How crop-killing witchweed senses its victims

From a distance, a pretty field of pink-lavender Striga plants suggests a commercial flower crop, but this "witchweed" and related parasite plants cause billions of dollars in crop losses a year. Now, three teams, one reporting this week in Science, have deciphered how witchweed works part of its evil magic. By characterizing the long-sought molecular receptors that Striga seeds depend on to find new hosts and also unraveling their evolutionary history, they've set the stage for new anti-Striga strategies. One team came up with a way to make the receptors fluoresce, a technique that paved the way not only for pinpointing these molecules, but also for identifying compounds or crops that thwart this parasite. A second group's mutants of the lab plant Arabidopsis that carry Striga genes revealed the biochemistry involved in this signaling system. And a third built a family tree that traces the convoluted evolution of these receptors. www.elisakitgs.com