cDNA microarray analysis of gene expression in rice plants treated with probenazole, a chemical inducer of disease resistance

 Probenazole (3-allyloxy-1,2-benzisothiazole-1,1-dioxide; PBZ) is a chemical inducer of disease resistance and has been used practically for protecting crops against pathogen infection. Using cDNA microarray, the expression of 1265 rice genes was monitored in rice plants after PBZ treatment. Ten cDNA clones exhibited more than threefold overexpression in the PBZ-treated plants compared to untreated controls. Some of the induced genes have identities with disease resistance- and pathogenesis-related genes. The enhanced gene expression was confirmed for 9 of the 10 genes using Northern blot or reverse transcription-polymerase chain reaction analysis. Expression of several clones was further investigated using RNA from rice plants infected with blast fungus. Under the conditions used, expression of three genes also showed an increased level of mRNA accumulation in fungus-infected plants. These results suggested that the genes enhanced during PBZ treatment were involved in the interactions between plants and pathogens.