QTL Mapping of Seed Physical Traits in Upland Cotton (Gossypium hirsutum L.)

Cotton is a leading natural fiber crop in the world, and also provides important plant oil and protein. Cotton fiber is developed from a single cell of seed epidermis, so QTL mapping of seed traits is important to reveal the genetic characteristics of seed traits and to understand the genetic relationship among seed, yield and fiber quality traits. Six seed physical traits of upland cotton recombinant inbred line population identified in three environments presented continuous segregation, and the significant variances existed in the six physical traits were affected by environments. The linkage map constructed from the upland cotton recombinant inbred line population (T586 × Yumian1) F2:7 were used to map QTLs for six seed physical traits by MQM method, and thirty-four QTLs were detected, including nine QTLs for seed weight (qSW), five QTLs for fuzz weight (qFW), three QTLs for fuzz percentage (qFP), eight QTLs for kernel weight (qKW), six QTLs for seed hull weight (qHW), and three QTLs for seed kernel percentage (qKP), with explained phenotypic trait variance ranging from 4.6% to 80.1%. Out of thirty-four QTLs, nine QTLs were identified in two or three environments, and they included two large-effect QTLs controlling fuzz weight and fuzz percentage at N1 locus on chromosome 12, and other seven small-effect QTLs. A total of 34 QTLs were mapped on 15 chromo- somes, and among them 20 QTLs distributed on A sub-genome and 14 QTLs distributed on D sub-genome. Twelve chromosome regions have two or more QTLs for seed physical traits in each region, and directions of most QTLs for different seed physical traits, which originated from the same parent in the same chromosome region, were consistent with the correlation coefficients of traits.