Possible roles of insoluble proanthocyanidin in Tartary buckwheat (Fagopyrum tataricum) leaves

Insoluble proanthocyanidins are reported as plant defence compounds against herbivorous insects. This is the first report to demonstrate the occurrence of insoluble proanthocyanidins in plants of the Polygonaceae family. In this study, we identified a mutant Tartary buckwheat (Fagopyrum tataricum) cultivar, ‘Hokkai T10’, that lacks insoluble proanthocyanidins accumulation in leaves and shows a role in defence against common cutworm (Spodoptera litura Fabricius). We did not detect insoluble proanthocyanidins in p‐dimethylaminocinnamaldehyde stain in ‘Hokkai T10’. The expression of the trait should be regulated by at least one recessive gene named iPA. The leaves of ‘Hokkai T10’ were ingested in larger amount by S. litura than the wild type. This fact supports the hypothesis that insoluble proanthocyanidins have a role in protection against insects. This is the first report to demonstrate a resistance role of insoluble proanthocyanidins using insect preference. In addition, the germination rate of ‘Hokkai T10’ was significantly higher than wild type; indicating to show firstly the effects of insoluble proanthocyanidins on seed germination.