ICOM1 Abstract

or Talk: 4 - Biodiversity and Ecology BONELLO, PIERLUIGI & THOMAS D. BRUNS. Dept. of Environmental Science, Policy, and Management, University of California at Berkeley, 151 Hilgard Hall, Berkeley, CA 94720-3110, USA. - Genetic structure of Suillus pungens in a coastal Pinus murricata community of northern California The population structure of Suillus pungens was investigated in a 40 year old coastal forest of Bishop pine (Pinus muricata) in Northern California. Using regular PCR, RAPDs and AP-PCR (arbitrary primer PCR) of fruitbody tissues, 11 polymorphic loci were selected for single stranded conformational polymorphism (SSCP) analysis. A total of six different genotypes were detected in a 1200 m2 study area. Five of the six genotypes were represented by single fruitbodies. The largest genotype, comprising 13 fruitbodies, covers an area of at least 300 m2, with maximum measured dimensions of 40 m and 14 m. This genotype is the largest vegetative clone of an ectomycorrhizal fungus ever described, because apomixis could be excluded as a propagative mechanism. The fruitbody population had an observed average heterozygosity level of 0.423, indicating that outcrossing is a major component of the reproductive behavior of S. pungens. This implies that potential secondary homothallism, suggested by the dikaryotic nature of a proportion of the basidiospores, and which would result in selfing, is not ecologically significant. The combination of rapid growth and the abundant fruiting suggests S. pungens has a larger carbon budget than might be expected for a species known to be only a very minor ectomycorrhizal component of this community. Evidence suggests that this ectomycorrhizal fungus has saprophytic potential: S. pungens was able to grow in vitro with peat as the sole organic carbon source.