QTLs Mapping For Yield And Fiber Quality Traits In Double-Cross Segregating Population Of Chromosome Segment Introgression Lines From Gossypium Hirsutum � Gossypium Barbadense

Cotton is a kind of natural textile fiber crop.Two tetraploid species,Gossypium hirsutum and Gossypium barbadense,are two main cultivated species.Gossypium hirsutum has a wide environmental adaptability and high yield,while a poor quality.Gossypium barbadense has an excellent fiber quality and high resistance to Verticillium wilt,but low yield.Therefore,we can improve the yield and fiber quality at the same time and breed high yield and quality cotton lines by introgressing excellent gene segments of sea island cotton to upland cotton.It is of great concern to improve the fiber quality of cotton in China,which is also of great significance to promote the development of cotton textile industry.In this study,two sets of high quality chromosome segment introgression lines,which were obtained by advanced backcrossing and continuously inbreeding from Gossypium hirsutum and Gossypium barbadense,were used as parents to construct double-cross segregating population F₁ and verification population F_1:2.They are respectively in the genetic background of CCRI36 and CCRI45,which were widely cultivated in China.The segregating populations,Pop36 and Pop45,were evaluated for yield and fiber quality traits.The segregating population of double-cross F₁ and F_1:2 were quantified by using SSR to evaluate the genotyping of parents and map the quantitative trait locus?QTL?for yield and fiber quality traits.It provides a theoretical basis for further QTL fine mapping and molecular marker assisted selection?MAS?.1.The yield and fiber quality traits of double-cross F₁ and F_1:2:2 populations under different genetic backgrounds were analyzed by descriptive statistics.They were all in normal distribution.The transgressive ratio of fiber length and strength of two populations in CCRI36 genetic background were at78.31%-94.85%;the average of lint percentage were 35.10%?42.32%,and the transgressive rate were55.38%?47.43%.The transgressive ratio of fiber length and strength of two populations in CCRI45 genetic background were at 82.18%-98.30%;the average of fiber elongation were 7.10%?7.17%,and the transgressive rate were 97.70%?83.82%.2.527 SSR markers,which cover the whole genome of cotton,were used to detect the genotype of parents and double-cross F₁ segregating populations.The recovery rate of the recurrent parent background for the parent materials in CCRI36 genetic background?MBI4098?MBI4097?MBI4068?MBI4067?were all above 95%.The average recovery rate of the CCRI36 background for the double-cross F₁population was 96.58%.The number of introgression fragments was mainly concentrated in 14-21,and the length of introgression fragments was mainly concentrated in 120-160 cM.The recovery rate of the recurrent parent background for the parent materials in CCRI45 genetic background?MBI7115?MBI7412?MBI7153?MBI7346?were all above 97%.The average recovery rate of the CCRI45 background for the double-cross F₁ population was 97.70%.The number of introgression fragments was mainly concentrated in 12-18,and the length of introgression fragments was mainly concentrated in 100-160 cM.3.Mapping QTLs of yield and fiber quality traits in two generations with different genetic background respectively by using Icimapping.A total of 75 QTLs were identified in the populations with CCRI36background,among which 59 QTLs for fiber quality,16 QTLs for yield traits.12 QTLs were simultaneously detected in the two generations and 10 belong to the newly discovered.41 QTLs were detected in the populations with CCRI45 background,including 30 QTLs for fiber quality,11 QTLs for yield traits.5 QTLs were simultaneously detected in the two generations and belong to the newly discovered.4.The results showed a phenomenon that QTLs were cluster distribution.QTLs with different traits were closely linked to the same marker site.There are 20 markers were closely linked with 62 QTLs in the CCRI36 background population.27 QTLs were closely linked with 7 markers in the CCRI45 background population.In addition,3 clusters were found,which can be used in marker-assisted selection?MAS?to improve the yield and fiber quality of upland cotton at the same time.