Molecular Marker Of Cotton Fiber Quality And Yield Using Advanced Backcross Recombinational Lines Between Upland Cotton (G.hirsutum. L) And Island Cotton (G.barbadense. L)

As one of important natural fiber sources, cotton has been played a leading role in the economy of China, one of the largest cotton producing and textile manufacturing countries in the world. Because of the quick development of spinning technology, the better fiber quality will be required. Compared to sea-island cotton's quality, upland cotton generally has low-quality fibers, i.e., shorter or coarse fibers of relatively lower strength. Owing to narrow genetic background of upland cotton and weak fiber quality and resistance to Verticillium wilt. It is a better important approach to improve cotton fiber that introgress elite QTL alleles of G. barbadense L. for fiber quality and resistance to Verticillium wilt into G. hirsutum L, and enlarge the narrow genetic base of G. hirsutum and provid more new gerplasm resource for the variety development.In this study, the elite G. barbadense 'Giza70' and G. hirsutum variety'34B' were crossed, backcrossed with 34B as recurrent parent and produced backcross advanced recombinational populations 'BC₂F_4:6 and BC₂F_4:7 lines'. These lines were used to analysis the correlation between fiber quality and yield related traits under four environments. And four hunder and forty one pairs of SSR primers were used to analyze these lines. QTL analysis of fiber quality and yield-related trait in four environments were proceeded by the Composite inter mapping.In this study, a linkage map was developed in a BC2F4:6 population. This map was based on simple sequence repeat (SSR) markers. Totally 2041 SSR markers were employed to screen polymorphisms between '34B' and 'Giza70', approximately 21% of all SSR markers revealed polymorphic bands, then yielded 476 polymorphic loci in BC2F4:6. According to previous research, 397 polymorphic loci were linkage to 26 Chromosomes. The linkage map span 3677.1 Cm with an average distance of 9.21cM.All of fiber quality traits and yield-related traits fitted the normal distribution in the Kolmogorov-Smirnov test.The correlation analysis indicated that bill weight was positive significantly correlated with upper half mean length and Micronaives, negative significantly correlation with elongation rate; lint percentage was negative significantly correlation with upper half mean length and fiber strength, positive significantly correlation with elongation rate and Micronaives.Thirty seven QTLs about fiber quality traits were found based on four environments .Seven QTLs were found above two environments and the effect direction was unanimous. QTL numbers for upper half mean length, length uniformity, elongation ratio were 3,2,1,1. Out of 37 QTLs, 17 QTLs (45.94%) with plus effect were from Sea Island cotton, which could be used for marker assisted selection. Each QTL could explain 6%～13% of phenotypic variance.Forty nine QTLs for yield-related traits were found were found based on four environments Three QTLs were found above two environments and the effect direction was unanimous. QTL numbers for boll weight, seed cotton yield and lint cotton yield were 1,1 and 1. Out of 49 QTLs, 5 QTLs (10.20%) with plus effect were from Sea Island cotton. And each QTL could explain 1%～18% of phenotypic variance.Twelve QTLs could control several traits simultaneously. And these QTLs could partially indicate the relationship among fiber fineness-related traits in phenotypic level. It shows that QTLs distributes as clusters and one cause led to many effects exist whole geneome However, the present study could not distinguish linkage from pleiotropy. It is important how to eliminate the undesirable linkage QTLs effects when the desired traits were selected for cotton Marker-assited Selected breeding.