Molecular cloning and characterization of a jasmonate biosynthetic pathway gene for allene oxide cyclase from Jatropha curcas

Herein, we cloned a full-length cDNA encoding allene oxide cyclase (AOC, EC 5.3.99.6) that is a key enzyme in jasmonates (JAs) biosynthetic pathway from Jatropha curcas L., an important plant species as its seed is the raw material for biodiesels, named as JcAOC (GenBank accession no. FJ874630). The cDNA was 924 bp in length with a complete open reading frame of 750 bp, which encoded a polypeptide of 250 amino acids including a putative signal peptide of 65 amino acid residues and a mature protein of 185 amino acids with a predicted molecular mass of 20.7 kDa and a isoelectric point of 6.24. Phylogenetic analysis indicated that JcAOC belonged to the AOC superfamily. Semi-quantitative RT-PCR analysis revealed that JcAOC mRNA was expressed in roots, stems, leaves, young seeds, endosperms, and flowers, but that the expression level was highest in leaves and lowest in seeds, and mRNA expression of JcAOC could be induced by salt stress (300 mM NaCl) and low temperature (4A degrees C). Furthermore, the full-length coding region of JcAOC excluding signal peptide sequence was inserted into pET-30a and was successfully expressed in Escherichia coli. Overexpression of JcAOC in E. coli conferred its resistance to salt stress and low temperature.