Effects of Exotic Alleles and Genetic Backgrounds on Fiber Quality Traits in Upland Cotton (G. hirsutum L.)

The genetic base of modern cotton varieties is severely constricted due to evolutionary and breeding bottlenecks imposed by speciation, domestication and selection. Incorporation of favorable alleles from exotic Gossypium accessions appears to be a plausible approach to broaden the genetic base of cultivated cotton. To analyze and evaluate the effects of exotic alleles on a range of fiber quality traits across different genetic backgrounds of cultivated cotton, we developed intraspecific populations from crosses between an exotic/converted accession of upland cotton (MDN101), that was prioritized for several important attributes, and four elite cultivars that sample the gene pools of different US production regions, studying the F2 and F3 generations for fiber length, strength, fineness, elongation, uniformity and short fiber content. We observed transgressive segregation for these traits, supporting the hypothesis that the exotic donor contains novel alleles of value for improving elite cottons, and providing strong justification for genetic mapping to identify diagnostic DNA markers. We revealed a significant positive relationship between fiber length and strength, fiber length and uniformity index, and fiber strength and uniformity index. Significant positive regression coefficients in the F2-F3 generations for fiber elongation in the MDN101×Acala Maxxa population, and for fiber length and strength in the MDN101×PMHS200 population indicate relatively high heritability of these traits and suitability of early-generation populations for diagnostic marker identification. Genetic mapping and expected validation of the presence of favorable transgressive alleles would provide strong support for deeper exploration of diversity within exotic G. hirsutum genotypes.