Chasmogamous mutant, a novel character enabling commercial hybrid seed production in mungbean

Abstract

Mungbean (Vigna radiata (L.) Wilczek) is a self-pollinating crop that displays significant hybrid vigor in seed yield of F1 hybrids. Thus there is the possibility to use hybrid varieties as a breakthrough to raise the yield plateau of mungbean. However, hybrid mungbean seeds can only be accomplished by hand-pollination and thus commercial production is not possible. To encourage hybrid seed set, the plant breeder needs to develop characters that promote higher outcrossing rate such as open flower (chasmogamy). In this experiment, new chasmogamous mutants were induced by gamma irradiation at the rate of 100 and 200 Gy. The mutants were identified at a low rate of 0.4–0.7% in the M2 generation of accession V1197, and observed for their purity by growing in plant-to-row in the M3 and M4 generations. A uniform chasmogamous line was hybridized to normal flower lines to study the inheritance of this character. All F1 plants had normal flowers, while the F2 plants segregated well with 3 normal : 1 chasmogamous ratio. When the F1 was backcrossed to the chasmogamous parent, the progeny gave a ratio of 1 normal to 1 chasmogamous. Thus, chasmogamy was controlled by a single recessive gene, cha.