Linker histone H1 regulates defense priming and immunity in plants

Abstract

Linker H1 histones play an important role in animal and human pathogenesis, but their function in plant immunity is poorly understood. Here, we analyzed mutants of the three canonical variants of Arabidopsis H1 histones, namely H1.1, H1.2 and H1.3. We observed that double h1.1h1.2 and triple h1.1h1.2h1.3 (3h1) mutants were resistant to Pseudomonas syringae and Botrytis cinerea infections. Transcriptome analysis of 3h1 mutant plants showed that histone H1s play a key role in regulating the expression of early and late defense genes upon pathogen challenge. Moreover, 3h1 mutant plants showed enhanced production of reactive oxygen species and activation of mitogen activated protein kinases upon pathogen-associated molecular pattern (PAMP) treatment. However, 3h1 mutant plants were insensitive to priming with flg22, a well-known bacterial PAMP which induces enhanced resistance in WT plants. The defective defense response in 3h1 was correlated with the enhanced DNA methylation and reduced H3K56ac levels upon priming. Our data place H1 as a molecular gatekeeper in governing dynamic changes in the chromatin landscape of defense genes during plant pathogen interaction.

Transcriptomic and methylation analysis of susceptible and tolerant grapevine genotypes following Plasmopara viticola infection

“…Furthermore, the linker histone 1 (H1) was downregulated at T genotype at 6 hpi. Histone H1 is known to regulate chromatin condensation (Sheikh et al, 2022 ). Sheikh and colleagues observed the effect of the absence of H1 in Arabidopsis when inoculated with Pseudomonas syringae and treated with flagellin flg22 for priming analysis (Sheikh et al, 2022 ).…”

“…Histone H1 is known to regulate chromatin condensation (Sheikh et al, 2022 ). Sheikh and colleagues observed the effect of the absence of H1 in Arabidopsis when inoculated with Pseudomonas syringae and treated with flagellin flg22 for priming analysis (Sheikh et al, 2022 ). They eluded that the genes related to defence are influenced by H1 to respond immediately or not to the pathogen attack (Sheikh et al, 2022 ).…”

“…Sheikh and colleagues observed the effect of the absence of H1 in Arabidopsis when inoculated with Pseudomonas syringae and treated with flagellin flg22 for priming analysis (Sheikh et al, 2022 ). They eluded that the genes related to defence are influenced by H1 to respond immediately or not to the pathogen attack (Sheikh et al, 2022 ). Also, while analysing the role of DNA methylation and histone modifications within the plant immune defence system, Arabidopsis H1 indicated a possible role in plant immunity since it impacts chromatin rearrangement through the influence of the epigenetic profile (Sheikh et al, 2022 ).…”

“…They eluded that the genes related to defence are influenced by H1 to respond immediately or not to the pathogen attack (Sheikh et al, 2022 ). Also, while analysing the role of DNA methylation and histone modifications within the plant immune defence system, Arabidopsis H1 indicated a possible role in plant immunity since it impacts chromatin rearrangement through the influence of the epigenetic profile (Sheikh et al, 2022 ). H1 is part of the defence and epigenetic machinery in our work.…”