| Soybean(Glycine max L.)is one of the most important food and oil crops in the world,and soil salinization seriously affects soybean yield and quality.To locate soybean salt-tolerant genes,and then to cultivate salt-tolerant varieties is one of the important ways to improve soybean salt-tolerance.In this study,128 RIL populations constructed by crosses between the salt-tolerant cultivated soybean variety Jinda 53 and the salt-sensitive wild soybean variety Pingnan were used for QTL mapping of salt-tolerant traits,and the salt-tolerance identification of soybean seedlings was conducted using nutrient solution hydroponics.Using the greenhouse pot culture method to identify the salt tolerance in the flowering and pod stage and maturity of soybeans,combined with the constructed genetic map to locate the salt tolerance traits QTL,and then screen the stable and common salt tolerance QTL loci,Analysis salt tolerance genes sequence of the candidate segment variation and expression difference.The main findings are as follows:1.The salt tolerance of the two-year soybean RIL population at the seedling stage was identified and QTL mapping for the salt tolerance traits were carried out.The salt tolerance traits of the two-year population control group were mapped to 16 QTL loci,which were distributed on 9 different chromosomes.The treatment group salt tolerance traits and the relative values of salt tolerance traits were co-mapped to 28 QTL loci,which were distributed on 14 different chromosomes.Among them,chromosome 3 and chromosome 13 have two-year concentrated QTL loci for traits.2.QTL mapping for the salt tolerance traits in the flowering and pod stage of soybean,each of the salt tolerance traits was mapped to 22 QTL loci,distributed on 10 different chromosomes,and after removing the QTL loci that are not related to salt tolerance,there are multiple concentrated QTL loci on chromosome 3’s72.5 c M-84.5 c M and 93.5 c M-115.5 c M on chromosome 13.3.QTL mapping for salt-tolerant traits in soybean maturity.All salt-tolerant traits were mapped to 22 QTL loci which were distributed on 11 different chromosomes,which may be greatly affected by the environment,these QTL loci were scattered and no multiple centralized QTL loci were found.4.Correlation analysis of the respective salt tolerance traits of soybeans at the three stages showed that the same type of salt tolerance traits showed an obvious positive correlation.The salt stress had the same effect on the same salt tolerance traits.The results of the variance analysis of the salt tolerance traits at the seedling stage showed that the environment and salt stress treatment together affect the variation of salt tolerance traits.The population was divided into salt tolerance grades based on the salt tolerance traits,and the families of No.82 and 161 are salt-tolerant varieties in the seedling stage and the family No.71 is the salt-tolerant variety in the middle and late stages of soybean growth.It was also found that the families of the population had different periods of soybean growth may have different salt tolerance grade and salt tolerance.5.A comprehensive analysis of the salt-tolerant QTL loci located in the three stages of soybean growth was carried out to find a stable co-locus of salt-tolerance.As a result,the 80 c M of chromosome 3 and 115 c M of chromosome 13 were selected as candidate segments.5 and 13 salt-tolerant-related genes were obtained at the corresponding positions on the 2 chromosomes of the reference genome,and only two genes,Glyma.03g166900 and Glyma.13g303600,had effective SNP mutation sites in the exon regions of the two genes,and these two genes were used as candidate genes.6.Analyzed the expression of candidate genes in the tissues of salt-sensitive and salt-tolerant soybean materials after salt stress.It was found that the expression of the two candidate genes in the tissues of salttolerant materials was higher than that of the control after salt stress.However,the expression level in all tissues of the sensitive salt material was lower than the control as a whole,which indicated that the candidate gene may be related to the salt tolerance of soybean. |
