Changing directions: Mellon-enabled discoveries in plant ecophysiology reveal novel behaviors in plants

Background/Question/Methods

Textbooks tell us that water is taken up by plant roots and lost to the atmosphere from plant leaves. But plant ecophysiologists have challenged this dogma when new measurements and the analysis of the stable isotope composition of water have revealed strong evidence showing that water uptake and loss from plant roots and leaves can be multidirectional. Research enabled by support from the A.W. Mellon Foundation and aided by the keen interests of Bill Robertson helped launch a range of investigations of water uptake and use dynamics by plants that has shown that water moves both into and out of roots (termed hydraulic lift or redistribution).  Such behavior, now documented in plants from a wide variety of ecosystems and climatic zones, has been shown to have a marked impact on the resource relations of the plant itself, its neighbors, the ecosystem it inhabits and even local climate. Likewise water intercepted by plant leaves and whole crowns in fog or cloud inundated environments can be directly absorbed, bypassing root uptake altogether. This direct foliar uptake improves plant water status and extends and increases plant water use and carbon fixation. Since their discovery evidence continues to grow showing that such above- and below-ground behaviors may actually be widespread across the plant kingdom and that our “textbook” views need revising.

Results/Conclusions

I will share examples of research done with many students, postdocs and collaborators that touch on these themes. The research would have never been possible with the inquisitive nature of Bill Robertson and the support of the Mellon Foundation. Bill encouraged us to take some risks, explore unknown frontiers and develop and apply new methods because he saw that high risk research could lead to high reward outcomes that have advanced our knowledge in important ways. Bill’s support allowed us to reveal novel water movement behaviors in plants that set our research agenda and views on plant functional biology on a whole new course.