The Sg-6 saponins, new components in wild soybean (Glycine soja Sieb. and Zucc.): polymorphism, geographical distribution and inheritance
Hypocotyl saponin composition of 1,198 accessions of wild soybean (Glycine soja) collected from China, Korea, Japan and Russia Far East was analyzed by thin-layer chromatography to determine polymorphic variation and geographical distribution. Eight common distinguishable saponin phenotypes were identified: Aa, Ab, AaBc, AbBc, Aa+α, Ab+α, AaBc+α and AbBc+α. The latter four +α type were new. All eight types were identified in China. Type Ab+α was absent in Korea. Types Ab+α and AbBc+α, and Aa+α and Ab+α were not identified in Japan and Russia far east, respectively. Six new triterpene saponins were detected in +α type via LC-PDA/MS/MS analyses. They were, tentatively, designated as H-αg, H-αa, I-αg, I-αa, J-αg and J-αa. These saponins were inherited together by a single dominant allele. A gene symbol Sg-6 was assigned. Hence, the new saponins were collectively named as Sg-6 saponins. The frequency of Sg-6 allele was 17.6 % in Chinese, 10.0 % in Korean and 1.0 % in Japanese wild soybean. The wild soybeans having Sg-6 saponins can be utilized in soybean breeding programs as well as in saponin biosynthesis studies in soybean.
KeywordsGlycine soja Sieb. and Zucc. Soyasaponin polymorphism Triterpene glycosides Wild soybean Soybean
We thank Dr. Sang-Mi Sun for maintaining the germplasm collection. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0013600).
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