Archaeal abundance in relation to root and fungal exudation rates

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Archaeal abundance in relation to root and fungal exudation rates. / Sterngren, Anna; Johansson, Tomas; Bengtson, Per.

In: FEMS Microbiology Ecology, Vol. 80, No. 2, 2012, p. 305-311.

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T1 - Archaeal abundance in relation to root and fungal exudation rates

AU - Sterngren, Anna

AU - Johansson, Tomas

AU - Bengtson, Per

PY - 2012

Y1 - 2012

N2 - Archaea are ubiquitous in forest soils, but little is known about the factors regulating their abundance and distribution. Low molecular weight organic compounds represent an important energy source for archaea in marine environments, and it is reasonable to suspect that archaeal abundance is dependent on such compounds in soils as well, represented by, for example, plant and fungal exudates. To test this hypothesis, we designed a microcosm experiment in which we grew ponderosa pine, sitka spruce, and western hemlock in forest soil. Root and mycorrhizal exudation rates were estimated in a 13C pulse-chase experiment, and the number of archaeal and bacterial 16S rRNA genes was determined by qPCR. Archaeal abundance differed among plant species, and the number of archaeal 16S rRNA genes was generally lower in soil receiving high concentration of exudates. The mycorrhizal fungi of ponderosa pine seemed to favor archaea, while no such effect was found for mycorrhized sitka spruce or western hemlock. The low abundance of archaea in the proximity of roots and mycorrhiza may be a result of slow growth rates and poor competitive ability of archaea vs. bacteria and does not necessarily reflect a lack of heterotrophic abilities of the archaeal community.

AB - Archaea are ubiquitous in forest soils, but little is known about the factors regulating their abundance and distribution. Low molecular weight organic compounds represent an important energy source for archaea in marine environments, and it is reasonable to suspect that archaeal abundance is dependent on such compounds in soils as well, represented by, for example, plant and fungal exudates. To test this hypothesis, we designed a microcosm experiment in which we grew ponderosa pine, sitka spruce, and western hemlock in forest soil. Root and mycorrhizal exudation rates were estimated in a 13C pulse-chase experiment, and the number of archaeal and bacterial 16S rRNA genes was determined by qPCR. Archaeal abundance differed among plant species, and the number of archaeal 16S rRNA genes was generally lower in soil receiving high concentration of exudates. The mycorrhizal fungi of ponderosa pine seemed to favor archaea, while no such effect was found for mycorrhized sitka spruce or western hemlock. The low abundance of archaea in the proximity of roots and mycorrhiza may be a result of slow growth rates and poor competitive ability of archaea vs. bacteria and does not necessarily reflect a lack of heterotrophic abilities of the archaeal community.

KW - archaea

KW - bacteria

KW - mycorrhiza

KW - rhizosphere

KW - root exudation

KW - soil

U2 - 10.1111/j.1574-6941.2012.01298.x

DO - 10.1111/j.1574-6941.2012.01298.x

M3 - Article

VL - 80

SP - 305

EP - 311

JO - FEMS Microbiology Ecology

JF - FEMS Microbiology Ecology

SN - 1574-6941

IS - 2

ER -