Abstract
Temperature has generally great effects on both the activity and
composition of microbial communities in different soils. We tested the
impact of soil temperature and three different boreal forest tree
species on the archaeal populations in the bulk soil, rhizosphere, and
mycorrhizosphere. Scots pine, silver birch, and Norway spruce seedlings
were grown in forest humus microcosms at three different temperatures,
7–11.5°C (night–day temperature), 12–16°C, and 16–22°C, of which 12–16°C
represents the typical mid-summer soil temperature in Finnish forests.
RNA and DNA were extracted from indigenous ectomycorrhiza,
non-mycorrhizal long roots, and boreal forest humus and tested for the
presence of archaea by nested PCR of the archaeal 16S rRNA gene followed
by denaturing gradient gel electrophoresis (DGGE) profiling and
sequencing. Methanogenic Euryarchaeota belonging to Methanolobus sp. and Methanosaeta
sp. were detected on the roots and mycorrhiza. The most commonly
detected archaeal 16S rRNA gene sequences belonged to group I.1c
Crenarchaeota, which are typically found in boreal and alpine forest
soils. Interestingly, also one sequence belonging to group I.1b
Crenarchaeota was detected from Scots pine mycorrhiza although sequences
of this group are usually found in agricultural and forest soils in
temperate areas. Tree- and temperature-related shifts in the archaeal
population structure were observed. A clear decrease in crenarchaeotal
DGGE band number was seen with increasing temperature, and
correspondingly, the number of euryarchaeotal DGGE bands, mostly
methanogens, increased. The greatest diversity of archaeal DGGE bands
was detected in Scots pine roots and mycorrhizas. No archaea were
detected from humus samples from microcosms without tree seedling,
indicating that the archaea found in the mycorrhizosphere and root
systems were dependent on the plant host. The detection of archaeal 16S
rRNA gene sequences from both RNA and DNA extractions show that the
archaeal populations were living and that they may have significant
contribution to the methane cycle in boreal forest soil, especially when
soil temperatures rise.
Original language | English |
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Pages (from-to) | 205-217 |
Journal | Microbial Ecology |
Volume | 62 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2011 |
MoE publication type | A1 Journal article-refereed |