Genetic Analysis of Yield and Fiber Quality Traits in A Backcross Inbred Line Population of Cotton.

Upland cotton (Gossypium hirsutum), producing >90% world cotton fiber, is known for its wide adaptation and high yield; whereas Pima cotton (G. barbadense), accounting for ~5% world cotton production, has superior fiber qualities. To test the hypothesis that Upland and Pima cotton each has accumulated different desirable genes through divergent natural and artificial selections after they were derived from a common ancestor about 1-2 million years ago, several breeding populations through interspecific hybridization, backcrossing, and selfing have been developed and tested. This presentation will be focused on one backcross inbred line (BIL) population with regard to its development and field performance, transcript profiling, DNA markers, and quantitative trait locus (QTL) analysis. This BIL population was developed using an advanced backcrossing (AB) strategy with Upland cotton as the recurrent parent followed by several generations of selfing. The BIL population was tested in two locations and three years. The BIL lines have, in general, Upland cotton plant type and morphological characteristics; individual plants within a line are highly uniform, indicating minimal within-line variation; plant height, maturity, boll size, and productivity display tremendous between-line variation; and the fiber quality results reveal successful introgression of varying portions of the Pima cotton genome within the primarily Upland cotton BIL lines. Approximately 500 markers have been generated for linkage mapping and QTL identification in this population. Our analysis indicated that many functional cDNA-AFLP markers with known sequence information are associated with the agronomic and fiber traits.