Plants in a fascinating arms race

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I don't think about the world from the point of view of plants very often. I mostly consider our friends in the plant kingdom as the stationary green stuff around me when I'm outdoors, and possibly the makings of salad in the summers.

But plants are also teaching me a thing or two as I grow older. I've taken to planting trees in middle age, I guess because of the emotional connection between trees and spans of time that are beyond those of a human lifetime. Nothing quite satisfies me as much as planting a hardwood.

Plants have still more to teach. They are experts in nanotechnology, it turns out. I'm trying to learn more about that realm -- so I have good reason to pay attention to the lessons that can be drawn from plants' tiny pieces.

Just like us animals, plants need a circulation system. That's partly because they distribute the calorie-bearing "phloem sap" they make in their leaves when those leaves are bathed in sunlight. I think of that good stuff as a bit like dilute Gatorade, the material that fuels other plant cells.

If you are an insect like an aphid that's intent on eating the circulating Gatorade, it might seem all you'd need to do is fly over, land on a small stem, bite into the cells that are circulating the good stuff, and drink your fill.

But some plants are actually able to mount a serious defense against the attacks of insects. Recently I got to see first-hand the microscopic changes inside a living plant cell that attempts to block the circulation of the good stuff of a plant under attack by an aphid. That amazing detailed imaging work is done by professor Michael Knoblauch of Washington State University with highly advanced microscopes.

Knoblauch showed me a video clip of a legume cell's response to being punctured by an aphid intent on a meal. (Through the miracle of the Internet, you can see the video anytime you'd like at rockdoc.wsu.edu/forisome.) The aphid's attack makes a tiny chemical change in the cell. That tiny chemical change alters a nano-sized part of the interior of the cell. The nano-part changes in size -- a lot -- and as it changes, it blocks the circulation of the natural "Gatorade" in the plant that the aphid is after.

Or, at least, that's what would happen if the aphids were not just as sophisticated as the nano-defenses of the plant. Over the epochs aphids have developed a chemical "spit" they add to the cell just after they puncture it. That helps neutralize the poor plant's nano-defenses and keep the Gatorade flowing. It's a bit like mosquitoes biting my arm in the summer: as soon as they pierce my skin, they add an anticoagulant fluid to the area to keep my blood flowing freely toward their nefarious "beaks."

Plants perform many daily miracles on a nano-scale in ways scientists are now learning about in detail. And there's much room for practical applications from the new knowledge. We could potentially use genetic engineering to put the protective nano-pieces into the cells of crop plants that don't have them. Their aphids are not the same type as the legume aphids, so the bugs might well miss their lunch. In one stroke, those plants would have a new and better defense against insect attack than anything Mother Nature has given them up to this point. Harvest yields could increase greatly, always useful for a hungry planet.

No matter how I slice the nano-particle story, the main lesson for me, as a pretty ignorant animal, is that plants are not just passive victims of anything or everything we animals can do to them. They look like they are just standing around, but that's far from the truth. Some plants produce poisons to ward us off, and some even shut down a part of their circulation system to thwart our desires.

We can learn a lot more from our silent, green neighbors on the Earth. And that knowledge, potentially, could have practical benefits as well as scientific rewards.

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