Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Review Article
Publication Acceptance Date: May 31, 2001
Publication Date: July 3, 2001
Citation: SZABO, L.J., BUSHNELL, W.R. HIDDEN ROBBERS: THE ROLE OF FUNGAL HAUSTORIA IN PARASITISM OF PLANTS. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES. 2001. v. 94. p. 7654-7655. Technical Abstract: Biotrophic fungi have developed a range of "life styles" in their relationship with plants from the mutualistic to the parasitic. Powdery mildew and rust fungi form an obligately parasitic relationship in which the host plant becomes a source for sugars, amino acids and other nutrients. These parasites develop a specialized organ, the haustorium within plant cells for transfer of nutrients from host cell to fungal thallus. The haustorium is assumed to have a key role in the ability of these parasites to compete with the developing plant for photoassimilates and other nutrients. Uptake studies have demonstrated that sugars and amino acids are transferred from the host plant into biotrophic parasites and strongly support the idea that haustoria play a major role. However, because of the intracellular locations of haustoria and the complexities of the haustorium-host interface, it has been difficult to determine what transfer processes are involved and where they are located. In the last several years a different approach has been taken, in which cDNAs for developmentally expressed genes haustoria have been isolated. One of the most abundantly expressed genes encodes a glucose transporter and supports a proton symport model for nutrient transport at the haustorial interface. In this model, a membrane H+-ATPase generates a proton gradient across the haustorial plasma membrane, which provides the energy for transport of nutrients from the extrahaustorial matrix into the haustorium. This recent work has provided an important piece of the puzzle regarding the nutrient transport pathway across the host-parasite interface. However, many questions remain regarding this interface and mechanisms the obligate parasite uses to manipulate the host.