Ultrastructure of Haustoria of Plant Pathogenic Fungi

Abstract

Most plant pathogenic fungi that are obligate parasites produce haustoria which are thought to be involved in nutrient absorption. A haustorium is a specialized hyphal branch that penetrates the host cell wall and invaginates the host cell plasma membrane. The host plasma membrane ensheathing the haustorium is termed the extrahaustorial membrane. This presentation provides examples of different types of haustoria produced by plant pathogenic fungi. Species considered here are 1) Cronartium quercuum f. sp.fusiforme, the cause of fusiform gall rust of pine, 2) Puccinia arachidis, the cause of peanut rust1, 3) Uncinuliella australiana, the cause of powdery mildew of crape myrtle, 4) Exobasidium camelliae, a pathogen of Camellia sasanqua2, and 5) Cercosporidium personatum, the cause of late leaf spot of peanut.Rust fungi typically require two different host species to complete their life cycles. The dikaryotic phase of the rust life cycle consists of intercellular hyphae that give rise to specialized haustoria known as D-haustoria which are remarkably similar from one species to the next.