Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 3, 2000
Publication Date: January 3, 2000
Citation: ULLOA, M., MEREDITH JR, W.R. A GENETIC LINKAGE MAP AND QTL ANALYSIS FOR AGRONOMIC AND FIBER QUALITY TRAITS IN AN INTRASPECIFIC COTTON POPULATION (G. HIRSUTUM X G. HIRSUTUM). JOURNAL OF COTTON SCIENCE. 2000. v. 4. p. 161-170. Interpretive Summary: Molecular techniques have been developed that can enhance breeding methodologies and facilitate the identification, characterization, and manipulation of genetic trait variation. Restricted fragment length polymorphism (RFLP) molecular markers have provided an increase in genetic knowledge for the cotton crop. The association between a marker and a trait of interest is called Quantitative Trait Loci (QTL). An RFLP genetic linkage map of cotton was developed from a 119 bulk-sampled plot of F2 -derived F3 ('MD5678ne' X 'Prema') population, and used for QTL analysis for agronomic and fiber quality cotton traits. In this study, the RFLP molecular data identify 25 agronomic and fiber QTLs, and indicate that genes for fiber quality may be linked and carried on DNA blocks on the same cotton chromosome(s). The tendency for the majority of the Prema parent's RFLP informative fragments was for low yield, long, strong, and fine fibers, while for the MD5678ne was for high yield, short, coarse, and weak fibers. QTLS may lead us to the identification of gene(s) controlling the trait and enhance selection efficiency in cotton by targeting molecular marker-based genes that substantially reduce the amount of work required to determine their relative breeding value and lead to the identification of superior cottons.
Technical Abstract: An RFLP genetic linkage map of cotton (Gossypium hirsutum L.) was developed from 119 bulk-sampled plot of F2 -derived F3 ('MD5678ne' X 'Prema') population, and used for Quantitative Trait Loci (QTL) analysis for agronomic and fiber quality cotton traits. The genetic linkage map comprises 17 linkage groups with an average distance between two markers of f8.7 centiMorgan (cM), and includes 81 loci covering 700.7 cM which is approximatly 15% of the cotton genome. Agronomic as well as fiber quality traits were significantly correlated with each other. A strong negative correlation between lint percent (Lint %) and fiber strength (g/Tex, T1) was observed (r = - 0.41). In addition T1 was positive correlated to fiber span length at 50% (r = 0.36) and 2.5% (r = 0.31). To avoid false-positives, the reported QTLs were detected and located by at least two of the three QTL analysis programs used in this study. Twenty-five QTLs were detected and placed on nine linkage groups of the cotton genetic linkage map. The tendency for the majority of the Prema parent's informative fragments was for low yield, long, strong, and fine fibers while for the MD5678ne the alleles had the tendency for high yield, short, coarse, and weak fibers. The QTL positions on the linkage groups indicate that genes for fiber quality traits may be linked and carried on DNA blocks on the same cotton chromosome(s). However, these observations did not discard the possibility that genes for fiber quality may also work together to produce a pleiotropic effect in the quality of the cotton fiber.