LAUSR

BACKGROUND Systemic resistance stimulated by rhizosphere bacteria is an important strategy for the management of plant viruses. The efficacy of Bacillus subtilis subsp. subtilis was assessed for protection of cucumber and Arabidopsis against Cucumber mosaic virus (CMV). Moreover, transcriptomic analysis was carried out for A. thaliana colonized with Bacillus subtilis subsp. subtilis and infected with CMV. RESULTS Treatment with a cell suspension of Bacillus revealed a significant reduction of CMV severity in comparison to their control. All Arabidopsis mutants treated with B. subtilis showed a clear reduction in CMV accumulation. Disease severity data and virus concentration titer measurements correlated with gene upregulation in microarray and RT-qPCR experiments. Bacillus treatment increased Arabidopsis growth characteristics (fresh and dry weights and number of leaflets) under pot conditions. The molecular mechanisms by which Bacillus activated resistance to CMV were investigated. Using the microarray hybridization technique, we were able to determine the mechanism of resistance elicited by B. subtilis against CMV. The transcriptomic analysis confirmed the upregulation of more than 250 defence-related genes in Arabidopsis expressing ISR. RT-qPCR results validated the overexpression of defence genes (YLS9 and PR1 in Arabidopsis and PR1 and LOX in cucumber), implying their important roles in the stimulated defense response. CONCLUSION Through the study of microarray and RT-qPCR analyses, it can be concluded that the overexpression of pathogenesis-related genes was necessary to stimulate CMV defense in cucumber and Arabidopsis by Bacillus subtilis subsp. subtilis. This article is protected by copyright. All rights reserved.