Role of Hydrogen Peroxide in Symptom Expression of Barley Susceptible and Resistant to Powdery Mildew

Hafez, Y. M. and Király, Z. (2003) Role of Hydrogen Peroxide in Symptom Expression of Barley Susceptible and Resistant to Powdery Mildew. Acta Phytopathologica et Entomologica Hungarica, 38 (3-4). pp. 227-236. ISSN 0238-1249

Preview

Text aphyt.38.2003.3-4.2.pdf Download (1MB) | Preview

Abstract

Three genotypes of barley (cultivar Ingrid) expressing the genes Mlo (susceptible), Mla12 (resistant with HR symptoms) and mlo5 (resistant without HR) in relation to infection by race A6 of Blumeria graminis f. sp. hordei have been sprayed with a solution of H2O2 after establishment of infection (2-3 days after inoculation). Under the influence of H2O2, leaves of the susceptible Mlo and mlo5-resistant plants exhibited HR-type symptoms with tissue necroses. The Mla12-resistant genotype produced HR earlier and the number of necrotic lesions increased, as compared to untreated control leaves. Treatment with H2O2 before establishment of infection (one day after inoculation), resulted in all the three genotypes in inhibition of the pathogen and symptomless response. It was possible to reverse the inhibitory as well as the HR-producing actions of H2O2 with injection of leaves with a combination of superoxide dismutase (SOD) and catalase (CAT) before treatment with H2O2.  It is suggested that the hypothetical negative regulation of HR-associated resistance in susceptible plants carrying the gene Mlo as well as in barley displaying HR-independent resistance and carrying the gene mlo5, could be associated with the limited production of H2O2 in infected plants. Supplying H2O2 to barley leaves that are either susceptible or display HR-independent resistance after establishment of infection, releases the negative regulation of symptoms of HR-associated resistance. This action of H2O2 is sensitive to antioxidant enzymes, such as SOD and CAT.

Actions (login required)

Edit Item