The Effect of X-Rays upon Dominant Mutation in Maize

Abstract

In order to estimate the frequency of a dominant mutation in maize, a gene (a, colorless aleurone) was studied which rarely if ever shows spontaneous mutation but which mutates frequently in the presence of another factor (Dt). The frequency of losses of color and the no. of cells involved were counted on other seeds of the same ears and provide a basis for estimation of the no. of opportunities for occurrence of detectable mutation. X-rays failed to induce mutation of a to A (or to any other aleurone allele) in populations large enough to yield approx. 400,000 mutations to A under the influence of homozygous Dt or 900,000 losses of A by deficiency or by mutation to a colorless allele.