Abstract
“Tanbaguro” (Glycine max) is a local variety of Japanese soybean characterized by a large seed size and black seed coat. We examined a method to distinguish Tanbaguro seeds, which were maintained and managed in domestic production as the standard strains, from seeds of other black soybean varieties. We selected 18 pairs of soybean simple sequence repeat (SSR) primers as primer sets to distinguish the seed varieties. Our analysis revealed that 4 strains and 20 seeds cultivated in Japan and distributed as Tanbaguro exhibited total agreement with standard strains, while 12 strains and 60 seeds cultivated in China and distributed as Tanbaguro exhibited only 13% agreement. These results suggested a wide genetic diversity of black soybeans cultivated in China. We then confirmed that our identification method using the same 18 primer sets can also be applied to processed foods. Identification of Tanbaguro products that were boiled, steamed and roasted was as successful as that of seeds ; the method could not be applied to fermented (natto) Tanbaguro products. Analysis of commercially processed foods containing Tanbaguro indicated that some foods of unknown source included soybeans cultivated in China, confirming that these foods are mixtures of Tanbaguro standard strains and other varieties.
