Characterization of the first specific Jasmonate biosynthetic pathway gene allene oxide synthase from Artemisia annua.

Allene oxide synthase (AOS) is the first committed step in the biosynthetic pathway of Jasmonate. In this study, a full-length cDNA of AOS gene (named as AaAOS) was cloned from Artemisia annua. The gene was 1891 bp in size containing an open reading frame (1581 bp) encoding 526 amino acids. Comparative and bioinformatic analysis revealed that the deduced protein of AaAOS was highly homologous to AOSs from other plant species. Phylogenetic analysis indicated that the protein of AaAOS belonged to the dicotyledonous group, which was consistent with the category of A. annua. Southern blot analysis revealed that it was a low-copy gene. Quantitative Real-time PCR (qRT-PCR) analysis showed that AaAOS mRNA accumulated most abundantly in leaves and flowers. The qRT-PCR analysis revealed that MeJA, ABA and ethylene treatments significantly enhanced AaAOS transcript expression.