Molecular tagging and marker-assisted selection of fiber quality traits using chromosome segment introgression lines (CSILs) in cotton

Gossypium barbadense L is an important genetic resource to improve fiber quality of Gossypium hirsutum L., but breeders have generally encountered difficulties in introgression following whole genome crosses primarily due to genomic incompatibility, complex genetic basis and low efficiency of phenotypic evaluation and selection on fiber quality. Chromosome segment substitution lines (CSILs) are a powerful tool to dissect and introgress alien alleles while minimizing negative effects from alleles on other chromosome segments of the donor parent. In the present study, using a CSIL+F₂ mapping strategy, three QTLs each for fiber length (FL), fiber strength (FS) and micronaire value (MIC) were identified on chromosome 11 and 1, explaining 6.23–10.73 % of the phenotypic variation in the F_2:3 population. In addition, through marker-assisted backcrossing, the G. barbadense alleles of these QTLs were incorporated into two elite commerical Upland cotton cultivars, Lumianyan28 (L28) and Shannongmian6 (SNM6). Field evaluation indicated that 80 % of the BC₂F₃ lines containing the qFL-c11-1 and qFS-c11-1 from Hai7124 had significantly higher FL and FS, while only 14.5 % BC₂F₃ lines containing the qMIC-c1-1 in SNM6 genetic background showed significant decrease in MIC. Some BC₂F₃ lines with improved target fiber quality traits and without remarkable deviations in non-target lint yield components were obtained.