Allene oxide synthase (AOS) is the first enzyme in the lipoxygenase pathway which leads to the formation of jasmonic acid (JA). A full length cDNA of TaAOS was cloned in winter wheat (Triticum aestivum L. cv. Jinghua No.3) seedlings. The open reading frame encompassed 1410 bp encoding a polypeptide of 470 amino acids with calculated molecular mass of 51.9 kD. Southern blot analysis suggested there are three copies of the gene in wheat genome. The TaAOS mRNA could be strongly induced by exogenous JA, and the highest level JA was observed after a 10 h induction. In situ RNA hybridization of seedling indicated preferential gene expression in young leaves, especially in the parenchyma cells around the vascular bundles, and the hybridization also showed that exogenous La(3+) could not suppress the expression of TaAOS induced by JA.