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Chemical Genomics Approach Used to Understand and Improve Plant Survival of Drought.


A goal of University of California Riverside’s Center for Plant Cell Biology Chemical Genomics Interdisciplinary Graduate Research and Training (ChemGen IGERT) program, funded by the National Science Foundation (NSF), is to identify small molecules that alter plant traits to benefit agriculture. Plant cell biologist, Sean Cutler, also Assistant Director of the ChemGen IGERT program, has pioneered the use of chemical genomics to decipher mechanisms used by plants to survive adverse environments. The Cutler lab’s discovery of a small molecule that functions as an agonist (mimic) of the plant hormone abscisic acid (ABA) led to the discovery of a bone fide hormone receptor. This discovery was selected by Science magazine as one of top 10 breakthroughs of 2009. The Cutler lab and their international collaborators discovered receptor proteins that bind ABA in a functional manner. This interaction between ABA and its receptor initiates a signaling pathway within the plant. Sean Cutler describes this process as, “functioning like a boss relaying orders to the team below that then executes particular decisions in the cell.”

The perception of ABA in cells when water is limiting is essential for survival. It allows plants to reduce further loss of water and puts the brakes on growth. The discovery of the ABA receptor was a chemical genomics project targeting the model plant Arabidopsis. The research was initiated in Cutler’s lab by screening small molecular libraries for antagonists and agonists of the hormone ABA, itself a small molecule. A compound called pyrabactin was identified that mimicked ABA’s role in inhibiting seed germination. Cutler’s group then sought mutants that were insensitive to the effects of pyrabactin.

The labor-intensive characterization of PYRABACTIN RESISTENT (PYR) mutants ultimately led to the discovery of the PYR family of proteins. A series of six high impact publications in Science and Nature followed the initial discovery of the ABA receptor in April 2009. These reports define the intimate interaction between ABA and its receptor, leading to the inhibition of protein phosphatases, triggering a chain of signal transduction events that alter physiology to allow endurance of a water deficit. The explosion in research on ABA signaling is largely attributed to Sean Culter’s willingness to share chemicals, plant mutants, and knowledge with other scientists. This pioneering study also provides the best demonstration in the field of plant biology of the effectiveness of a chemical genomics approach to identify a critical mechanism to agricultural productivity.

The study combines biology, chemistry, and computer modeling, exemplifying the student projects of the ChemGen IGERT program. IGERT fellow Andrew Defries contributed to research in the patent application associated with the use of pyrabactin and other synthetic agonists to improve drought tolerance of crops.

Cutler, S.R., Park, S.Y., Defries, A.J. (2010). Control of Plant Stress Tolerance, Water Use Efficiency and Using Novel ABA Receptor Proteins and Synthetic Agonists. Worldwide Patent Application No. 61/207,684. Washington, DC: U.S. Patent and Trademark Office.

Park SY, Fung P, Nishimura N, Jensen DR, Fujii H, Zhao Y, Lumba S, Santiago J, Rodrigues A, Chow TF, Alfred SE, Bonetta D, Finkelstein R, Provart NJ, Desveaux D, Rodriguez PL, McCourt P, Zhu JK, Schroeder JI, Volkman BF, Cutler SR. (2009) Abscisic acid inhibits type 2C protein phosphatases via the PYR/PYL family of START proteins. Science. 22;324(5930):1068-1071.

Address Goals

The discovery described in the highlight has broad application to agriculture, with the potential to increase productivity under adverse environmental conditions. The project has been widely reported in the media, including print, radio and television.
The importance of basic research in plants and agriculture:
New insight into how plants survive drought:
How plants handle drought on a molecular level:
Working to control a plant’s stress tolerance:
A novel approach to trigger a survival response in plants and crops: