Plants have evolved complex mechanisms to deal with water shortages, which vary in timing and severity from place to place, season to season. How efficiently a plant draws water from the soil, howwell cells retain water, how much water is released through leaf openings called stomata, the timing of flowering relative to the seasonal onset of drought, all factor in drought tolerance. Roots produce molecules that allow them to suck water out of ever, drier soils, and leaves respond by closing stomata. Cells mop up free radicals produced during dehydration or produce molecules that preserve their ability to hold on to what water they have. Researchers are employing two strategies to decipher and harness these responses to drought. Some take a relatively traditional approach, growing and crossing varieties and evaluating how the progeny vary in their ability to deal with stress. They then select and grow the best-adapted plants. Some researchers head straight for the genes. Genes of the plants Arabidopsis and maize are found out, that play a major role in drought tolerance.
