Quantitative genetic variation photoinduced by 8-methoxypsoralen in yeast

The variation in cell mass production within cultured populations of Saccharomyces cerevisiae derived from untreated cells and from cells treated with 8-methoxy-psoralen plus near-UV light (8MOP-NUV) was determined. Spontaneous mutation was not a significant source of variation, since no genetic component of variance was detected in the untreated population. Following mutagenesis significant levels of genetic variation were found, showing that 8MOP-NUV was effective in inducing quantitative genetic variation among clonal populations of the yeast. The magnitudes of the estimates of the heritability and of the genetic coefficient of variation, indicate that, in phenotypic selection, greater genetic progress can be expected after mutagenic treatment than with untreated populations. The highest estimate of genetic gain was obtained at the intermediate survival level.