Mapping Of QTL For Important Agronomic Traits From A Population Of G.hirsutum Line × G.hirsutum Race Punctatum

Cotton is the primary economic crop that can produce natural fiber.As the main cultivation of cotton,upland cotton has good high yield and relatively high fiber quality.However,due to long-term orientation selection and using founder parents,the genetic diversity of G.hirsutum has become a bottleneck problem of genetic improvement.G.hirsutum race punctatum is one of semi-wild cotton,which is unique in boll setting,fiber quality and drought resistance.By crossing G.hirsutum and G.hirsutum race punctatum,the favorable genes of punctatum can be introduced into G.hirsutum,which is an effective way to solve the narrow genetic diversity of G.hirsutum.In this study,a recombinant inbred line(RIL)population,consisting of 185 lines,was established from a cross between Gossypium hirsutum accession HN10-1and G.hirsutum race punctatum accession TX-230.Construction of high-density genetic maps using SLAF-seq sequencing developed SNP markers and complementary SSR markers.Combining phenotypic data across multiple environments to identify cotton yield and fiber quality trait QTL.The main results are as follows:1.Construction of genetic mapThe genetic map contains a total of 3136 loci(3024 SNP loci,112 SSR loci),which 1623 loci(1577 SNP loci and 46 SSR loci)were on subgenome A and 1513 loci on subgenome D(1447 SNP loci and 66 SSR loci).The total length of the genetic map was 4590.574 c M(2286.88 c M for subgenome A and 2303.694 c M for subgenome D),the average interval between markers was 1.57 c M,and the genome coverage was98.14%.2.Performance of yield and fiber quality traitsThe results of the two-year yield and fiber quality traits of the population showed that the population variation range was wide,and the whole showed a continuous normal distribution.Except for lint index,the maximum values of all other yield and fiber quality traits were larger than those of the parent,showing obvious transgressive inheritance.Analysis of variance showed that each character was affected by genotype and environment,and all traits were in line with the characteristics of quantitative traits.Correlation analysis results showed that the seed index were very significant negative correlation with lint percentage and fiber micronaire,fiber micronaire were very significant negative correlation with fiber strength and fiber length.There was a very significant positive correlation between boll weight,lint precentage,lint index,fiber length,fiber uniformity,fiber strength,and fiber elongation in at least one environment.3.Identification of QTL for yield and fiber quality traitsA total of 161 yield and fiber quality QTL were identified.Among them,there were 113 yield QTL(18 QTL for boll weight,37 QTL for lint percentage,40 QTL for lint index and 18 QTL for seed index),and 48 fiber quality QTL(14 QTL for fiber length,8 QTL for fiber uniformity,7 QTL for fiber strength,11 QTL for fiber micronleons and 8 QTL for fiber elongation).There were 88 QTL in subgenome A,including 59 yield QTL and 29 fiber quality QTL.There were 74 QTL in subgenome D,including 54 yield QTL and 20 fiber quality traits QTL.The LOD values ranged from2.01 to 11.14,explaining 4.9 to 27% of the phenotypic variation.A total of 42 QTL were stable across multiple environments,of which 34 QTL were detected in two environments and 8 QTL were detected in three environments.100 QTL were distributed in 41 QTL clusters on 19 chromosomes.Subgenome A contained 23 QTL clusters,and subgenome D contained 18 QTL clusters.