Abstract
Brassinosteroids (BRs) have the ability to protect plants from various environmental stresses, such as drought, salinity, heat stress, and pathogens. Treatment of brassinolide (BL), considered to the most important BRs, induced systemic resistance against a broad range of pathogens in tobacco and rice plant. However, the mechanisms of brassinosteroid-mediated disease resistance (BDR) have not been clarified. In this study, we characterized the mechanism of BDR using Arabidopsis thaliana. BDR was also effective in Arabidopsis and suppressed the growth of the virlent pathogen Pseudomonas syringae pv. tomato DC3000 (Pst). Treatment with BL did not induce the accumulation of mRNA of the systemic acquired resistance-associated PR-1 and the ethylene- and jasmonic acid-dependent PDF1.2 genes. The expression of PR-1 induced by pathogen infection in BDR-induced plants was earlier than in control plants, which is a priming effect of BDR and could be an important mechanism of BDR.
