Evaluation Of Drought Resistance Of Transgenic Tadreb3a Soybean Lines

Soybean is one of the five major crops in the world and an important grain and oil crop.Soybean needs more water during growth and is extremely sensitive to water shortage.Drought has seriously affected the growth and development of soybean,resulting in reduction of yield and quality of soybean.Drought resistance in plants is a complicated process,and a single gene cannot be completed.Applying transcription factors to induce the expression of a series of genes related to drought resistance can achieve the goal of drought resistance.DREB transcription factors are the most widely studied type of transcription factors in recent years.They are protein molecules that can specifically bind to DRE/CRT cis-acting elements in the promoter region of true stone organisms,thus inducing the expression of drought-related genes.Studies have shown that DREB transcription factors participate in abiotic stress responses of many plants and can significantly improve drought resistance of plants.In this study,T₄ transgenic soybean plants with Ta DREB3 a gene and control plants were subjected to PEG simulated drought treatment and PCR identification at bud stage respectively,and 5 positive Ta DREB3 a overexpressed lines were obtained.Drought stress treatment is carried out at seedling stage and flowering stage respectively,and the optimal drought resistance identification period is determined according to phenotypes,measured relative water content,relative conductivity,chlorophyll content and other physiological indexes;Five transgenic lines were divided into drought-resistant grades by drought-resistant membership function values,and two lines with stronger drought resistance were determined.The T₅ generation plants of these two lines were analyzed for gene RNA expression level.Drought resistance physiological indexes such as SOD,POD,CAT,malondialdehyde and proline were systematically determined.Meanwhile,significant differences in agronomic traits such as plant height,pod number,grain number and root length were investigated and analyzed,and the transgenic Ta DREB3 a gene high generation lines with stable genetic drought resistance expression were identified.This will lay a theoretical foundation for clarifying the expression characteristics of Ta DREB3 a gene during drought stress and establishing the identification system of soybean drought-resistant materials.The main research results are as follows:?1?Using polyethylene glycol?PEG-6000?solution to simulate water stress,10 soybean materials of T₄ generation transformed with Ta DREB3 a gene were screened for drought resistance in bud stage,and 6 soybean lines with better drought resistance and germination rate over 90%were screened out.?2?Through PCR detection,Bar gene test strip detection and polyethylene glycol?PEG-6000?solution simulated drought and other methods,6 resistant strains screened in bud stage were screened for drought resistance at seedling stage,and finally 5 positive strains with better drought resistance at seedling stage were determined.?3?Potted drought stress method is adopted to screen the T₄ generation and T₅ generation lines of Ta DREB3 a gene transfer for drought resistance at seedling stage and flowering stage respectively.physiological indexes such as phenotype,leaf relative water content,electrical conductivity,chlorophyll content and the like of the Ta DREB3 a gene transfer line and a control line are subjected to membership functions to classify drought resistance grades,so that seedling stage is determined to be the best drought resistance identification period,and HL16-16-6 and HL16-17-1 lines are determined to be high resistance lines.?4?Fluorescence quantitative PCR analysis of T₅ generation showed that Ta DREB3 a gene was expressed in all parts of transgenic lines,and the expression level in leaves was the highest,followed by root expression.The expression of Ta DREB3 a in transgenic lines increased first with the deepening of stress.The trend of decline after high.?5?Further,through SOD,POD,CAT,MDA,Pro content and other drought-resistant physiological index analysis and agronomic traits analysis of transgenic lines HL16-16-6 and HL16-17-1 T₅,it is proved that HL16-16-6 and HL16-17-1 have significantly higher water retention capacity and antioxidant capacity under drought stress than the control lines,showing stronger drought resistance.