Molecular Mechanism Of Jasmonate-regulated Plant Defense Controled By JAV1

In order to adapt to the environment，plants have evolved potent mechanisms toprotect themselves from environmental stresses. Analogous with prostaglandins, whichfunction as the primary animal defense regulators, jasmonate have been recognized as aclass of vital hormone signals to defend against insect attack and pathogen infection inthe plant kingdom. Jasmonate are also emerged as a significant growth regulator tomediate various aspects of plant development. As so far, there are no key signalingcomponents in jasmonate pathway reported to mediate plant defense independent ofdevelopmental responses. Through screening of transgenic plants, we identify JAV1, akey gene in jasmonate-regulated plant defence, but the molecular mechanism of howJAV1controls jasmonate-regulated plant defence remains unknown.The morphological phenotypes of the JAV1RNAi transgenic lines, including rootgrowth, inflorescence, flower and seeds, seem similar to the wield type, indicating thatJAV1does not play detectable role in plant developmental processes.In the plant defense test, JAV1RNAi transgenic lines exhibited obvious resistanceagainst Botrytis cinerea, Spodoptera exigua, Bradysia impatiens and aphids, whereasthe JAV1overexpression transgenic lines displayed severe susceptible symptoms. Itsuggested that JAV1functions as a negative regulater to controll plant defense viajasmonate pathway.Affymetrix microarray data and quantitative real-time PCR analysis both show that,when treated with wounding or jasmonate, the defense-related genes of JAV1RNAiplants were highly induced, compared to wild-type plants.Further analysis of JAV1protein uncover that, jasmonates can induce degradationof the JAV1protein via the26S proteasome pathway, and degradation pathwaydependents on the COI1protein.Our results suggest that, when suffering insect attack or pathogen infection, plantssynthesis aberrant jasmonates that trigger JAV1degradation via the26S proteasomepatyway to activate defensive gene expression and enhance plants resistances toenvironmental stress.