Variation in seed protein subunits among species of the genus Fagopyrum Mill

Seed protein subunits of 75 accessions belonging to 10 species of buckwheat (7 species of the big-achene group and 3 of the small-achene group) were studied by means of SDS-PAGE. The subunits varied greatly both within a species and among different species. The seven buckwheat species of the big-achene group have 42 different subunits whereas those of the small-achene group have only 16. Each buckwheat species has at least a few unique subunits, which could be used for species identification in the genus Fagopyrum. In the small-achene group, F gracillipes and F pleioramosum are closely related. Based on the number, distribution and cluster analysis of the seed protein subunits, common buckwheat, wild common buckwheat, F esculentum var. homotropicum, F zuogongense and F megaspartanium. are close to one another and tartary buckwheat, wild tartary buckwheat, F plius, F cymosum and F giganteum are also close to each other, supporting the hypothesis that F megaspartanium and E pilus are ancestral species of common buckwheat and tartary buckwheat respectively.