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Lint percentage is an important character of cotton yield components and it is also correlated with cotton fibre development. In this study, we used a high lint percentage variety, Baimian1, and a low lint percentage, TM-1 genetic standard for Gossypium hirsutum, as parents to construct a mapping populations in upland cotton ( G. hirsutum). A quantitative trait locus/loci (QTL) analysis of lint percentage was performed by using two mapping procedures; composite interval mapping (CIM), inclusive composite interval mapping (ICIM) and the F populations in 2 years. Six main-effect QTL (M-QTL) for lint percentage (four significant and two suggestive) were detected in both years by CIM, and were located on chr. 3, chr. 19, chr. 26 and chr. 5/chr. 19. Of the six QTL, marker intervals and favourable gene sources of the significant M-QTL, qLP-3(2010) and qLP-3(2011) were consistent. These QTL were also detected by ICIM, and therefore, should preferentially be used for marker-assisted selection (MAS) of lint percentage. Another M-QTL, qLP-19(2010), was detected by two mapping procedures, and it could also be a candidate for MAS. We detected the interaction between two M-QTL and environment, and 11 epistatic QTL (E-QTL) and their interaction with environment by using ICIM. The study also found two EST-SSRs, NAU1187 and NAU1255, linked to M-QTL for lint percentage that could be candidate markers affecting cotton fibre development. [ABSTRACT FROM AUTHOR]

Improving early maturity in upland cotton (Gossypium hirsutum L.) is an important target in breeding. The node of the first fruiting branch (NFFB) and its height (HNFFB) are two important indexes to measure early maturity in cotton. To facilitate breeding for early maturity traits in upland cotton and reveal the genetic control underlying the two traits, a genome-wide association study was performed using 53,848 high-quality single nucleotide polymorphisms (SNPs) from 77,774 of a recently developed CottonSNP80K array. A total of 55 target trait-associated SNPs were detected, of which 12 SNPs were for NFFB and 43 were for HNFFB. Two SNPs for NFFB and 22 SNPs for HNFFB were repeatedly detected in at least two environments and/or by two models. These 24 SNPs also exhibited high phenotypic contributions of more than 10% and could be used for marker-assisted selection in future breeding programs. Furthermore, 89 candidate genes were identified in the genome sequence of upland cotton. These genes were categorized through Gene Ontology analysis. Gh_A05G1482 might be a potential candidate gene for improving the early maturation of cotton. These findings reveal the genetic control underlying NFFB and HNFFB and provide insight into genetic improvements for early maturity in upland cotton. [ABSTRACT FROM AUTHOR]