Determining the outcome of field‐based competition between two Rhizopogon species using real‐time PCR

Molecular Ecology - Tập 16 Số 4 - Trang 881-890 - 2007
Peter G. Kennedy1, Sarah E. Bergemann2, Sara Hortal3, Thomas D. Bruns1
1Department of Plant and Microbial Biology, 321 Koshland Hall, University of California, Berkeley, CA, USA,
2Department of Environmental Science and Policy Management, 137 Mulford Hall, University of California, Berkeley, CA, USA,
3IRTA, Departament de Proteccio Vegetal, Ctra Cabrils km 2, 08348 Cabrils, Spain

Tóm tắt

AbstractInterest in the ecology of ectomycorrhizal (ECM) fungi has increased considerably, but little is known about interspecific interactions among ECM species. We examined competitive interactions between Rhizopogon occidentalis and R. salebrosus at Point Reyes National Seashore, California, USA. At three field sites, species abundances were compared in single‐ and two‐species treatments on Pinus muricata seedlings inoculated with spores. Competition for root tips was assessed using real‐time polymerase chain reaction (PCR) of internal transcribed spacer rDNA. In general, we found strong competitive exclusion of R. salebrosus by R. occidentalis, with ≥ 75% of the seedlings in the two‐species treatment colonized exclusively by R. occidentalis after 5 and 10 months. However, on the seedlings that were co‐colonized, we observed no significant difference in the abundances of R. salebrosus and R. occidentalis, suggesting that once R. salebrosus was established, it was no longer competitively inferior. There were no significant differences in survival, growth, or percentage leaf nitrogen of seedlings colonized with either Rhizopogon species, but both growth and percentage leaf nitrogen were significantly higher for ECM than non‐ECM seedlings. We also observed strong positive correlations between actual ECM root tip weight and that inferred from real‐time PCR for both species, indicating that this method provided an accurate assessment of root tip occupation and hence ECM competitive dynamics. In conjunction with a previous experiment, our results indicate that competition between these two Rhizopogon species occurs similarly in both field and laboratory settings and that when colonizing from spore, timing largely determines the outcome of initial competitive interactions.

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Thông tin xuất bản

Molecular Ecology

Tập 16 Số 4

881-890

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