Cloning And Analysis Of Drought Stress Genes In Soybean

RT-PCR and3’race technology were used to clone drought stress related genes insoybean. Seven different soybean varieties were used as materials to research theexpression levels of the drought stress related genes and the relevant physiologicaland biochemical indexes under the drought stress conditions. The drought conditionswere imitated with20%PEG6000at soybean seedling stage. Changes in expressionlevels of the drought stress related related genes were measured by semi-quantitativeRT-PCR method. Superoxide dismutase (SOD) and peroxidase (POD) activities andfree proline (Pro), soluble sugar (WSS), chlorophyll and malondialdehyde (MDA)contents and expression levels of the drought stress related genes were measured fromthe first day to sixth day after drought treatment.The size of cloned drought stress related gene sequence was3375bp, andsuccessfully registered in the GenBank (accession number KJ017967). It was polgenes sequence of Ty3-gypsy type retrotransposons which containing three openreading frames. Their length were597bp,543bp and951bp, and they encodedreverse transcriptase, RNaseH and integrase respectively. The three genes werenamed GmRT, GmRNaseH and GmINT.Semi quantitative RT-PCR system of the drought stress related genes wasestablished in this study. The result showed that expression amount of the genesincreased after drought stress. So the conclusion could be reached that the expressionof cloned drought related transposon genes were induced by drought.The activities of SOD and POD increased at first and decreased later with theincrease of stress time. Contents of Pro, WSS and MDA appeared rise continually.Meanwhile, chlorophyll contents increased in the first day to second day. Theresponse speed of SOD and POD of wild soybeans to drought stress was significantlyfaster than that of cultivated soybeans. Chlorophyll content of wild soybeans changedrelatively gently, while the variation of cultivated soybeans was drastic. MDA contentof wild soybeans grew much less than cultivated varieties during the whole drought stress.