GENETIC DIVERSITY OF COLORED COTTON ANALYZED BY SIMPLE SEQUENCE REPEAT MARKERS

The genetic diversity of 61 colored-cotton lines, including 40 brown cottons and 21 green cottons, was analyzed based on agronomic traits and simple sequence repeat (SSR) markers. A total of 344 alleles from 66 polymorphic SSR loci were detected among the colored cottons. The number of alleles per SSR locus ranged from two to 12, with an average of 5.212. The polymorphism information content was 0.355-0.886, with an average of 0.716. Cluster analysis by UPGMA showed that these colored-cotton lines could be divided into four main groups, including nine subgroups. Three out of 10 agronomic traits had remarkable differences among groups, and 18 of 21 green cottons were classified into one group. This showed that the genetic diversity of the SSR markers reflected, to a certain extent, the diversity of agronomic traits and fiber color. The genetic similarity value of different strains recently developed in China was higher than 0.800, indicating that the new lines were very similar. However, some basic genetic colored-cotton germplasm with poor agronomic characters had a far greater genetic relationship compared with lines developed in recent years. In summary, the genetic background of colored cotton with elite properties was narrow.