Construction Of High-density Genetic Map And QTL Analysis Of Lint Percentage In Upland Cotton

Cotton (Gossypium spp.) not only provides most of the world’s natural fiber, but also is an important source of pant pritein and oil. The genus Gossypium comprises of about45diploid (n=x=13) and5tetraploid species (n=2x=26). Of the species, cultivated species are diploid G. arboretum and G. herbaceum, and tetraploid G. hirsutum and G. barbadense. As a major cultivated species, upland cotton, G. hirsutum accounted for more than95%of world production.At present, breeding cotton varieties with high yield and high fiber is still the main object. Traditional breeding methods characterize with long time and low efficiency. Therefore, it needs a high efficiency method of genetic improvement.Marker assisted selection based DNA marker technology provides a high efficiency method of genetic improvement. Marker assisted selection need to construct high marker-density genetic linkage and to exactly identify the gene controlling the targeted traits. However, the genetic map constructed from upland cotton has low maker density, and it cann’t meet the requirement of marker assited slection for cotton yield and fiber quality impovement.Based on the genetic map constrcted from (Yumian1×T586) recombinant inbred line population in our laboratory, the present study increases the marker density of previous genetic map using new available SSR and detects QTL controlling lint percentage, and the results are as following:1. Screening of polymorphic primers between mapping parents and genotyping of populationIn total,2,449NBRI new SSR primer pairs,100NBRI new SSR primer pairs and 23,060SSR primer pairs early used to construct the genetic map in recombinant inbred line population (Yumian1×T586), were used to screen the polymorphic primers between Yumian1and T586, and475new SSR polymorphic primers were obtained. The475SSR polymorphic primers were used to genotype recombinant inbred line population (Yumian1×T586), and489marker loci were obtained.2. Increasing marker density of genetic mapA total of2,069loci including489loci obtained in the present study,1,572loci obtained in our lab’s previous study and8morphic makers were employed to perform the linkage analysis, and a genetic map with2,019marker loci was obtained. The map spanned3,592.2cM with an average distance of1.8cM between two markers. A-genome contained992loci, and spanned1,733.3cM with an average distance of1.8cM between two markers. D-genome contained1027loci, and spanned1,858.9cM with an average distance of1.8cM between two markers.3. QTL mapping of lint percentageBased on the updated genetic map and the phenotypic data of lint percentage in two environments (in2011and2012), seven QTL for lint percentage were detected. These QTL explained phenotypic variation from3.5%to52.7%. Among the QTL detected, three QTL were detected in two environments and three QTL were identified in the same QTL-region in other populations. Six favorable alleles of QTL derived from Yumian1, and one favorable allele derived from T586.