The transcription factor WRKY75 positively regulates jasmonate-mediated plant defense to necrotrophic fungal pathogens

Abstract

Necrotrophic fungi cause devastating diseases in both horticultural and agronomic crops, but our understanding of plant defense responses against these pathogens is still limited. In this study, we demonstrated that AtWRKY75 positively regulates the jasmonate (JA)-mediated plant defense against necrotrophic fungal pathogens Botrytis cinerea and Alternaria brassicicola and also affects plants’ sensitivity to JA-inhibited seed germination and root growth. Quantitative RT-PCR analysis indicated that the expression of several JA-associated genes, such as ORA59 and PDF1.2, was significantly reduced in wrky75 mutants and significantly enhanced in 35S:WRKY75 transgenic plants. Immunoprecipitation assays revealed that WRKY75 directly binds to ORA59 promoters and represses its transcription. In vivo and in vitro experiments suggested that WRKY75 interacts with several JASMONATE ZIM-domain proteins, which are repressors of the JA signaling pathway. We determined that JAZ8 represses the transcriptional function of WRKY75, thereby attenuating the expression of its regulon. Consistent with this finding, overexpression of JAZ8 repressed plant defense response to B. cinerea. Taken together, our study provides evidence that WRKY75 functions as a critical component of the JA-mediated signaling pathway to positively regulate Arabidopsis defense response to necrotrophic pathogens.

Function and Mechanism of Jasmonic Acid in Plant Responses to Abiotic and Biotic Stresses

“…GhJAZ2 interacted with GhbHLH171 to restrain the JA-mediated defense response to the fungus Verticillium dahliae in cotton [194]. JAZ8 repressed the transcriptional function of WRKY75, whereas JAZ8 overexpression repressed plant defense responses to necrotrophic pathogens in Arabidopsis [195]. These results demonstrate that resistance against necrotrophic pathogens can be strengthened by JA signaling-related genes (Figure 7).…”

Genome-Wide Characterization of Jasmonates Signaling Components Reveals the Essential Role of ZmCOI1a-ZmJAZ15 Action Module in Regulating Maize Immunity to Gibberella Stalk Rot

“…In particular, JAs display inhibitory effects on primary root growth [12][13][14]. On the other hand, JAs positively regulate stamen development [15], male and female fertility [16,17], anthocyanin biosynthesis [17,18], and defense against insects and necrotrophic pathogens [1,19]. Multiple roles of JA in maize are best illustrated in the study of the opr7opr8 double mutant, which is deficient in JA biosynthesis, is male-sterile, lacks anthocyanin production, and is susceptible to soil-borne pathogen Pythium spp.…”

The Meloidogyne javanica effector Mj2G02 interferes with jasmonic acid signalling to suppress cell death and promote parasitism in Arabidopsis

“…Consistent with this speculation, we found that the concentrations of JA-Ile were significantly lower in the Mj2G02transgenic Arabidopsis lines than in WT plants. Moreover, the expression levels of four JA-responsive genes, MYC3, UPI, THI2.1, and WRKY75, which have been reported to be involved in plant defence against plant pathogens (Chen et al, 2020;Fernandez-Calvo et al, 2011;Kammerhofer et al, 2015;Laluk & Mengiste, 2011), were also significantly reduced in the Mj2G02-transgenic Arabidopsis lines.…”