Journal of Plant Pathology & Microbiology

Abstract

Enzymatic Responses of Ginger Plants to Pythium Infection after SAR Induction

Rajyasri Ghosh

A variety of enzymatic responses of ginger plants to Pythium infection after induction of SAR (systemic acquired resistance) have been investigated. Results of pathogenicity test of P. aphanidermatum on a susceptible ginger cultivar showed that disease intensity increased with time up to 28 days but Polyphenol oxidase (PPO), Lipoxygenase (LOX) and Phenyl alanine ammonia lyase (PAL) activities increased up to 14 days following inoculation and then declined whereas Peroxidase (PO) activity reached their peaks on 21st day after inoculation and then decreased sharply. To induce SAR, rhizome seeds were soaked separately in salicylic acid (SA-5 mM) and Acalypha leaf extract (ALE – 10%) for 1 hour prior to sowing. Significant disease reduction was observed in both SA and ALE treated plants. SA and ALE treatment enhanced activities of all four defence related enzymes in ginger leaves but the rate of increase was higher in untreated inoculated and treated non-inoculated plants in relation to their respective controls. Treated inoculated plants exhibited maximum activity for all four enzymes. SA stimulated PO and PAL more than that of ALE. Results suggest that a correlation exists between reduction of disease intensity due to SAR induction and greater stimulation of specific enzymatic activities in ginger plants although not all four enzymes are equally responsive to a defence activator.