An Inhibitor Gene for Flower Standard Development in Korean Lespedeza1

Abstract

Crosses were made between two lines of Korean lespedeza (Lespedeza stipulacea Maxim.) with mutant flower characters. F1, F2, F3, and F4 data were used to determine whether the mutant gene s for small purple flower standard and the mutant gene a for fused accessory wings and no standard (formerly designated narrow white standard nws) were alleles, whether dominance between the two existed, and whether there was any linkage or recessive epistasis involved if the two genes were not alleles.F1 plants from this cross all produced normal flowers, indicating that the two genes >s> and >a were not alleles. Flower data from the F2 plants indicated a segregation ratio of 9 normal standards: 3 small purple standards: 4 fused accessory wings. Flower data from the F3 and F4 generations provided further support for the proposed 9:3:4 F2 ratio. All evidence indicated that the genotypes of the mutant parent with small purple flower standard, the mutant parent with fused accessory wings, and the F2 plants were ss AA, SS aa, and Ss Aa, respectively, and that no linkage was involved. It was concluded that the gene a in the homozygous condition completely inhibits flower standard development (recessive epistasis), regardless of whether the gene for standard is homozygous dominant (SS), homozygous recessive (ss), or heterozygous (Ss). When flower standard development is inhibited by the gene a, it is suggested that fused accessory wings develop in place of the flower standard.