MSA - Systematics/Evolution
Picard, Kathryn T. , Letcher, Peter M. , Powell, Martha .
Investigating a Primitive Mycobiont-Photobiont Symbiosis.
Although mutualistic mycobiont-photobiont symbioses are commonplace among, and even characteristic of, higher fungal lineages, there are no known mutualistic interactions between the chytrid fungi and phototrophs. Consequently, chytrid fungi have long been thought to occupy three ecological roles: saprobes, parasites, or pathogens. Rhizidium phycophilum, a recently delineated saprobic soil-dwelling chytrid from Australia, exhibits a unique mode of nutrition in which the presence of a chlorococcalean green alga is required for maintenance on nutrient media. Using a combination of microscopic, molecular, and biochemical analyses, we have characterized the physical and metabolic interaction between these two organisms. Herein, we present evidence that the interaction between R. phycophilum and its algal cohort represents a primitive facultative symbiosis, the first of its kind among the basal fungi. The ability of R. phycophilum to alternate between saprobic and symbiotic behaviors suggests that early fungal symbioses may have been optional ecological strategies. Thus, the discovery of R. phycophilum not only expands the ecological role of chytrid fungi in terrestrial ecosystems, but also provides a model for investigating symbiotic interactions between early fungi and photobionts.
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1 - The University of Alabama, Biological Sciences, Box 870344, Tuscaloosa, AL, 35487, USA
2 - University of Alabama, Department of Biological Sciences, Po Box 870344, Tuscaloosa, Alabama, 35487, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Cottonwood A/Snowbird Center
Date: Tuesday, July 28th, 2009
Time: 8:00 AM