Fine Mapping QTL For Fiber Strength And Length Using Chromosome Segment Substitution Lines Cotton In Genetic Standard Line,TM-1 Of G Hirsutum

Cotton(Gossypium spp.)is one of the most important cash crops worldwide.Improvements in the standard of living in the country and the elimination of textile quotas are expected to rapidly increase the consumption and export of textile products.Upland and Sea Island cotton are two cultivated tetraploid cotton varieties.Upland cotton(Gossypium hirsutum L.)is characterized by high yield and moderate fiber quality performance.Sea Island cotton(G.barbadense L.)is characterized by low yield,increased fiber fineness and strength.Sea Island cotton is used as the raw material for fine count yarn.Intraspecific narrow genetic base has become a main problem for genetic improvement of Gossypium hirsutum.Transmission of valuable genes extensively and efficiently between G.hirsutum and G.barbadense is essential for their breeding improvements,which is limited mainly by linkage drag.Chromosome segment introgression lines(CSIL)consist of a battery of near-isogenic lines covering whole genome of crop.Except for one homozygous chromosome segment transferred from donor parent each line,the remaining parts of genome are the same as the recipient parent.It is an ideal material for genome research and especially for QTL mapping.Based on an advanced backcross population between G.hirsutum � G.barbadense,Sea Island cotton chromosome segment introgression lines of cotton in background of genetic standard line of Upland cotton TM-1 were developed.QTLs were mapped by advanced backcross population and CSIL population.Fine mapping QTL for fiber strength by F2 populations.The main results were summarized as follows:1.Among eight CSILs developed,CSIL-35431 and CSIL-31134 produced longer and stronger fiber compared with recurrent parent TM-1.CSIL-31068 and CSIL-31044 were dramatically better than the TM-1 in fiber length.CSIL-31010,CSIL-31036 and CSIL-31064 was better than TM-1 in fiber strength.However,CSIL-35368 produced weaker fiber than TM-1.2.According to the theory of major gene plus polygenes model,the major gene and polygene model analysis was made on CSIL-35431,CSIL-31134 and CSIL-31010.For fiber strength,one and two major genes were detected in CSIL31134 and CSIL-31010,respectively.But no major gene was found in CSIL-35431.For fiber length,two major genes were detected in CSIL-35431 with.additive effect,dominance effect,epistatic effect,the biggest heritability of 63%and genetic stable performance of the materials,suggesting that it is suitable for planting in Nanjing and other places.Heritability of CSIL-31134 CSIL-31010 was also basically at 60%and genetically stable.3.Through scaning whole genome,intregressed G.barbadense chromosome segments were identified on 13 chromosomes,including Al,A3,A4,A5,A7,A8,A9,A10,D1,D10,D11,A12 and D12.Among these 13 chromosomes,A3,A8,A12,Dll,D12 chromosomes import better with more linkage group and a larger fragment.However,only one pair of markers was detected on A4,A5 and A7 chromosomes.QTL mapping work on these chromosomes was not easy to be carried out.There were a few markers in the vicinity of the centromere chromosomes and chromosomal endpoints.4.The QTL for fiber length and strength in CSIL-35431 was detected between NAU3207 and NAU2665 on A8(63 cM-74 cM).In CSIL-31134,QTL for fiber strength was detected between NAU7463 and NAU7678 on A12(39.5 cM-45.8 cM).And in CSIL-31010,the QTL for fiber strength was detected between NAU3485 and NAU7206 on D2(42.2 cM-43.2 cM).