Overexpression of BSK5 in Arabidopsis thaliana Provides Enhanced Disease Resistance.

Plant surface-localized pattern recognition receptors (PRRs) recognize pathogen- or damage-associated molecular patterns (PAMP/DAMPs) and activate pattern-triggered immunity (PTI). PRRs recruit receptor-like cytoplasmic kinases (RLCKs) to transduce the perceived signal to downstream signaling components. Brassinosteroid-signaling kinase 5 (BSK5) is a member of the RLCK XII subfamily and mutational analysis revealed its involvement in plant immunity. Here, we provide evidence that overexpression of BSK5 in transgenic Arabidopsis plants enhanced disease resistance to the bacterial pathogen Pseudomonas syringae and to the fungus Botrytis cinerea. Remarkably, upon treatment with the flg22, elf18 and pep1 PAMP/DAMPs, BSK5-overexpressing plants displayed higher levels of immune responses, including production of reactive oxygen species, callose deposition at the cell wall, and PATHOGENESIS-RELATED1 (PR1) gene expression. Together, these findings further substantiate the role of BSK5 in plant immunity and illustrate its potential use for improving plant disease resistance.