Identification of stable QTLs for fiber quality and plant structure in Upland cotton (G. hirsutum L.) under drought stress

Cotton is an economically important commodity for nearly fifty industries including the textile sector which is largely based on cotton fiber. Identification of markers linked to loci for fiber traits under drought stress may be particularly beneficial because such loci could provide the genetic adaptability needed to produce good fiber under water limitation. In the present study, 177 simple sequence repeat (SSR) markers were used to detect significant quantitative trait loci (QTLs) linked to 11 fiber quality and plant structure traits in a panel of 99 Upland cotton (Gossypium hirsutum L.) genotypes using GLM and MLM analysis. The fiber quality traits, including fiber length (FL), fiber fineness (FF), fiber strength (FS), fiber elasticity (FE), fiber uniformity (FU), spinning conversion index (SCI), earliness (EAR), 1st position boll retention (1st PBR), 2nd position boll retention (2nd PBR), total boll number (TBN) and plant height (PH), were tested under both well-watered and water-limited irrigations in two locations. At both locations, GLM identified a total of 74 and 70 QTLs under well-watered and water limited conditions, respectively, at p ≤ 0.005. MLM detected seven and 23 QTLs under well-watered and water-limited conditions, respectively. Of the identified QTLs, some QTLs were detected in both locations: three for well-watered and two for water-stress conditions. Moreover, a total of 19 QTLs were stable under both watering-regimes. The QTLs identified herein could be useful in the development of cotton cultivars that have adaptability to drought conditions worldwide.