Cloning and characterization of a putative 12-oxophytodienoic acid reductase cDNA induced by osmotic stress in roots of foxtail millet.

Foxtail millet is a gramineous crop with low water requirement. Cloning of osmotic responses-related genes from foxtail millet is a key step for understanding the mechanism of its tolerance to drought. Here we reported the cloning and characterization of a cDNA (SiOPR1) encoding a putative 12-oxophytodienoic acid reductase 1 from foxtail millet by using RACE methods. Sequence analysis showed that SiOPR1 encoded a polypeptide of 374 amino acids with a predicted molecular mass of 41.9 kDa and pI of 5.14. Multiple alignment result showed that OPR1 protein was very conservative among gramineous crops. RNA gel blot analysis results indicated that SiOPR1 was up-regulated by osmotic stress, and its expression was limited in the roots of foxtail millet. However, SiOPR1 expression was not affected by ABA, NaCl and MeJA treatments both in roots and shoots. Therefore, it is suggested that SiOPR1 gene play an important role in response to drought stress.