Arbuscular mycorrhizal fungi in soil, roots and rhizosphere of<i>Medicago truncatula</i>: diversity and heterogeneity under semi-arid conditions

Mahmoudi, Neji; Cruz, Cristina; Mahdhi, Mosbah; Mars, Mohamed; Caeiro, Maria Filomena

doi:10.7717/peerj.6401

Cited by 31 publications

(20 citation statements)

References 74 publications

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“…This low abundance may be connected with the fact that analyses were performed in the bulk soil. AMF were detected in higher abundance in the rhizosphere or roots than in the bulk soil [47][48][49].…”

Section: Discussionmentioning

confidence: 93%

Forecrop Effects on Abundance and Diversity of Soil Microorganisms during the Growth of the Subsequent Crop

2020

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Plant residues introduced into the soil influence the soil’s physical, chemical, and consequently, biological parameters, which have an influence on plant health and yields. This study was undertaken to evaluate the effects of the cultivation of widespread plant species, faba bean (Vicia faba L., F) and wheat (Triticum aestivum L., W) (as forecrops) grown under conventionally tilled fields, on the diversity of microorganisms and the enzymatic activities of soil during the growth of the subsequent wheat. Bulk soil samples (0–20 cm) were taken three times from two months after residue incorporation into the soil to the maturity of the subsequent wheat crop in order to assess the fungal and bacterial communities (Next Generation Sequencing (NGS), terminal restriction fragments lengths polymorphism (t-RFLP)), ammonia oxidizing archaea (t-RFLP, denaturing gradient gel glectrophoresis (DGGE)), and the enzymatic activity of soil. Differences in the genetic structure of ammonia-oxidizing archaea (AOA) were observed for each treatment and sampling term, indicating that plant and weather conditions are the driving force for microorganism selection and adaptation. We observed that the fungal community was more influenced by the forecrop type used than the bacterial community. The activities of the enzymes changed in response to the forecrop and sampling period. A higher number of microorganisms that are associated with plant benefits with respect to nutrients and growth, as well as higher amounts of N in the residues, was noted in faba bean than in wheat soil. This could indicate better growth conditions after faba bean and, consequently, better yield quality and quantity. This may also indicate some protective role of the soil after faba bean against pathogens, which may be connected with lower fungicide requirements. The obtained results lead to a deeper understanding of the microorganism reactions to faba bean and wheat residues during wheat cultivation. In addition, they may be helpful in improving our understanding of subsequent crop yield responses to forecrops.

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Section: Discussionmentioning

confidence: 93%

Forecrop Effects on Abundance and Diversity of Soil Microorganisms during the Growth of the Subsequent Crop

2020

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“…For soil hyphae, AMF could be separated from other fungal groups under the dissecting microscope via the presence or absence of septa (Smith and Read 2008 ). Choosing the isolation of intraradical hyphae from roots potentially reduces the diversity of other fungal groups than AM fungi relative to soil (Gao et al 2019 ; Mahmoudi et al 2019 ) due to plants’ selection mechanisms, while potentially increasing the AM fungal diversity (Mahmoudi et al 2019 ). To increase chances of high AM fungal colonization, multiple fine-root fragments instead of single long roots should be sampled (cf.…”

Section: Resultsmentioning

confidence: 99%

“…To increase chances of high AM fungal colonization, multiple fine-root fragments instead of single long roots should be sampled (cf. Mahmoudi et al 2019 ).…”

Section: Resultsmentioning

confidence: 99%

Stable C and N isotope natural abundances of intraradical hyphae of arbuscular mycorrhizal fungi

et al. 2020

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Data for stable C and N isotope natural abundances of arbuscular mycorrhizal (AM) fungi are currently sparse, as fungal material is difficult to access for analysis. So far, isotope analyses have been limited to lipid compounds associated with fungal membranes or storage structures (biomarkers), fungal spores and soil hyphae. However, it remains unclear whether any of these components are an ideal substitute for intraradical AM hyphae as the functional nutrient trading organ. Thus, we isolated intraradical hyphae of the AM fungus Rhizophagus irregularis from roots of the grass Festuca ovina and the legume Medicago sativa via an enzymatic and a mechanical approach. In addition, extraradical hyphae were isolated from a sand-soil mix associated with each plant. All three approaches revealed comparable isotope signatures of R. irregularis hyphae. The hyphae were 13C- and 15N-enriched relative to leaves and roots irrespective of the plant partner, while they were enriched only in 15N compared with soil. The 13C enrichment of AM hyphae implies a plant carbohydrate source, whereby the enrichment was likely reduced by an additional plant lipid source. The 15N enrichment indicates the potential of AM fungi to gain nitrogen from an organic source. Our isotope signatures of the investigated AM fungus support recent findings for mycoheterotrophic plants which are suggested to mirror the associated AM fungi isotope composition. Stable isotope natural abundances of intraradical AM hyphae as the functional trading organ for bi-directional carbon-for-mineral nutrient exchanges complement data on spores and membrane biomarkers.

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“…In contrast, PLFA requires the additional analysis of neutral lipid fatty acids (otherwise discarded in the extraction) to measure AMF spores because PLFA 16:1ω5c does not originate from spores or vesicles and may also be confounded by GMN (Sharma & Buyer, 2015). Under this premise, EL-FAME has an advantage for detecting AMF in rhizosphere soil over PLFA (Sharma & Buyer, 2015), but whether this holds true in bulk soil, as is typically sampled, is not clear since there are fewer plant roots and possibly also AMF spores (Mahmoudi, Cruz, Mahdhi, Mars, & Caeiro, 2019). Due to the focus on the role of AMF in important soil functions relevant to soil health (e.g., aggregate stability, nutrient and water acquisition for plants, plant protection from some pathogens), further work should test the utility of the different approaches to best represent this key biomarker as impacted by management and soil properties.…”

Section: Soil Properties Associated With Key Fame Biomarkers May Servmentioning

confidence: 99%

A comparison between fatty acid methyl ester profiling methods (PLFA and EL‐FAME) as soil health indicators

Cano

Acosta-Martínez

et al. 2020

Soil Science Soc of Amer J

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Fatty acid methyl ester (FAME) profiling for characterizing microbial community composition typically is conducted via phospholipid fatty acid (PLFA) or ester‐linked fatty acid methyl ester (EL‐FAME) methods. As soil health assessments aim to be utilized across the nation and globe, the robust measurement and interpretation of microbial communities across a range of soils and environments will be necessary. This study compared PLFA and EL‐FAME methods for detecting and interpreting profiles of microbial community composition in croplands across a wide geographic area using a total of 172 soil samples from 14 states representing a wide range of soil properties. Overall, PLFA and EL‐FAME provided comparable biomarkers in terms of microbial community composition. The Spearman's Rank correlation test showed positive correlations (r = 0.37–0.71) between PLFA and EL‐FAME methods for absolute abundance of total FAME and individual microbial groups including fungi (saprophytic fungi [SF], arbuscular mycorrhizal fungi [AMF], and general fungi [F]) and all bacterial groups (Gram positive [GMP], Gram negative [GMN], and Actinobacteria). In both methods, a common set of fatty acids were influential in differentiating samples. The main differences in biomarker abundances between the two methods were that fungal and Actinobacteria biomarkers (e.g., 16:1ω5c [AMF], 18:1ω9c [F], 18:3ω6c [F], and 10Me16:0 [Actinobacteria]) were more abundant or critical in EL‐FAME profiling (large variation among soil samples and sensitive to soil properties), but bacterial biomarkers such as i15:0 (GMP), 16:1ω7c (GMN), 18:1ω7c (GMN), and cy19:0ω7c (GMN) were more dominant and responsive to soil properties in PLFA profiling. The practical advantages of EL‐FAME are lower cost and simpler methodology. Although both methods produced similar microbial profile abundances for important microbial markers, PLFA was more sensitive to the wide range of soil chemical properties in this sample set including pH, clay content, soil organic matter, and active carbon.

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Arbuscular mycorrhizal fungi in soil, roots and rhizosphere ofMedicago truncatula: diversity and heterogeneity under semi-arid conditions

Cited by 31 publications

References 74 publications

Forecrop Effects on Abundance and Diversity of Soil Microorganisms during the Growth of the Subsequent Crop

Forecrop Effects on Abundance and Diversity of Soil Microorganisms during the Growth of the Subsequent Crop

Stable C and N isotope natural abundances of intraradical hyphae of arbuscular mycorrhizal fungi

A comparison between fatty acid methyl ester profiling methods (PLFA and EL‐FAME) as soil health indicators

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