Bunketsu-waito, one of the tillering dwarfs, is controlled by a single recessive gene in rice (Oryza sativa L.)

Bunketsu-waito, one of the tillering dwarfs, was reported to be controlled by triplicate genes, d3, d4 and d5. Although a segregation ratio fitting to 15:1 for bunketsu-waito was observed in the F₂s of the crosses between H-52 (bunketsu-waito) and genetic marker lines No.201 or H-61, the backcross of (H-52 x H-61) F₁ x H-52 showed a segregation ratio of 1:1 for normal vs. bunketsu-waito and the reciprocal backcross showed a decrease of the segregation ratio for bunketsu-waito from 1:1. These results demonstrated that bunketsu-waito was controlled by a single recessive gene and suggested that the abnormal segregation of bunketsu-waito in the F₂ of H-52 x H-61 was caused by a gametophyte gene linked to a gene for bunketsu-waito. Furthermore, the decrease of the segregation ratio of bunketsu-waito in the F₂ of H-125 x Kasalath was also observed and was considered to be due to a gametophyte gene, based on the results of reciprocal backcrossing between H-125 and the F₁ of H-125 x Kasalath. Thus, it was assumed that bunketsu-waito was controlled by a single recessive gene, and that the bunketsu-waito gene was mapped between RM 587 and RM 4608 on chromosome 6, based on linkage analysis using SSR markers.