Mechanism Study Of CAT-regulated Rice Leaves Antioxidant System In Photorespiration

Catalase is one of main antioxidases in organism, H2O2which was produced in peroxisome can be decomposed into O2and H2O. There are3isozymes in rice:CATA, CATB, CATC. OsCATA CDS fulllength was amplified from rice cDNA, overexpression and interference vector was constructed and transformed into rice, interfere vector positive plant was got and its seeds were harvested. After treated with different gases, the activity of antioxidase and the content of antioxidant substance. The tests mainly include the following aspects:Firstly, Leaves from the japonica variety Nipponbare full-length gene was cloned OsCATA CDS sequence, sequencing results showed that, OsCATA gene length CDS is1488bp, contains all of exon sequences with the NCBI database sequence homology is100%.Secondly, Constructed overexpression rice OsCATA carrier interference vector with GUS and hygromycin gene, and through Agrobacterium-mediated transformation of rice by GUS histochemical activity assay and the total DNA PCR detection and identification, screening out interference vector transfer positive plants and empty vector transfected positive plants.Thirdly, RT PCR results showed that CATA gene of interference rice, expression is controlled36.8%; western results show that the interference vector transfected CAT protein synthesis decreased rice, basically not detected; activity results showed that CAT activity in turn interfere with the carrier for the control of rice0.85%, with the western similar results.Finally, by gas transgenic plants stress to the empty vector plants and gene interference phenotypic and physiological analysis of the indicators, interference the CATA activity of the plants was significantly lower than the control plants, a significant increase in the activity of other antioxidant enzymes. The determination of the rate of photosynthesis and photorespiration, interference plants was significantly lower than the control plants.MDA, hydrogen peroxide (H2O2) and superoxide anion radical (O2·-) was significantly higher than the control plants. In addition, the interference rice also showed increased activities of antioxidant enzymes ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD) and Superoxide Dismutase (SOD) compared to control plants.The results show that between different gas treatment, compared with no treatment, empty vector transfected rice at high CO2treatments, CAT, POD, GPX, GR activity decreased; at low02treatments, CAT, POD, GPX, GR, SOD, APX activity increased; at high02treatments, CAT, POD, GPX, GR, SOD, APX activity increased; Three gas treatment two weeks later, rubisco oxygenase activity was decreased slightly.