Identifying and characterising effector molecules corresponding to disease outcomes in wheat stripe rust disease

Abstract

Plant disease is a severe limiting factor in crop production. Tracking the functional parts of pathogen genomes can inform fungicide application, resistance, and susceptibility of specific crop varieties to quickly predict the epidemic potential of new fungal incursions. This is hindered in wheat rust fungi where there are relatively few fungal avirulence (Avr) and host resistance (R) gene pairs that have been cloned and whose interactions are functionally characterised.

This thesis aims to investigate wheat immunity and the molecular interactions between wheat and cereal rust fungi, contributing to knowledge through the development of a platform based on transient transformation of wheat protoplasts.

The developed transient transfection assay in wheat protoplasts successfully screens Avrs without R gene overexpression. The defence-activated reporter and normalisation constructs demonstrate reduced variability and applicability across pathogen species and cultivars. This work also explores new tools for controlling plasmid expression and induction, as well as demonstrating the use of the wheat protoplast assay for undertaking functional studies, by investigating the effect of AvrSr50 on wheat gene expression in a susceptible host.

Better understanding of the fundamental biology of the wheat/rust fungi pathosystem facilitates genome informed surveillance and provides the foundation for modern plant breeding. This research provides insights into plant-microbe interactions and immune signalling, contributing improved tools and approaches for functional studies in complex plant-pathogen systems. The studies in this thesis have applications across diverse pathogen species and host cultivars, ultimately benefiting genome-informed crop protection strategies in major cereal crops. Show more