Secrets of Drought Resistance Revealed
Julian L. Schroeder, Ph.D.
University of California San Diego
NIEHS Grant P42ES010337
The three-dimensional structure of abscisic acid, a plant hormone critical for drought survival, has been discovered by a team of scientists including Superfund Research Program-funded grantees at the University of California San Diego. The elucidation of the molecular structure helps to explain the mechanism behind drought tolerance in plants.
Drought resistant plants synthesize abscisic acid when they detect dry conditions. Increased levels of the hormone cause changes in all parts of the plants. Seeds lie dormant in the soil, leaf pores are closed conserving water, and growth is slowed. Plants reprogram themselves for the sole purpose of surviving.
The research team made crystals of abscisic acid bound to its protein receptor called PYR1. Using x-ray crystallography they determined the three-dimensional structure of the complex and found that PYR1 has an open space, akin to the inside of a tin can, where abscisic acid binds. As the binding occurs, a part of the protein called “the lid” is induced to close. Other structural changes to other parts of PYR1 initiate binding with other proteins triggering processes for drought resistance.
The authors suggest that chemicals mimicking the action of abscisic acid could be developed and sprayed on crops to protect them from droughts. It may also be possible to alter crops through selective breeding or genetic manipulation to produce more abscisic acid. According to NOAA, major droughts in the US in the last three years alone have caused more than $10 billion in crop losses.
Citation: Nishimura N, Hitomi K, Arvai AS, Rambo RP, Hitomi C, Cutler SR, Schroeder JI, Getzoff ED. Structural mechanism of abscisic acid binding and signaling by dimeric PYR1. Science. 2009 Dec 4;326(5958):1373-9.
▲ Up: Gene Packaging is Important in Cancer (http://www.niehs.nih.gov/research/supported/sep/2008/gene-packaging/index.cfm)
▼ Down: Natural Food Products Can Treat Cancer (http://www.niehs.nih.gov/research/supported/sep/2009/natural/index.cfm)
