Abstract
To initiate defense responses against invasion of pathogenic organisms, animal and plant recognize microbe-associated molecular patterns (MAMPs). In this study, we examined the elicitor activity of bacterial DNA on model plant Arabidopsis thaliana. EcoRI-digested plasmid DNA induced defense responses such as generation of reactive oxygen species and callose depsition, whereas SmaI- and HapII-digested plasmid DNA and EcoRI-digested herring DNA did not remarkably induce these responses. Further, methylation of CpG sequence of plasmid DNA and E. coli DNA reduced the level of defense responses. We next tested the effect of endocytosis inhibitor for the DNA on DNA-induced defense responses. The endocytosis inhibitor, wortmannin and amantadine, significantly inhibited the defense responses induced by EcoRI-digested plasmid DNA. These results suggested that non-methylated CpG DNA induced defense responses on Arabidopsis as MAMPs and non-methylated DNA seems to be translocated into cytoplasm by endocytosis.
