AsJAZ1 represses the expression of the sesquiterpene synthase gene based on the JA signaling pathway in Aquilaria sinensis (Lour.) Gilg

Aquilaria sinensis is a species of plant endemic to China, which is typical wound-induced economic plant. It is widely used in the production of perfume, incense and traditional Chinese medicine. A healthy A. sinensis tree cannot produce agarwood. It forms agarwood only when wounded. Sesquiterpenes and phenylethyl chromone derivatives have been demonstrated to be the main active compounds in agarwood, but little is known about jasmonate (JA) signaling that regulates the biosynthesis of agarwood sesquiterpenes. In this work, we firstly cloned the full-length cDNA sequence of a JA signaling suppressor gene (JAZ) from A. sinensis, and then characterized its roles through bioinformatics prediction, tissue expression, wounding-induced expression, subcellular localization, protein interaction and overexpression analysis in Arabidopsis thaliana. The results showed that the full-length cDNA sequence of JAZ gene (termed as AsJAZ1, GenBank accession number: KP677281) is 1507 bp, containing a complete open reading frame (ORF) of 990 bp. The bioinformatics analysis shows that the deduced amino acid residues contain a tify (ZIM) domain, the same as A. thaliana JAZ3 protein. Mechanical wounding and MeJA were found to up-regulate the expression level of the AsJAZ1 gene. The AsJAZ1 could interact with the MYC2 transcription factor in vitro. The MYC2 transcription factor in Arabidopsis thaliana (AtMYC2) was minimally expressed in transgenic plants and had a weak response to MeJA treatment. The AsJAZ1 overexpression in A. thaliana was observed to down-regulate the expression of sesquiterpene synthase genes (TPS21 and TPS11), suggesting that AsJAZ1 might serve as a repressor to regulate the expression of sesquiterpene synthase genes in Aquilaria plants. Taken together, this work may lay a foundation for identifying the JA signaling pathway and exploring the role of JA signaling in agarwood sesquiterpene biosynthesis in A. sinensis trees.