Mapping QTLs of traits contributing to yield and analysis of genetic effects in tetraploid cotton.

Fiber yield and yield components - including lint index (LI), seed index (SI), lint yield (LY), seed cotton yield (SCY) and number of seeds per boll (NSPB) - were investigated on the farm of Huazhong Agricultural University in a population of 69 F-2 individuals and corresponding F-2:3 families derived from a cross between high-fiber-yield Gossypium hirsutum CV Handan 208 and a low-fiber-yield Gossypium barbadense CV Pima 90. On the basis of the genetic map constructed previously from the same population by Lin et al. (Plant Breed., 2005), quantitative trait locus (QTL) analysis was performed with the software QTL Cartographer V2.0 using composite interval mapping method (LOD >= 3.0). A total of 21 QTLs were identified, which were located in 15 linkage groups. The number of QTLs per trait ranged from one to seven. Of these QTLs detected, one affecting LI explained 24.3\\% of phenotypic variation (PV), five influencing SI explained 16.15-39.21\\% of PV, seven controlling LY explained 13.01-28.35\\% of PV, and two controlling SCY explained 22.76 and 39.97\\% of PV, respectively. Simultaneously, the detected six QTLs for NSPB were located on five linkage groups, which individually explained 28.01-38.32\\% of the total phenotypic variation. The results would give breeders further insight into the genetic basis of fiber yield.