Submitted to: Acta Genetica Scinica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/6/2001
Publication Date: 8/6/2001
Citation: Yuan, Y.L., Zhang, T.Z., Guo, W.Z., Shen, X.L., Yu, J., Kohel, R.J. 2001. Molecular tagging and mapping of QTLs for super quality fiber properties in upland cotton. Acta Genetica Scinica. 28(12):1-11. Interpretive Summary: Upland cotton consists of over 90% of fiber production by the farmers and it has high yield potential but low fiber quality, relative to Sea Island cotton or extra long staple (ELS) cotton. Improvement of fiber quality in the Upland cotton is a necessary objective in breeding programs. However, most genetic factors or genes for fiber quality will have to be transferred from the Sea Island cotton to the Upland cotton. This study identified two major genes called quantitative trait loci (QTLs) that were responsible for fiber quality in an Upland cotton line called 7235. One gene was determined to reside on chromosome 10 of cotton and the location of the other gene remained to be determined. Field tests from four environments in China and USA showed that these two genes improved fiber strength, length, and fineness, important in fiber quality. DNA markers linked to these genes are valuable tools to select high-yield cotton with superior fiber.
Technical Abstract: A G. anomalum introgression line, 7235, characterized as super quality fiber properties, was used to identify molecular markers linked to fiber property QTLs. By use of (7235 x TM-1)F2 in Nanjing and College Station, USA, and (7235 x TM-1)F3 in Nanjing and Hainan. Bulked segregation analysis was employed to produce 3 pairs of mixed DNA pools for fiber strength, micornaire and fiber length according to indivdual value of (7235 X TM-1)F2 and F2:3. A total of 221 pairs of SSR primers, 1 840 arbitrary 10-mer oligonucleotide primers and 77 ISSR primers were used to screen polymorphism betweem two parents, and 3 pairs of bulked DNA pools. Fifteen markers amplified by thirteen primers were identified to be linked with fiber quality QTLs through DNA polymorphism surveying between the parents, and then paired bulked DNAs, and screening the individuals plant of (7235 x TM1)F2. Linkage test indicated 15 markers could be mapped to three linkage groups. In the first linkage group, eight markers (two SSR and six RAPD markers) associated with chromosome 10 in cotton. Two major QTLs for fiber quality characters were identified. One for fiber strength could explain 35% of the phenotypic variation in F2, and 53.8% in F2:3 at Hainan, which has the greatest single QTL effect of fiber strength and could be identified in all four environments, and tightly linked to 6 RAPD markers and 2 SSR markers with genetic distance no more than 16 cM in chromosome10, in which FSRl933 is the nearest with the distance no more than 0.6cM. One QTL linked to FMR1603 for Micronaire could expain 7.8% of the phenotypic variation in F2, and 25.4% in F2:3 at Hainan, and expressed in all four environments. One QTL linked to FLR11550 for fiber length could explain 9.5% of the phenotypic variation in F2:3 at Hainan, very little in other environments. So they can be used in marker-assisted selection in increasing fiber quality of commercial cultivars.