Patchiness and spatial distribution of laccase genes of ectomycorrhizal, saprotrophic, and unknown basidiomycetes in the upper horizons of a mixed forest cambisol.

Decomposition of plant litter by the soil microbial community is an important process of controlling nutrient cycling and soil humus formation. Fungal laccases are key players in litter-associated polyphenol degradation, but little is known about the diversity and spatial distribution of fungal species with laccase genes in soils. Diversity of basidiomycete laccase genes was assessed in a cambisolic forest soil, and the spatial distribution of the sequences was mapped in a 100-m(2) plot by using polymerase chain reaction (PCR) on soil DNA extracts. Diversity of laccase sequences was higher in the organic horizon and decreased with the depth. A total of 167 different sequences sharing 44-96% oligonucleotide similarity was found in 13 soil cores harvested in the 100-m(2) plot. Dissimilarity in laccase sequence content was 67% between adjacent cores; 45.5%, 35.5% and 19% of laccase sequences were attributed to ectomycorrhizal, unknown and saprotrophic basidiomycetes, respectively. Most dominant sequences were attributed to the extramatrical hyphae of known ectomycorrhizal taxa (e.g., Russulaceae) and restricted to small patches (<0.77 m(2)) in a specific soil horizon. Soil fungi with laccase genes occupied different niches and showed strikingly variable distribution patterns. The distribution of laccase sequences, and corresponding fungi, likely reflected a part of the oxidative potential in soils.