Drought stress is one of the important restricted factors on crop production in the tropical and semi-tropical areas. Therfore, plant breeders are trying to improve crop production under these regions using producing resistant varieties in drought stress. Drought stress causes several effects on plant such as phenotypic, enzymatic and gene expression changes. On the molecular level, the major reason for harmful effects of drought stress is found large amount of free radical oxygen burst-out. These radicals could be seriously harmful to cellular activities at high concentration, whereas, they act as a signaling factor at low concentration. This experiment has taken place in Golestan province Agriculture research station in split plot format with RCBD design with four replicate. Drought stress as a main factor included three levels (irrigation after 50, 100, and 150 millimeters evaporation from the A 0in 0in 10pt" dir=rtl Keywords: Gene Expression, Drought Stress, Soybean, Catalase, Chlorophyll amount, DREB 1
