Abstract
The ultraviolet B insensitive 4 (uvi4) mutant is one of the four UV-B resistant mutants that have been previously isolated. The fresh weight of uvi4 plants grown under supplemental UV-B light was more than twice of that of the wild type. No significant difference was found in the UV-B absorbing compounds extracted in acidified methanol. The induction and reduction in level of cyclobutane pyrimidine dimers was not significantly different between uvi4 and wild type. We found that the leaf cells of uvi4 undergoes one more round of endoreduplication as compared to those of wild type. This enhanced ploidy level may contribute the higher tolerance of uvi4 mutant. The uvi4 is mapped on the bottom of chromosome 2 and the positional cloning is ongoing.
