Two independent gene loci controlling non-brittle pedicels in buckwheat

The shattering habit in buckwheat occurs because of brittle or weak pedicels. Brittle pedicels are observed in wild buckwheat but not in cultivated buckwheat. Using 2 self-compatible lines, 01AMU2 with brittle pedicels and Kyukei SC2 (KSC2) with non-brittle pedicels, produced by an interspecific cross between Fagopyrum esculentum cv Botansoba (non-brittle) and F. homotropicum (brittle), we investigated the inheritance of brittle pedicels. F1 plants derived from crosses between Botansoba × 01AMU2 and Botansoba × KSC2 had brittle pedicels. The F2 population derived from the cross between Botansoba × 01AMU2 showed segregation of brittle and non-brittle pedicels that fit the expected 3:1 ratio, suggesting that non-brittle pedicel in Botansoba is controlled by a single recessive gene (sht1). Another F2 population, derived from the cross between Botansoba × KSC2, showed segregation of brittle and non-brittle pedicels that fit an expected ratio of 9:7, suggesting that non-brittle pedicel in KSC2 is controlled by a different single recessive gene (sht2). Thus, brittle pedicel is achieved by 2 complementary genes Sht1 and Sht2. The sht1 locus is linked to the S locus with a recombination frequency of 5.46±1.18 (%). We investigated whether common buckwheat has the allele sht2 by crossing 6 common buckwheat lines with KSC2. An analysis of the preliminary data showed that some of the F1 had brittle pedicels and others had non-brittle pedicels, suggesting that some common buckwheat lines possess both the alleles Sht2 and sht2.