Volatile methyl jasmonate is a transmissible form of jasmonate and its biosynthesis is involved in systemic jasmonate response in wounding

Abstract

Volatile organic compounds (VOCs) easily diffuse due to their high hydrophobicity. Because of this physical property, VOCs are able to act as crucial signalling molecules mediating intercellular and interplant communication. Methyl jasmonate (MeJA) is a volatile ester form of jasmonic acid (JA) that is involved in interplant communication in response to biotic and abiotic stresses. Despite its function in interplant communication, the specific role of MeJA in the regulation of intercellular jasmonate responses have been poorly understood. In this study, we demonstrated that MeJA is much more effective than JA in inducing jasmonate response, and the higher efficacy of MeJA relies on its volatile property. To understand the function of MeJA in the regulation of the jasmonate response, we analysed function of JMT gene, Jasmonic acid Methyl Transferase using its knockout mutant (jmt) and overexpressing plants (35S:JMT). Mutant plants that lack JMT expression exhibited reduced jasmonate response, while JMT-overexpressing plants exhibited a higher jasmonate response to JA treatment compared to wild-type plants. In this study, we also showed that JMT is specifically expressed in the phloem, the main vascular system for the transport of phytohormones, and that JMT expression affects systemic jasmonate response in wounding. These results suggest the volatile MeJA is a transmissible form of jasmonate and that its biosynthesis is involved in systemic jasmonate response in wounding.