The H3K4 demethylase Jar1 orchestrates ROS production and expression of pathogenesis‐related genes to facilitate Botrytis cinerea virulence

Abstract

Histone 3 Lysine 4 (H3K4) demethylation is ubiquitous in organisms, however the roles of H3K4 demethylase JARID1(Jar1)/KDM5 in fungal development and pathogenesis remain largely unexplored. Here, we demonstrate that Jar1/KDM5 in Botrytis cinerea, the grey mould fungus, plays a crucial role in these processes.The BcJAR1 gene was deleted and its roles in fungal development and pathogenesis were investigated using approaches including genetics, molecular/cell biology, pathogenicity and transcriptomic profiling.BcJar1 regulates H3K4me3 and both H3K4me2 and H3K4me3 methylation levels during vegetative and pathogenic development, respectively. Loss of BcJAR1 impairs conidiation, appressorium formation and stress adaptation; abolishes infection cushion (IC) formation and virulence, but promotes sclerotium production in the DBcjar1 mutants. BcJar1 controls reactive oxygen species (ROS) production and proper assembly of Sep4, a core septin protein and virulence determinant, to initiate infection structure (IFS) formation and host penetration. Exogenous cAMP partially restored the mutant appressorium, but not IC, formation. BcJar1 orchestrates global expression of genes for ROS production, stress response, carbohydrate transmembrane transport, secondary metabolites, etc., which may be required for conidiation, IFS formation, host penetration and virulence of the pathogen.Our work systematically elucidates BcJar1 functions and provides novel insights into Jar1/ KDM5-mediated H3K4 demethylation in regulating fungal development and pathogenesis.

Transcriptome analysis and functional validation reveal a novel gene, BcCGF1, that enhances fungal virulence by promoting infection‐related development and host penetration

“…Endogenous ROS and the cAMP signalling pathway play crucial roles in B. cinerea infection-related development, including conidial germination and IFS formation (Marschall and Tudzynski, 2016b;Feng et al, 2017;Hou et al, 2020). Our data indicated that disruption of BcCGF1 impairs the pathogen conidial germination, IFS formation, host penetration, and virulence (Figures 3-6).…”

“…DAB is converted to dark-brown polymers in the presence of H 2 O 2 and NBT forms a dark-blue water-insoluble formazan precipitate on reduction by superoxide radicals. We also determined the influence of cAMP signalling on conidial germination and/or IFS formation of the tested strains as previously described (Feng et al, 2017;Cao et al, 2018;Hou et al, 2020). Our data demonstrate that the ∆Bccgf1 mutants are difficult to be stained in the germ-tubes and growing mycelia during conidial germination, appressorium, and infection structure formation (Figures 8a and S7); quantification analysis indicated that the relative ROS production by the mutants was significantly reduced (Figure 8b).…”

“…Two P450 monooxygenase genes (BCIN_07g05430 and BCIN_03g06490) involved in ABA biosynthesis in B. cinerea were upregulated (Table S5). NADPH oxidases are required for ROS production and are involved in conidial germination, differentiation, and vegetative and pathogenicity development as well as virulence in B. cinerea (Marschall and Tudzynski, 2016a;Cao et al, 2018;Hou et al, 2020). NADPH oxidase genes BcNOXA (BCIN_05g00350) and…”

“…The mutant strains displayed reductions in conidial germination and subsequent hyphal growth (Figure 7a,c) and reductions in radial growth of mycelia on CM containing the assorted stress agents (Figure 7b,d). Further analysis indicated that the relative mycelial radial growth inhibition (Cao et al, 2018;Hou et al, 2020) of the ΔBccgf1 strains significantly increased when cultured on CM containing the stress-mimicking agents compared to that of the control and complemented strains (Figure 7e,f). These data suggest that BcCGF1 is required for pathogen osmotic and oxidative stress adaptation as well as cell wall integrity.…”

“…Data represent means ± SD from at least four independent experiments. **, ***Significance at p < .01 and p < .001, respectively nitroblue tetrazolium (NBT) staining approaches (Cao et al, 2018;Hou et al, 2020). DAB is converted to dark-brown polymers in the presence of H 2 O 2 and NBT forms a dark-blue water-insoluble formazan precipitate on reduction by superoxide radicals.…”