Structure and regulation of OPR1 and OPR2, two closely related genes encoding 12-oxophytodienoic acid-10,11-reductases from Arabidopsis thaliana

The genes of two closely related 12-oxophytodienoic acid reductases (EC 1.3.1.42), OPR1 and OPR2, were identified on a 7079-bp-long genomic fragment from Arabidopsis thaliana (L.) Heynh. The organization of these two genes was determined and putative cis elements were identified. Promoter-β-glucuronidase (GUS) fusions expressed in transgenic Arabidopsis thaliana and Nicotiana tabacum L. plants revealed differences in OPR-promoter-driven GUS expression in flowers. While the OPR1 promoter directed GUS expression in young seeds, the OPR2 promoter directed pollen-specific expression. Both OPR1 and OPR2, were predominantly expressed in roots. Stress treatments, like local and systemic wounding, UV-C illumination and coldness, resulted in transient changes in steady-state OPR mRNA levels, but no concurrent changes in polypeptide level or enzyme activity were detected. Received: 2 October 1998 / Accepted: 22 December 1998