Construction And Evaluation Of G. Barbadense Cv. Pima90 CSILs In The Genetic Background Of G. Hirsutum Cv. Handan208

Cotton comprises diploid and tetraploid species. Nearly 98% of the cotton production in world is taken up by upland cotton （Gossypium hirsutum）, and sea-island cotton （G. barbadense）. In the recent ten years, the yield-improvement proceeded slowly and was likely to reach a platform. Further more, due to the increased consumption demands for cotton fiber commodity, it is urgent to improve the fiber quality. Consequently, cotton breeders should pay more efforts to improve cotton fiber quality when improving yield.Conventional genetic strategies have contributed a lot to enhance the fiber properties for over half a century; however, their efficiency was limited. Recent advances in DNA markers offer crop breeders a rapid and precise alternative approach to conventional selection schemes for improving quantitative traits. At present, many researchers have constructed some genetic linkage maps for cotton, by means of morphological markers, cytogenetical markers, iso-enzyme markers and molecular markers. Above all, gentic linkage maps using the interspecific cross of G. hirsutum×G. barbadense are more saturated than others.In this study, in the light of problems as encountered in QTL mapping for cotton and other crops such as genetic background variation, we tried to construct choromosome segment introgression lines （CSILs） carrying G. barbadense segments in the uniform genetic background of G. hirsutum. One of the parents was G. hirsutum cv. Handan208 （characterized as high fiber yield）, used as receptor; the other was G. barbadense cv. Pima90 （characterized as excellent fiber quality）, used as a donor. After 1-2 backcrossing between （（?）- Handan208×（?） Pima90） F₇RIL and Handan208 with marker assisted selection, we obtained a junior CSILs. The main experimental results were as follows:1. Using graphical genotyping, 101 individuals were selected from 80 lines of F7BC1 and F7BC2. All of them harboured 300 introgression segments from Pima90 and no more than 10 with a total length of 5971.2 cM. The shortest fragment of the CSILs was 8.2 cM, the longest was 205.4 cM, the average length was 19.9 cM. This CSILs had 99.40% of the genome proportion of the recurrent parent. Chr19 was located the maximal number of 24 introgression segments, while Chr 11 only 2. CSILs had introgression segment length ranged from 0.7 cM to 10.0 cM on 11 chromosomes, while 10.1 cM to 20.0 cM on 13 chromosomes.2. Above 80% of the CSILs contained very a few （1-4） introgression segments. More than 6 individuals of CSILs had 1 introgression segment on most of the chromosomes. 1 -4 individuals had 2 introgression segments on 15 chromosomes, only 1 individual had 4 introgression segments on Chr26 on which there were about 23 introgression segments.3. 35.6% of CSILs had the introgression segment length ranging from 8.2 cM to 40.0 cM, while 41.6% from 40.1 cM to 80.0 cM, almost 80% of selected individuals had comparatively ideal introgression segments.4. This CSILs were composed of two generations: F₇BC₁ and F₇BC₂. The actual genetic background recoverage rate of them was 99.00%、99.50%, respectively, higher than their theoretical genetic background recoverage rate.