CONICET | Buscador de Institutos y Recursos Humanos

Ultraviolet-B (UV-B; 280315 nm) radiation is an integral part of the sunlight and induces a broad range of physiological responses. The absorption of UV-B causes cellular damage and the formation of photoproducts (CPDs) in DNA, which affect the structural and dynamic properties of chromatin. In maize, chromatin remodeling has been implicated in the response to UV-B. Many of the chromatin-associated factors that have been characterized in plants mediate posttranslational histone tail modifications or DNA methylation. To further investigate the role of chromatin remodeling in DNA repair, we analized an Arabidopsis mutant with affected DNA methylation status. REPRESSOR OF SILENCING 1 (ROS1) catalyze the release of 5-methylcytosine from DNA by a glycosylase-lyase mechanism and is required for release of transcriptional silencing of a hypermethylated transgene. We found that Ros1 gene is UV-B downregulated and ros1 deficient mutants accumulate significatively less CPDs than WT plants. By qRT-PCR, we determined that after UV-B exposure these plants have increased levels of some DNA repair genes and transcription factors of the UV-B-induced photomorphogenic pathway. Our data suggests that ROS1, in a still unknown way, is involved in the modulation of UV-B responses in Arabidopsis.