SlMAPK3, a key mitogen-activated protein kinase, regulates the resistance of cherry tomato fruit to Botrytis cinerea induced by yeast cell wall and beta-glucan

Induced disease resistance of fruit by bio-based compounds is a promising strategy to control fruit decay. This research was aimed at studying the resistance of cherry tomato fruit to Botrytis cinerea induced by the yeast cell wall component from Saccharomyces cerevisiae and investigate a role of MAPKs in regulating the resistance response. The disease resistance of cherry tomato fruit was effectively enhanced by yeast cell wall and beta-glucan. The expression of SIMAPK3 (but not of SIMAPKI and SIMAPK2) was significantly increased by yeast cell wall and beta-glucan and reached peak at 1 h. The yeast cell wall component also induced high expression of PR genes (SIPRI, SIP12.5 and SICHI9) and the transcription factors (SIERFI and SIPti.5) that specifically bind to the promoter of PR genes. The expression of PR genes (S1PRE SIP12.5 and SICHI9) peaked after 24 h (at 24 or 48 h). The peak of SIERFI and S1Pti5 gene expression mostly appeared at around 4 h. It supposed to be a chronological order in the peaks of gene expression profile among SIMAPK3, PR genes and transcription factors. U0126 (1,4-diamino-2,3-dicyano-1,4-bis(o-amino-phenylmercapto)butadiene) significantly inhibited transcription of SIMAPK3, PR genes and transcription factors. The yeast cell wall and beta-glucan could not induce high expression of SIMAPK3 and the downstream genes of SIMAPK3 in the U0126 treatment. These findings indicated that the yeast cell wall component that acts as microbe associated molecular patterns (MAMPs) could effectively induce disease resistance in cherry tomato fruit after harvest. The mechanism of induced resistance was associated with the expression of SIMAPK3 and defense-related genes. SIMAPK3, as an important upstream signaling kinase, had a direct regulatory effect on the downstream transcriptional factors (SIERFI and SIPti.5) to activate the expression of PR genes in the yeast cell wall component-induced immune responses in cherry tomato fruit.