Induction of systemic acquired resistance (SAR) using synthetic signal molecules against Colletotrichum falcatum in sugarcane

Abstract

Red rot of sugarcane caused by the fungal pathogen Colletotrichum falcatum is one of the major constraints in India and other South Asian countries. Studies were conducted under field conditions to induce systemic resistance against red rot of sugarcane using Benzo (1, 2, 3) thiadiazole — 7 — carbonic acid S — methyl ester (BTH) and salicylic acid (SA). The pre-treatment with these inducers significantly arrested the pathogen growth and reduced the disease severity in the pathogen-inoculated canes. Antifungal assay of tissue-bits from inducer treated canes showed clear inhibition of pathogen in the plates. The study on the possible mechanism(s) of induced resistance revealed induction of defense-related enzymes like phenylalanine ammonia-lyase (PAL), peroxidase (POX), polyphenol oxidase (PPO) and accumulation of phenolics in systemically protected sugarcane stalks. The study clearly established that, systemic acquired resistance holds a promise in managing red rot in elite commercial varieties under field conditions and it can be used as an effective management strategy for control of the disease in an environment expected to favour a disease outbreak.