GhJAZ2 attenuates cotton resistance to biotic stresses via the inhibition of the transcriptional activity of GhbHLH171

Abstract

Plants have evolved effective mechanisms to protect themselves against multiple stresses, and employ jasmonates (JAs) as vital defence signals to defend against pathogen infection. The accumulation of JA, induced by signals from biotic and abiotic stresses, results in the degradation of Jasmonate-ZIM-domain (JAZ) proteins, followed by the de-repression of JAZ-repressed transcription factors (such as MYC2) to activate defence responses and developmental processes. Here, we characterized a JAZ family protein, GhJAZ2, from cotton (Gossypium hirsutum) which was induced by methyl jasmonate (MeJA) and inoculation of Verticillium dahliae. The overexpression of GhJAZ2 in cotton impairs the sensitivity to JA, decreases the expression level of JA-response genes (GhPDF1.2 and GhVSP) and enhances the susceptibility to V. dahliae and insect herbivory. Yeast two-hybrid and bimolecular fluorescence complementation assays showed that GhJAZ2 may be involved in the regulation of cotton disease resistance by interaction with further disease-response proteins, such as pathogenesis-related protein GhPR10, dirigent-like protein GhD2, nucleotide-binding site leucine-rich repeat (NBS-LRR) disease-resistant protein GhR1 and a basic helix-loop-helix transcription factor GhbHLH171. Unlike MYC2, overexpression of GhbHLH171 in cotton activates the JA synthesis and signalling pathway, and improves plant tolerance to the fungus V. dahliae. Molecular and genetic evidence shows that GhJAZ2 can interact with GhbHLH171 and inhibit its transcriptional activity and, as a result, can restrain the JA-mediated defence response. This study provides new insights into the molecular mechanisms of GhJAZ2 in the regulation of the cotton defence response.

Comprehensive analyses of the annexin (ANN) gene family in Brassica rapa, Brassica oleracea and Brassica napus reveals their roles in stress response

“…It is the causative agent of stem rot, one of the most devastating diseases of B. napus 65,66 . Previous studies have shown the role of JA signaling in plant resistance to hemibiotroph pathogens [67][68][69][70] . The transcriptional profiling of B. napus susceptible (Westar) and tolerant (ZY821) genotypes infected with S. sclerotiorum (GSE81545: https://www.ncbi.nlm.nih.gov/geo/query/ acc.cgi?acc=GSE81545) (Table S5) showed that the group II BnaANN were induced by S. sclerotiorum infection, and the expression level in the susceptible genotype (Westar) was more than that in the tolerant (ZY821) genotype; some members from group III and group V BnaANN were induced, while some members were repressed by S. sclerotiorum infection (Fig.…”

GbSOBIR1 confers Verticillium wilt resistance by phosphorylating the transcriptional factor GbbHLH171 in Gossypium barbadense

“…We showed previously that GbJAZ2 could interact with GbbHLH171 and inhibit the transcriptional activity of GhbHLH171 (He et al ., ). In this study, we demonstrated that GbSOBIR1 could phosphorylate GbbHLH171 and therefore facilitate its transcriptional activity.…”

“…A bHLH and R2R3-MYB transcription factor N-terminal domain and a helix-loop-helix domain can be found in the predicted protein. Based on a previous phylogenetic analysis (Yan et al, 2015), we named this protein GbbHLH171 (He et al, 2018). The ORF of GbbHLH171 was cloned and mated to GbSOBIR1 in yeast to confirm the interaction (Figure 4a).…”

The Gossypium hirsutum TIR‐NBS‐LRR gene GhDSC1 mediates resistance against Verticillium wilt

“…ROS accumulation as a Verticillium wilt resistance response also has been reported in association with several other candidate genes, including GbaNA1 (Li et al ., ), Gh‐LYK1 and Gh‐LYK2 (Gu et al ., ) and GbRVd (Yang et al ., ), suggesting that ROS accumulation plays a critical role in cotton resistance to V. dahliae . Furthermore, hormone‐mediated signalling is one of the most important aspects of this defence mechanism, (Fujita et al ., ), and SA, JA and ETH are three main hormones contributing to defence against V. dahliae (Duan et al ., ; Gao et al ., ; Guo et al ., ; He et al ., ; Li et al ., , ; Mo et al ., ; Parkhi et al ., ; Sun et al ., ; Wang et al ., ; Xu et al ., ; Yang et al ., ; Zhang et al ., ; Zuo et al ., ). Several functional studies have explored the roles of novel genes implicated in cotton defence, and some of these modulate JA signalling, such as GbSBT1 (Duan et al ., ), GbSSN (Sun et al ., ), GhNINJA (Wang et al ., ), GhJAZ2 and GhbHLH171 (He et al ., ) and GbSSI1 (Gao et al ., ).…”