Introduction

We have a strong interest in the interaction between eukaryotic organisms
leading to symbiosis and pathogenesis. This has lead to an interest in the
fungal pathogenesis of plants by the smut and rust fungi. Fungi in these two
pathogenic groups share a requirement for growth and development within a
host plant, often referred to as a biotrophic phase, to complete their life
cycles. Key to understanding pathogenesis by these organisms is a complete
assessment of fungal gene expression during this in planta developmental
phase. Knowledge of this gene expression will significantly increase our
ability to fight these diseases by identifying virulence factors and
enabling plant breeders to design new and novel resistance strategies. We
use the causal agent of common smut of corm, Ustilago maydis, as a model to
investigate gene expression during key developmental transitions in the smut
life cycle. Ustilago maydis requires growth in planta for the completion of
it's life cycle but, unlike most rusts and some smuts, U. maydis is readily
cultured outside the host and is amenable to genetic analysis and molecular
manipulation including transformation and homologous gene replacement. The
long-term objective of the lab is to determine the function of all genes
whose expression is altered as U. maydis proceeds through its many
developmental transitions. In the near term we are focusing on two growth
stages, teliospore germination and filamentous growth within the plant. In
both instances we are creating EST libraries and studying gene expression on
a near genome wide scale. Other supporting lines of investigation involve
the identification and functional analysis of key signal transduction genes
in U. maydis.