Induction of systemic resistance in tomato against root-knot nematode, Meloidogyne incognita by Pseudomonas fluorescens

Abstract

Induction of defence enzymes by Pseudomonas fluorescens isolate Pfl against challenge inoculation of Meloidogyne incognita in tomato was studied in vitro. The activities of peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), chitinase and catalase were assayed. Ibe isoforms of PO and PPO were examined by discontinuous native polyacrylamide gel electrophoresis. Activities of all the enzymes were significantly higher in bacterized tomato root tissues challenged with the nematode. Isoform analysis revealed unique PO and PPO isoforms induced in P. fluorescens-treated plants. There was also a significant reduction in the root-knot nematode population in roots of and soil around bacterized plants. The results suggest that induction of defence enzymes involved in the phenylpropanoid pathway and accumulation of phenolics and pathogenesis related proteins would have contributed to the restriction of invasion of M. incognita in tomato roots.