Abstract
Double-stranded DNA breaks (DSBs) induced by irradiation is sensed mainly by the ATM signaling cascade. ATM protein is involved not only in the regulation of DNA repair activities and apoptosis but also in DNA damage cell cycle checkpoints. ATM induces the expression of DNA repair genes and cell cycle-related genes following irradiation immediately. In yeast or mammalian cells, ionizing radiation induces a strong, rapid, and transient transcriptional activation of genes involved in the cell cycle response to or repair of DSBs. It is suggested that basic machinery that repairs DSBs and controls cell cycle progression in plants is similar to that of yeast and mammals. Although the ATM pathway is highly conserved over species, the mechanisms by which plant cells stop their cell cycle and repair DSBs in response to the loss of genome integrity are unclear.
Arabidopsis thaliana (ecotype Columbia) plants were grown under long day conditions on germination medium. For proton beam irradiation treatments, 5-day-old plantlets were irradiated with 200MeV proton beams. Plant material was harvested and total RNA was extracted according to a time course. The transcript profiles of Arabidopsis thaliana homologues of human DNA repair genes and Arabidopsis thaliana homologues of human cell cycle-related genes following irradiation were determined by real-time RT-PCR.
