Transformation And Functional Analysis Of Ascorbate Peroxidase OsAPX2 Involved In Drought Tolerance In Soybean(Glycine Max)

Drought stress is an important limiting factor of affecting crop yield increase and quality improvement. According to statistics, crop yield loss caused by drought stress is about the sum of yield loss by all the other abiotic stress factors every year. Thus, to solve this problem, it is an important way to discover and development drought-tolerant plants and breed new varieties of genetically modified drought-tolerant plants.In this study, rice ascorbate peroxidase Os APX2 was transformed into different soybean varieties to research the function of Os APX2 under drought tolerance conditions, and to obtain transgenic germplasms for breeding new lines of drought tolerance transgenic soybean plants(species) in the future. The main results were as follows: 1. The ability of Os APX2 in improving drought tolerance was confirmed by Agrobacterium rhizogenes mediated transformation of soybean hairy root. Os APX2-GUS, Os APX2-GFP fusion constructs were made and transformed into Agrobacterium rhizogenes strain K599, and transgenic soybean hairy roots were detected by PCR, with p BI121-GUS, p Cam A-GFP, p Cambia3301-Os APX2 constructs as negative controls. GUS staining and fluorescence microscopy observations proved that the fusion gene Os APX2::GUS, Os APX2::GFP can express in soybean hairy roots normally. In the conditions of drought stress, the accumulation of hydrogen peroxide (H2O2), malondialdehyde(MDA) and proline(Pro) in soybean hairy roots of transgenic Os APX2::GUS and Os APX2::GFP were significantly lower than that in the wild-type soybean plants, which indicates that Os APX2 improves drought tolerance in the hairy roots of transgenic soybeans.2. The function of Os APX2 in improving drought tolerance was verified by Agrobacterium tumefaciens mediated transformation of soybean plants. With Agrobacterium mediated cotyledonary-node and germ tip transformation method, Os APX2 was introduced into different soybean varieties and nine transgenic lines was obtained by PCR test. Real-time quantitative PCR data indicated that the expression level of the target gene in nine transgenic lines was significantlt different, with the L1, L2, L33 and L34 lines displayed higher than others. Ascorbate peroxidase activity of Os APX2 in L1, L2, L33 and L34 lines was also higher, which is consistent with real-time quantitative PCR results; In the conditions of drought stress, the accumulation of H2O2, MDA, Pro were lower in L33 and L34 transgenic lines compared with the wild-type soybean plants, and the relative water content in transgenic soybean leaves were not significantly changed, which indicates that Os APX2 could improve drought tolerance in genetically modified soybean plants. 3. The new transgenic soybean germplasms with Os APX2 were obtained via pollen tube pathway transformation method. Based on the ability in drought tolerance, Os APX2 was introduced into soybean varieties which presented excellent traits of agronomic, yield and larger application. And some new transgenic germplasms of Os APX2 with excellent comprehensive traits and drought-tolerant property were acquired.