Genetic tweak

PARIS: Researchers on Tuesday unveiled a genetic modification that enables plants to use a quarter less water with scant reduction in yield. By altering a single gene, scientists coaxed tobacco plants -- a model crop often used in experiments -- to grow to near normal size with only 75 percent of the water they usually require. If major food crops respond the same way, they said, the first-of-its-kind genetic "hack" could help feed the growing population of an increasingly water-starved world.  "This is a major…