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.