QTL Mapping and Genetic Analysis of Fiber Quality Traits in Hybrid Cotton

‘Ji1518’ is a new hybrid cotton variety suitable for mechanized harvesting, the two parents of ‘Ji228’ and ‘Ji567’ were crossed to established F2, F2:3 and F2:9 (recombinant inbred lines RILs) population. Simple sequence repeats (SSR) was performed to construct two different genetic maps based on the F2 and F2:9 populations respectively. The QTL mapping of five fiber quality traits was performed in three populations above. A genetic map was constructed by F2 population, which contained 15 loci in 4 linkage groups, with a full-length coverage of 237.10 cM. While the other linkage map was constructed by F2:9 population, which contained 45 loci in 11 linkage groups, with a full-length coverage of 554.42. Based on the inclusive composite interval mapping method with QTL IciMapping 4.1, 15 QTLs related to upper half mean length, fiber strength, the micronaire value, the elongation and the uniformity were both detected in F2 and F2:3 segregating populations, among them, the QTL locus qFM-4-2 related to the micronaire value explained the highest phenotypic variation rate at 21.10%. QTLs with dominant or super-dominant effects accounted for 66.7% of the total, which showed that dominant genes were the main source of fiber quality heterosis in ‘Ji1518’. Meanwhile, 6 QTLs related to the above five traits of fiber quality were detected in the RIL (F2:9) population, and the contribution rate was between 5.10% and 10.26%. QTL loci related with FS and MIC were detected near HAU2349 in all three populations, and QTL loci related with FU were detected near HAU2710 in all three populations, and the markers above were linked on A6 chromosome. These stable and common QTLs are beneficial to the MAS breeding, which could improve the breeding efficiency.