The Genetic Diversity of 69 Widely Used Chinese Sorghum Hybrids Released between the 1970s and 2010s

Abstract

Sorghum has a long history of cultivation in China. In this study, we aimed to clarify the genetic relationships and genetic variation trends in widely used Chinese sorghum hybrids which were released from the 1970s to 2010s and attempted to analyze the changes in sorghum breeding. A total of 257 alleles were detected by 51 polymorphic SSR markers among 69 widely used hybrids; an average of 5.04 alleles were detected by each marker. The average Shannon’s index and polymorphism information content (PIC) of markers were 1.39 and 0.70, respectively. Nei’s genetic diversity index continuously increased in four different breeding development stages (1973–1982, 1983–1992, 1993–2002, and 2003–2014). Genetic diversity gradually increased among the sorghum hybrids. Genetic similarity coefficients in the four breeding development stages first showed an increasing trend, and then a decreasing trend, finally stabilizing with an average value of 0.65. The genetic similarity changes in hybrids in early and late maturing areas were consistent at different breeding development stages. The genetic similarity coefficients in late maturing areas were constantly higher than those in the early maturing areas. This is related to China’s creative utilization of A2 cytoplasmic male sterile materials in the 1990s. A cluster analysis determined that 69 hybrids were divided into two groups, A and B. Group A could be further subdivided into four subgroups. These findings could provide a reference for parental selection and hybrid breeding in sorghum improvement programs.

Keywords

• cluster analysis
• genetic diversity
• hybrid
• sorghum
• SSR marker