Plant responses to genotoxic stress are linked to an ABA/salinity signaling pathway

Cells have developed a complex network of reactions to avoid or reduce the deleterious consequences of DNA damage. Responses to genotoxic stress inclu de activation of distinct stress signaling pathways, delay of cell cycle pr ogression and induction of DNA repair. In contrast to other organisms, it i s not known which signal transduction pathways sense genotoxic stress in pl ants. Here we describe an Arabidopsis mutant (uvs66) that appears to be aff ected in the perception of signals triggered by genotoxic treatments. The m utant uvs66 was identified as hypersensitive to UV-C and to the DNA-damagin g chemicals methyl methane sulfonate (MMS) and mitomycin C (MMC), but seems to perform light dependent repair, nucleotide excision repair and homologo us recombinational repair as efficiently as the wild type. Exposure of uvs6 6 plants to various environmental stresses revealed a normal response, with the exception of elevated salinity and abscisic acid (ABA). The hypersensi tivity to NaCl and ABA is correlated with aberrant regulation of transcript s that are regulated by ABA (RAB18), or are induced by DNA damaging treatme nts (AtRAD51). The properties of the mutant uvs66 suggest an unexpected lin k between ABA and/or salt stress mediated signals and genotoxic stress resp onses, and provide an important connection between the physiological and ge netic responses of plants to abiotic stress factors.