Pretreatment of rice seedlings by fo-liar spraying with benzothiadiazole(BTH) could induce systematic ac-quired resistance (SAR) against blast( Magnaporthe grisea ) and bacterialleaf blight ( Xanthomonas oryzae pv.oryzae) diseases. To elucidate thephysiological and biochemical mecha-nisms of the SAR induced by BTH,we analyzed the changes in activities Pretreatment of rice seedlings by fo-liar spraying with benzothiadiazole (BTH) could induce systematic ac-quired resistance (SAR) against blast (Magnaporthe grisea) and bacterialleaf blight (Xanthomonas oryzae pv.oryzae) diseases. To elucidate the physiology and biochemical mecha-nisms of the SAR induced by BTH, we analyzed the changes in activities