Patchiness and Spatial Distribution of Laccase Genes of Ectomycorrhizal, Saprotrophic, and Unknown Basidiomycetes in the Upper Horizons of a Mixed Forest Cambisol

Abstract

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.

Soil Enzyme Activities in Pinus tabuliformis (Carriére) Plantations in Northern China

“…As a result, activities of microbial extracellular enzymes involved in C and N cycling and fungal laccases decline with increasing soil depth [64,65]. This decrease in microbial activity is similar to our results in which invertase and urease activities decreased with the increasing depth of soil (Table 4).…”

Distribution of Extracellular Enzymes in Soils: Spatial Heterogeneity and Determining Factors at Various Scales

“…For example, the enzyme distribution in a hardwood forest soil and litter exhibited spatial autocorrelations similar in scale to that of the microbial biomass (Baldrian et al, 2010a). This corresponds with the autocorrelation in the composition of the laccase gene pool in the organic horizon of a beech-oak forest, which was up to 1 to 2 m (Luis et al, 2005b). Urease activity, in contrast, was autocorrelated at distances >15 m in forest soil but <1 m in pasture (von Steiger et al, 1996).…”

“…The activities reported from several ecosystems often spanned several orders of magnitude across relatively small areas (Gömöryová, 2004;Luis et al, 2005b;Prietzel, 2001;Šnajdr et al, 2008b). For example, the activity of laccase in the litter and organic soil horizon of a Quercus petraea (Matt.)…”

Enzyme secretion by ECM fungi and exploitation of mineral nutrients from soil organic matter

“…Enzymes with the potential to break phenol-protein complexes (Bending and Read 1996;Joanisse et al 2009;Wu et al 2003) are largely the same as those involved in lignin degradation, namely phenoloxidases and peroxidases. While laccase genes were demonstrated in several ECM (Chen et al 2003;Luis et al 2005), there is only limited evidence for the presence in ECM of other lignolytic enzymes, e.g. lignin peroxidase or manganese peroxidase (Baldrian 2006;Cairney et al 2003).…”