Understanding how barley interacts with Rhynchosporium secalis and Pyrenophora teres as a basis for improving disease resistance to necrotrophic fungal pathogens

Abstract

The role of reactive oxygen species (ROS) in the induction of the hypersensitive reaction (HR) has been well characterised during various interactions between biotrophic fungi and plants. However, given that necrotrophic fungi thrive on dead tissue, one could assume that the HR is not a viable defence mechanism. In an attempt to understand the interaction between barley and the fungal necrotroph Rhynchosporium secalis (causal agent of barley leaf scald) we have been investigating cytoskeletal changes, ROS production and the enzyme status related to the redox levels of the cell during susceptible and resistant responses. Our study of the interaction between barley and the spot and net forms of the net blotch pathogen Pyrenophora teres (f. maculata and f. teres respectively) has provided us with insight of both the biotrophic and necrotrophic stage of this interaction. In particular, we have established the types of toxins produced by P. teres, the timing of gene expression and activity of various defence-related enzymes, and the involvement of redox status in determining tolerance to this pathogen. The potential ability of necrotrophic pathogens to hijack the plant defences usually reserved for biotrophic fungi to ensure their progress into plant tissue will be discussed.