In vivo bioluminescence monitoring of defense gene expression in response to treatment with yeast cell wall extract

Abstract

Previous studies indicated that Housaku Monogatari (HM), a plant activator made from yeast cell wall extract, is effective for control of various plant diseases. To investigate the effect of HM treatment on plant gene expression, we tested the expression of defense related gene induction by exploiting tobacco pathogenesis-related protein 1a (PR-1a) gene promoter- and the Arabidopsis plant defensin 1.2 (PDF1.2) gene promoter-luciferase fusions as reporter genes. Transgenic Arabidopsis plants harboring promoter-luciferase fusion genes were treated with HM and the promoter activity was monitored as changes in luciferase activity in planta. Results of bioluminescence monitoring assay indicated that the promoters were activated at different times after the treatment of test plants with HM. Maximum activation of the PR-1a promoter occurred 4 days, and of the PDF1.2 promoter 4 h, after treatment. These results suggest that HM might contain multiple microbe-associated molecular patterns (MAMPs) that activate systemic acquired resistance and induced systemic resistance signaling pathways at different times. This may explain the mechanisms involved in the induction of defense responses against multiple plant pathogens by HM treatment.