Abstract
Hydrogen peroxide is a signal and effector molecule in the plant response to pathogen infection. Wheat resistance to Puccinia triticina Eriks. is associated with necrosis triggered by oxidative burst. We investigated which enzyme system dominated in host oxidative reaction to P. triticina infection. The susceptible Thatcher cultivar and isogenic lines with defined resistance genes were inoculated with P. triticina spores. Using diamine oxidase (DAO) and polyamine oxidase (PAO) inhibitors, accumulation of H2O2 was analyzed in the infection sites. Both enzymes participated in the oxidative burst during compatible and incompatible interactions. Accumulation of H2O2 in guard cells, i.e., the first phase of the response, depended on DAO and the role of PAO was negligible. During the second phase, the patterns of H2O2 accumulation in the infection sites were more complex. Accumulation of H2O2 during compatible interaction (Thatcher and TcLr34 line) moderately depended on DAO and the reaction of TcLr34 was stronger than that of Thatcher. Accumulation of H2O2 during incompatible interaction of moderately resistant plants (TcLr24, TcLr25 and TcLr29) was DAO-dependent in TcLr29, while the changes in the remaining lines were not statistically significant. A strong oxidative burst in resistant plants (TcLr9, TcLr19, TcLr26) was associated with both enzymes’ activities in TcLr9 and only with DAO in TcLr19 and TcLr26. The results are discussed in relation to other host oxidative systems, necrosis, and resistance level.
Highlights
Localized accumulation of reactive oxygen species (ROS) known as the oxidative burst is a plant response to pathogen infection and is an important component of plant resistance
We investigated whether the oxidative burst in the wheat–leaf rust system typically associated with necrotic reactions relies on polyamine oxidation
We investigated whether the oxidative burst and necrotic response in wheat infected with leaf rust relied upon the activities of two polyamine oxidation enzymes, and whether these activities depended on the genetic background of wheat lines
Summary
Localized accumulation of reactive oxygen species (ROS) known as the oxidative burst is a plant response to pathogen infection and is an important component of plant resistance. ROS production was documented for the first time by Doke [1] in potato tubers infected with Phytophthora infestans. Results published since have documented production of different ROS molecules in the response to pathogen invasion [2] and in a number of biological processes including growth, development and reaction to environmental stresses [3]. Reactive oxygen species (ROS) include singlet oxygen (1O2), hydroxyl radicals (OH), superoxide anion (O2−) and hydrogen peroxide. The majority of ROS generated in response to pathogen infection is accumulated in the apoplast. After infection and recognition of the pathogen, the membrane-bound NADPH oxidases and the apoplastic peroxidases are activated and serve as the source of apoplastic ROS in the so-called oxidative response [6]
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