Abstract
The improvement of fiber quality is an essential goal in cotton breeding. In our previous studies, several quantitative trait loci (QTLs) contributing to improved fiber quality were identified in different introgressed chromosomal regions from Sea Island cotton (Gossypium barbadense L.) in a primary introgression population (Pop. A) of upland cotton (G. hirsutum L.). In the present study, to finely map introgressed major QTLs and accurately dissect the genetic contribution of the target introgressed chromosomal segments, we backcrossed two selected recombinant inbred lines (RILs) that presented desirable high fiber quality with their high lint-yielding recurrent parent to ultimately develop two secondary mapping populations (Pop. B and Pop. C). Totals of 20 and 27 QTLs for fiber quality were detected in Pop. B and Pop. C, respectively, including four and five for fiber length, four and eight for fiber micronaire, two and four for fiber uniformity, five and four for fiber elongation, and six and four for fiber strength, respectively. Two QTLs for lint percentage were detected only in Pop. C. In addition, seven stable QTLs were identified, including two for both fiber length and fiber strength and three for fiber elongation. Five QTL clusters for fiber quality were identified in the introgressed chromosomal regions, and negative effects of these chromosomal regions on lint percentage (a major lint yield parameter) were not observed. Candidate genes with a QTL-cluster associated with fiber strength and fiber length in the introgressed region of Chr.7 were further identified. The results may be helpful for revealing the genetic basis of superior fiber quality contributed by introgressed alleles from G. barbadense. Possible strategies involving marker-assisted selection (MAS) for simultaneously improving upland cotton fiber quality and lint yield in breeding programs was also discussed.
Highlights
Cotton (Gossypium spp.) is the leading worldwide textile fiber crop and provides the majority of the raw materials for the textile industry
Germplasm with improved fiber quality conferred by chromosomal introgressions from other species within the genus Gossypium has been developed; one of those species is another cultivated allotetraploid cotton, Sea Island cotton (G. barbadense L.), whose lint yield is much lower than that of G. hirsutum L. but whose fiber quality is markedly superior
In our previous study, using an introgression germplasm with superior fiber quality, we identified components introgressed from G. barbadense into upland cotton at a genome-wide level, and found that the majority of favorable alleles for fiber quality traits were derived from the introgression genomic components (Wang et al, 2011)
Summary
Cotton (Gossypium spp.) is the leading worldwide textile fiber crop and provides the majority of the raw materials for the textile industry As both the textile industry rapidly develops and the demand for textile products continues to diversify, the high requirements for fiber quality continue to increase; the improvement of cotton fiber quality is very important (Kohel et al, 2001). Germplasm with improved fiber quality conferred by chromosomal introgressions from other species within the genus Gossypium has been developed; one of those species is another cultivated allotetraploid cotton, Sea Island cotton (G. barbadense L.), whose lint yield is much lower than that of G. hirsutum L. but whose fiber quality is markedly superior. Due to the negative genetic correlation between fiber quality and lint yield (Zhou et al, 2003; Shen et al, 2007; Shang et al, 2015), the use of introgressed germplasm to improve fiber quality and lint yield simultaneously in upland cotton breeding is difficult (Meredith, 2005; Wang et al, 2011, 2013)
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