摘要
Plants respond to wounding such as caused by insect herbivores by activating their defenses and thus increasing their resistance against attacking pests and opportunistic pathogens(Howe and Schaller,2008).The phenomenon was first described more than 50 years ago by Green and Ryan,who reported that wounding triggers tomato and potato plants to produce proteinase inhibitors that inhibit digestive proteases in the gut of leaf-eating insects to starve them of nutrients(Green and Ryan,1972).They also observed that the accumulation of proteinase inhibitors is not restricted to wounded leaves but occurs throughout the aerial parts of the plants.The search for a chemical signal that is released locally in response to wounding and that mediates systemic activation of defense gene expression led to the identification of systemin,the first ever peptide with hormonelike activity in plants(Pearce et al.,1991).These seminal findings sparked much research into systemic defense responses and peptide signaling in general,and we know now that systemin is one of many phytocytokines that regulate a multitude of immune responses in plants(Schilmiller and Howe,2005;Gust et al.,2017).
