Mining Genes Related To Lint Percentage In Cotton (G.hirsutum L.)based On BSA-Seq Method

Cotton is an important cash crop,which is closely related to the basic necessities of the people.With the improvement of people’s living quality,people’s demand for cotton textile is increasing day by day,and the contradiction between grain and cotton for land is becoming increasingly serious,resulting in insufficient supply of cotton industry.Therefore,increasing cotton yield has become the main goal of breeding work at present.Lint percentage is positively correlated with lint yield,the increase of lint percentage is of great significance to the increase of cotton yield.In this study,F₂ and F_2:3 segregating populations were constructed with an upland cotton variety of CCRI127 with excellent fiber quality as male parent and high lint percentage line of GH07-44 as female parent.According to phenotypic performance of yield and fiber quality traits in the segregated populations,the extreme phenotypic individual plants were select to construct extreme mixed pools for lint percentage and fiber length,and identify major QTLs related to lint percentage and fiber length using high-throughput sequencing technology.Indel markers were developed to fine identify lint percentage major QTLs and the candidate genes.1.There are abundant genetic variation and super parent separation in F₂ and F_2:3populations.The coefficient of variation is 1.15%～15.19%,and the proportion of super parent separation is 1.71%～66.86%for the fiber yield and quality traits.The skewness and kurtosis of each trait is less than 1,which showed the normal distribution for the fiber yield and quality traits.Simple correlation analysis showed that lint percentage was significantly positively correlated with micronaire value and maturity,and significantly negatively correlated with fiber length and uniformity.Canonical correlation analysis showed the relative correlation between yield traits group and fiber quality traits group.In this study,nine materials with better fiber quality and more than 43%of lint percentage in F₂ and F_2:3 were selected（mean micronaire value<4.5,mean fiber length>30 mm）,which provided basic materials for the synchronous improvement of cotton yield and fiber quality.2.Three lint percentage candidate regions with a total length of 10.52 Mb for q LP-A06-1,8.67 Mb for q LP-A08-1 and 28.7 Mb for q LP-A13-1were located.by BSA-seq method.And four fiber length candidate regions with a total length of 62.26 Mb were located on chromosomes A03,A06,A10 and A13.3.Referring to the reference genome of TM-1,In Del marker was developed to fine identify the q LP-A06-1 for the lint percentage with the additive effect of 0.45,the LOD value of 3.46,and the explained variance rate of 2.59%on the region between primers 4-32 and L-12 with the length of 0.8Mb which included 41 genes.Combined with parental resequencing,transcriptome data,and fluorescence quantitative analysis,two differentially expressed candidate genes of GH＿A06G1851and GH＿A06G1860 were selected in the region of lint percentage.In this study,the major QTLs of lint percentage were located by BSA-seq technology,and the candidate genes related to lint percentage were screened,which laid a foundation for the genetic improvement of lint percentage traits.