Genetic And Molecular Marker Study Of Fiber-related Traits In Upland Cotton (Gossypium Hirsutum L.)

The modern textile industry depends on the improvement of fiber quality, especially strength for meeting the needs of higher spinning speed. Advances in the use of DNA markers for marker-assisted selection (MAS) are promising for streamlining plant breeding programs. It is possible to identify the excellent fiber quality plants at seedling stage with the one or a few molecular markers tightly linked to major genes controlled the important fiber qualities, which will help to improve the fiber qualities of cotton variety rapidly, prominently and efficiently in China. Genetic and molecular marker study of fiber related traits in Upland cotton were conducted in the present paper.Two crosses 9708x0-153 and 6177x0-212 were made among four parents, which included two parents with high fiber strength, 0-153 and 0-212, originating from crossing G.hirsutum L with G arboreum L and backcrossing with Ghirsutum L, and other two commercial transgenic varieties with resistance to budworm, 9708 and 6177.The results of joint analyses of multiple generations of P₁ , P₂, F₁ , F₂ and F_2:3 of two crosses showed one major gene plus polygene mixed inheritance model in all fiber quality characters, except for fiber elongation. There were highest heritability of major gene for fiber strength, 14.36% in F₂, very little for other fiber quality traits, which indicated the heritability of polygene were prominent for fiber quality characters, 27.88%-50.42% in F₂.A total of 940 SSR primers were used to screen polymorphism among two parents 0-153 and 9708, and their F₁ ,which resulted in 57 polymorphism locus in F₂ population from the cross of 9708×0-153. Linkage test indicated 35 locus could be mapped to 11 linkage groups and covered a total genetic distance of 497.9 cM, approximately 11.07%.of total cotton genome.20 QTLs for fiber yield related traits were found in F₂ and F_2:3 generations using IM (Interval Mapping) and CIM (Compose Interval Mapping) methods, 10 of them can be detected by the two methods. QTL numbers for Plant seed yield, boll weight, lint percent, lint index, seed index, boll branch numbers, first harvest percent and resistance disease index were 1,4,4,3,1,4,2 and 1, respectively. 16 QTLs for fiber quality characters were found, 9 of them can be detected by the two methods, QTL numbers for Fiber strength, fiber length, micromaire, fiber elongation and fiber uniformity were 5, 5, 2, 2 and 2, respectively. No same QTL for fiber yield related traits could be detected in different generations, which shows needs of multiple self-crossing lines for QTL analysis of yield traits. 2 QTLs for fiber strength, 2 QTLs for fiber length, 1 QTL for Micronaire and 1 QTL for fiber elongation could be detected meanwhile in F₂ and F_2:3, which indicated theses QTLs show stable genetic effects and could be used for marker assisted selection breeding.One QTL of fiber strength, linked tightly to marker s1591 could explain 12.37% of phenotypic variance in F₂, and linked tightly to marker s111h could explain 20.36% of variance in F_2:3. The another one of fiber strength linked tightly to marker s5295f₁₇₀ in two generations, could explain 10.68% and 27.77% of variance, respectively. Moreover, The very high additive genetic effects from...