Mapping QTL For Fiber Yield And Quality From A (G.Hirsutum Cultivar × G.Hirsutum Race Punctatum) Population

Cotton is a natural fiber crop and an indispensable raw material for the textile industry.At the same time,cotton is also an important oil source crop.After processing and production of cottonseed,it can be an indispensable non-polluting diesel and highquality vegetable oil in our lives.Upland cotton has a wide range of cultivation and high yield,but the genetic basis within species is relatively narrow,which cannot meet the increasing demand for cotton improvement.Gossypium hirsutum races are closely related to Gossypium hirsutum cultivars.The hybrid offspring are fertile and can be directly used as breeding materials;and the races of upland cotton have many excellent traits,such as remarkable resistance to insects,disease resistance,drought-and salttolerant ability for broadening the genetic basis of upland cotton.In this study,upland cotton cultivar CCRI35 as female parent was crossed with G.hirsutum race punctatum accession TX-230 as male parent to construct a recombinant inbred line population.SLAF-seq SNP and SSR were used to construct a high-density genetic linkage map,and QTL yield and fiber quality traits were identified.The main findings are as follows:1.Performance of fiber quality traitsIn the four environments from 2019 to 2020,the yield and fiber quality traits of population are continuously distributed.The correlation analysis shows that in all four environments,fiber uniformity,fiber elongation,fiber length,and fiber strength are all significantly positively correlated;seed index and lint index are both extremely significantly negative correlation;lint index and micronaire value are extremely significantly positively correlated;in the three environments of 2019 Hainan,2020 Kuerle,and 2020 Kuitun,lint index are significantly positive with boll weight,seed index,fiber length,and micronaire value,respectively.2.Construction of genetic mapThe SNPs detected by SLAF-seq and SSRs were used to construct a high-density genetic map.The map contained 2412 loci(2338 SNP and 74 SSR),the total map distance is 4696.77 c M,and the average genetic distance between markers is 1.95 cM.Sub-genome A has 1354 loci with a coverage length of 2434.55 cM,and the average genetic distance between markers is 1.80 c M.Sub-genome D has 1058 loci,with a coverage length of 2262.25 cM,and an average genetic distance between markers of 2.14 cM.3.Detection of yield and fiber quality QTLA total of 130 QTL for yield and fiber quality traits were mapped,including 81 QTL for yield traits and 49 QTL for fiber quality.Six QTL could be detected under 4 environments(5 QTL for lint percentage,1 QTL for seed index);9 QTL could be detected under 3 environments(6 QTL for lint percentage,2 QTL for lint index QTL,1 seed index QTL);28 QTL could be detected under 2 environments(14 lint percentage QTL,4 seed index QTL,5 lint index QTL,1 boll weight QTL,4 fiber length QTL).These stable QTL detected in 3 or 4 environments can be used for the next step of fine mapping and map-based cloning.