抄録
Rutin, anthocyanins and proanthocyanidins are representative flavonoids that are synthesized through the flavonoid biosynthetic pathway in common buckwheat (Fagopyrum esculentum). These flavonoids have beneficial properties such as antioxidant activity. The basal buckwheat stem is usually red or pink owing to an accumulation of anthocyanins. We found novel spontaneous green stem (GS) mutants in a common buckwheat population. To characterize GS mutants physiologically and genetically, and to deduce where the flavonoid biosynthetic pathway was disrupted and whether other flavonoids were affected by this disruption of anthocyanin synthesis, we measured the anthocyanin, rutin and proanthocyanidin contents in seedlings and performed genetic analysis. HPLC analysis of GS mutants showed no anthocyanin production, but rutin and proanthocyanidins accumulated in the seedlings. GS plants showed no red pigmentation in stems, petioles, leaf veins and anthers. Genetic analysis indicated that GS mutation involves a single recessive gene (designated tentatively as gs1). The proanthocyanidin content of GS plants in the F2 segregating population was significantly higher than in the wild type. The GS phenotype might be caused by the lack of an enzyme or by a defect of transcriptional factor between leucocyanidin or cyanidin and anthocyanin in the biosynthetic pathway.
