Environmental Safety Of Transgenic TaDREB3a Drought-resistant Soybean Lines Bert-DB3-2

China,as the country of origin of soybean,has more than five thousand years of planting history.For current time,the development of soybean industry is facing severe challenges in China.China imported 93 million tons of soybean in 2021,it means the rate of self-sufficiency of soybean is less than 15%.The transgenic soybean has achieved big success which totally changed the production model and trade structure of soybean worldwide.Under this kind of situation,the development of transgenic soybean is really urgent in our country.Although planting of transgenic soybean can offer us with economic benefits,the ecological risks of post-release cannot be ignored.Thus,it is necessary to conduct environmental safety evaluation of those transgenic soybean lines which have possibility to use.In this study,based on our previous obtained stress-resistant soybean Bert-DB3-2,a line that staying in the stage of environment release,which contains TaDREB3a gene,we identified genetic stability,drought-resistance and herbicide-tolerance of both transgenic soybean Bert-DB3-2 and receptor Bert.Also we systematically evaluated the transmission ability,reproductivity,dormancy period and adaptability of both lines.The main results are showed here:1 Using PCR technology,the target gene TaDREB3a and marker gene Bar were tested in T₂-T₄generations of transgenic soybean Bert-DB3-2,the results showed that the target gene TaDREB3a and marker gene Bar can be inherited stably in transgenic soybean Bert-DB3-2 for 3 consecutive generations.2 qPCR results indicated that the target gene and marker gene can express in different tissues in transgenic soybean Bert-DB3-2 T₂ to T₄ generations.Especially,the expression level is relatively high in leaves,but relatively low in seeds.Western blot results showed that TaDREB3a and Bar protein can be expressed stably in T₂ to T₄ generations.Elisa was also used to quantitatively test TaDREB3a protein level in Bert-DB3-2 T₄ generation.The TaDREB3a and Bar protein expressed in roots,stems,leaves,pod skin and seeds in transgenic T₄ generation,especially,the TaDREB3a protein content in leaves has the highest level in seedling stage,flowering and podding stage and filling stage.The TaDREB3a level is relatively high in leaves of mature stage and in pod skin of flowering and podding stage.3 Drought treatment was carried out for transgenic Bert-DB3-2 at germination,seedling and whole growth stages,and evaluated drought resistance of Bert-DB3-2 in both greenhouse and field.In germination stage,the drought resistance of transgenic Bert-DB3-2 T₂ to T₄ generations are higher than receptor significantly and the drought resistance is resistant,while the receptor Bert is relatively resistant.After two times of drought treatment in seedlings stage,the survival rate of T₄transgenic plants is 85%±5%,and the drought resistance is relatively resistant.However,the survival rate of receptor Bert is 43.3%±5.8%,which is relatively sensitive.For whole growth stage,after drought resistance treatment,the number of 2-branches,pods per plant,seeds per plant and seeds weight of transgenic soybean Bert-DB3-2 are higher than receptor Bert significantly,which means that transgenic soybean Bert-DB3-2 has high drought resistance in whole growth stage.4 Analysis of tolerance and resistance of transgenic soybean Bert-DB3-2 against target and non-target herbicides.The results showed that transgenic T₄generations displayed good tolerance to 1500 ppm BASTA.To non-target herbicides like Glyphosate,Enoxadine and Benazone,there is no significantly differences were found between transgenic plants and receptor.These results indicated that expressing TaDREB3a and Bar in receptor Bert wasn’t change the resistance against non-target herbicides.5 Analysis of dispersal capacity of transgenic soybean Bert-DB3-2.There is no significantly differences in pollen diameter and viability between Bert-DB3-2 and Bert.Germination rate of pollen was also not that significantly different between transgenic plants and receptor after treatment with 25℃,30℃and 35℃for 1 h,3 h and 6 h,respectively.This suggested that the dispersal capacity wasn’t change when expressing TaDREB3a and Bar in receptor.6 Analysis of reproductivity of transgenic soybean Bert-DB3-2.The setting rate of Bert-DB3-2 is 83.82%±8.93%,which is no significant difference with receptor.The germination rate of transgenic plants also showed no significant difference compared to receptor.These results indicated that reproductivity isn’t change after expressing TaDREB3a in receptor.7 Analysis of dormancy period and adaptability of transgenic soybean Bert-DB3-2.The results showed that expressing TaDREB3a in receptor soybean Bert only increase ability of dough resistance,but not change their dormancy and adaptability.8 Analysis of seeds protein and oil content of transgenic Bert-DB3-2.The protein and oil content of transgenic Bert-DB3-2 is 40.90±0.44 and 20.37±0.12,respectively,which displayed no significant difference with receptor Bert,suggesting that expressing TaDREB3a in Bert is not change its nutrition.