CC-type glutaredoxin gene CsGRX4 in cucumber responds to Botrytis cinerea via JA signaling pathway

Abstract

Botrytis cinerea is an important necrotrophic fungal pathogen with a broad host range. Its infection in cucumber can lead to great economic losses. CC-type glutaredoxin was reported to be involved in the defense response of plants against B. cinerea infection. However, its mechanism in cucumber with B. cinerea infection is not well understood. In this study, we observed that the gene encoding CC-type glutaredoxin, namely, CsGRX4, was markedly upregulated after B. cinerea infection in cucumber and also after exogenous application of salicylic acid (SA) and jasmonic acid (JA). Overexpression of CsGRX4 in Arabidopsis facilitated susceptibility to B. cinerea and increased H2O2 levels and death cells compared with wild type. Moreover, CsGRX4 overexpression in Arabidopsis suppressed the JA levels and transcript level of AtPDF1.2 (JA marker gene), indicating that both the synthesis and signal transduction of JA pathway were suppressed. To understand the mechanism underlying the action of CsGRX4 in the defense response against B. cinerea infection, the yeast two-hybrid assays were conducted between CsGRX4 and CsbZIP transcription factors. It was revealed that CsGRX4 can interact with CsbZIP transcription factors including CsbZIP800, CsbZIP510, CsbZIP420, CsbZIP250, and CsbZIP820, irrespective of the mutation in the ALWL motif of the C-terminal of CsGRX4. Therefore, our study suggested that CsGRX4 negatively regulated the resistance to B. cinerea by blocking JA signal pathway.