Abstract
A mutagenic factor, mutator, that was detected in the progeny from a γ-ray irradiated M1 seed of a japonica rice variety Gimbozu, generated novel mutations at many different loci, when activated by the reversion of a mutable slender-glume gene slg, which was induced by γ rays in the above identical M1 seed. For the effective utilization of the mutator in plant breeding, the reversion mutability of slg was analyzed for its genetic behavior and relationship with the mutator activity. First, changes in the reverse mutation frequency of slg (RMF) were traced among several generations, using 39 slender-glume lines which originated from a single slender-glume mutant but were more or less different from each other in background genotype. The results revealed that the mutability of slg was essentially an inherited character, but that it often increased or decreased. Secondly, eleven of the 39 slender-glume lines were each estimated for the mutator activity by examining the frequency of mutator-induced heading-date mutations that appeared in the progenies of non-slender-glume plants from the slender-glume lines, using 424 sublines derived from the 11 lines. As a result, it was found that the mutability of slg did not influence the mutagenic activity of the mutator.
