Induction of resistance in rice against Xanthomonas oryzae pv. oryzae by foliar application of cow dung water extract

Pretreatment of rice leaves with 20 per cent cow dung water extract (CDWE) was found to reduce bacterial blight disease of rice to about 50 per cent. The suppression of the disease by the extract was not due to direct inhibition of the pathogen. Pretreatment of rice leaves with cow dung water extract as foliar spray induced the accumulation of phenolics and enhanced the activities of peroxidase, chitinase and ß-1,3-glucanase. The induced defense mechanisms might have played a role in reducing the disease

Induction of resistance in host against the infection of leaf blight pathogen (Alternaria palandui) in onion (Allium cepa var aggregatum)

371-377The Pseudomonas fluorescens isolate Pf1 was found to inhibit the growth of pathogen Alternaria palandui, in vitro. In the present study, foliar application of a talc-based formulation of Pf1 significantly reduced the incidence of leaf blight of onion, caused by A. palandui. Induction of defense-related proteins viz., chitinase, β-1,3 glucanase, peroxidase (PO) and polyphenol oxidase (PPO) by application of Pf1, was studied against A. palandui infection in resistant (IHR 56) and susceptible (MDU1) onion cultivars. Chitinase in both cultivars, with or without challenge-inoculation of A. palandui revealed changes in the isoform pattern. The Native-PAGE of PO showed induction of PO2 isoform in both the cultivars, in response to inoculation of pathogen. Isoform analysis of PPO also exhibited induction in the Pf1-treated plants challenged with pathogen. Similarly, the activity of β-1,3-glucanase was greatly induced in Pf1-treated plants, challenged with pathogen as compared to controls. Thus, the P. fluorescens-treated plants showed significant increase in the levels of the defense enzymes, in comparison to the plants challenged with the pathogen

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