Knockout of SIMAPK3 Reduced Disease Resistance to Botrytis cinerea in Tomato Plants

Mitogen-activated protein kinases (MAPKs) play an important role in defense responses to biotic and abiotic stresses. In order to investigate the role of S1MAPK3 in tomato plant resistance to Botrytis cinerea, two lines of slmapk3 mutants and wild-type (WT) tomato plants were used. The results showed that slmapk3 mutants were more susceptible to B. cinerea and that knockout of SIMAPK3 reduced the activities of defense enzymes and enhanced the accumulation of reactive oxygen species (ROS). Furthermore, we detected the expressions of salicylic acid (SA) and jasmonic acid (JA) signaling-related genes and found that knockout of SIMAPK3 enhanced the expressioris of S1PR1, S1PAD4 and S1EDS1, whereas reduced the expressions of SILoxC, S1PI I and S1PI II and enhanced the expressions of SlJAZ1 and SIMYC2. We postulate that SIMAPK3 plays a positive role in tomato plant resistance to B. cinerea through regulating ROS accumulation and SA and JA defense signaling pathways.