Fine Mapping Of Salt Tolerance Genes In Soybean Seedling Stage

Soybean is an important oil crop and cash crop,which occupies an important position in agricultural production.Previous studies have shown that soybean is a moderately salt-tolerant crop,and the increasingly severe salinization of soil will cause damage to soybean such as seed germination rate,plant height,fresh weight reduction in underground and overground parts,leaf yellowing and even necrosis,and reduced yield,which will seriously affect soybean plant growth and agricultural production.Therefore,salt tolerance gene and salt tolerance mechanism of soybean should be studied to cultivate salt tolerance soybean varieties.But the salt tolerance mechanism of soybean is not fully understood.In this paper,the salt tolerance phenotype of soybean seedling was firstly identified by using the recombinant inbred line population derived from the crosses of Guizao 1×Brazil 13(GB13).Then,the obtained localization interval was analyzed and the possible candidate genes were predicted,and the following conclusions were obtained:The salt tolerance of the recombined inbred line was identified by three indexes:sodium ion content,leaf chlorosis classification and chlorophyll content ratio.The results showed that the salt tolerance of the recombined inbred line was significantly different among different lines of the population material,but the data were positively or negatively distributed on the whole.The leaves of the colony material were yellowed,with the highest reaching level 1 and the lowest reaching level 5.The chlorophyll content ratio of leaves was 0.46 at the lowest and 1.18 at the highest.The content of sodium ions in the leaves ranged from 301.06mg/Kg to 2025mg/Kg.Three salt tolerance indexes were used to distinguish the salt tolerance of different lineages.The phenotypic data obtained were used to map the salt-tolerant QTL of the recombinant inbred line population,and a total of 23 salt-tolerant QTL sites were obtained,distributed on 9 chromosomes.Through analysis,there are 10 QTL loci that are different from the predecessor localization results,7 QTL loci are on the same chromosome and close to the predecessor results,and 6 QTL loci are consistent with the predecessor location results.Among them,the content of sodium ions in leaves and the chlorosis of leaves were used as salt tolerance indicators to locate a stable QTL site on chromosome 6Gm6＿bin114-bin145.The LOD value was 2.76-5.85,and the interpretation rate of phenotypic variation was 2.64-10.28.A stable QTL was located in the Gm14＿bin109-130 interval of chromosome 14 and the Gm17＿bin110-bin141 interval of chromosome 17 by using the ratio of leaf sodium ion content and chlorophyll content as indicators,with LOD values of 5.27-8.50 and 5.06-6.20,phenotypic variation the interpretation rates are2.92-5.82 and 3.53-4.23.Through the Soybase and phytozome databases,the genes in the three stable QTL loci on chromosomes 6,14 and 17 were analyzed,and the function of the genes was further predicted.Combining annotations and previous studies,five possibilities were speculated The candidate genes include Glyma.06G260200,Glyma.06G260300,Glyma.06G271600,Glyma.14G152100 and Glyma.17G207900.