Seasonal carbon allocation to arbuscular mycorrhizal fungi assessed by microscopic examination, stable isotope probing and fatty acid analysis

TY - JOUR

T1 - Seasonal carbon allocation to arbuscular mycorrhizal fungi assessed by microscopic examination, stable isotope probing and fatty acid analysis

AU - Lekberg, Karin Ylva Margareta

AU - Rosendahl, Søren

AU - Michelsen, Anders

AU - Olsson, Pål Axel

PY - 2013/7

Y1 - 2013/7

N2 - Background and Aim: Climate change models are limited by lack of baseline data, in particular carbon (C) allocation to - and dynamics within - soil microbial communities. We quantified seasonal C-assimilation and allocation by plants, and assessed how well this corresponds with intraradical arbuscular mycorrhizal fungal (AMF) storage and structural lipids (16:1ω5 NLFA and PLFA, respectively), as well as microscopic assessments of AMF root colonization. Methods: Coastal Hypochoeris radicata plants were labeled with 13CO2 in February, July and October, and 13C-allocation to fine roots and NLFA 16:1ω5, as well as overall lipid contents and AM colonization were quantified. Results: C-allocation to fine roots and AMF storage lipids differed seasonally and mirrored plant C-assimilation, whereas AMF structural lipids and AM colonization showed no seasonal variation, and root colonization exceeded 80 % throughout the year. Molecular analyzes of the large subunit rDNA gene indicated no seasonal AMF community shifts. Conclusions: Plants allocated C to AMF even at temperatures close to freezing, and fungal structures persisted in roots during times of low C-allocation. The lack of seasonal differences in PLFA and AM colonization indicates that NLFA analyses should be used to estimate fungal C-status. The implication of our findings for AM function is discussed.

AB - Background and Aim: Climate change models are limited by lack of baseline data, in particular carbon (C) allocation to - and dynamics within - soil microbial communities. We quantified seasonal C-assimilation and allocation by plants, and assessed how well this corresponds with intraradical arbuscular mycorrhizal fungal (AMF) storage and structural lipids (16:1ω5 NLFA and PLFA, respectively), as well as microscopic assessments of AMF root colonization. Methods: Coastal Hypochoeris radicata plants were labeled with 13CO2 in February, July and October, and 13C-allocation to fine roots and NLFA 16:1ω5, as well as overall lipid contents and AM colonization were quantified. Results: C-allocation to fine roots and AMF storage lipids differed seasonally and mirrored plant C-assimilation, whereas AMF structural lipids and AM colonization showed no seasonal variation, and root colonization exceeded 80 % throughout the year. Molecular analyzes of the large subunit rDNA gene indicated no seasonal AMF community shifts. Conclusions: Plants allocated C to AMF even at temperatures close to freezing, and fungal structures persisted in roots during times of low C-allocation. The lack of seasonal differences in PLFA and AM colonization indicates that NLFA analyses should be used to estimate fungal C-status. The implication of our findings for AM function is discussed.

U2 - 10.1007/s11104-012-1534-7

DO - 10.1007/s11104-012-1534-7

M3 - Journal article

SN - 0032-079X

VL - 368

SP - 547

EP - 555

JO - Plant and Soil

JF - Plant and Soil

IS - 1-2

ER -