Evaluation of genetic structure of Korean wild soybean (Glycine soja) based on saponin allele polymorphism

Abstract

Korean wild soybeans (Glycine soja) hypocotyl exhibit seven common saponin allele combinations: Sg-1 a /sg-4/sg-6 (phenotype: Aa), Sg-1 b /sg-4/sg-6 (Ab), Sg-1 a /Sg-4/sg-6 (AaBc), Sg-1 b /Sg-4/sg-6 (AbBc), Sg-1 a /sg-4/Sg-6 (Aa + α), Sg-1 a /Sg-4/Sg-6 (AaBc + α) and Sg-1 b /Sg-4/Sg-6 (AbBc + α). Diversity of saponin allele frequency (Haf) and saponin allele combination frequency (Hacf) was evaluated by Shannon–Weaver Index that was ranged from 0.75 to 1.04 and 0.28 to 1.25, respectively. High values of Haf and Hacf were found in Jeollanam-do and its adjoining regions Jeollabuk-do and Gyeongsangnam-do. The genetic index of Korean wild soybean increased towards south from north and west from east regions. The frequency of Sg-1 b and Sg-6 allele combinations increased towards south region (Jeollanam-do). These results suggest that Jeollanam-do region is the primary center of diversity, Jeollabuk-do and Gyeongsangnam-do regions are the secondary center of diversity and the remaining regions (Gyeonggi-do, Gangwon-do, Chungcheongbuk-do, Chungcheongnam-do, Jeollabuk-do, Gyeongsangbuk-do and Jeju-do) are the tertiary center of diversity for soyasaponin polymorphism in Korea. Furthermore, saponin allele frequency distribution suggested that alleles Sg-1 b and Sg-6 dispersed from Jeollanam-do to other regions of Korea. Our findings have laid the foundation for uncovering genetic diversity in Korean wild soybeans that could be exploited in soybean breeding programs.