Interactions between an arbuscular mycorrhizal fungus and a soil microbial community mediating litter decomposition

Donald J. Herman, Mary K. Firestone, Erin Nuccio, Angela Hodge

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We investigated arbuscular mycorrhizal fungi (AMF) alteration of microbial
mediation of litter decomposition. AMF (Glomus hoi) were either allowed
access to or excluded from Plantago lanceolata L. root litter embedded in soil;
litter was labeled with either 13C only or 13C and 15N. Plant N uptake was
significantly increased if AMF accessed the litter, and 15N analysis of the plant
material indicated that 2–3% of plant N originated from litter. Succession of
the soil community mediating decomposition was assessed by phospholipid
fatty acids (PLFA) combined with 13C-PLFA. During the first 21 days of
decomposition, saprotrophic fungi and Gram-negative bacteria were the dominant
consumers of litter C. As decomposition progressed however, 13C content
of the fungal biomarkers declined substantially, and Gram-negative and Grampositive
bacteria became the primary reservoirs of labeled litter C. The putative
PLFA marker for AMF (16:1x5c) originated primarily from non-AMF sources.
In AMF-invaded root litter, Gram-negative, Gram-positive, and 16:1x5c
markers became less 13C-enriched relative to their counterparts in non-AMFinvaded
microcosms during active decomposition. These patterns of 13C: 12C
enrichment may result from AMF supply of 12C from the plant to the decomposing
soil microbial community; such C inputs could alter the microbial
mediation of litter decomposition.
A key function of the arbuscular mycorrhizal (AM) symbiosis
is to enhance nutrient capture for the associated
host plant, while in return, the fungus obtains a supply of
carbon (Smith & Read, 2008). AM fungal hyphae can
explore a large volume of soil and acquire phosphorus
(P) beyond the phosphate depletion zone that rapidly
builds up around the root surface (Sanders & Tinker,
1973). More recently however, an arbuscular mycorrhizal
fungi (AMF) role in plant N capture has been demonstrated,
at least under some (Atul-Nayyar et al., 2009;
Leigh et al., 2009; Barrett et al., 2011), but not all
(Hodge, 2003a; Reynolds et al., 2005), conditions. In
addition, a plant ammonium transporter has been identified
in Lotus japonicas, which is mycorrhizal-specific and
preferentially expressed in arbusculated cells (Guether
et al., 2009a, b). This suggests that the arbuscule may also
be involved as a site for N
Original languageEnglish
Pages (from-to)236-247
Number of pages12
Issue number1
Early online date17 Jan 2012
Publication statusPublished - 1 Apr 2012


  • phospholipid fatty acid; 13C; 15N. Glomus hoi; Plantago lanceolata.

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