A methodology for heterosis breeding of common buckwheat involving the use of the self-compatibility gene derived from Fagopyrum homotropicum

We propose an alternative breeding methodology for common buckwheat (Fagopyrum esculentum Moench), involving the use of the self-compatibility (Sh) gene derived from F. homotropicum Ohnishi. This methodology involves inbred development of homostyle (ShSh) and pin (ss) lines by using the self-compatibility gene (Sh). Further, single-cross hybrid seeds are produced using these inbred homostyle and pin lines as pollen and seed parents, respectively. This strategy successfully produced self-compatible homostyle hybrids (Shs); the percentage of hybrid plants among the progeny was more than 90%. In a greenhouse trial, the heterosis (best parent) in top dry weight, including stem and leaves, was 29.1–48.1% during the early growth stage. The seed yield of the progeny obtained in single-cross experiments was superior to that of an open-pollinated standard variety “Kitawasesoba” by 10% on average. These results suggest that heterosis breeding can be used to increase seed yield in common buckwheat.