Hence, f3gI expressed both rutin-3-O-diglycosidase and isoquercitrin-3-O-glucosidase activity. The f3g activity was measured by the intensity of quercetin fluorescence after incubation, but specificities about the released sugars were not addressed [Suzuki02b]. Flavonol-3-O-glucosidase activity and the metabolic pattern of rutin metabolism are more or less matching each other during seedling development. However, the activity of the flavonol-3O-glucosidase was mostly found in the testa whereas the highest concentration of rutin was found in the embryo of the seed indicating that f3g is not the controlling factor of rutin content in seeds [Suzuki02b] and might also have different physiological roles in the various buckwheat species during seed development [Suzuki07b].