An Arabidopsis photolyase mutant is hypersensitive to ultraviolet-B radiation

An Arabidopsis photolyase mutant is hypersensitive to ultraviolet-B radiation

^*The Boyce Thompson Institute for Plant Research and Section of Genetics and Development, Cornell University, Tower Road, Ithaca, NY 14853-1801; ^‡Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020; and ^¶Department of Agricultural Chemistry, Oregon State University, Corvallis, OR 97331

Abstract

Photolyases are DNA repair enzymes that use energy from blue light to repair pyrimidine dimers. We report the isolation of an Arabidopsis thaliana mutant (uvr2-1) that is defective in photorepair of cyclobutylpyrimidine dimers (CPDs). Whereas uvr2-1 is indistinguishable from wild type in the absence of UV light, low UV-B levels inhibit growth and cause leaf necrosis. uvr2-1 is more sensitive to UV-B than wild type when placed under white light after UV-B treatment. In contrast, recovery in darkness or in light lacking photoreactivating blue light results in equal injury in uvr2-1 and wild 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 photolyase is required for plant survival in the presence of UV-B light.

Footnotes

↵ † Present address: Biology Department, Monmouth University, West Long Branch, NJ 07764-1898.
↵ § Present address: Department of Biological and Environmental Sciences, University of Tennessee at Chattanooga, Chattanooga, TN 37403-2598.
↵ ‖ To whom reprint requests should be addressed. e-mail: RLL3{at}cornell.edu.
Charles J. Arntzen, Boyce Thompson Institute for Plant Research, Ithaca, NY
Abbreviations: (6–4′) photoproduct, pyrimidine pyrimidinone (6–4) dimer; CPD, cyclobutylpyrimidine dimer; UV-B, ultraviolet-B; UV-B_BE, biologically effective UV-B; WT, wild type.