MAPKs modulate chemical defenses against stink bugs (Nezara viridula) in developing seeds of soybean

ROMINA GIACOMETTI; JORGE ZAVALA

Congreso; International Society for Chemical Ecology and the Chemical Signals in Vertebrates group; 2014

Stink bugs (Nezara viridula) are a key pest in soybean (Glycine max), which attack decreases yield crop. Plant responses to insect attack begin with the recognition of cell injury and oral secretions, triggering mitogen activated protein kinases (MAPK) pathway and inducing defenses against herbivores. Soybean MAPK?s role in mediating responses to stink bugs attack remains largely unexplored. In this work we examined early and late MAPKs signaling responses in developing seeds under attack of stink bugs and its involvement in defense regulation. We found that MAPK3, MAPK4 and MAPK6 as well as a MAPKK (MAPKK1) are differentially transcribed in time after insect perception. We analyzed the phosphorylation status and identified soybean MAPK6 as an herbivore and wound-induced kinase, while MAPK3 and MAPK4 were found to be activated after SA and JA treatments. Although two critical genes involved in flavonoid synthesis in seeds, Phe-ammonia lyase (PAL2) and chalcone synthase (CHS7) were up-regulated under all treatments, only stink bug attack induced isoflavone synthase (IFS), an enzyme responsible for the synthesis of daidzein and genistein, which are the main chemical defenses against these insects. These results suggest that stink bugs feeding on developing seeds triggers JA and SA-mediated defenses through a tightly regulated induction of MAPKs transcription and also phosphorylation of a particular MAPK module in a time-dependent fashion.