QTL Mapping Of Saline-alkaline Tolerance Related Genes At The Seedling Stage In Wild Soybean

Soil salinization is a worldwide resource and ecological problem that severely constrains crop production and agricultural development.Increasing the salt tolerance of crops has important practical significance for improving agricultural production and expanding arable land.As a near-wild species of cultivated soybean,wild soybean has formed a large number of excellent traits during the evolution process,and has no reproductive isolation from cultivated soybeans so that is easy to exchange genetic material,thus wild soybean has becoming an important genetic germplasm for soybean breeding material.In this experiment,salt-tolerant wild soybean ZYD000659 and sensitive saline-alkaline cultivated soybean Jikedou No.1 were selected as parents,and F_10:11recombinant inbred lines（RIL）containing 111 strains.Using molecular markers technique constructs a high-density genetic map containing 4024 single nucleotide polymorphisms（SNPs）molecular markers,and combines the resistance of a single plant to salt and alkaline in a population to locat salt and alkaline tolerance related quantitative trait loci（Quantitative trait locus,QTL）.Candidate genes are predicted by changes in the relative expression of genes and analyzed.The main results of this study are as follows:1.Identification of salt and alkali resistance of parents and populations at seedling stage and correlation analysis with other phenotypic traitsThe salt-alkali stress was applied to the population by the combination of Na₂CO₃ and Na HCO₃ mixed lye at a concentration of 100 m M and pH=8.85.The relative salt-alkali damage index（SDI）at the seedling stage was used as an indicator.The tolerance of the female Jikedou No.1 to salt-alkali was Sensitive（SDI=1）,the tolerance of the father ZYD000659 to salt-alkali is medium tolerance（SDI=0.56）.and the material of mediumresistance（0.4<SDI≤0.7）to salt-alkali in the RIL₁₀population is 13,which is lesssensitive（0.7<SDI≤0.9）material was 51 parts,and thesensitive material（0.9<SDI≤1）was 47 parts.It is also clear that the salt tolerance and alkalinity at seedling stage are significantly correlated with the two traits of 100-grain weight and grain thickness,and are significantly correlated with grain width.2.QTL mapping interval for salt-alkali tolerant-related genes was obtainedThree QTLs were detected by the composite interval mapping method,which were located in the 10th and 16th linkage groups,respectively.The 10th linkage group colocalized to two QTLs,q SAT10-1 could explain 14.91%of genetic variation,q SAT10-2 could explain 8.07%of genetic variation;q SAT16 located in the 16th linkage group could explain 16.71%of genetic variation.A single-interval mapping method was used to detect a QTL locus q SAT4 at the 4th linkage group,which explained 13.45%of the genetic variation.The SSR molecular marker was further screened in the q SAT10-1 localization interval,and finally the candidate gene was restricted to the 112 kb region of the 10th linkage group.3.Validation of differences in expression levels and sequences of candidate genes between parents linesAccording to the relative quantitative analysis of real-time PCR,the Glyma.10g004700 gene was induced differently at different time points of stress treat ment and differences in the parents.Therefore,the gene Glyma.10g004700 was initially identified as a candidate gene.The gene contains three exons and two intron segments,and the male parent has seven SNPs in the exon region,which results in three SNP sites encoding amino acid changes.