The Genetic Effects Due To Special Chromosome From Sea Island Cotton And QTL Mapping In Main Traits

Chromosome substitution lines(CSB lines), in which a pair of chromosomes of upland cotton, TM-1, substituted by the corresponding chromosomes of sea island cotton, 3-79,was developed by Stelly. CSB lines can be used to investigate genetic effects of substituted chromosome, to locate important genes and cloning, and to improve characteristics of upland cotton. They can also overcome the shortages of long separation generations and polarizing toward parents. The genetic effects of only a few of CSB lines have been evaluated. This paper investigated 16 CSB lines in evaluation and molecular dendrogram, genetic effects and heterosis from special chromosomes or chromosome arms, molecular genetic linkage map constructions of chromosomes as well as QTLs fine maps by use of CSB lines.1. Evaluation and molecular dendrogram of CSB lines. Chromosomes 22Lo and 22Sh can increase lint percentage and elongation ,but reduce fiber quality. Chromosome 14Sh and 26Lo can increase fiber length, 14Sh and 15Sh increase fiber strength, It is beneficial to use CSB06 and CSB12Sh as parents to improve boll size, to use CSB14Sh and CSB01 as parents to improve fiber quality. As for hybrid cotton breeding, it is reasonable using CSB01 to improve lint yield traits, and using CSB01, CSB11Sh and CSB06 to improve fiber length. The molecular dendrogram indicated that there are far genetic relationship between CSB26Lo, CSB01 and other CSB lines.2. Genetic effects and heterosis due to special chromosomes from sea island cotton was investigated, thus the research level was gone from whole genome deep into chromosomes. The results showed that chromosome 14Sh from sea island cotton has positive effects on fiber length and strength, chromosome 22Sh has positive effect on lint percentage but negative effect on fiber quality. Chromosome 11Sh positive affected heterosis of fiber quality, and chromosome 06 and 12Sh have positive effects on boll weight.3. Molecular markers in important traits. Genetic linkage map was constructed using CCRI43XCSB22Sh combination. Linkage test indicated that 72 loci could be mapped to 16 linkage groups and covered a total genetic distance of 320.4cM, taking account for 6.4% of whole genome. 14 stable single QTLs and 5 stable epistasis QTLs in main traits were mapped in three generations and four environments. Four dense regions combining many QTLs were also mapped.CSB14Sh and CSB22Sh, were crossed with TM-1 respectively, and the F2 populations were produced. Molecular genetic maps of Chromosome 14Sh and 22Sh were constructed. 21 loci were mapped on chromosome 14Sh and covered 65cM. genetic distance. Every 1 stable QTL of fiber length and strength was determined on chromosome 14Sh.. These results indicated that there indeed are QTLs affecting those traits on chromosome 14Sh. The most dense genetic linkage map of the short arm of chromosome 22 was constructed, This map contains 63 markers, with 89cM long. The mean distance between markers is 1.43 cM, the minimum distance between markers is 0.048cM, while maximum distance is 5.367cM. On chromosome 22Sh, 1 epistasis QTL of lint percentage was determined in two different populations, which was measured by some previous study through different populations. Every 1 stable QTL of 5 of fiber quality characters was tested in this research. These results indicated that there indeed are QTLs affecting those traits on 22Sh.