| Cotton is an important natural fiber crop in the world.Most of the cotton grown are upland cotton（Gossypium hirsutum L.）,which has high yield and wide planting area,but the genetic diversity in upland cotton is poor.In order to improve the genetic diversity of upland cotton,and improve the yield,fiber quality,and stress resistance of upland cotton varieties,it is necessary to carry out distant hybridization with wild cotton.Gossypium tomentosum L.is tetraploid wild cotton,which has many traits such as resistance to insects,drought resistance and elite fiber quality,but the yield is not high.Therefore,the excellent allele of cotton can be introduced into the upland cotton,there improving the fiber quality and resistance of the upland cotton.In the prevous study in our laboratory,the genetic linkage map between upland cotton and G.tomentosum was constructed.In this study,181 SSR markers even distributed on the A subgenome of the upland cotton and G.tomentosum genetic map were selected to genotype 559 individuals from BC3F2 population,and QTL mapping was performed on fiber quality and yield traits in BC3F2 and BC3F2:3.The main results are as follows:1.Analysis of introgression segment of BC3F2The background recovery rate of CSILs ranged from 74.5%-99.7%,and the average recovery rate was 89.7%.The introgression segment number of CSILs ranged from 5-39,with an average number of 16.The length of the total introgression segment ranged from 6.1cM-151.1cM,with an average length of 186.3cM,and the average introgresssion rate was 9.2%.2.Analysis of introgression segment of A sub-genomeThe A sub-genome chromosome segment introgression lines results in genotype analysis of each chromosome.The average genetic background recovery rate of 13chromosomes is 89.8%;the genetic background recovery rate of Chr.7 was the highest,accounting for 95.9%;the background recovery rate of Chr.10 was the lowest,accounting for 84%.The homozygous introgresssion segment of each chromosome averaged 3.9cM,and the homozygous introgresssion segment of the Chr.5 had the longest average length of 7.1cM,and the homozygous introgresssion segment of Chr.4and Chr.7 had the shortest average length of 1.0cM;The average length of the heterozygous introgresssion segment was 11.2cM,and the average length of the heterozygous introgresssion segment on the Chr.10 was the longest,which was 22.0cM,and the average length of the heterozygous introgresssion segment on the Chr.4 was the shortest,3.0cM;The average length of the introgresssion segment was 15.1cM,and the average length of the introgresssion segment on the Chr.10 was the longest,which was28.7cM,and the average length of the introgresssion segment on the Chr.4 was the shortest,4.0cM.3 QTL analysis of fiber quality and yield traitsIn this study a total of 64 QTLs were identified in 2017 and 2018,and 17 of them were detected simultaneously in both environments.There are 33 QTLs for fiber quality,including 4 QTLs for fiber strength,6 QTLs for fiber uniformity,8 QTLs for fiber micronaire,4 QTLs for fiber elongation and 11 QTLs for fiber length;There are 31QTLs for yield,including 6 QTLs for lint percentage,9 QTLs for boll weight and 16QTLs for seed index.The 64 QTLs explained phenotypic variation ranged from from1.7%to 11.3%.Among them,28 QTLs favorable alleles were derived from G.tomentosum,and 36 QTLs favorable alleles were derived from CCRI35. |
