AUTHOR=Liu Lu , Wang Di , Zhang Chao , Liu Haiyang , Guo Huiming , Cheng Hongmei , Liu Enliang , Su Xiaofeng 

TITLE=The heat shock factor GhHSFA4a positively regulates cotton resistance to Verticillium dahliae

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1050216

DOI=10.3389/fpls.2022.1050216

ISSN=1664-462X

ABSTRACT=<p>Heat shock factors (HSFs) play a crucial role in the environmental stress responses of numerous plant species, including defense responses to pathogens; however, their role in cotton resistance to <italic>Verticillium dahliae</italic> remains unclear. We have previously identified several differentially expressed genes (DEGs) in <italic>Arabidopsis thaliana</italic> after inoculation with <italic>V. dahliae</italic>. Here, we discovered that <italic>GhHSFA4a</italic> in <italic>Gossypium hirsutum</italic> (cotton) after inoculation with <italic>V. dahliae</italic> shares a high identity with a DEG in <italic>A. thaliana</italic> in response to <italic>V. dahliae</italic> infection. Quantitative real-time PCR (qRT-PCR) analysis indicated that <italic>GhHSFA4a</italic> expression was rapidly induced by <italic>V. dahliae</italic> and ubiquitous in cotton roots, stems, and leaves. In a localization analysis using transient expression, GhHSFA4a was shown to be localized to the nucleus. Virus-induced gene silencing (VIGS) revealed that downregulation of <italic>GhHSFA4a</italic> significantly increased cotton susceptibility to <italic>V. dahliae.</italic> To investigate <italic>GhHSFA4a-</italic>mediated defense, 814 DEGs were identified between <italic>GhHSFA4a-</italic>silenced plants and controls using comparative RNA-seq analysis. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that DEGs were enriched in “flavonoid biosynthesis”, “sesquiterpenoid and triterpenoid biosynthesis”, “linoleic acid metabolism” and “alpha-linolenic acid metabolism”. The expression levels of marker genes for these four pathways were triggered after inoculation with <italic>V. dahliae</italic>. Moreover, <italic>GhHSFA4a</italic>-overexpressing lines of <italic>A. thaliana</italic> displayed enhanced resistance against <italic>V. dahliae</italic> compared to that of the wild type. These results indicate that <italic>GhHSFA4a</italic> is involved in the synthesis of secondary metabolites and signal transduction, which are indispensable for innate immunity against <italic>V. dahliae</italic> in cotton.</p>