Getting In Touch With Plant Defense

The Venus flytrap is famous for snapping shut to score a meal when it feels a fly land, a task it achieves by using the plant hormone jasmonate to send a signal to close the trap. Plant biologists have now discovered that other plants use their sense of touch and jasmonate to kick-start defense programs when under attack by insects or fungi. A team led by Rice University’s E. Wassim Chehab and Janet Braam found that when Arabidopsis thaliana plants are touched they maintain enhanced levels of the conjugate jasmonate-isoleucine, which activates biochemical signals to produce protective metabolites (Curr. Biol., DOI: 10.1016/j.cub.2012.02.061). These metabolites give insects digestive problems, and they also thwart fungi. The researchers suggest that because plants can’t move to escape stressful situations, they use their sense of touch to react to changes in their environment—from predators or from nature. For example, plants repeatedly touched in a lab to mimic windy conditions typically grow shorter and slower, the researchers note, much like plants growing on a rugged coastline.