Powdery mildew of barley is caused by the ascomycete pathogen Blumeria graminis f. sp.
hordei (Bgh). Bgh is economically important throughout the world, causing crop losses
varying between 5 to 20 % and in extreme cases as much as 60 %. Bgh is an obligate
biotroph, relying on its host for growth and reproduction. This characteristic has hindered
attempts to carry out biochemical and molecular biological analysis.
Previous work had highlighted differential gene expression during Bgh development on
surfaces other than the host. Consequently, this thesis had three aims. The first attempted to
elucidate the nature of this gene expression. Work listed within includes studies of Bgh
morphological development on the host barley, wheat, cellulose membrane, and glass.
Additional studies included the assessment of gene expression, via RT-qPCR, on glass
surfaces enhanced with 1-hexacosonal (a synthetic C26 aldehyde known to spur Bgh
development), 16-hydroxyhexadecanoic acid (a cutin monomer found within the barley leaf),
as well as surfaces of differing hydrophobicity. Results collected reenforce the surface-dependent
nature of gene regulation, and highlight how gene expression is determined by the
integration of multiple signal inputs.
The second aim of this thesis was the transformation of Bgh utilising Agrobacterium
tumefaciens. Efforts are discussed as are approaches for future work aimed at transforming
this fungus.
The final aim of the thesis aimed to lay foundations for work involving the assessment of 5‟-regulatory regions of genes showing clustered, and differential, expression on alternate
surfaces. Utilising the phytopathogenic model fungus Magnaporthe oryzae (the causal agent
of rice blast disease), 22 promoter regions were tested for their ability to drive GFP in this
pathogen. 2 regions (for genes encoding a H4 histone and an aconitase) along with promoter
regions selected for their conservation, were able to do so
