Studying expression of some genes associated with drought stress in rice (Oryza sativa L.)

To investigate the effect of osmotic stress induced by polyethylene glycol 6000 on seed germination components and identifying drought tolerant and susceptible genotypes, 21 rice genotypes were studied at three levels of osmotic stress (0, -7.5 and -15 MPa) with factorial arrangement in a completely randomized design with three replications. The results indicate that there were significant differences among genotypes in different levels of osmotic stress for all studied traits including radicle length, shoot length, radicle to shoot length ratio, radicle fresh weight, radicle dry weight, shoot fresh weight and shoot dry weight. The effect of genotype and genotype osmotic stress interaction were significant in all studied components. Based on measured traits, the genotypes IR28 and Line 416 were selected as susceptible and tolerant genotypes to osmotic stress, respectively. After RNA extraction and cDNA synthesis, the expression pattern of four drought responsive genes (SOD, FNR, APX and NDH) in two genotypes, IR28 and 416, at seedling stage under treatments of 0, 4, 8, 10 and 24 hours of the dehydration stress were studied using real time PCR technique. The results of this study showed that drought responsive genes had higher expression in the tolerant Line 416 than the sensitive genotype IR28 and the expression of all genes except FNR increased with increasing osmotic stress. Also, APX gene didn’t show the significant expression in either genotype, but showed the highest expression at 24 hours after stress in the sensitive genotype IR28.