Erysiphe alphitoides, causing oak powdery mildew, is a major foliar pathogen of Quercus robur often infecting entire tree stands.
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) play a key role in the acclimation process of plants to various stresses. Phenolics are widely distributed in oak, some of them occur constitutively, whereas others are synthesized in response to a pathogen attack where their appearance is considered as part of active defense.
The aim of the present study was to determine the changes in a generation of ROS and RNS and activity of enzymes involved in their metabolism in oak leaves infected with Erysiphe alphitoides. Moreover visualisation of NO was performed by using confocal microscopy. Additionally, we determined the form of phenolic accumulation in oak leaves and them role in effective protection against pathogen attack The study material was constitute one-year old seedlings of oak uninfected and infected with Erysiphe alphitoides from the container nursery, Forest District Gidle, Poland. For analysis we used leaves with different size of infection area (<5%, 12-15%, 25%).
The results showed that the infection of oak leaves with biotrophic pathogen caused significant changes in the generation of ROS and RNS, as well as in the activity of selected enzymes comparing to the control. HPLC analysis indicated remarkable increases in the concentrations of 23 phenolics belonging to hydroxybenzoic acids, cinnamic acids, catechins, flavonols, flavons and flavanons in the plants infected with powdery mildew. We suggest that the changes in generation of ROS and RNS and accumulation of phenolic acids and flavonoids may strongly contribute to oak protection against Erysiphe alphitoides attack.
Keywords: oak powdery mildew, reactive oxygen and nitrogen species, biotrophic pathogen
Authors
M. Skwarek
University of Lodz, Faculty of Biology and Environmental Protection, Department of Plant Physiology and Biochemistry, Lodz
A. Witczak
Warsaw University of Life Science – SGGW, Faculty of Forestry Department of Forest Protection and Ecology, Warsaw
J. Nawrocka
University of Lodz, Faculty of Biology and Environmental Protection, Department of Plant Physiology and Biochemistry, Lodz
J. Patykowski
University of Lodz, Faculty of Biology and Environmental Protection, Department of Plant Physiology and Biochemistry, Lodz
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