Ethidium bromide uptake by peanut seeds and its relationship to varietal sensitivity and mutagenic efficiency

The mutagen ethidium bromide (EB), labelled with ¹⁴C in position 9 of the phenanthren ring, was used to test the relationship between differential varietal sensitivity in the M₁, mutagen uptake and mutagenic effectiveness and efficiency in treatments of mature seeds of two peanut cultivars. Differential physiological M₁ sensitivity was not related to differential uptake of EB. In both cultivars, the bulk of the mutagen was localized in the seed coats. EB uptake of the seeds and seed parts (testas, cotyledons and plumules plus radicles) was correlated with the logarithm of the treatment period. It was concluded that for increased mutagenic effectiveness and efficiency, shorter periods of treatment that suffice for the mutagen to reach the embryos should be preferred to prolonged ones.