Community shifts and carbon translocation within metabolically-active rhizosphere microorganisms in grasslands under elevated CO&lt;sub&gt;2&lt;/sub&gt;

Abstract. The aim of this study was to identify the microbial communities that are actively involved in the assimilation of rhizosphere-C and are most sensitive in their activity to elevated atmospheric CO2 in grassland ecosystems. For this, we analyzed 13C signatures in microbial biomarker phospholipid fatty acids (PLFA) from an in situ 13CO2 pulse-labeling experiment in the Gießen Free-Air Carbon dioxide Enrichment grasslands (GiFACE, Germany) exposed to ambient and elevated (i.e. 50% above ambient) CO2 concentrations. Carbon-13 PLFA measurements at 3 h, 10 h and 11 months after the pulse-labeling indicated a much faster transfer of newly produced rhizosphere-C to fungal compared to bacterial PLFA. After 11 months, the proportion of 13C had decreased in fungal PLFA but had increased in bacterial PLFA compared to a few hours after the pulse-labeling. Nevertheless, a significant proportion of the rapidly assimilated rhizosphere-C was still present in fungal PLFA after 11 months. These results demonstrate the dominant role of fungi in the immediate assimilation of rhizodeposits in grassland ecosystems, while also suggesting a long-term retention of rhizosphere-C in the fungal mycelium as well as a possible translocation of the rhizosphere-C from the fungal to bacterial biomass. Elevated CO2 caused an increase in the relative abundance of root-derived PLFA-C in the saprotrophic fungal PLFA 18:2ω6,9 as well as arbuscular mycorrhizal fungal PLFA 16:1ω5, but a decrease in the saprotrophic fungal biomarker PLFA 18:1ω9. This suggests enhanced rhizodeposit-C assimilation only by selected fungal communities under elevated CO2.

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Community shifts and carbon translocation within metabolically-active rhizosphere microorganisms in grasslands under elevated CO<sub>2</sub>

Biogeosciences ◽

10.5194/bg-4-769-2007 ◽

2007 ◽

Vol 4 (5) ◽

pp. 769-779 ◽

Cited By ~ 112

Author(s):

K. Denef ◽

H. Bubenheim ◽

K. Lenhart ◽

J. Vermeulen ◽

O. Van Cleemput ◽

...

Keyword(s):

Elevated Co2 ◽

Bacterial Biomass ◽

Arbuscular Mycorrhizal ◽

Fungal Species ◽

Elevated Atmospheric Co2 ◽

Grassland Ecosystems ◽

Free Air ◽

Carbon Translocation ◽

Community Shifts ◽

Arbuscular Mycorrhizal Fungal

Abstract. The aim of this study was to identify the microbial communities that are actively involved in the assimilation of rhizosphere-C and are most sensitive in their activity to elevated atmospheric CO2 in a temperate semi-natural low-input grassland ecosystem. For this, we analyzed 13C signatures in microbial biomarker phospholipid fatty acids (PLFA) from an in-situ 13CO2 pulse-labeling experiment in the Giessen Free Air Carbon dioxide Enrichment grasslands (GiFACE, Germany) exposed to ambient and elevated (i.e. 50% above ambient) CO2 concentrations. Short-term 13C PLFA measurements at 3 h and 10 h after the pulse-labeling revealed very little to no 13C enrichment after 3 h in biomarker PLFAs and a much greater incorporation of new plant-C into fungal compared to bacterial PLFAs after 10 h. After a period of 11 months following the pulse-labeling experiment, the 13C enrichment of fungal PLFAs was still largely present but had decreased, while bacterial PLFAs were much more enriched in 13C compared to a few hours after the pulse-labeling. These results imply that new rhizodeposit-C is rapidly processed by fungal communities and only much later by the bacterial communities, which we attributed to either a fungal-mediated translocation of rhizosphere-C from the fungal to bacterial biomass or a preferential bacterial use of dead root or fungal necromass materials as C source over the direct utilization of fresh root-exudate C in these N-limited grassland ecosystems. Elevated CO2 caused an increase in the proportional 13C enrichment (relative to the universal biomarker 16:0) of the arbuscular mycorrhizal fungal biomarker PLFA 16:1ω5 and one gram-positive bacterial biomarker PLFA i16:0, but a decrease in the proportional 13C enrichment of 18:1ω9c, a commonly used though questionable fungal biomarker PLFA. This suggests enhanced fungal rhizodeposit-C assimilation only by arbuscular mycorrhizal fungal species under elevated CO2.

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Faculty Opinions recommendation of Effects of elevated CO2 on grain yield and quality of wheat: results from a 3-year free-air CO2 enrichment experiment.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1196958.662056 ◽

2009 ◽

Author(s):

Christian Körner

Keyword(s):

Grain Yield ◽

Elevated Co2 ◽

Co2 Enrichment ◽

Yield And Quality ◽

Free Air Co2 Enrichment ◽

Free Air ◽

Grain Yield And Quality

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Arbuscular mycorrhizal symbiosis facilitates apricot seedling (Prunus sibirica L.) growth and photosynthesis in northwest China

International Journal of Coal Science & Technology ◽

10.1007/s40789-021-00408-6 ◽

2021 ◽

Author(s):

Yinli Bi ◽

Linlin Xie ◽

Zhigang Wang ◽

Kun Wang ◽

Wenwen Liu ◽

...

Keyword(s):

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Northwest China ◽

Shaanxi Province ◽

Mycorrhizal Symbiosis ◽

Seedling Physiology ◽

Grassland Ecosystems ◽

Time Period ◽

Seedling Biomass ◽

Experimental Treatments

AbstractArbuscular mycorrhizal (AM) fungi can successfully enhance photosynthesis (Pn) and plants growth in agricultural or grassland ecosystems. However, how the symbionts affect species restoration in sunlight-intensive areas remains largely unexplored. Therefore, this study’s objective was to assess the effect of AM fungi on apricot seedling physiology, within a specific time period, in northwest China. In 2010, an experimental field was established in Shaanxi Province, northwest China. The experimental treatments included two AM fungi inoculation levels (0 or 100 g of AM fungal inoculum per seedling), three shade levels (1900, 1100, and 550 µmol m−2 s−1), and three ages (1, 3, and 5 years) of transplantation. We examined growth, Pn, and morphological indicators of apricot (Prunus sibirica L.) seedling performances in 2011, 2013, and 2015. The colonization rate in mycorrhizal seedlings with similar amounts of shade is higher than the corresponding controls. The mycorrhizal seedling biomass is significantly higher than the corresponding non-mycorrhizal seedling biomass. Generally, Pn, stomatal conductance (Gs), transpiration rate (Tr), and water use efficiency are also significantly higher in the mycorrhizal seedlings. Moreover, mycorrhizal seedlings with light shade (LS) have the highest Pn. WUE is increased in non-mycorrhizal seedlings because of the reduction in Tr, while Tr is increased in mycorrhizal seedlings with shade. There is a significant increase in the N, P, and K fractions detected in roots compared with shoots. This means that LS had apparent benefits for mycorrhizal seedlings. Our results also indicate that AM fungi, combined with LS, exert a positive effect on apricot behavior.

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Responses of Forest Carbon Cycle to Drought and Elevated CO2

Atmosphere ◽

10.3390/atmos12020212 ◽

2021 ◽

Vol 12 (2) ◽

pp. 212

Author(s):

Jun-Lan Xiao ◽

Feng Zeng ◽

Qiu-Lan He ◽

Yu-Xia Yao ◽

Xiao Han ◽

...

Keyword(s):

Water Stress ◽

Elevated Co2 ◽

Carbon Sink ◽

Ecosystem Respiration ◽

Co2 Exchange ◽

Positive Influence ◽

Research Field ◽

Co2 Fertilization ◽

Global Trends ◽

Elevated Atmospheric Co2

Forests play a pivotal role in mitigating global warming as an important carbon sink. Recent global greening trends reflect a positive influence of elevated atmospheric CO2 on terrestrial carbon uptake. However, increasingly frequent and intense drought events endanger the carbon sequestration function of forests. This review integrates previous studies across scales to identify potential global trends in forest responses to drought and elevated CO2 as well as to identify data needs in this important research field. The inconsistent responses of ecosystem respiration to drought contributes to the change of forest net CO2 exchange, which depends on the balance of opposite effects of warming and water stress on respiration. Whether CO2 fertilization can offset the effects of drought remains controversial, however, we found a potential overestimation of global CO2 fertilization effects because of increasing water stress and other limitations such as light and nutrients (N, P) as well as the possibility of photosynthetic acclimation.

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Arbuscular Mycorrhizal Fungal Communities in the Soils of Desert Habitats

Microorganisms ◽

10.3390/microorganisms9020229 ◽

2021 ◽

Vol 9 (2) ◽

pp. 229

Author(s):

Martti Vasar ◽

John Davison ◽

Siim-Kaarel Sepp ◽

Maarja Öpik ◽

Mari Moora ◽

...

Keyword(s):

Plant Root ◽

Significant Proportion ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Illumina Miseq ◽

Desert Ecosystems ◽

Fungal Dna ◽

Root Symbionts ◽

Arbuscular Mycorrhizal Fungal

Deserts cover a significant proportion of the Earth’s surface and continue to expand as a consequence of climate change. Mutualistic arbuscular mycorrhizal (AM) fungi are functionally important plant root symbionts, and may be particularly important in drought stressed systems such as deserts. Here we provide a first molecular characterization of the AM fungi occurring in several desert ecosystems worldwide. We sequenced AM fungal DNA from soil samples collected from deserts in six different regions of the globe using the primer pair WANDA-AML2 with Illumina MiSeq. We recorded altogether 50 AM fungal phylotypes. Glomeraceae was the most common family, while Claroideoglomeraceae, Diversisporaceae and Acaulosporaceae were represented with lower frequency and abundance. The most diverse site, with 35 virtual taxa (VT), was in the Israeli Negev desert. Sites representing harsh conditions yielded relatively few reads and low richness estimates, for example, a Saudi Arabian desert site where only three Diversispora VT were recorded. The AM fungal taxa recorded in the desert soils are mostly geographically and ecologically widespread. However, in four sites out of six, communities comprised more desert-affiliated taxa (according to the MaarjAM database) than expected at random. AM fungal VT present in samples were phylogenetically clustered compared with the global taxon pool, suggesting that nonrandom assembly processes, notably habitat filtering, may have shaped desert fungal assemblages.

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