Identification and characterization of JAM1, a transcription factor that negatively regulates jasmonate signaling

NAKATA M; MITSUDA N; HERDE M; MORENO JE; KOO AJK; HOWE GA; OHME-TAKAGI M

Kyoto

Congreso; 53rd Annual Meeting of the Japanese Society of Plant Physiology; 2012

Japanese Society of Plant Physiology

Jasmonic acid (JA) is a plant hormone that controls trade-offs between plant growth and responses to biotic and abiotic stresses. In the current model of JA signaling, transcription factors that promote JA responses are actively repressed through direct binding to JAZ repressor proteins. Perception of bioactive JA-isoleucine by COI1-JAZ co-receptor complexes promotes JAZ degradation and release of transcription factors from repression, resulting in the expression of JA-response genes. Here, we report the identification and characterization of a basic-helix-loop-helix-type transcription factor JAM1, which has transcriptional repression activity. CRES-T plants expressing a chimeric repressor for JAM1 were male sterile and showed reduced anthocyanin accumulation and root growth inhibition in response to exogenous JA. These plants were also impaired in the expression of JA-response genes, and were compromised in resistance to insect attack. Conversely, jam1 loss-of-function mutants showed enhanced JA responsiveness, including increased resistance to insect attack. These results suggest that JAM1 plays a pivotal role in the negative regulation of JA signaling.