A Comprehensive Analysis of Genetic Diversity and Relationships of 13 Sweet Sorghum Varieties as Energy Sources

Abstract

To investigate the genetic diversity and relationships among the sweet sorghum varieties as energy sources currently bred in China, 13 sweet sorghum varieties were selected for comprehensive analysis through observations of 31 biological traits and examinations of RAPD and SSR molecular markers. The numerical analysis showed that the differences in biological traits existed among 13 varieties, and the genetic distance (DIST) ranged from 0.787 to 2.221, and the two varieties from Inner Mongolia and Xinjiang were distinctly separated from all other varieties. A total of 22 polymorphism primers were obtained from the screening using RAPD marker analysis. The polymorphism rate was 58.33%, and the genetic similarity (GS) coefficients among the studied cultivars ranged from 0.694 to 0.896. Cluster analysis results indicated that the three varieties from Inner Mongolia, Xinjiang and Heilongjiang exhibited significant genetic differences from the other varieties. SSR marker analysis using 31 selected pairs of polymorphic primers showed that the polymorphism rate of amplified fragments was 78.64%, and GS coefficients among the tested cultivars were 0.534 to 0.971. Cluster analysis showed that variety No. 12 from Xinjiang and variety No. 7 from Inner Mongolia clustered into one group, and variety No. 6 from Heilongjiang was in a single group. The other ten varieties were grouped into another separate cluster. The results based on combined data displayed a similar trend with results from the three individual data analyses, but could more comprehensively and objectively reflect the fundamental genetic differences among these varieties. In summary, certain genetic differences exist among the varieties tested from different regions or different breeding institutions. However, varieties from the same region, especially those from the same breeding institution, exhibited small genetic variations and high genetic similarities. At present, more attention should be paid to discovery and innovation in the breeding of sweet sorghum varieties.