Genomic Mutation in Lines of Arabidopsis thaliana Exposed to Ultraviolet-B Radiation

Studies that have attempted to estimate the rate of deleterious mutation have typically been conducted under low levels of ultraviolet-B (UV-B) radiation, a naturally occurring mutagen. We conducted experiments to test whether the inclusion of natural levels of UV-B radiation in mutation accumulation (MA) experiments influences the rate and effects of mildly deleterious mutation in the plant Arabidopsis thaliana. Ten generations of MA proved insufficient to observe significant changes in means or among-line variances in experimental lines maintained either with or without supplemental UV-B radiation. Maximum likelihood estimates of mutation rate for total flower number revealed a small but significant rate of mutation for MA lines propagated under supplemental UV-B exposure, but not for those in which supplemental UV-B was omitted. A fraction of the flower number mutations under UV-B (ca. 25-30%) are estimated to increase flower number. Results from the application of transposon display to plant materials obtained after MA, both in the presence and absence of supplemental UV-B, suggest that the average rate of transposition for the class I and II TEs elements surveyed was less than 10-4. Overall, the estimates of mutation parameters are qualitatively similar to what has been observed in other MA experiments with this species in which supplemental UV-B levels has not been used. As well, it appears that naturally occurring levels of UV-B do not lead to detectable increases in levels of transposable element activity.

Key Words: deleterious mutation, mutation accumulation experiments, plants, transposable elements, transposon display

Online ISSN: 1943-2361  Print ISSN: 0016-6731
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