RcMYB84 and RcMYB123 mediate jasmonate-induced defense responses against Botrytis cinerea in rose (Rosa chinensis).

Jasmonates (JAs) are important for pathogen resistance in many plants, but the role of these phytohormones in fungal pathogen resistance in rose is unclear. Here, we determined that exogenous application of methyl jasmonate increased resistance to the important fungal pathogenBotrytis cinereainRosa chinensis'Old blush', whereas silencing the JA biosynthetic pathway geneAllene Oxide Synthase(AOS) and JA co-receptor geneCORONATINE INSENSITIVE 1(COI1) suppressed this response. Transcriptome profiling identified various MYB transcription factor genes that responded to both JA andB. cinereatreatment. SilencingRi-RcMYB84/Ri-RcMYB123increased the susceptibility of rose plants toB. cinereaand inhibited the protective effects of JA treatment, confirming the crucial roles of these genes in JA-induced responses toB. cinerea. JAZ1, a key repressor of JA signaling, directly interacts with RcMYB84 and RcMYB123 to deplete their free pools. The JAZ1-RcMYB84 complex binds to theRcMYB123promoter via the CAACTG motifs to block its transcription. Upon JA treatment, the expression ofRcMYB123is de-repressed, and free forms of RcMYB84 and RcMYB123 are released due to JAZ1 degradation, thereby activating the defense responses of plants toB. cinerea. These findings shed light on the molecular mechanisms underlying JA-induced pathogen resistance in roses.