Genetic Diversity And Population Structure In Grain Sorghum Germplasm In China

Sorghum is the fifth largest cereal crops in the world, with the utilization for food, energy, feed. The glutinous grain sorghum with high quality is one of the main raw materials forbrewing Maotai-flavor liquor, such as Maotai, Xu etc.,which has more important economic value.Wine industry is a traditional pillar and local advantage industries, and is also an important source of financial income in Guizhou province. Becauseof the narrow genetic background in glutinous sorghum germplasm, the degradation in the main cultivars, and lack of new varieties with high yield and quality that meet the maotai-flavor liquor brewing technology, so in the study, Unweighted Pair-Group Method with Arithmetic mean(UPGMA) and Principal Coordinate Analysis(PCoA) were performed in two collections of grain sorghum(145 breeding parents and 156 germplasm resources), in order to investigate genetic diversity, to survey population structure, and to build heterotic groups, by using SSR molecular markers. The main results are as follows:1. Due to its unique brewing process in Moutai liquor, there are special requirements for the quality of glutinous sorghum. In order to investigate the genetic diversity of wine glutinous sorghum in Guizhou, 145 sorghum breeding lines were genotyped using 28 SSR markers. A total of 61 polymorphic loci were obtained, and its polymorphic index content(PIC) value ranged from 0.02 to 0.66, with an average of 0.42. The Jacard genetic similarity coefficient(GS) ranged from 0.60 to 0.98, with an average of 0.71. UPGMA cluster analysis showed that 2 major groups(GI and GII) were clustered at GS=0.63, according to the kinship of glutinous sorghum breeding lines. Further PCOA showed that the first principal coordinate(PCo-1) and the second principal coordinate(PCo-2) explained 5.6% and 3.7% of the population genetic variation, respectively. 145 sorghum materials formed two groups; one group contains 129 lines, which are more scattered. Another one gathered more closely, and composed of 16 accessions mainly derived from other provinces, which were not closely related to the wine sorghum varieties of Guizhou Province. The results showed that the Maotai liquor glutinous sorghum germplasm resource had poor genetic diversity at the molecular level.2. In order to investigate genetic diversity and population structure in Chinese grain sorghum, 156 grain sorghumgermplasm were scanned by 33 SSR markers. 186 polymorphic loci were obtained. SSRs PIC values ranged from 0.01 to 0.73, with an average of 0.45, and GS is between 0.15 and 0.9, with an average of 0.53. NJ cluster analysis and PCoA clearly divided 156 sorghum germplasm into three groups based on geographical regions. Group I was composed of 56 Southern sorghum, mainly originated from Guizhou, Sichuan and Yunnan. Group II were composed of 48 northern sorghum, mainly from Liaoning, Inner Mongolia, Beijing and other regions. Group III included 52 sorghum lines, main source from northern and southern regions, such as Heilongjiang, Shaanxi, Yunnan, etc. Our results revealed that the grain sorghum germplasm formed three heterotic groups, and could provide a theoretical basis for the enrichment of germplasm resources and the selection of cross parents in Guizhou glutinous sorghum breeding.