| Cotton is an important cash crop in our country, its fiber as the main product is an important raw material of textile industry. In order to meet the needs of rapid development of the textile in-dustry, developing new cotton varieties with high yield, disease resistance, insect resistance and high-quality has become an important task of breeding work. Gossypium barbadense has the cha-racteristic of high resistance to verticillium wilt and good fiber quality, but with low yield; Gossy-pium hirsutum has the characteristic of high yield, wide planting area, but poor fiber quality. Therefore, it is important for cotton breeder to introgress the fiber quality excellent genes to Gossypium hirsutum from Gossypium barbadense and obtain introgression lines (ILs) with high-yielding and excellent quality. In this study, four excellent quality introgression lines of MBI7746, MBI7421, MBI7358 and MBI7455 were used as parents to construct double-cross F1, F2 and F2:3 segregation populations originating from CCRI 45 genetic background with Goss-ypium barbadense (Hai) chromosome introgression segment,and the performance of its yield and fiber quality traits were evaluated for the three generations. SSR markers were used to detecting the genotype of double-cross F1 and F2 generations, identify QTL in the three introgression segregation populations and identify the number and size of Gossypium barbadense introgression fragment and its impact on yield and quality traits.(1) By phenotypic analysis of fiber quality and yield-related traits in double-cross F1, F2 and F2:3 three different generation populations, the mean of fiber length were 29.89mm,31.30 mm,31.62mm, and the transgressive rate over the recurrent parent CCRI 45 were between 89.25%-95.79%; the mean of fiber strength were 29.32 cN/tex,31.55cN/tex,31.17cN/tex, and the transgressive rate were between 82.97%-98.95%; the mean of boll weight were 5.15g,5.90g,6.04g, and the transgressive rate were between 68.41%-78.42%; the mean of lint percentage were 25.41%,29.79%,31.92%, and the transgressive rate were between 26.32%-35.08%.(2) 527 pairs of SSR markers distributed on 26 chromosomes were detected for parents, and 45 pairs of polymorphic markers distributed on 15 chromosomes were screened out. By analysing the genotype of double-cross F1 and F2 introgression lines populations, the average recovery ratio to the recurrent parent CCRI 45 background were between 95.86%-96.85%, with the average length of Gossypium barbadense introgression fragment between 140.84cM-176.06 cM, accounting for 2.81%-3.52% of detected length. The average length of Gossypium barbadense homozygous fragments were between 19.50cM-48.88 cM, accounting for 0.39%-0.98% of detected length; the average length of Gossypium barbadense heterozygous fragments were between 91.97 cM-156.56 cM, accounting for 1.84%-3.13% of detected length.(3) 80 QTLs were detected in the double-cross F1, F2 and F2:3 three different generations, which 28 QTLs associated with the yield related traits, explaining 1.17%-13.70% of phenotypic variation; and 52 QTLs associated with the fiber quality traits, explaining 3.03%-11.15% of phenotypic variation. In these QTLs,15 QTLs were detected in more than two generations:1 QTL for fiber strength was detected in three generations; the remaining 14 QTLs (three for fiber length, three for micronaire, two for elongation, one for fiber strength, three for plant height, one for boll per plant, one for lint percent) were detected in two generations.(4) Some ILs material with fiber length and fiber strength above 30mm and 30 cN/tex were selected through evaluation of double-cross F1, F2 and F2:3 three different generations, these ILs may be used for QTL fine mapping, functional genomics analysis, gene pyramiding. |
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