Fine‐mapping a fibre strength QTL QFS‐D11‐1 on cotton chromosome 21 using introgressed lines

An initial F₂ mapping population of 223 plants of the cross between TM‐1 (Gossypium hirsutum L.) × H102 (Gossypium barbadense L.) was used to map QTLs controlling fibre strength in cotton. A genetic linkage map with 408 SSR markers was constructed with a total length of 3872.6 cM. Multiple‐QTL model of the software MapQTL version 5.0 was used to map QTLs related to fibre strength of the F_2 : 3 population. QTL QFS‐D11‐1 conferring fibre strength was mapped between NAU2950 and NAU4855 on chromosome 21 (Chr. 21) which explained 23.4% of phenotypic variation. Introgressed lines (ILs), that is, IL‐D11‐1, IL‐D11‐2 and IL‐D11‐3 were obtained through marker‐assisted backcrossing in TM‐1 background. An F₂ population of 758 plants derived from cross IL‐D11‐2 × TM‐1 was used for fine‐mapping QTL QFS‐D11‐1. QFS‐D11‐1 was mapped between markers NAU2110 and NAU2950, adjacent to its initial interval NAU2950–NAU4855 with phenotypic variation explaining 35.8%. QFS‐D11‐1 was further mapped to 0.6 cM from the flanking marker NAU2950. The results will give a basis for marker‐assisted selection of QFS‐D11‐1 in cotton breeding and to lay the foundation for cloning QFS‐D11‐1.