Submitted to: World Cotton Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/4/1998
Publication Date: N/A
Interpretive Summary: A map of the genes in cotton would be useful to scientists working to improve cotton cultivars and their production. This research provides a linkage map that shows where many of the important fiber and agronomic genes are located in the cotton genome. We have used molecular markers called RFLP to make a genetic linkage map and then we have associated important fiber and agronomic genes with these molecular markers. By associating important genes with pieces of DNA that are in known arrange- ments we can more easily follow the important genes. We used an F2 population of 96 plants from a cross of two Upland cultivars, MARCABUCAGUS-1-88 and HS 46. These are very diverse parents. We mapped 138 mmolecular markers to 31 linkage groups. We then mapped 100 quantitative trait loci for fiber and agronomic genes to 60 maximum likelihood positions among these 31 linkage groups. We located genes in 24 of the 31 linkage groups. Several fiber genes related to fineness and maturity mapped to the same locations in the genome. Our analysis also gives the genetic value of the genes on the fiber or agronomic trait of interest.
Technical Abstract: Ninety-six F2.F3 bulk sampled families of Upland cotton, Gossypium hirsutum L., from a cross of MARCABUCAG8US1-88 x HS 46 were analyzed with 129 probe/enzyme combinations resulting in 138 RFLP loci. There were 84 codominant markers of which 76 fit a normal 1:2:1 ratio. There were 54 dominant markers of which 50 fit a normal 3:1 ratio. Using the MAPMAKER/EXP program these were arranged into 31 linkage groups with 120 linked loci and 18 unlinked loci. These covered 865 cM or 18.6% of the estimated cotton genome. We used the mixed model analysis of Zhu and Weir (1998) to analyze QTL's associated with 19 agronomic and fiber traits scored mostly in F2.F5 families. The model also provided estimates of the additive and dominance genetic effects. We mapped 100 QTL's to 60 maximum likelihood locations in 24 linkage groups. Several QTL's influenced more than one trait. For example, in linkage group 14 we found a QTL with significant genetic effects for micronaire, and three arealometer measurements. In linkage group 19, four closely linked QTL's had significant effects on strength, fineness, and maturity of fiber.