SSR Marker Location And Analysis Of Genetic Similarity Of Fiber Development Mutants In Cotton

The new fiber mutant GZnn was analyzed using traditional genetic method and it was sure that GZnn was qualitative trait controlled by one recessive gene. Using SSR molecular marker technology, we located this gene on chromosome 10. Since its position was different from N,(on chromosome 12), n2(on chromosome 26) and n3 that was found recently in America, we named it n4. The gene was closely linked with marker slocl and their distance was 10.8 cM. The gene was also linked with sloc2-l with their distance of 20.4 cM.22 loci were found after SSR screening the F2 of TM-1 X GZnn. Using software Mapmaker exp 3.0, we found 12 of them were distributed on 2 linkage populations that covered 198.4 cM. Using software WinQTLcart, we scanned the whole genome QTLs related to 7 quantity traits(Lint percent, seed index, fiber length, unitormity ration, fiber strength, elongation Micronaire value). When LOD is 3.0, one QTL (FL02) relevant to fiber length and one QTL (SI02) relevant to seed index were found. They could explain the phenotypic variance of 0.19% and 4.64% respectively. Therefore, we located FL02 and SI02 on chromosome 12.Using SSR marker technology, we undertook polymorphism analysis, genetic similarity and cluster analysis on 3 groups of fiber mutant NIL (Near Isogenic Line) and their SSR fingerprint atlas had been also built. The similarity coefficient between Xin and Zhl2 , Xin and Yu4 were 0.471 and 0.587. They differed from each other significantly. Therefore, Xin maybe originates from Yu4. Mutation of XZ142w was the same as Xin and their SSR genetic similarity reached 90 percent. However, their SSR fingerprint atlas showed they had different characters, which maybe due to their different genetic background. SSR genetic similarity analysis also revealed the difference between 4 NIL was significant and the similarity coefficient ranged from 0 .5 to 0.62. This proved that dominant or recessive mutation could lead to large genetic difference. The similarity coefficient of 2 recessive fiber mutation H-154 and GZnn reached 0.94. This strengthen their similarity of fiber characters and genetic ways and also proved that the same phenotype was of large intent of genetic similarity.With the application of software NTSYS 1.8, cluster analysis was also carried out on TM-1, GZnn, GZNn, H-154, Xin and XZ142w and the Dendrogram of these 6 lines was also built. When the genetic distance is 3, the 6 lines could be divided into 3 groups. GZnn, H-154 and GZNn belonged to one group and all of them have fuzzless and linted. Meanwhile, the mutant Xin and XZ142, which were fuzzless and lintless lines, were clustered in another group.