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

An initial F-2 mapping population of 223 plants of the cross between TM-1 (Gossypium hirsutum L.)xH102 (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 3872.6cM. 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 F-2 population of 758 plants derived from cross IL-D11-2xTM-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 0.6cM 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.