Molecular cloning and expression of a jasmonate biosynthetic gene allene oxide cyclase from Camellia sinensis

Abstract

As a family of signaling plant hormone, jasmonic acid plays an important role in coordinating plant defense responses to pests and pathogen attack through transcriptional and metabolic changes. In the jasmonate biosynthetic pathway of plants, allene oxide cyclase (AOC) is an essential enzyme. Here we cloned a cDNA from tea plant (Camellia sinensis), named as CsAOC (GenBank: HQ889679), which was 916 bp, containing an open reading frame (738 bp) encoding 245 amino acids. Comparative and bioinformatic analyses revealed that the deduced protein of CsAOC was highly homologous to AOC from other plant species. Phylogenetic analysis indicated that CsAOC was clustered in a closely related subgroup with AOC of Ipomoea nil. The full-length coding region of CsAOC was ligated with pET-32a and successfully expressed in E. coli BL21 (DE3), and purified. Real-time quantitative PCR analysis revealed that methyl jasmonate (MeJA) treatment on its own potently enhanced its expression over the control (healthy leaves), suggesting feedback activation of CsAOC. The expression under salicylic acid (SA) and wounding treatments was up-regulated. The mRNA expression of CsAOC could be induced by tea geometrids and tea green leafhoppers.