Jasmonic acid-mediated defense suppresses brassinosteroid-mediated susceptibility to Rice black streaked dwarf virus infection in rice.

Plant hormones play a vital role in plant immune responses. However, in contrast to the relative wealth of information on hormone-mediated immunity in dicot plants, little information is available on monocot-virus defense systems., We used a high-throughput-sequencing approach to compare the global gene expression of Rice black-streaked dwarf virus ( RBSDV)-infected rice plants with that of healthy plants. Exogenous hormone applications and transgenic rice were used to test RBSDV infectivity and pathogenicity., Our results revealed that the jasmonic acid ( JA) pathway was induced while the brassinosteroid ( BR) pathway was suppressed in infected plants. Foliar application of methyl jasmonate (MeJA) or brassinazole ( BRZ) resulted in a significant reduction in RBSDV incidence, while epibrassinolide ( BL) treatment increased RBSDV infection. Infection studies using coi1-13 and Go mutants demonstrated JA-mediated resistance and BR-mediated susceptibility to RBSDV infection., A mixture of Me JA and BL treatment resulted in a significant reduction in RBSDV infection compared with a single BL treatment. Me JA application efficiently suppressed the expression of BR pathway genes, and this inhibition depended on the JA coreceptor Os COI1. Collectively, our results reveal that JA-mediated defense can suppress the BR-mediated susceptibility to RBSDV infection. [ABSTRACT FROM AUTHOR]