Another route to drought-tolerant crops?
My book, Darwinian Agriculture, argues that the quickest route to crop genetic improvement is to identify tradeoffs that were rejected by past natural selection, but which we are willing to accept. Tradeoffs between individual-plant competitiveness and the collective performance of the whole crop are particularly promising. "MAT kinase", the Scientist Gardener suggests that this is the key to Monsanto's DroughtGard corn:
"From what I've heard, the yield gain of this variety under drought occurs because it slows its growth specifically under drought stress such that existing soil moisture is saved for the critical period surrounding flowering, resulting in less kernel abortion, higher harvest index and greater yield. This is certainly ironic given the expectations of many field physiologists and breeders. It also occurs to me that this is consistent with the thesis of Denison's Darwinian Agriculture - that evolution has already maxed out our crops' ability to deal with most stresses and environments, and that the greatest potential for improvement exist in traits that only work in an ecosystem (such as a farm field), where plants aren't in competition with their neighbors. "
This drought-tolerance-via-slower-growth would be quite interesting, if true, and similar to an idea I discuss in the book in the context of drought-tolerant Drysdale wheat.
In a recent post, I had suggested an alternative idea, that the bacterial gene they transferred to corn might result in a phenotype so radically different that natural selection had never had a chance to test it, in corn or its wild ancestors. I like The Scientific Gardener's hypothesis better. The problem with radically new phenotypes, of course, is that it's very hard to predict all of their effects and side effects.