QTL mapping for fiber quality traits across multiple generations and environments in upland cotton

Identification of quantitative trait loci (QTL) for fiber quality traits that are stable across multiple generations and environments could facilitate marker-assisted selection for improving cotton strains. In the present study, F-2, F-2:3, and recombinant inbred lines (RILs, F (6:8) ) populations derived from an upland cotton (Gossypium hirsutum L.) cross between strain 0-153, which has excellent fiber quality, and strain sGK9708, a commercial transgenic cultivar, were constructed for QTL tagging of fiber quality. We used 5,742 simple sequence repeat primer pairs to screen for polymorphisms between the two parent strains. Linkage maps of F-2 and RILs were constructed, containing 155 and 190 loci and with a total map distance of 959.4 centimorgans (cM) and 700.9 cM, respectively. We screened fiber quality QTL across multiple generations and environments through composite interval mapping of fiber quality data. Specifically, we studied F-2 and F-2:3 family lines from Anyang (Henan Province) in 2003 and 2004 and RILs in Anyang in 2007 and Anyang, Quzhou (Hebei Province), and Linqing (Shandong Province) in 2008. We identified 50 QTL for fiber quality: 10 for fiber strength, 10 for fiber length, 10 for micronaire, eight for fiber uniformity, and 12 for fiber elongation. Nine of these fiber quality QTL were identified in F-2, F-2:3 and RILs simultaneously. Two QTL for fiber strength on chromosomes C7 and C25 were detected in all three generations and all four environments and explained 16.67-27.86% and 9.43-21.36% of the phenotypic variation, respectively. These stable QTL for fiber quality traits could be used for marker assisted selection.