The OsJAZ1 degron modulates jasmonate signaling sensitivity during rice development

Abstract

Jasmonates (JAs) are crucial to the coordination of plant stress responses and development. JA signaling depends on JASMONATE-ZIM DOMAIN (JAZ) proteins that are destroyed by the SCFCOI1-mediated 26S proteasome when the JAZ co-receptor COI1 binds active JA or the JA-mimicking phytotoxin coronatine (COR). JAZ degradation releases JAZ-interacting transcription factors that can execute stress and growth responses. The JAZ proteins typically contain Jas motifs that undergo conformational changes during JA signal transduction and that are important for the JAZ-COI1 interaction and JAZ protein degradation. However, how alterations in the Jas motif and, in particular, the JAZ degron part of the motif, influence protein stability and plant development have not been well explored. To clarify this issue, we performed bioassays and genetic experiments to uncover the function of the OsJAZ1 degron in rice JA signaling. We found that substitution or deletion of core segments of the degron altered the OsJAZ1-OsCOI1b interaction in a COR-dependent manner. We show that these altered interactions function as a regulator for JA signaling during flower and root development. Our study therefore expands our understanding of how the JAZ degron functions, and provides the means to change the sensitivity and specificity of JA signaling in rice.