Abstract
Jasmonic acid (JA) is a plant hormone that control trade-off between plant growth and responses to biotic and abiotic stresses. Recently core mechanism of JA signal transduction has been revealed in Arabidopsis thaliana. Although MYC2 is sole transcription factor that was reported to function in the system, MYC2 is not responsible for all of JA-regulated phenomena such as male fertility. Here we report identification and characterization of a basic-helix-loop-helix type transcription factor HR0729. Plants expressing the chimeric repressor for HR0729 exhibited male sterile phenotype as well as reduced JA-responsiveness in root growth. Male sterility of HR0729 CRES-T plants was not restored by application of exogenous JA. In addition, induction of JA-responsive gene expression was suppressed in HR0729 CRES-T plant. HR0729 protein binds to JAZ proteins in vivo, indicating its function in core JA signal transduction pathway. These results suggest that HR0729 plays a pivotal role to regulate JA signaling especially in male fertility.
