Working group session:
Germplasm and Genetic Stocks
Presentation type:
poster
Authors:
Wang, Hongmei; Zhao, Yunlei; Chen, Wei
Presenter:
Wang, Hongmei
Correspondent:
Wang, Hongmei
Abstract:
To understand the genetic basis of the elite cotton germplasm in China, a total of 83 SSR markers (an average of three on each of the 26 chromosomes ) were randomly selected to analyze population structure and genetic diversity of 158 elite G. hirsutum variety accessions from the China cotton germplasm collection, which were collected from different cotton growing areas in China (114) as well as from American (39), Africa (3), Former Soviet Union (4), and Australia (1). 247 allelic variations were detected with an average allele number of 2.89. The average PIC ( polymorphism information content) and gene diversity values were determined to be 0.3534 and 0.4261, respectively, indicating a relatively low degree of genetic diversity. Phylogenetic analyses revealed genetic distance (GD) of all elite G. hirsutum variety accessions ranged from 0.0244 to 0.6743 with an average of 0.4234. The average GD within the G. hirsutum variety accessions of specific ecotypes (China, America, Former Soviet Union, and Africa) was very close and ranged from 0.4164 to 0.4348. The highest GD (0.673) among all elite G. hirsutum variety accessions was observed between the variety Handan33 (from China) and AcalaB (from America). The highest GD (0.6535) within the G. hirsutum variety accessions of specific ecotypes was observed between the variety Zhongmiansuo12 (an improved cultivar) and ZhongARC185（an innovative line）, both form the Chinese ecotype group. American varieties had the highest average GD (0.4348) and Chinese varieties had the lowest.
By population structure ( Bayesian clustering) analyses, the 158 genotypes were assigned into two subgroups (i.e. SG1 and SG2) with a wide range of gene flows among the cotton germplasm from China and from America. The two subgroups inferred from structure did not show an association with the geographic origin of the materials, reflecting the probable extensive exchange of parental lines by breeders nationwide.
Using a probability of membership threshold of 60%, 61 lines were assigned to SG1, 60 lines to SG2 and the remaining 37 lines were considered as intermediates. Furthermore, we performed an independent STRUCTURE run for each of the two subgroups. The results indicated there were two and five sub-subgroups existed in the subgroup SG1 and SG2, respectively, which accorded with the seven subgroup when running the structure using all 158 accessions in one. These results have provided valuable information for the association mapping of important agronomic traits, as well as for the breeding and exploit of new cotton germplsm.