Researchers from Purdue University found that engineering plants to produce high levels of the protein PYL9 dramatically boosted drought tolerance in rice and the model plant Arabidopsis. The new study offers insights into the drought survival mechanisms of plants and presents a possible means of protecting crops from severe drought stress.

Under severe drought conditions, the transgenic plants triggered the death of their old leaves - a process called senescence - to conserve resources for seeds and buds, a survival strategy referred to as "die and let live." During drought, plant responses are controlled by abscisic acid (ABA), a hormone which regulates plant growth, development, and reaction to stress. The researchers found that altering plants to overexpress PYL9 made them highly sensitive to ABA, and a stress-responsive promoter protein controlled the level of PYL9 expression in the plants. The alterations helped Arabidopsis and rice to better withstand severe drought stress. PYL9 transgenic rice had a 50 percent survival rate after a two-week drought compared with 10 percent survival in wild type rice.

The study did not test for yield, though, and first author Yang Zhao cautioned that the spike in survival rate does not mean that the yield of the transgenic plants under drought conditions would equal that of conventional rice varieties under good growing conditions. "We still can't really solve the problem of drought," he said. "But we can make it better. In extreme drought conditions, even a bad yield would be better than nothing in terms of preserving human life."

For more details, read the news article at the Purdue University Newsroom.

Figure: Yang Zhao, a research assistant in horticulture, found that engineering rice to produce high levels of the protein PYL9 can improve the crop's drought survival rate by 40 percent. (Purdue Agricultural Communication photo/Tom Campbell).