title: Efficient removal of cyclobutane pyrimidine dimers in barley: differential contribution of light-dependent and dark DNA repair pathways.
abstract: Barley stress response to ultraviolet radiation (UV) has been intensively studied at both the physiological and morphological level. However, the ability of barley genome to repair UV-induced lesions at the DNA level is far less characterized. In this study, we have investigated the relative contribution of light-dependent and dark DNA repair pathways for the efficient elimination of cyclobutane pyrimidine dimers (CPDs) from the genomic DNA of barley leaf seedlings. The transcriptional activity of barley CPD photolyase gene in respect to the light-growth conditions and UV-C irradiation of the plants has also been analyzed. Our results show that CPDs induced in the primary barley leaf at frequencies potentially damaging DNA at the single-gene level are removed efficiently and exclusively by photorepair pathway, whereas dark repair is hardly detectable, even at higher CPD frequency. A decrease of initially induced CPDs under dark is observed but only after prolonged incubation, suggesting the activation of light-independent DNA damage repair and/or tolerance mechanisms. The green barley seedlings possess greater capacity for CPD photorepair than the etiolated ones, with efficiency of CPD removal dependent on the intensity and quality of recovering light. The higher repair rate of CPDs measured in the green leaves correlates with the higher transcriptional activity of barley CPD photolyase gene. Visible light and UV-C radiation affect differentially the expression of CPD photolyase gene particularly in the etiolated leaves. We propose that the CPD repair potential of barley young seedlings may influence their response to UV-stress.
authors.affiliation: Department of Molecular Genetics, Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Sofia, 1113, Bulgaria. vmanova@bas.bg.
authors.forename: Vasilissa
authors.identifier: http://orcid.org/0000-0002-8339-5057
authors.initials: V
authors.lastname: Manova
authors.affiliation: Department of Molecular Genetics, Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Sofia, 1113, Bulgaria.
authors.forename: Ralitsa
authors.initials: R
authors.lastname: Georgieva
authors.affiliation: Department of Molecular Genetics, Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Sofia, 1113, Bulgaria.|National Bank for Industrial Microorganisms and Cell Cultures, Sofia, 1756, Bulgaria.
authors.forename: Borislav
authors.initials: B
authors.lastname: Borisov
authors.affiliation: Department of Molecular Genetics, Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Sofia, 1113, Bulgaria.
authors.forename: Lubomir
authors.initials: L
authors.lastname: Stoilov
mesh_terms: D004249:DNA Damage; D004260:DNA Repair; D004255:Deoxyribodipyrimidine Photo-Lyase / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000235:genetics* / Q000502:physiology; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011740:Pyrimidine Dimers / Q000235:genetics*; D036226:Seedlings / Q000235:genetics / Q000502:physiology; D014466:Ultraviolet Rays
chemical_list: D010940:Plant Proteins; D011740:Pyrimidine Dimers; D004255:Deoxyribodipyrimidine Photo-Lyase