Citation: SZABO, L.J. RUST FUNGI: AN OBLIGATE-PARASITIC LIFE STYLE. AMERICAN PHYTOPATHOLOGICAL SOCIETY ABSTRACTS. 2002. Phytopathology. v. 92. p. S103. Interpretive Summary:
Technical Abstract: Rust fungi have developed a complex infection pathway in which the plant host plays a major role. Infection begins with the germination of a spore on the leaf surface, followed by the development of an appressorium. The development of the appressorium depends on a thigmotrophic signal triggered by the specific topography of the host plant surface. An infection peg formed by the appressorium enters the leaf through a stoma, followed by the development of a substomatal vesicle, infection hypha, haustorial mother cell, penetration of a photosynthetic mesophyll cell, and the establishment of a haustorium. Recent work has begun to elucidate the genes and proteins involved in this complex infection pathway and the specific role of the haustoria in nutrient transfer. These include proteases and cellulases involved in cell wall degradation as well as amino acid permeases and sugar transporters involved in nutrient uptake. Given the complexity of the infection pathway and the intimate nature of the interaction, a diverse array of genes will be necessary to establish and maintain the obligate-parasitic lifestyle.