Browsing by Subject "Phospholipid fatty acids"

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Microbial drivers of plant richness and productivity in a grassland restoration experiment along a gradient of land‐use intensity
(2022) Abrahão, Anna; Marhan, Sven; Boeddinghaus, Runa S.; Nawaz, Ali; Wubet, Tesfaye; Hölzel, Norbert; Klaus, Valentin H.; Kleinebecker, Till; Freitag, Martin; Hamer, Ute; Oliveira, Rafael S.; Lambers, Hans; Kandeler, Ellen
Plant–soil feedbacks (PSFs) underlying grassland plant richness and productivity are typically coupled with nutrient availability; however, we lack understanding of how restoration measures to increase plant diversity might affect PSFs. We examined the roles of sward disturbance, seed addition and land‐use intensity (LUI) on PSFs. We conducted a disturbance and seed addition experiment in 10 grasslands along a LUI gradient and characterized plant biomass and richness, soil microbial biomass, community composition and enzyme activities. Greater plant biomass at high LUI was related to a decrease in the fungal to bacterial ratios, indicating highly productive grasslands to be dominated by bacteria. Lower enzyme activity per microbial biomass at high plant species richness indicated a slower carbon (C) cycling. The relative abundance of fungal saprotrophs decreased, while pathogens increased with LUI and disturbance. Both fungal guilds were negatively associated with plant richness, indicating the mechanisms underlying PSFs depended on LUI. We show that LUI and disturbance affect fungal functional composition, which may feedback on plant species richness by impeding the establishment of pathogen‐sensitive species. Therefore, we highlight the need to integrate LUI including its effects on PSFs when planning for practices that aim to optimize plant diversity and productivity.
Revisiting soil fungal biomarkers and conversion factors: interspecific variability in phospholipid fatty acids, ergosterol and rDNA copy numbers
(2024) Camenzind, Tessa; Haslwimmer, Heike; Rillig, Matthias C.; Ruess, Liliane; Finn, Damien R.; Tebbe, Christoph C.; Hempel, Stefan; Marhan, Sven; Camenzind, Tessa; Institute of Biology, Freie Universität Berlin, Altensteinstr. 6, 14195, Berlin, Germany; Haslwimmer, Heike; Institute of Soil Science and Land Evaluation, Soil Biology Department, University of Hohenheim, 70599, Stuttgart, Germany; Rillig, Matthias C.; Institute of Biology, Freie Universität Berlin, Altensteinstr. 6, 14195, Berlin, Germany; Ruess, Liliane; Institute of Biology, Ecology group, Humboldt-Universität zu Berlin, Philippstraße 13, 10115, Berlin, Germany; Finn, Damien R.; Thünen Institut für Biodiversität, 38116, Braunschweig, Germany; Tebbe, Christoph C.; Thünen Institut für Biodiversität, 38116, Braunschweig, Germany; Hempel, Stefan; Institute of Biology, Freie Universität Berlin, Altensteinstr. 6, 14195, Berlin, Germany; Marhan, Sven; Institute of Soil Science and Land Evaluation, Soil Biology Department, University of Hohenheim, 70599, Stuttgart, Germany
Refined conversion factors for soil fungal biomarkers are proposed. High interspecific variability is present in all fungal biomarkers. A modeling approach supports the validity of biomarker estimates in diverse soils. ITS1 copies vary strongly, but are fungal-specific with least phylogenetic bias. A combination of fungal biomarkers will reveal soil fungal physiology and activity. The abundances of fungi and bacteria in soil are used as simple predictors for carbon dynamics, and represent widely available microbial traits. Soil biomarkers serve as quantitative estimates of these microbial groups, though not quantifying microbial biomass per se. The accurate conversion to microbial carbon pools, and an understanding of its comparability among soils is therefore needed. We refined conversion factors for classical fungal biomarkers, and evaluated the application of quantitative PCR (qPCR, rDNA copies) as a biomarker for soil fungi. Based on biomarker contents in pure fungal cultures of 30 isolates tested here, combined with comparable published datasets, we propose average conversion factors of 95.3 g fungal C g −1 ergosterol, 32.0 mg fungal C µmol −1 PLFA 18:2ω6,9 and 0.264 pg fungal C ITS1 DNA copy −1 . As expected, interspecific variability was most pronounced in rDNA copies, though qPCR results showed the least phylogenetic bias. A modeling approach based on exemplary agricultural soils further supported the hypothesis that high diversity in soil buffers against biomarker variability, whereas also phylogenetic biases impact the accuracy of comparisons in biomarker estimates. Our analyses suggest that qPCR results cover the fungal community in soil best, though with a variability only partly offset in highly diverse soils. PLFA 18:2ω6,9 and ergosterol represent accurate biomarkers to quantify Ascomycota and Basidiomycota . To conclude, the ecological interpretation and coverage of biomarker data prior to their application in global models is important, where the combination of different biomarkers may be most insightful.