Abstract

Jasmonates (JAs) are the most effective inducers for the biosynthesis of various secondary metabolites. Currently, jasmonate ZIM domain (JAZ) and its interactors, such as MYC2, constitute the main JA signal transduction cascade, and such a cascade fails to directly regulate all the taxol biosynthesis genes, especially the rate-limit gene,DBAT. Another JA signaling branch, JAV and WRKY, would probably fill the gap. Here, TcJAV3 was the closest VQ-motif-containing protein inTaxus chinensisto AtJAV1. Although TcJAV3 was overexpressed inAtJAV1knockdown mutant,JAVRi17, the enhanced disease resistance toBotrytis cinereacaused by silencingAtJAV1was completely recovered. The results indicated that TcJAV3 indeed transduced JA signal as AtJAV1. Subsequently, TcWRKY26 was screened out to physically interact with TcJAV3 by using a yeast two-hybrid system. Furthermore, bimolecular fluorescence complementation and luciferase complementary imaging also confirmed that TcJAV3 and TcWRKY26 could form a protein complex in vivo. Our previous reports showed that transientTcWRKY26overexpression could remarkably increaseDBATexpression. Yeast one-hybrid and luciferase activity assays revealed that TcWRKY26 could directly bind with the wa-box of theDBATpromoter to activate downstream reporter genes. All of these results indicated that TcWRKY26 acts as a direct regulator ofDBAT, and the TcJAV3–TcWRKY26 complex is actually another JA signal transduction mode that effectively regulates taxol biosynthesis inTaxus. Our results revealed that JAV–WRKY complexes directly regulatedDBATgene in response to JA stimuli, providing a novel model for JA-regulated secondary metabolism. Moreover, JAV could also transduce JA signal and function non-redundantly with JAZ during the regulation of secondary metabolisms.Keywords:JAV;WRKY;JA signal transduction;DBAT;taxol biosynthesis