| Object: The traditional strategy of targeted-breeding have caused genetic basis of our national uplandcotton to be increasingly narrow. Besides, intraspecific upland cotton is lacked of relatively excellentgermplasm resources. therefore, it is difficult to make a breakthrough in improvement of fiber quality traitsthrough intraspecific breeding. Given the existence of several limited factors of interspecific breeding,ultilizing developed Gossypium barbadense chromosome segement substitution lines and combining withmolecular marker-assisted selection technology to introgress Gossypium barbadense chromosomesegements associated with fiber quality trait into upland cotton can achieve the purpose of improving fiberquality traits of upland cotton.Method: In this experiment, substitution lines CSSL-122was used as non-recurrent parent, Xinjiang earlymaturing upland cotton varieties of Xinluzao33, Xinluzao45and cultivars of Jinken69-2were used asrecurrent parents. The BC2F1population was derived from hybrids and backcross between CSSL-122andXinjiang upland cotton. Nineteen SSR markers which were linked with fiber quality traits and proved to belocated in Gossypium barbadense chromosome were used to screen out obvious polymorphism primersbetween the parents, we then detected chromosome segment of Gossypium barbadense in the BC2F1population to identify the individual plants which carried alien Gossypium barbadense chromosome seg-ment. Simultaneously, according to the test results of fiber quality traits and statistic analysis, we analyzedimprovement effects and after introgressing alien Gossypium barbadense chromosome segments intoXinjiang upland cotton. The research results were as follows：Results:1.The obviously polymorphic SSR markers between the parents were screened out. Among nineteenSSR primers linked with fiber quality traits, two primers, NAU2987and BNL3145, were screened outpolymorphism between substitution line CSSL-122and Xinjiang upland cotton, accounted for10.53%among the total primers. These two primers were respectively amplified specific markers of NAU2987360,NAU2987480and BNL3145430, BNL31451200from CSSL-122, which were available to be used foridentifying and analyzing Gossypium barbadense chromosome segments of controlling fiber quality traitsin the BC2F1population.2.We identified the plants which carried the markers linked with Gossypium barbadense chromosomesegments in the BC2F1population. The primers of NAU2987and BNL3145which were located in the samelinkage group could detect the specific markers amplified from CSSL-122in the BC2F1population,moreover, the identification results by the two markers were the same.3.The effects of improvement for fiber quality of Xinjiang upland cotton ultilizing Substitution linesCSSL-122were obvious. The fiber quality of positive plants is significantly better than non-positive plantsin three BC2F1populations derived from hybrids and backcross between CSSL-122and Xinluzao33,Xinluzao45, Jinken69-2, especially fiber length, through comparison of average fiber length betweenpositive plants and non-positive plants, the difference reached a significant level. Fiber length of positiveplant in the BC2F1population derived from CSSL-122and Xinluzao45was improved significantly and thedecrease of fiber strength and unifomity reached a significant level. Only fiber length of positive plnts inthe BC2F1population derived from CSSL-122and Xinluzao33was improved significantly, and other mainfiber quality traits were also improved but the effect was not obvious.4. A method of detecting positive plants in large population based on PCR-SSR matrix mixing tank waseatablished. In the process of screening and identifing individual plant in the BC2F1population, a rapid testmethod of detecting alien chromosome segment based on SSR-PCR and matrix mixing tank, which wereproperly used to quickly detect posotive plants carried alien chromosome segment of Gossypiumbarbadense from the population derived from hybrid and backcross between upland cotton and Gossypiumbarbadense chromosome segment substitu-tion lines, when the frequency of positive samples was less than 7.81%, the savings rate of detecting samples could be maintained at above50%.Conclusions: These results indicated that we achieved introgression of Gossypium barbadense chromo-some segment from chromosome segment substitution lines into genome of Xinjing upland cotton in theBC2F1population through developing the BC2F1population derived from hybrid and backcross and byusing SSR molecular marker technology. The test results of fiber quality traits and statistic analysis showedthat the effect of improvement for fiber quality traits was obvious after introgression of alien Gossypiumbarbadense chromosome segments into Xinjiang upland cotton, which indicated that Gossypiumbarbadense chromosome segment substitution lines could effectively improved fiber quality traits ofupland cotton. In addition, we established a rapid method based on PCR-SSR and constructing matrixmixing tank for the identification of positive plants from a large group in the process of screening andidentifing the BC2F1population, which provided a rapid and effective method for identifing alienGossypium barbadense chromosome segment from background of Gossypium hirsutum L.. |
