in your lifetime? Your grandchildren's? Thousands or millions of years into the future? If the latter, there is not much point in devoting precious national funds to help bring them about, but if the former, it might be worth the expense of hurrying the process along. To determine the likely timing of future technological advances, we need to determine the speed of advancement. To measure this speed, we can look at the rate at which advances have occurred in the past, and ask what will happen in the future if advances continue along at the same rate. This approach is influential in the modern computer industry in the guise of "Moore's Law." However it was propounded at least as early as about 2,500 years ago, when Chinese philosopher Confucius is said to have noted, "Study the past if you would divine the future." It would be nice to know when we can expect to grow and eat potatoes with small hamburgers in the middle, pluck nuggets of valuable metals from trees, power our homes by plugging into electricity-generating trees growing in our back yards, or terraform Mars.
Opening the floodgates of genetic engineering innovation. Properly regulated to optimally benefit society, genetic engineering of plants has enormous potential, from better and better-tasting food to growing amazing things on trees. However governmental regulation is currently suppressing such advances. Preparing applications to government regulatory agencies for permission to commercially grow genetically engineered plants currently costs many millions of dollars in many countries. Thus only genetic modifications to major commodity crops like corn and soy are generally cost-effective to commercialize. Worse, only big agribusinesses can afford the costs. And why should they object? After all, who needs small, game-changing startup companies moving in, upending the status quo, creating new economic growth and value with new kinds of crops, and generally making life complicated for the giant agribusinesses? Simpler just to keep the costs of applying for permission to grow so high that such upstarts are kept out of the picture. That way predictable profits flow in even if, overall, innovation and the consequent economic expansion is suppressed. But you can't blame the giants, which are legally obligated to serve the interests of their shareholders. It is illegal for a corporation in the US to further the interests of society at substantial expense to its shareholders! Governments should regulate commercialization of genetically engineered crops optimally, protecting the world from harmful frankenplants while promoting exciting, progressive and beneficial crop innovations.
References
"Babies are puzzled by fruit...the first time they have it. But within a day or two practically all of them decide they love it": B. Spock and M. B. Rothenberg, Dr. Spock's Baby and Child Care, revised edition, 1985, Simon & Schuster. ISBN 0-671-73965-4.
"Perhaps weirdly, it now appears that photosynthesis...uses the esoteric physics phenomenon known as quantum entanglement to do its work." M. Sarovar, A. Ishizaki, G. R. Fleming and K. B. Whaley, Quantum entanglement in photosynthetic light-harvesting complexes, Nature Physics, vol. 6, pp. 462-467, 2010, executive summary at http://newscenter.lbl.gov/feature-stories/2010/05/10/untangling-quantum-entanglement/.
"Acaryochloris marina uses chlorophyll d, which absorbs infrared light for photosynthesis": R. Mohr, B. Vosz, M. Schliep, T. Kurz, I. Maldener, D. G. Adams, A. D. Larkum, M. Chen, and W. R. Hess, A new chlorophyll d-containing cyanobacterium: evidence for niche adaptation in the genus Acaryochloris, The ISME Journal (27 May 2010), http://dx.doi.org/10.1038/ismej.2010.67.
"Extra hairy soy varieties have already been bred such that...the average temperature of those regions would decrease by about 2 degrees F." C. E. Doughty, A. McMillan and M. Goulden, Climate Management Through Agricultural Albedo Manipulation, Eos Transactions of the American Geophysical Union (2007), vol. 88, no. 52, Fall Meeting Supplement, Abstract GC52A-10, http://www.agu.org/meetings/fm07/fm07-sessions/fm07_GC52A.html. See also: Super-hairy plants could battle global warming, New Scientist, issue 2637, Jan. 9, 2008, http://www.newscientist.com/article/mg19726370.700-superhairy-plants-could-battle-global-warming.html.
"The trick is to keep the peanut root systems properly bathed in a clear nutrient solution in a glass laboratory flask." F. Medina-Bolivar, J. Condori, A. M. Rimando, J. Hubstenberger, K. Shelton, S. F. O'Keefe, S. Bennett, and M. C. Dolan, Production and secretion of reveratrol in hairy root cultures of peanut, Phytochemistry, vol. 68, pp. 1992-2003, 2007.
"Already genetic engineering has been shown to enable plants to extract certain heavy metals like cadmium, lead, and copper from the soil..." P. Kotrba, J. Najmanova, T. Macek, T. Ruml and M. Mackova, Genetically modified plants in phytoremediation of heavy metal and metalloid soil and sediment pollution, Biotechnology Advances (Nov.-Dec. 2009), Vol. 27, Issue 6, pp. 799-810.
"We may never be able to plug something into a swimming fish, but we can already make batteries out of potatoes." A. Golberg, H. D. Rabinowitch, and B. Rubinsky, Zn/Cu-vegetative batteries, bioelectrical characterizations, and primary cost analyses, Journal of Renewable Sustainable Energy (2010), Vol. 2, Issue 3, http://jrse.aip.org/jrsebh/v2/i3/p033103_s1, doi:10.1063/1.3427222.
"This organism is named Pyrococcus furiosus...": G. Fiala and K. O. Stetter, Pyrococcus furiosus sp. nov. represents a novel genus of marine heterotrophic archaebacteria growing optimally at 100°C, Archives of Microbiology (June 1986), vol. 145, no. 1, pp. 56-61.
"By splicing such genes into the plant Arabidopsis thaliana...this small and nondescript-looking plant can be made much more resistant to heat and lack of water." W. F. Boss and A. M. Grunden, Redesigning living organisms to survive on Mars, NASA Institute for Advance Concepts Annual Meeting (2006), http://www.niac.usra.edu/files/library/meetings/annual/oct06/1194Boss.pdf
"They have also been spliced into tomatoes, which could help feed future colonists." W. Boss, http://www.cals.ncsu.edu/plantbiology/BossLab/hfiles/overview.html, 5/29/10.
Spore Storm. Anthrax bacteria can kill quickly, overwhelming an animal's natural defenses by multiplying and secreting toxins. The toxins build up in the body and they, not the organisms themselves, are what ultimately cause death. Once dead, the animal host is no longer a suitable source of food, shelter, and oxygen for the anthrax. Now something interesting happens. Some of the anthrax bacteria succeed in growing, inside their bodies, a tough cover encapsulating their genes and certain other cell components. This is called an endospore, and is capable of withstanding environmental conditions for long periods of time - several decades has been documented. When conditions finally become favorable (e.g. it is eaten by a host animal), it comes back to life, attempts to grow and divide, infects the new host, and the cycle begins anew.
Many terms derived from "spore" exist, from aeciospores to zygospores, and endospores are just one kind. Some plants reproduce via spores, ferns for example. Spores do nothing until conditions for growth are promising. Then they spring into action. Plant spores sprout into baby plants called sporelings (spores become sporelings, like seeds become seedlings). The sporelings eventually become full grown plants if all goes well. However, many familiar plants produce seeds, not spores. Seeds are much bigger and carry much more nutrition, used to give a baby plant a good start, or perhaps sustain an animal that eats it. Spores, on the other hand, are microscopic.
Oaks produce acorns, which are large seeds, not microscopic spores. But even the mightiest oak, like a tiny blade of grass, is missing a big opportunity. That is the opportunity for each cell in each leaf to create an endospore, instead of uselessly falling to the ground to rot when the leaf gets old or winter approaches. In the future, by natural accident or human design, some plant may become the first to grab that opportunity, and things may never be the same again. Instead of dropping their leaves, these plants will release a dust storm as each leaf transforms into millions upon millions of endospores, blowing in the wind. These endospores will eventually land and try to start a new plant, in the spring in temperate climates or any time in warmer conditions. Such spore-producing plants could continue to also produce seeds as they always have, but rather than waste their spent leaves along with an additional opportunity to propagate, they will instead much more efficient convert those leaves into quantities of endospores. This will give them an advantage over traditional plants, out-competing them and eventually dominating the earth, just as flowering plants have come to dominate since they first evolved at least 140 million years ago. Let us hope these superplants make useful crops. That way their domination will be useful to us.
When beans take over the world. Beans use a biological strategy that may be only beginning to play out. This strategy may ultimately change the biosphere radically, enabling considerably more living biomass and thus increasing the profusion and exuberance of life. The strategy is nitrogen fixation, which is the ability of a few plants (notably beans) to get their nitrogen directly from the air. The vast majority of plant life relies for nitrogen on decaying vegetable matter, lightning strikes whose concentrated heat forces nitrogen in the air to combine with oxygen to put it into bioavailable form, and other processes not under the plant's control. In the ocean, however, some species of cyanobacteria ("blue bacteria," commonly if problematically called "blue-green algae" since algae are plants, and cyanobacteria are technically not) can fix nitrogen from the air. Beans (more generally, legumes) do not actually fix nitrogen themselves but instead rely on bacteria that they shelter in root nodules.
Once the idea of fixing one's own nitrogen directly from the air takes hold in the plant kingdom, nitrogen need never be a bottleneck again. Then the Earth will be able to support a thicker, heavier, and more diverse blanket of vegetation. Since the animal kingdom ultimately depends on plants, the Earth will also then support more animal life (and potentially human life) as well. Fertilizer manufacturers may have one less component to worry about including in their products, but on the other hand might find less demand for their products. You might not have thought of beans as the vanguard of a new paradigm of domination among plants. But beans and many thousands of species of their descendants might take over the plant world analogously to how flowering plants began their ascendancy starting more than 100 million years ago.
At least they'll taste good. The idea of beans as masters of the Earth may be tough to swallow if you're not crazy about bean dishes. But maybe genetic engineering will change your mind and those of future generations. Genetically engineered crops will become increasingly important, accepted and desired, because there is little chance of stemming the coming tide of crop plants engineered to produce new and delicious foods at reasonable cost. Flavorings are metabolically cheap for plants to produce compared to soil fertility-draining and solar energy-intensive metabolic products like oils, proteins, and carbohydrates. Thus, there is no downside to major changes and improvements in plant product flavors. And it is relatively easy to do compared to some of the genetic engineering goals mentioned earlier. Even old-fashioned selective breeding, the "low tech" approach to genetic engineering, has produced such familiar taste-enhanced foods as sweet corn that is much sweeter than the corn eaten a couple of generations ago. Take beans, for instance (please don't tire of my discussing them - as future monarchs of the plant kingdom, they are entitled to some respect!). They are already a nutritious protein source, like meat but with less fat. Yet they don't taste as good as meat to many people. There is no reason they can't be engineered to taste like small chicken nuggets. Processed fungus mycelium (i.e., roots), sold in grocery stores, taste like chicken already. Try it if you don't believe it. Yum!. We could make chickpeas that taste like chicken, and rename them "chickenpeas." But why stop there? Potatoes with small hamburgers in the middle sound good (let's call them "hamburgatoes"), and there is no reason they can't be grown once genetic engineering gets a little further along. Carrots are crunchy, as are potato chips. So why not grow carrots that taste like potato chips? Or like Cheetos or other crunchy, cheese-flavored snacks. Kids would want to eat more veggies, and carrot sales would skyrocket.
Speaking of cheese flavor, consider the pits of avocados. They are so large that it seems a waste to just throw them out, as we do now. Avocados already contain lots of fats in the edible part, as cheeses do, so genetic engineering to put more fats in the pit would help make them edible and even taste like a hard cheese, say romano or parmesan. Then grate the pit it on food to taste! Avocado pits are a specialty item of course, but just a start.
Giant seeds taste better. Ever eat pumpkin or other winter squash seeds? They are both delicious and nutritious, roasted or just placed raw into foods before cooking. You can buy pumpkin seeds in small snack bags. The problem for many people is the coverings, which are challenging to bite off because there are so many of them, as the seeds may seem relatively small. Genetic engineering to increase the seed size could solve that problem, since genetic engineering of size is probably easier than a lot of other generic engineering goals. Instead of a pumpkin with a couple hundred or so small seeds, it could grow 5-10 large seeds. Or just one, as big as an avocado seed but a lot better tasting... delicious. Speaking of seed size as a critical factor, sunflower seeds present a similar situation. You can get packages of them in the supermarket as a snack, but the ones with the seeds still in their shells seem less popular because they are harder to eat. You have to tediously bite off the shells to get to the seed inside. They taste good once you get them out though. And you get a lot of hand and mouth activity per seed, slowing down the intake of calories and making them a nutritious and satisfying snack for dieters. Yet the sunflower seed market would almost certainly grow dramatically if the seeds were 10x larger or more. Imagine eating an enormous sunflower seed the size of an egg...hefting its weight in the palm of your hand...cracking off its shell to reveal the rich, tasty meat within...and finally sinking your teeth into it to savor its nutritious and distinctive flavor! Hmm. A future sunflower could produce a seed like that, if it wasn't spending its energy growing dozens and dozens of smaller seeds instead, like current sunflowers.
Fruits form a ready target for genetic engineers. Fruit is healthy and has near-universal appeal. Even people who have never eaten fruit in their lives rapidly develop a taste for it (who are these people, you ask? "Babies are puzzled by fruit... . But within a day or two practically all of them decide they love it." - Baby and child care icon Dr. Spock). To plant the seeds of some ideas for such babies and others who will become the next generation of genetic engineers, consider the following possibilities.
- Fruit transgenic hybrids that taste like apple and pear at the same time (pearapples?), or perhaps peach and cherry together instead (peacherries?). Watermelons that taste like nectarines (nectarmelons). And so on and so forth. If you can dream up the flavor, size and texture, it will be possible.
- Fruit with calorie-free sweetness, instead of high sugar content. They could be engineered to contain aspartame ("Nutrasweet"), sucralose ("Splenda"), cyclamate, or benzoic sulfimide (saccharin) instead (or all four). This would taste good while lowering the caloric content of the fruit (and thus the metabolic cost to the plant of growing the fruit, so it could afford to grow more or bigger fruits).
- Fruit with a high alcohol content, enough to enhance the taste but not intoxicate those eating it. Fruit with M&M-sized lumps of chocolate in them. Fruit containing a little brandy and a chocolate lump or two, and at a price anyone could afford (or grow).
- Fruit that tastes like ice cream...whoops, not necessary, it already exists! Some varieties of durian fruit are like ice cream or custard. Others are quite strong in odor. Banned from the premises of some hotels, it is reputed to be the only fruit that tigers eat. Surely if nature can conjure something as remarkable as this heavy fruit, covered with spikes, genetic engineers could cook up the things in this list.
- Fruit with intense flavor. People love flavorful foods and some fruits are mild, currently, though some are quite strong (citrus, for example).
Black salad grows faster, looks funny. Most plants are green, and everyone can appreciate the healthy green glow of a vigorous plant. Would you say that plants like green light? Not so - green plants are green because they reflect green light, while absorbing red and blue. Consequently the green light goes into the eyes of the viewers, who thus see plants as green. By reflecting green light, plants are rejecting it. They use light that they absorb as solar energy, powering a process that sucks carbon dioxide out of the air and converts it, ultimately, into plant contents using a process known a photosynthesis. Perhaps weirdly, it now appears that photosynthesis, the biological process that terraformed the Earth in the distant past, creating and now maintaining at 21% the oxygen in the atmosphere so necessary for human life, uses the esoteric physics phenomenon known as quantum entanglement to do its work. A green color may be a sign of health, but it is also a sign of inefficiency. If the could only absorb and use green light better, it would be using solar energy more effectively and could grow faster, for either its own or human purposes. If a plant absorbed and used all light falling upon it, it would be black, not green, because black is what we see when all colors are absorbed and not reflected into our eyes.
If black plants would be better, then what are the prospects for mountains, plains, and rolling hills of deep black instead of striking green? Plants absorb light using special pigments which begin the solar energy harvesting process. Well-known and prevalent pigments are chlorophyll, of which there are several varieties named chlorophyll a, b, c, c1, c2, and others. Different chlorophylls (chloro- from a Greek word for green, -phyll from the Greek for leaf) are of varying shade depending on the type. However there are also other pigments useful for photosynthesis. Various xanthophylls (xantho- from the Greek for yellow) are also used. Carotenes, which make carrots orange, are another. There are hundreds of them. Opsins (ops- from the Greek for sight, as in 'optical,' and -in which indicates a biochemical substance) are not only used for sight in the human eye (namely rhodopsin, rhodo- for rose-colored, also named "visual purple"), but for photosynthesis (using bacteriorhodopsin, a misnomer since the organisms using it are archaea, not bacteria). Bacteriorhodopsin preferentially absorbs green light and reflects red and blue, thus appearing reddish-blue (that is, "purple"). Bacteriochlorophylls are related to chlorophylls and can be greenish or purplish. Phycobilins are used in photosynthesis in certain microorganisms and come in a variety of colors, from red to blue. Phycocyanins are another category of pigment used in photosynthesis (cyan meaning blue-green). Phycoerythrins too, which are red (-eryth from Greek and meaning red, as in erythrocytes - red blood cells).
Even invisible light is important. The water-dwelling microorganism Acaryochloris marina contains chlorophyll d, which is particularly good at absorbing infrared light for photosynthesis. On the other hand, some plants reflect infrared light. But they could reflect more, enough to actually change the world's climate significantly. It seems that leaf hairs can help reflect infrared while allowing visible light through for photosynthesis. By breeding plants with leaves that are quite hairy, more infrared could be reflected back into space, with a cooling effect on the climate. Extra hairy soy varieties have already been bred such that if they and other crops similarly bred were grown extensively enough in temperate regions, the average temperature of those regions would decrease by about 2 degrees F. It is a tough call which would be better, crops with pigments that use infrared light for photosynthesis, or crops that reflect as much of it as possible away from the Earth.
Be that as it may, a plethora of pigments exist to support photosynthesis and there seems no intrinsic reason why a plant could not eventually evolve naturally or be genetically engineered to mix and match the pigments so as to absorb and use nearly all light. Such plants would potentially have an evolutionary advantage over other plants that waste resources by taking the trouble to grow leaves and then not use all the light that falls upon them. Thus future plants that solve this problem would tend to take over, both in nature and in agriculture. Though the real action would be at the biomolecular level, visually such plants would be near-black, not green. Would black salad taste better than green? Only a future taste test will resolve this important question!
Alternamorphs: plants with options. All organisms are at least a little "alternamorphic": their form depends on the environment they grew in. A plant may be bigger under optimal conditions, smaller or even stunted under poor ones. A single cell may be bigger after a meal. A human may be darker or lighter depending on degree of sun exposure. Perhaps more interestingly, some kinds of grasshoppers, when crowded, change strikingly in appearance, becoming...locusts which gather in huge, hungry, migrating clowds, leaving devastated farmland in their paths. These are the locust swarms of biblical fame.
If properly endowed by natural evolution or genetic engineering, plants could turn the concept of alternamorphism to their advantage in many interesting ways. For example, consider the humble corn (zea mays) plant. It is a staple of the world food supply but is not particularly easy to grow successfully in one's garden, as many an inexperienced gardener can attest. Now imagine a new kind of corn plant that, after bearing its ear of corn, alternamorphically either dies or sinks a taproot that lasts the winter and then, in its second spring, sends up a new shoot that grows more slowly than before, but more sturdily. That grows, in fact, without producing any ear of corn that year but rather is built to last the following winter, so that it can build on that growth with further development in its third spring - eventually turning into a large corn tree that produces dozens of ears every year, and with far less work than farming an equivalently productive corn patch.
But what would determine which alternative the corn plant chooses, dying off as happens now, or beginning the process of turning into a corn tree? A reasonable genetic code for this would be to opt for the tree strategy if the ear is destroyed early in its development or fails to develop properly for whatever reason. In that case it makes sense for the corn plant to devote its energy to something else, such as trying to grow into a tree. Indeed, any excess of vitality would be a good reason to pursue the tree strategy, even if the initial ear is growing well. Perhaps the corn plant is simply experiencing highly favorable growth conditions and has the werewithal to both produce an ear, and grow the required large taproot. Similarly, any annual crop or other plant could potentially alternamorphically become a tree. Farmers and gardeners would be delighted. On the other hand, hundred foot ragweed trees would be bad news for many an allergy sufferer. Alternamorphic trees are just a start. The reader may enjoy dreaming up other kinds of alternamorphisms. In a number of years it may be possible to actually create these in a do-it-yourself basement bio lab.
A return to roots. The sun moves around in the sky, in many places casting its life-giving rays on different spots throughout the day. A plant that could move to the nearest sunny spot would have an advantage over ordinary plants that are stuck in one place. But plants have it rough. Unlike people, they can't pull up roots and relocate somewhere else.
Ambulatory plants that simply walk over to the nearest sunny spot would outcomplete regular plants, eventually becoming rulers of the plant kingdom. Unfortunately, it all seems a bit unlikely. Except for some interesting exceptions like species of Tillandsia (the so-called "air plants," which are discussed below), plants need their roots. And roots are, well, rooted in place. However, while the vast majority of plants do need roots, they don't need them every minute. As everyone who has experienced the concept of cut flowers in a vase of water knows, plants can go for quite some time without roots. And roots can do fine without the rest of the plant for a considerable time as well - just check your fridge, pantry, or grocery store for an assortment of potatos, carrots, etc., which do just that. In nature, in fact, many plants over-winter with just the underground roots alive all winter long, then grow new above-ground parts come Spring. The trick, then, is to build a plant that can separate temporarily at the base. The above-ground part then wanders off in search of maximum sunlight. As evening approaches, the plant literally returns to its roots, reattaches, and spends the night with its above-ground and below-ground sections in metabolic union.
It is unclear if such a plant variety would ever evolve spontaneously. However, genetic engineering should be able to do it at some point. Moving short distances would be feasible for plants based on their current capabilities - many plants can and do change in shape fast enough over the course of a day already. Flowers open and close, leaves move around, etc. For example the immature flower heads of the sunflower face the sun, tracking it as it crosses the sky over the course of the day. Engineering a plant that can detach at the base, walk off looking for sun, return in the evening and reattach until morning presents a number of varied challenges, all of which must be solved before it can work, including a detachment and reattachment mechanism, a slow but real walking capability, and the sensory capacity to find its way back to its roots. Yet there seems no fundamental reason why it could not be done.
Once such plants are on the march, additional genetic changes will be possible. Plants need not return to their own roots, but could instead return to the roots of another plant, perhaps even of a different species. Animals looking for a nutritious drink might try to suck juice from the exposed detachment point of the roots after the top of the plant has wandered off for the day in search of sun. Plants could evolve or be further engineered to allow animals to suck for juice only if they fertilize the plant as a down payment, by urinating at the base! Plants that can walk around would be strongly motivated (in an evolutionary sense) to develop better sensory systems and faster movements to compete with other plants. Such capabilities are normally associated with animals, not plants, so these plants of the future, as they evolve, would tend to increasingly blur the line between plants and animals. A world with walking plants would be different indeed!
Another strategy for adding walking plants to the biosphere would start with plants like Tillandsia, the air plants, which either do not have roots at all or have small ones used only to hold them in place. The genetic engineering complexities of a detachment/reattachment mechanism and a homing mechanism for finding roots earlier left behind would be unnecessary, simplifying the problem greatly. However as for soil-rooted plants. creating the capacity for locomotion would still be a challenge. Tillandsia plants absorb water and nutrients through their leaves, so an ambulatory version would have considerable advantages. They could walk around (and climb around, since they typically live on trees), looking for sun, taking a dip when thirsty, and loading up on compost (or, predator-like, trimming leaves off of other plants) to absorb nutrients from. Perhaps ambulatory descendants of the Tillandsia genus will one day rule the Earth.
Plants with mirror molecules. Suppose you had two identical dice with sides numbered 1 to 6 as usual. Typically one corner will have three sides numbered 1, 2, and 3 going around the corner in that order clockwise, with a 6 on the side opposite the 1 (because opposite sides add up to 7 on normal dice). Now take one of the dice and change it slightly. Paint a 6 over the 1, and a 1 over the 6. Now the sides numbered 1, 2 and 3 meet at a different corner and, what is more, they are arranged going around the corner counterclockwise instead of clockwise. Although both dice still function identically and may appear identical to a casual glance, in fact they are different: they are now mirror images of each other. In fact you don't need 6 faces for this mirror image situation. It can also occur with 4-sided tetrahedrons (tetra- means 4), which look like 3-sided pyramids. The 4th side is the triangular base and the top corners of the 3 triangular sides meet at the apex. Similarly, some organic molecules consist of a carbon atom in the middle with 4 different atoms or atom groups sprouting outward. These four branches are like the sides of the tetrahedron: if you switched any two of them you would get a different molecule, a mirror image of what it was, and no amount of rotating it or otherwise moving it around will erase that difference. Mirror image molecules are technically called "enantiomers," enantio- from the Greek for 'opposite,' and -mer meaning member of a group (from the Greek for 'part'). They relate to plants as follows.
1. Proteins are necessary for all living things, including plants, to make, have, and use. While the earliest life on planet Earth might not have contained proteins (the "RNA world" conjecture), every known life form today contains numerous kinds of protein as a major component.
2. Every protein molecule is made from building blocks, called amino acid molecules, which are connected together end-to-end like beads on a string.
3. There are 20 different kinds of amino acids heavily used in building proteins, of which all except glycine have a central carbon atom with four different branches.
4. Thus 19 of the 20 common amino acids have two enantiomers, called L (for "levorotatory," levo- from the Greek for 'left' because of the direction its solutions rotate polarized light), and D (for "dextrorotatory," dextro- from the Greek for 'right').
5. Organisms generally contain only the L versions of these amino acids. No one knows why. Organisms based on D amino acids could exist, but we don't see either plants or animals that do. (D forms have been observed in a few microorganisms.)
6. If we engineered plants to be based on D-amino acids, their nutritional value to pests (and humans) would be much lower, because animals can't build their own proteins from D-amino acids.
7. Such plants would therefore be pest resistant, hence agriculturally valuable - as long as we're talking about plants grown for purposes other than edible protein, such as vegetable oils, wood, etc. Pest resistance is an incentive that suggests that humans will, in fact, eventually create and grow such plants.
The pest resistance of D-amino acid based plants will give them a selective advantage over normal plants, and they could therefore come to significantly displace normal plants. Call them frankenplants if you like, but the world risks becoming significantly different, a planet overrun with plants that resist being eaten, and therefore, able to feed fewer animals of all kinds, from insects to humans.
Manufacturing plants. There is green manufacturing, and there is green manufacturing: an ordinary factory can be made more green, but it will never be as environmentally friendly as a real, growing green plant. Green plants have manufactured things for us since the dawn of our species. Green plants manufacture the oxygen we need to breathe and live, from the carbon dioxide they remove from the atmosphere. Indeed without plants, the oxygen in the air would dwindle away and humans (and other oxygen-breathing animals) could no longer survive on Earth. Plants also manufacture food, from grain to veggies to oils to mouth-watering fruits, nuts and spices; wood, from Douglas-fir for construction to beautiful furniture wood to light balsa wood to heavy ebony for piano keys; drugs, from traditional cures to modern pharmaceuticals to intoxicants like tobacco, opium, magic mint, and lactarium; and chemicals of endless variety. Green plants are manufacturing devices - they perform green manufacturing in every sense.
On the other hand, one often hears that such-and-such does not grow on trees. Money, for example, does not grow on trees. Yet numerous solid objects found in everyday life would be relatively simple to genetically engineer trees to produce. A chair for example merely needs a sapling (let's call it a "front left leg") to reach the height of a seat, then send out two horizontal branches at right angles. When they grow about two feet long, they send shoots straight down to the ground where they take root. They also send shoots out horizontally at right angles to their current direction, which meet to form the last corner of the seat, whereupon they send down the 4th leg. Similarly, extra branches can grow into a back, as well as arms and various bracing bars if desired. The banyan tree is an example of a plant whose branches send down shoots that turn into extra trunks already, so that part of the general concept is clearly feasible. The chair still needs a seat, which could grow from a network of tough, viny stems that give enough when sat upon to be comfortable. Or add a cushion if you like. Of course, you still have to pull it out of your garden, but that is no more trouble (probably less, actually) than a trip to the furniture store. The entire chair is one piece without fastened joints that could loosen with age or otherwise require maintenance, so it could be long-lasting and strong. How strong? That depends on how long you grow it...for stouter legs and other parts, a chair tree farm would just let the chair tree grow a couple years longer before harvesting to let the trunks and branches thicken.
Various other useful items could grow on trees in your yard or in tree farms, or the seeds might get loose and grow in vacant lots or in the wild. Tables might need a flat top to be added later. Ladders would be a natural. Railings (just turn a ladder on its side!). Marbles already grow on bushes (they're called "marble seeds") and plants could be engineered to grow many other small solid toy and light household items as well, from checkers and chess pieces to knobs and knick-knacks.
Here's another kind of thing that "doesn't grow on trees." Gold and silver. But no doubt they could and hopefully they will. Roots are chemical factories. Solar powered chemical factories. They extract raw materials from dirt, using energy captured by leaves from sunlight to convert the raw materials into useful chemicals. Mother nature has caused plants to make chemicals useful to the plant, but humans are increasingly causing them to make chemicals useful to humans. For example resveratrol is a chemical found in red grapes, peanuts, Japanese knotweed and some other plants. Some experiments suggest it increases the life spans of certain animals (and thus, perhaps humans). It can be produced not only by the roots of entire peanut plants, but by the peanut plant root system alone without benefit of light, leaves, or stems - the trick is to keep the peanut root systems properly bathed in a clear nutrient solution in a glass laboratory flask.
Back to gold and silver. Plants could be genetically "programmed" so their roots extract metal compounds as desired from the soil, transport molecules containing those metals within the plant, and concentrate and deposit them where they could be - literally - harvested. Already genetic engineering has been shown to enable plants to extract certain heavy metals like cadmium, lead, and copper from the soil for storage in the plant's tissues (for de-polluting soils, this is termed "phytoremediation," meaning, literally, "plant remedy").
Large trees are clearly a good kind of plant for this. Their root systems are extensive and access a large volume of soil and, hence, a lot of whatever metal compounds might be present in the soil. A good place for trees to concentrate and deposit the metal compounds is the bark, because the bark is relatively straightforward for humans to collect as it gradually flakes off, which occurs slowly, giving plenty of opportunity to concentrate its metal content as it grows. It would also be easier to genetically engineer bark deposition than many other options. The bark thus becomes metal ore from which the desired metal can be extracted. Almost any metal desired could be programmed into the tree's genetic code. Valuable metals like copper, silver, or even a longish list of various unusual and valuable metals could be mined this way. The platinum, rhodium, or other specific metals could be extracted from the valuable mixture later, or the biochemical pathway needed for extracting any given specific metal could be engineered. Gold might present special challenges because, when present in richer quantities, it tends to be in the form of pure metal particles. Roots would need special genetic engineering to dissolve and uptake the free metal. Yet some gold atoms are everywhere (even seawater, suggesting use of seaweed as an alternative to trees) and could be absorbed without the extra level of genetic engineering needed to dissolve the metal first.
Metal-enriched bark is nice, but even better are actual lumps of pure silver, gold, copper, even platinum or anything else. Another level or few of genetic engineering would be required, because now the metal not only needs to be uptaken by the roots and transported within the plant, it also needs to be deposited in a specific spot (the nugget), biochemically converted to metallic form, and provided with a covering of special-purpose plant tissue responsible for conversion, deposition, and protection. Each of these requires a fair amount of new genetic machinery. But what a result! For every tree, a "berry" containing a nugget of shining and perhaps precious metal, there for the plucking. For rare metals barely present in the soil the berry would be small. For common but useful metals (aluminum, for example) the berry would be larger, more like a pear if not a golden pear. Multiple aluminum pears might be more convenient than one massive aluminum "watermelon"!
But why stop there? No one really needs bumpy aluminum pears except to sell on the metals market. Nor do we need amorphous lumps of alloys like stainless steel, bronze or brass (after all, specific alloys instead of elemental metals are just a few more genetic tweaks away once we've gotten this far). But we do need stainless steel silverware, cups, bowls and colanders; beautiful brass doorknobs and other ornamental pieces; steel nails, hammer heads, screws, screwdrivers, bolts, nuts, plyer parts, wingnuts, washers, door hinges; aluminum and iron frying pans; plumbing fittings, and many other specially-shaped lumps of metal. Once we've got metal berries and pears growing on trees, another level of genetic programming or two and they'll no longer look like lumpy fruit but like anything from forks to frying pans, screws to screwdrivers, washers to wingnuts. Think silver spoons and copper wire will never grow on trees? Think again. And coins...let's not forget them, since who wouldn't want money to grow on trees.
Power plants. Trees could do a lot, as we have seen - and they're solar powered, too. Once trees can suck metals from the soil and grow useful, shaped objects like copper wire, a few more levels of genetic engineering could enable the tree to use this copper wire to deliver electricity. Since a tree is already, now, a solar energy converter, we can build on that by having the tree grow tissues that convert energy into electricity. Electric eels can already do that, producing enough of a jolt to be lethal to humans. Even ordinary fish produce small amounts of electricity to create electric fields in the water around them. Any object nearby disrupts the field, enabling the fish to tell that something is near, even in total darkness. We may never be able to plug something into a swimming fish but we can already make batteries out of potatoes. So why not trees that grow into electricity providers all by themselves? It would be great to be able to plug your electrical devices into a tree (or at least a socket in your house that is connected to the tree). Then you would no longer need to connect to the grid, purchase solar panels, or install a windmill. You would, however, need to keep your trees healthy and vigorous! Tree care specialists would become a highly employable occupation.
Greening the desert. The Sahara and various other less notorious but still very dry deserts around the world have plenty of sand and rocks. But they don't have much greenery. The main problem is lack of water. Vast swaths of the Sahara, for example, are plant free. It's just too dry. However this problem is solvable! Cacti and other desert plants could potentially extract water from the air. Plants already extract carbon dioxide molecules from the air. Even very dry air contains considerable water vapor, so why not extract water molecules too. Indeed, plants already transport water molecules in the ground into their roots, so is it really such a big step to do the same from the air? Tillandsia (air plant) species can already pull in water with their leaves, but it has to be rain or other liquid water. Creating plants that can extract gaseous water vapor from the air in a harsh desert environment would require sophisticated genetic engineering, or a leap for mother nature, but it is still only the first step. Plants get nutrients out of the soil by absorbing fluid that has dissolved them, so dry soil would be a problem even for a plant that contained plenty of water pulled from the air. Another level of genetic engineering or natural evolution would be required to enable them to secrete fluid out of their roots to moisten chunks of soil to dissolve its minerals, and reabsorb the now nutritious, mineral-laden liquid back into their roots.
Once this difficult task is accomplished, whether by natural evolution in the distant future or genetic engineering sooner, things will be different in the desert. Canopies of vegetation that hide the ground will be possible. Thus shaded and sheltered, the ground will be able to support a much richer ecosystem of creatures and maybe even humans than is currently the case in deserts. One of Earth's harshest environments would be tamed.
Phyto-terraforming. To terraform means to transform a place into an Earth-like state (terra is Latin for Earth). Mars for example is a desert wasteland, but it once ran with rivers, and it would be great if the Martian surface was made habitable - in other words, terraformed. Venus might be made habitable if we could only get rid of its dense blanket of carbon dioxide, which causes such a severe greenhouse effect that its surface is over 800 degrees Fahrenheit, toasty indeed. And why not consider terraforming inhospitable terrain right here on earth, like the Sahara desert, or Antarctica. Phyto-terraforming is terraforming using plants. Actually plants are so favored for this task that when people discuss terraforming, they usually mean phyto-terraforming. Long ago, plants did in fact terraform the Earth, converting a hostile atmosphere with no oxygen but plenty of carbon dioxide into a friendly one with enough oxygen that we can comfortably exist. Plants worked on Earth, and might work on Mars or even Venus, but not on the moon. The reason is that plants need carbon dioxide and water. Venus has these (and reasonable temperatures) high in the atmosphere, suggesting airborne algae cells. Mars is a more likely bet as it has water (as ice) available to surface-dwelling plants at least in places.
If Mars is the most likely candidate for phyto-terraforming, what efforts have been made to move in that direction? A first step has been to splice genes into ordinary plants from an organism that lives in hot water associated with deep ocean thermal vents. This organism is named Pyrococcus furiosus (Pyro- means fire in Greek, coccus refers to ball-shaped bacteria, hence "fireball"). Pyrococcus is most comfortable living at about the boiling point of water and can grow furiously, double its population in 37 minutes. It has evolved genes for destroying free radicals that work better than those naturally present in plants. Free radicals are produced by certain stressors in plants (and humans), cause cell damage, and can even lead to death of the organism. By splicing such genes into the plant Arabidopsis thaliana, the experimental mouse of plant research, this small and nondescript-looking plant can be made much more resistant to heat and lack of water. These genes have also been spliced into tomatoes, which could help feed future colonists. Of course Mars requires cold, not heat tolerance, but the lack of water part is a good start. The heat and drought parts might be useful for building plants to terraform deserts here on Earth, bringing terraforming of Earth deserts a couple of steps closer. With several additional levels of genetic modification, we might eventually terraform Mars yet.
Recommendations
When the advances described here are likely to happen would be good to know. Will they occur in your lifetime? Your grandchildren's? Thousands or millions of years into the future? If the latter, there is not much point in devoting precious national funds to help bring them about, but if the former, it might be worth the expense of hurrying the process along. To determine the likely timing of future technological advances, we need to determine the speed of advancement. To measure this speed, we can look at the rate at which advances have occurred in the past, and ask what will happen in the future if advances continue along at the same rate. This approach is influential in the modern computer industry in the guise of "Moore's Law." However it was propounded at least as early as about 2,500 years ago, when Chinese philosopher Confucius is said to have noted, "Study the past if you would divine the future." It would be nice to know when we can expect to grow and eat potatoes with small hamburgers in the middle, pluck nuggets of valuable metals from trees, power our homes by plugging into electricity-generating trees growing in our back yards, or terraform Mars.
Opening the floodgates of genetic engineering innovation. Properly regulated to optimally benefit society, genetic engineering of plants has enormous potential, from better and better-tasting food to growing amazing things on trees. However governmental regulation is currently suppressing such advances. Preparing applications to government regulatory agencies for permission to commercially grow genetically engineered plants currently costs many millions of dollars in many countries. Thus only genetic modifications to major commodity crops like corn and soy are generally cost-effective to commercialize. Worse, only big agribusinesses can afford the costs. And why should they object? After all, who needs small, game-changing startup companies moving in, upending the status quo, creating new economic growth and value with new kinds of crops, and generally making life complicated for the giant agribusinesses? Simpler just to keep the costs of applying for permission to grow so high that such upstarts are kept out of the picture. That way predictable profits flow in even if, overall, innovation and the consequent economic expansion is suppressed. But you can't blame the giants, which are legally obligated to serve the interests of their shareholders. It is illegal for a corporation in the US to further the interests of society at substantial expense to its shareholders! Governments should regulate commercialization of genetically engineered crops optimally, protecting the world from harmful frankenplants while promoting exciting, progressive and beneficial crop innovations.
References
"Babies are puzzled by fruit...the first time they have it. But within a day or two practically all of them decide they love it": B. Spock and M. B. Rothenberg, Dr. Spock's Baby and Child Care, revised edition, 1985, Simon & Schuster. ISBN 0-671-73965-4.
"Perhaps weirdly, it now appears that photosynthesis...uses the esoteric physics phenomenon known as quantum entanglement to do its work." M. Sarovar, A. Ishizaki, G. R. Fleming and K. B. Whaley, Quantum entanglement in photosynthetic light-harvesting complexes, Nature Physics, vol. 6, pp. 462-467, 2010, executive summary at http://newscenter.lbl.gov/feature-stories/2010/05/10/untangling-quantum-entanglement/.
"Acaryochloris marina uses chlorophyll d, which absorbs infrared light for photosynthesis": R. Mohr, B. Vosz, M. Schliep, T. Kurz, I. Maldener, D. G. Adams, A. D. Larkum, M. Chen, and W. R. Hess, A new chlorophyll d-containing cyanobacterium: evidence for niche adaptation in the genus Acaryochloris, The ISME Journal (27 May 2010), http://dx.doi.org/10.1038/ismej.2010.67.
"Extra hairy soy varieties have already been bred such that...the average temperature of those regions would decrease by about 2 degrees F." C. E. Doughty, A. McMillan and M. Goulden, Climate Management Through Agricultural Albedo Manipulation, Eos Transactions of the American Geophysical Union (2007), vol. 88, no. 52, Fall Meeting Supplement, Abstract GC52A-10, http://www.agu.org/meetings/fm07/fm07-sessions/fm07_GC52A.html. See also: Super-hairy plants could battle global warming, New Scientist, issue 2637, Jan. 9, 2008, http://www.newscientist.com/article/mg19726370.700-superhairy-plants-could-battle-global-warming.html.
"The trick is to keep the peanut root systems properly bathed in a clear nutrient solution in a glass laboratory flask." F. Medina-Bolivar, J. Condori, A. M. Rimando, J. Hubstenberger, K. Shelton, S. F. O'Keefe, S. Bennett, and M. C. Dolan, Production and secretion of reveratrol in hairy root cultures of peanut, Phytochemistry, vol. 68, pp. 1992-2003, 2007.
"Already genetic engineering has been shown to enable plants to extract certain heavy metals like cadmium, lead, and copper from the soil..." P. Kotrba, J. Najmanova, T. Macek, T. Ruml and M. Mackova, Genetically modified plants in phytoremediation of heavy metal and metalloid soil and sediment pollution, Biotechnology Advances (Nov.-Dec. 2009), Vol. 27, Issue 6, pp. 799-810.
"We may never be able to plug something into a swimming fish, but we can already make batteries out of potatoes." A. Golberg, H. D. Rabinowitch, and B. Rubinsky, Zn/Cu-vegetative batteries, bioelectrical characterizations, and primary cost analyses, Journal of Renewable Sustainable Energy (2010), Vol. 2, Issue 3, http://jrse.aip.org/jrsebh/v2/i3/p033103_s1, doi:10.1063/1.3427222.
"This organism is named Pyrococcus furiosus...": G. Fiala and K. O. Stetter, Pyrococcus furiosus sp. nov. represents a novel genus of marine heterotrophic archaebacteria growing optimally at 100°C, Archives of Microbiology (June 1986), vol. 145, no. 1, pp. 56-61.
"By splicing such genes into the plant Arabidopsis thaliana...this small and nondescript-looking plant can be made much more resistant to heat and lack of water." W. F. Boss and A. M. Grunden, Redesigning living organisms to survive on Mars, NASA Institute for Advance Concepts Annual Meeting (2006), http://www.niac.usra.edu/files/library/meetings/annual/oct06/1194Boss.pdf
"They have also been spliced into tomatoes, which could help feed future colonists." W. Boss, http://www.cals.ncsu.edu/plantbiology/BossLab/hfiles/overview.html, 5/29/10.