Effect of Acibenzolar-S-methyl (ASM) pre-treatment in inducing resistance against Pythium aphanidermatum infection in Curcuma longa

►Our data suggest that different regulatory mechanisms may participate in the induction of these two classes of inhibitors in turmeric. Interestingly, there is correlation between reduction of disease symptoms in terms of cell death and increased activities of protease, PI and peroxidase and in rhizomes pretreated with ASM. Such increases in enzyme activity restricted the development of disease symptoms on rhizomes pretreated with ASM followed by inoculation with P. aphanidermatum. The results of this study show a correlation between an increase of protease, protease inhibitors and peroxidase in turmeric rhizomes following infection and reduction in disease symptoms of those rhizomes to P. aphanidermatum. Enhanced activities of protease, peroxidase and protease inhibitors together contribute to plant defense responses in turmeric against P. aphanidermatum. Further studies will elucidate the regulatory mechanisms of PI and peroxidase accumulation in disease resistance of turmeric rhizomes against rhizome rot. Based on the promising results of this study and our previous report (Radhakrishnan and Balasubramanian, 2009), experiments are underway to study the efficacy of salicylic acid and ASM separately and in combination with developing resistance against P. aphanidermatum under field conditions.