Tomato plants emit a scent to resist bacterial attacks. This aroma—or volatile compound—is hexenyl butanoate (HB). A team from the Research Institute for Plant Molecular and Cellular Biology (IBMCP), a joint center of the Universitat Politècnica de Valencia (UPV) and the Spanish National Research Council (CSIC), has discovered that its mode of action is novel, as it works independently of the classic hormone involved in the process of stomatal closure (abscisic acid).