Probenazole (Oryzemate®) — A Plant Defense Activator

Abstract

Most plants have the ability to fight off pathogens by invoking various defense systems, including systemic acquired resistance (SAR). Chemicals that activate SAR are called plant activators. Among the most effective known plant activators is probenazole (3-allyloxy-1,2-benzisothiazole-1,1- oxide; PBZ, Figure 1), developed by Meiji Seika Kaisha Ltd. Oryzemate® granule, containing PBZ, has been widely used against rice blast by Japanese farmers since 1975. In the past several years, it has been applied in some 25–30% of all paddy fields in Japan to control blast. Since PBZ activates plant defense systems, the study of PBZ’s mode of action has helped clarify how rice plant defense systems function. These studies suggest that PBZ is not only an essential protectant for rice cultivation, but also a useful probe in research into plant defense mechanisms.