Lg. Landry et al., AN ARABIDOPSIS PHOTOLYASE MUTANT IS HYPERSENSITIVE TO ULTRAVIOLET-B RADIATION, Proceedings of the National Academy of Sciences of the United Statesof America, 94(1), 1997, pp. 328-332
Photolyases are DNA repair enzymes that use energy from blue tight to
repair pyrimidine dimers. We report the isolation of an Arabidopsis th
aliana mutant (uvr2-1) that is defective in photorepair of cyclobutylp
yrimidine dimers (CPDs). Whereas uvr2-1 is indistinguishable from wild
type in the absence of UV light, low UV-B levels inhibit growth and c
ause leaf necrosis. uvr2-1 is more sensitive to UV-B than wild type wh
en placed under white light after UV-B treatment. In contrast, recover
y in darkness or in light lacking photoreactivating blue light results
in equal injury in uvr2-1 and mild type. The uvr2-1 mutant is unable
to remove CPDs in vivo, and plant extracts lack detectable photolyase
activity. This recessive mutation segregates as a single gene located
near the top of chromosome 1, and is a structural gene mutation in the
type II CPD photolyase PHR1. This mutant provides evidence that CPD p
hotolyase is required for plant survival in the presence of UV-B light
.