Evaluation of Some Defense Gene Expression in Soybean Cultivars under Drought Stress

Drought stress on soybean is a research-demanding matter for negative influence that agricultural drought brings about. This study was designated to evaluate the effect of drought stress on some gene expression in flowering and pod elongation stages in soybean. This experiment was carried out in split-plot format with RCBD design with four replicates. Drought stress as the main factor included three levels (irrigation after 50, 100, and 150 millimeters evaporation from the A-class evaporation pot) of which 50 millimeters evaporation is considered as control. The sub-factor included a factorial combination of 3 varieties (DPX, Sari and WE6) and two sampling stages (flowering and pod elongation). The gene expression analysis was carried out by using the QRT-PCR technique. According to our results, all genes have shown overexpression in drought stress despite this result was not the same for all genotypes and stress levels. Some genes have up-regulated in mediate stress (treatment 100) level (like as Gmdreb 2, Gmdreb 5, GmRD20A, GmaxACD2) and other genes up-regulated in serve stress (treatment 150) level. Between genotypes, DPX cultivar and WE6 line were better than of the sari cultivar for all genes up-regulated.