AUTHOR=Xiong Jiawei , Wan Xiaoping , Ran Maolin , Xu Xiumei , Chen Lezhang , Yang Feng 

TITLE=Brassinosteroids Positively Regulate Plant Immunity via BRI1-EMS-SUPPRESSOR 1-Mediated GLUCAN SYNTHASE-LIKE 8 Transcription

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.854899

DOI=10.3389/fpls.2022.854899

ISSN=1664-462X

ABSTRACT=<p>Plant hormone brassinosteroids (BRs) play key roles in plant adaptation to biotic stresses, including various pathogen infections. As a core factor in BR signaling, the transcription factor BRI1-EMS-SUPPRESSOR 1 (BES1) activates BR responses <italic>via</italic> regulating the expression of target genes. However, the molecular mechanism of BRs in regulating plant immunity is unclear, and the key components are not identified. In this study, we found that BR biosynthesis and signaling transduction are essential for plant resistance to pathogen infection, and BR biosynthesis or BR signaling-deficient mutants displayed susceptibility to <italic>Pseudomonas syringae</italic> pv. <italic>tomato</italic> DC3000 (<italic>Pst</italic> DC3000) infection [including more serious symptoms and more photosystem II (PSII) photochemistry damage]. We identified a callose synthase gene <italic>GLUCAN SYNTHASE-LIKE 8</italic> (<italic>GSL8</italic>) as a direct target of BES1, and its expression was induced by BRs/BES1. Meanwhile, BRs induced callose accumulation after <italic>Pst</italic> DC3000 infection. Moreover, BES1 gain-of-function mutant <italic>bes1-D</italic> showed promoted <italic>Pst</italic> DC3000 resistance. <italic>GSL8</italic> T-DNA insertion mutant <italic>gsl8-1</italic> was susceptible to DC3000, while brassinolide (BL) treatment partially rescued <italic>gsl8-1</italic> susceptible phenotypes. Our study suggests that BR-induced pathogen resistance partly depends on the BR-induced BES1-GSL8 cascade to mediate callose accumulation.</p>