Expression analysis of allene oxide synthase gene from Aquilaria sinensis / 药学学报

ABSTRACT

Jasmonic acid (JA) is an important signal molecule involved in plant resistance, and allene oxide synthase (AOS) is a key enzyme in the biosynthesis of jasmonates. In this study, a full-length cDNA of AsAOS1 gene was cloned from Aquilaria sinensis. Meanwhile, the sequence analysis, prokaryotic expression, purification, tissue-specific expression analysis and expression analysis under different abiotic stresses and hormone treatments were performed. The open reading frame (ORF) of AsAOS1 gene was 1 575 bp, encoding a protein of 524 amino acid residues, with a predicted molecular mass of 58.70 kDa. AsAOS1 protein possessed the conserved sequences of cytochrome P450 (CYP450). The phylogenetic analysis indicated that AsAOS1 protein had the highest level of homology with AOS protein of Citrus sinensis. The recombinant AsAOS1 protein was successfully expressed in Escherichia coli BL21(DE3) cells using the prokaryotic expression vector pET28a-AsAOS1 and the recombinant AsAOS1 was purified by Ni2+ affinity chromatography. Expression analysis results in different tissues showed that AsAOS1 was primarily observed in stems, and then roots, followed by leaves. AsAOS1 transcript level was significantly induced after 12 h treatment of NaCl, cold temperature and CdCl2. Furthermore, AsAOS1 expression level was enhanced upon methyl jasmonate (MeJA), salicylic acid (SA) and abscisic acid (ABA) treatment. However, mannitol and gibberellin (GA3) treatments had little influence on the expression level of AsAOS1. These results provides valuable insights into the role of JA in the mechanism of agarwood formation and plant resistance.