Abstract
DNA can be damaged by extracellular and intercellular insults. Eukaryotic cells have DNA checkpoint system, which arrests the cell cycle in response to damaged or incompletely replicated DNA to provide time for the cell for repair damaged chromosome before entering mitosis. Plants are always exposed to high levels of environmental stresses, and get more DNA damage than mammals. Therefore, plants should have more robust and effective mechanisms to cope with DNA stress. Comparative sequence analysis among plants and mammals indicates that some factors involved in DNA checkpoint are conserved between them. However, some checkpoint defective plants show different phenotype from that of mammals'. Furthermore, plants have no homolog of some checkpoint genes identified in mammal. These studies indicate that plants might have evolved unique DNA checkpoint system. We previously reported that Arabidopsis SOG1, which was a plant-specific transcription factor, played an important role in DNA checkpoint. Now, we are trying to reveal new aspects of plants' checkpoint system centering on SOG1.
