Identification Of Soybean Salt Tolerance Genes And Their Application In Breeding

Soybean originated from China is an important crop for oil,food and forage production.However,our domestic soybean yield is far from meeting the needs of demand,and a large number of imports are need.How to solve the increasing import of soybean in our domestic is the key problem to be solved urgently.At present,the area of land suffers from salinization is increasing year by year in China,breeding for soybean varieties with improved salt tolerance is one of the effective approaches to utilize the salinized land,increasing soybean growth area,raising soybean production in China,and lightening our dependence of soybean importation.Soybean response to salt stress is a complex biological process,which depends on the co-expression of multiple genes in a complex network.At present,although some progresses has been made in understanding the mechanism of soybean response to salt tolerance,the meolecular mechanism of its salt tolerance network is still not very clear.In this study,transcriptome techniques were used to study genes response to soybean seedlings under salt stress,which laid a solid foundation for analyzing the mechanism of soybean salt tolerant network and cultivating salt tolerant varieties.Firstly,the collected soybean varieties were evaluated for their survival probability under salt stress and salt tolerance and sensitive materials were identified,respectively.Two selected materials were treated with salt stress at different time periods of 0,2,4 and 8 h at soybean seedlings,and transcriptome sequencing was performed on the collected root samples.The resulting transcriptome data was then screed for differentially expressed genes,and genes show significant differential expression were further used for function enrichment as well as pathway enrichment analysis.Two salt-tolerant candidate genes were identified and their gene functions were verified using hairy roots system of soybean.The major findings of the present research are as follows:(1)The salt-tolerant material Qi Huang34 and the salt-sensitive material Dong Nong50 were selected from the 22 soybean materials in the laboratory;(2)Total 6113 differentially expressed genes were obtained from the transcriptome data of the samples under salt stress,of which,657,3421 and 2035 differentially expressed genes were identified from sampled treated with salt after 2,4 and 8 h,respectively.At the same time 101 differential expressed genes were shared at time periods of 2,4 and 8 h;(3)Functional annotation,metabolic pathway enrichment and expression pattern analysis of differentially expressed genes were performed to identify salt-tolerant candidate genes GmCCoAOMT1(Glyma.01G187700)and GMCYP75B1(Glyma.06G202300),and the gene function was verified by soybean hairy roots;(4)Through the analysis of the relative elongation of hairy roots,growth status and above-ground phenotype of transgenic plants under salt stress,the results showed that the overexpression of GmCCoAOMT1 and GmCYP75B1 could improve the salt tolerance of soybean plants,which would provide an important theoretical basis for the mining of soybean salt tolerance genes and the cultivation of salt tolerant varieties.