Determination of Genetic Variation and Expression Pattern of DHNs and HSPs in Some Rice Genotypes under Water Stress

The present study aimed to investigate the different responses of sensitive and tolerant rice genotypes under water stress conditions induced by using poly ethylene glycol (PEG 6000). The studied genotypes were Giza177, Giza181, Giza182 and Sakha103 (sensitive), Sakha104 (moderate) and Orabi2 (tolerant). The present investigation included the determination of germination %, fresh and dry weight, shoot and root length, cell membranes stability as rate of electrolyte leakage (EL) and lipid peroxidation as MDA content. Semi-quantitative reverse transcriptase polymerase chain reaction (sqRT-PCR) for some protective proteins such as heat stable proteins (HSPs) and dehydrins (DHNs) standardized on actin transcript amounts were carried out to investigate the changes in the expression pattern of those genes. All determinations were carried out for all studied genotypes under both control and drought conditions. The obtained results revealed that water stress tolerance of tolerant genotypes was accompanied with decreasing of electrolyte leakage rate and low content of MDA comparing with sensitive ones. sqRT-PCR analysis for expression pattern of studied genes showed increasing in the expression of HSP-13, HSP-12, HSP-9 and DHN-2 in the seedlings of tolerant genotypes comparing with sensitive ones. The present study pointed to the participation of those genes in the acquisition of drought tolerance in tolerant genotypes.