Investigating Host Induced Meiosis in a Fungal Plant Pathogen

Abstract

Fungal spores lend the smut and rust plant diseases their names. Smut fungi produce massive numbers of dark, dust like, thick walled teliospores and the name, smut, is derived from the older definition meaning dark smudge from soot, smoke or dirt. The rust fungi produce diseases characterised by the production of pustules erupting from the plant surface. They contain urediniospores which are often orange or rusty in colour. Spores are essential for fungal survival, providing a means of dispersal and often a structure to protect the fungus; they are also integral to fungal meiosis. Smut and rust fungi are biotrophs, meaning they derive their nutrients from living plant hosts. This interaction is very intimate, involving fungal penetration of the plant cell walls but not the plasma membranes (e.g. Snetselaar & Mims, 1992; Voegele & Mendgen, 2003). As such, most smut and rust fungi have only evolved to infect (and become meiotically competent within) one or a limited number of host species.