Chemically and biologically mediated systemic resistance in cucumber (<em>Cucumis sativus</em> L.) against <em>Pseudoperonospora cubensis</em> and <em>Erysiphe cichoracearum</em>

Abstract

Azoxystrobin at concentrations of 0.25, 0.5 and 1.0 ml l-1, mancozeb at 2 g l-1 and Pseudomonas fl uorescens at 10 g l-1 were evaluated in cucumber for their effi cacy in inducing defense enzymes against Pseudoperonospora cubensis and Erysiphe cichoracearum. The activity of the defense enzymes peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), ß-1,3-glucanase, chitinase, catalase and defense-inducing chemicals (total phenols) increased in the azoxystrobin and P. fl uorescens treated cucumber plants. Increased expression of specifi c isoforms of PO and PPO was observed due to induced systemic resistance (ISR).