Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: June 12, 2000
Publication Date: N/A
Interpretive Summary: Most important traits in plants are controlled by many genes, each with small effects, and are inherited in a quantitative fashion. Plant breeders must combine these genes into the genetic makeup of the seeds of one plant to develop a strain that is improved for specific traits. For many years the plant breeder has needed a more efficient way to do this. The use of molecular markers in a marker assisted selection process appears to offer a new and more efficient approach to the plant breeder. The first step in marker assisted selection is to associate molecular markers with important traits, measure the strength of the associations, and the genetic effects of individual genes. We have begun to do this in upland cotton, Gossypium hirsutum L. We crossed two upland cotton lines and measured molecular markers, agronomic and fiber traits, and their associations in segregating generations. We arranged molecular marker loci into linkage groups and associated quantitative trait loci with 60 maximum likelihood locations in 24 of these linkage groups. We also measured the genetic effects of each locus on the traits. This research is the first to associate molecular markers and quantitative trait loci for important fiber and agronomic traits in a cross of two upland cotton lines.
Technical Abstract: The mixed model approach was used to analyze for QTLs associated with 19 agronomic and fiber traits in 92 F2 derived families from the cross of two upland cotton lines, MARCABUCAG8US1-88 x 'HS 46'. One-hundred QTLs were mapped to 60 maximum likelihood positions in 24 linkage groups. Several QTLs affected more than one trait. Estimates of additive and dominance genetic effects were also estimated for each QTL. Many fiber traits were highly correlated. Because maximum likelihood locations do not necessarily represent physical distances, a physical map of linkage groups would improve the capability of molecular markers for incorporation of quantitative traits. These mapped QTLs are the first to be assigned in upland by upland cotton crosses and will greatly refine the effort of breeders to use molecular markers for the improvement of cotton.