What Makes a Plant Drought Tolerant?
by Roger Snell
From the PDF: HRN Newsletter, December 2009
Biologists in California, led by researchers at The Scripps Research Institute and the University of California (UC), San Diego have solved the structure of a critical molecule that helps plants survive during droughts.
National Oceanic and Atmospheric Administration (NOAA) has reported that major droughts in the last three years have caused more than ten billion dollars in losses to crops United States, particularly in California, which is now three years into a severe drought.
The newly solved molecule structure shows the plant hormone called abscisic acid, attached to its "target" protein called PYR1. Abscisic acid is key survival tactics in challenging environmental conditions.
During dry conditions, drought tolerant plants synthesize abscisic acid, causing them to conserve water. Their seeds lie dormant in the ground, their leaves close pores to stop water loss, and they slow their own growth, in the pursuit of survival.
Abscisic acid, discovered in the early 1960s, has been known for decades to play a crucial role in keeping plants alive during drought, but how has not been known.
Earlier this year, two separate groups of scientists discovered a cluster of genes associated with the hormone. Mutations in four of these related genes led to an impaired abscisic acid response and reduced drought resistance.
By solving how the structure worked may reveal new ways of improving drought tolerance in plants. Not just a boon for agriculture, which is the single largest use for water in most of the world, consuming up to 90 percent of available water in some of the hottest and most arid parts of the world, reduced dependence on water has many fold implications for humans.
The possibility of designing chemicals to mimic the action of abscisic acid and spraying these chemicals on crops to protect them from drought is quite tantalizing, but the process for producing abscisic acid is very expensive and sunlight can convert the it into an inactive form. Hopefully more research will be done to mimic or cheapen the process in the future and let’s hope the technology is kept in the public domain.