The effect of chemicals on somatic homologous recombination in the rice blast fungus: its possible application for detection of mycotoxins

Abstract

  We previously established a detection/selection system for somatic homologous recombination (HR), which is one of the genetic modification mechanisms in eukaryotes. Because HR is stimulated by the protein synthesis inhibitor blasticidin S, it is presumed that HR in Pyricularia oryzae can be induced by various chemical stresses. To evaluate the effects of chemical stresses on the frequency of HR, several chemical agents were applied to P. oryzae and HR were detected using our detection system. Three well-known DNA-damaging agents－methyl methanesulfonate, bleocin, and methyl viologen－considerably increased the frequency of HR. Adding the amino acid synthesis inhibitor bialaphos, or the protein synthesis inhibitor T-2 toxin, to the medium also significantly increased the frequency of HR. These results suggest that the increased frequency of HR caused by inhibitors of the primary metabolic pathway reflect destabilization of the genome by chemical stressors. Taken together, these findings suggest that the HR detection system may become one of the most useful biological assays for detecting mycotoxins.