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A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Plant Microbe Interactions".

Deadline for manuscript submissions: closed (15 December 2020) | Viewed by 52524

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Prof. Dr. Mohamed Hijri

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Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, Montréal, QC, Canada
Interests: environmental microbiology; plant-microbe interaction; mycorrhizal symbiosis; fungal biology; microbial genomics
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Dear Colleagues,

Mycorrhiza is among the most common and widespread symbiosis between fungi and plant roots on earth. In recent decades, interest in this symbiosis has increased substantially, not only because of its potential benefits to agriculture, forestry, and phytoremediation but also because it helps us to understand the basis of complex mechanisms involved in plant–microbe interactions. Trappe and Fogel (1977) said 'Most woody plants require mycorrhizae to survive, and most herbaceous plants need them to thrive. Despite their relatively small biomass, the mycorrhizal fungi (mycobionts) are vital for uptake and accumulation of ions from soil and translocation to hosts because of their high metabolic rate and strategically diffuse distribution in the upper soil layers'. It is now well recognised that mycorrhizal symbiosis helps plants exposed to biotic and abiotic stresses, including salinity, drought, toxic trace elements, pH, extreme temperatures, and soilborne pathogens. These aspects attract media attention as well as public interest.

This Special Issue of Microorganisms welcomes researchers to contribute research articles, reviews, and opinions addressing the latest knowledge on mycorrhizas, including molecular biology, genomics, functional biodiversity, ecology, phytoremediation, biological control, biofertilizers, microbial interaction, and sustainable management, both in fundamental research and its applications.

* Trappe, J. M. & Fogel, R. C. (1977) Range Science Department Science Series (Colorado State Univ., Fort Collins, CO), Vol. 26, pp. 205-214.

Prof. Dr. Mohamed Hijri
Guest Editor

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Keywords

arbuscular mycorrhiza
ectomycorrhiza
ericoïd mycorrhiza
orchid mycorrhiza
mycorrhizal fungi
symbiosis
mycorrhiza–microbe interactions
rhizosphere biology
mycorhizosphere
mycorrhiza-based inoculants
biofertilizers

Published Papers (13 papers)

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Research

18 pages, 1081 KiB

Open AccessArticle

Analysis of Arbuscular Mycorrhizal Fungal Inoculant Benchmarks

by Sulaimon Basiru, Hopkins Pachalo Mwanza and Mohamed Hijri

Microorganisms 2021, 9(1), 81; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms9010081 - 31 Dec 2020

Cited by 45 | Viewed by 7409

Abstract

Growing evidence showed that efficient acquisition and use of nutrients by crops is controlled by root-associated microbiomes. Efficient management of this system is essential to improving crop yield, while reducing the environmental footprint of crop production. Both endophytic and rhizospheric microorganisms can directly promote crop growth, increasing crop yield per unit of soil nutrients. A variety of plant symbionts, most notably the arbuscular mycorrhizal fungi (AMF), nitrogen-fixing bacteria, and phosphate-potassium-solubilizing microorganisms entered the era of large-scale applications in agriculture, horticulture, and forestry. The purpose of this study is to compile data to give a complete and comprehensive assessment and an update of mycorrhizal-based inoculant uses in agriculture in the past, present, and future. Based on available data, 68 mycorrhizal products from 28 manufacturers across Europe, America, and Asia were examined on varying properties such as physical forms, arbuscular mycorrhizal fungal composition, number of active ingredients, claims of purpose served, mode of application, and recommendation. Results show that 90% of the products studied are in solid formula—powder (65%) and granular (25%), while only 10% occur in liquid formula. We found that 100% of the products are based on the Glomeraceae of which three species dominate among all the products in the order of Rhizophagus irregularis (39%), Funneliformis mosseae (21%), Claroideoglomus etunicatum (16%). Rhizophagus clarus is the least common among all the benchmark products. One third of the products is single species AMF and only 19% include other beneficial microbes. Of the sampled products, 44% contain AMF only while the rest are combined with varying active ingredients. Most of the products (84%) claimed to provide plant nutrient benefits. Soil application dominates agricultural practices of the products and represents 47%. A substantial amount of the inoculants were applied in cereal production. Recommended application doses varied extensively per plant, seed and hectare. AMF inoculant seed coating accounted for 26% of the products’ application and has great potential for increased inoculation efficiency over large-scale production due to minimum inoculum use. More applied research should also be conducted on the possible combination of AMF with other beneficial microbes. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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16 pages, 1592 KiB

Open AccessArticle

Secretion of Iron(III)-Reducing Metabolites during Protein Acquisition by the Ectomycorrhizal Fungus Paxillus involutus

by Firoz Shah, Markus Gressler, Susan Nehzati, Michiel Op De Beeck, Luigi Gentile, Dirk Hoffmeister, Per Persson and Anders Tunlid

Microorganisms 2021, 9(1), 35; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms9010035 - 24 Dec 2020

Cited by 11 | Viewed by 2527

Abstract

The ectomycorrhizal fungus Paxillus involutus decomposes proteins using a two-step mechanism, including oxidation and proteolysis. Oxidation involves the action of extracellular hydroxyl radicals (•OH) generated by the Fenton reaction. This reaction requires the presence of iron(II). Here, we monitored the speciation of extracellular iron and the secretion of iron(III)-reducing metabolites during the decomposition of proteins by P. involutus. X-ray absorption spectroscopy showed that extracellular iron was mainly present as solid iron(III) phosphates and oxides. Within 1 to 2 days, these compounds were reductively dissolved, and iron(II) complexes were formed, which remained in the medium throughout the incubation. HPLC and mass spectrometry detected five extracellular iron(III)-reducing metabolites. Four of them were also secreted when the fungus grew on a medium containing ammonium as the sole nitrogen source. NMR identified the unique iron(III)-reductant as the diarylcyclopentenone involutin. Involutin was produced from day 2, just before the elevated •OH production, preceding the oxidation of BSA. The other, not yet fully characterized iron(III)-reductants likely participate in the rapid reduction and dissolution of solid iron(III) complexes observed on day one. The production of these metabolites is induced by other environmental cues than for involutin, suggesting that they play a role beyond the Fenton chemistry associated with protein oxidation. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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12 pages, 2061 KiB

Open AccessArticle

Differential Response of Mycorrhizal Plants to Tomato bushy stunt virus and Tomato mosaic virus Infection

by Neda Khoshkhatti, Omid Eini, Davoud Koolivand, Antreas Pogiatzis, John N. Klironomos and Sepideh Pakpour

Microorganisms 2020, 8(12), 2038; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8122038 - 19 Dec 2020

Cited by 6 | Viewed by 2547

Abstract

Tomato bushy stunt virus (TBSV) and Tomato mosaic virus (ToMV) are important economic pathogens in tomato fields. Rhizoglomus irregulare is a species of arbuscular mycorrhizal (AM) fungus that provides nutrients to host plants. To understand the effect of R. irregulare on the infection by TBSV/ToMV in tomato plants, in a completely randomized design, five treatments, including uninfected control plants without AM fungi (C), uninfected control plants with AM fungi (M) TBSV/ToMV-infected plants without AM fungi (V), TBSV/ToMV-infected plants before mycorrhiza (VM) inoculation, and inoculated plants with mycorrhiza before TBSV/ToMV infection (MV), were studied. Factors including viral RNA accumulation and expression of Pathogenesis Related proteins (PR) coding genes including PR1, PR2, and PR3 in the young leaves were measured. For TBSV, a lower level of virus accumulation and a higher expression of PR genes in MV plants were observed compared to V and VM plants. In contrast, for ToMV, a higher level of virus accumulation and a lower expression of PR genes in MV plants were observed as compared to V and VM plants. These results indicated that mycorrhizal symbiosis reduces or increases the viral accumulation possibly via the regulation of PR genes in tomato plants. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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16 pages, 1652 KiB

Open AccessArticle

Effects of Ectomycorrhizal Fungi and Heavy Metals (Pb, Zn, and Cd) on Growth and Mineral Nutrition of Pinus halepensis Seedlings in North Africa

by Chadlia Hachani, Mohammed S. Lamhamedi, Claudio Cameselle, Susana Gouveia, Abdenbi Zine El Abidine, Damase P. Khasa and Zoubeir Béjaoui

Microorganisms 2020, 8(12), 2033; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8122033 - 19 Dec 2020

Cited by 26 | Viewed by 3881

Abstract

The pollution of soils by heavy metals resulting from mining activities is one of the major environmental problems in North Africa. Mycorrhizoremediation using mycorrhizal fungi and adapted plant species is emerging as one of the most innovative methods to remediate heavy metal pollution. This study aims to assess the growth and the nutritional status of ectomycorrhizal Pinus halepensis seedlings subjected to high concentrations of Pb, Zn, and Cd for possible integration in the restoration of heavy metals contaminated sites. Ectomycorrhizal and non-ectomycorrhizal P. halepensis seedlings were grown in uncontaminated (control) and contaminated soils for 12 months. Growth, mineral nutrition, and heavy metal content were assessed. Results showed that ectomycorrhizae significantly improved shoot and roots dry masses of P. halepensis seedlings, as well as nitrogen shoot content. The absorption of Pb, Zn, and Cd was much higher in the roots than in the shoots, and significantly more pronounced in ectomycorrhizal seedlings—especially for Zn and Cd. The presence of ectomycorrhizae significantly reduced the translocation factor of Zn and Cd and bioaccumulation factor of Pb and Cd, which enhanced the phytostabilizing potential of P. halepensis seedlings. These results support the use of ectomycorrhizal P. halepensis in the remediation of heavy metal contaminated sites. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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26 pages, 3829 KiB

Open AccessArticle

Potential of Native Arbuscular Mycorrhizal Fungi, Rhizobia, and/or Green Compost as Alfalfa (Medicago sativa) Enhancers under Salinity

by Raja Ben-Laouane, Marouane Baslam, Mohamed Ait-El-Mokhtar, Mohamed Anli, Abderrahim Boutasknit, Youssef Ait-Rahou, Salma Toubali, Toshiaki Mitsui, Khalid Oufdou, Said Wahbi and Abdelilah Meddich

Microorganisms 2020, 8(11), 1695; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8111695 - 30 Oct 2020

Cited by 60 | Viewed by 4224

Abstract

Salinity is one of the devastating abiotic stresses that cause reductions in agricultural production. The increased salinization affects alfalfa growth, metabolism, and rhizobium capacity for symbiotic N₂ fixation negatively. This study was undertaken to investigate the efficiency of green compost (C; made from green waste), arbuscular mycorrhizal fungi (M; field-sourced native consortium), and/or rhizobium (R; a salt-tolerant rhizobium strain) individually or in combination as an effective strategy to improve alfalfa productivity under non-saline and high-saline (120 mM NaCl) conditions. In addition, we aimed to understand the agro-physiological and metabolic basis as well as glomalin content in the soil of biofertilizers-induced salt tolerance in alfalfa. Here, we show that mycorrhizal infection was enhanced after MR inoculation, while C application decreased it significantly. Salinity reduced growth, physiological functioning, and protein concentration, but the antioxidant system has been activated. Application of the selected biofertilizers, especially C alone or combined with M and/or R improved alfalfa tolerance. The tri-combination CMR mitigated the negative effects of high salinity by stimulating plant growth, roots and nodules dry matters, mineral uptake (P, N, and K), antioxidant system, synthesis of compatible solutes, and soil glomalin content, sustaining photosynthesis-related performance and decreasing Na⁺ and Cl⁻ accumulation, lipid peroxidation, H₂O₂ content, and electrolyte leakage. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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20 pages, 2731 KiB

Open AccessArticle

Granular Calcite Stimulates Natural Mycorrhization and Growth of White Spruce Seedlings in Peat-Based Substrates in Forest Nursery

by Mohammed S. Lamhamedi, Mario Renaud, Isabelle Auger and J. André Fortin

Microorganisms 2020, 8(7), 1088; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8071088 - 21 Jul 2020

Cited by 5 | Viewed by 2298

Abstract

The acidity of peat-based substrates used in forest nurseries limits seedling mineral nutrition and growth as well as the activity of microorganisms. To our knowledge, no study has yet evaluated the use of granular calcite as a covering material to increase pH, calcium and CO₂ concentrations in the rhizosphere and ectomycorrhizal development. The objective is to compare different covering treatments on early colonization of the roots by ectomycorrhizal fungi, as well as the growth and calcium nutrition of white spruce seedlings in the forest nursery. Three treatments were used to cover the plant cavities (Silica (29 g/cavity; control treatment), Calcite (24 g/cavity) and calcite+ (31 g/cavity)) and were distributed randomly inside each of the five complete blocks of the experimental design. The results show that calcite stimulates natural mycorrhization. Seedlings grown with calcite have significant gains for several growth and physiological variables, and that the periphery of their root plugs are more colonized by the extramatrical phase of ectomycorrhizal fungi, thus improving root-plug cohesion. The authors discuss the operational scope of the results in relation to the tolerance of seedlings to environmental stress and the improvement of their quality, both in the nursery and in reforestation sites. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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17 pages, 3006 KiB

Open AccessArticle

Arbuscular Mycorrhizal Fungus Rhizophagus irregularis Influences Artemisia annua Plant Parameters and Artemisinin Content under Different Soil Types and Cultivation Methods

by Erzsébet Domokos, Béla Bíró-Janka, János Bálint, Katalin Molnár, Csaba Fazakas, László Jakab-Farkas, József Domokos, Csilla Albert, Gyöngyvér Mara and Adalbert Balog

Microorganisms 2020, 8(6), 899; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8060899 - 15 Jun 2020

Cited by 7 | Viewed by 2617

Abstract

Artemisinin extracted from Artemisia annua has been used efficiently in malaria treatment since 2005. In this study, the variations in plant parameters (plant biomass, glandular trichome density, essential oil total chemical content, artemisinin production, and polyphenol oxidase (PPO) activity) were tested under different soil types (Luvisol, Gleysol, Anthrosol and sterile peat) and cultivation conditions (potted plants in semi-open field, and open field experiments) for plants inoculated with arbuscular mycorrhizal fungus (AMF) Rizophagus irregularis. Under semi-open field conditions, the AMF colonization of A. annua plant roots varied, and presented the highest percentage in Luvisol and sterile peat. The increase in the root colonization rate positively influenced some plant parameters (biomass, glandular trichome density, artemisinin concentration, essential oil quantity and composition), but no effects on PPO enzyme activity were detected. AMF fungus R. irregularis significantly increased the artemisinin content and essential oil yield of plants cultivated in Luvisol, Gleysol, Anthrosol and in peat. These soil types can offer appropriate conditions for A. annua cultivation and artemisinin production even on a smaller scale. Under open field conditions, low (about 5%) AMF colonization was observed. No differences in artemisin contents were detected, but essential oil yield significantly increased compared to control plants. AMF treatment increased beta-farnesene and germacrene D concentrations in Artemisia plants in the open field experiment. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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14 pages, 1078 KiB

Open AccessArticle

Arbuscular Mycorrhizal Fungal Communities of Native Plant Species under High Petroleum Hydrocarbon Contamination Highlights Rhizophagus as a Key Tolerant Genus

by Soon-Jae Lee, Mengxuan Kong, Marc St-Arnaud and Mohamed Hijri

Microorganisms 2020, 8(6), 872; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8060872 - 09 Jun 2020

Cited by 11 | Viewed by 2411

Abstract

Arbuscular mycorrhizal fungi (AMF) have been shown to play an important role in increasing plant fitness in harsh conditions. Therefore, AMF are currently considered to be effective partners in phytoremediation. However, AMF communities in high levels of petroleum pollution are still poorly studied. We investigated the community structures of AMF in roots and rhizospheric soils of two plant species, Eleocharis elliptica and Populus tremuloides, growing spontaneously in high petroleum-contaminated sedimentation basins of a former petrochemical plant (91,000 μg/Kg of C10–C50 was recorded in a basin which is 26-fold higher than the threshold of polluted soil in Quebec, Canada). We used a PCR cloning, and sequencing approach, targeting the 18S rRNA gene to identify AMF taxa. The high concentration of petroleum-contamination largely influenced the AMF diversity, which resulted in less than five AMF operational taxonomical units (OTUs) per individual plant at all sites. The OTUs detected belong mainly to the Glomerales, with some from the Diversisporales and Paraglomerales, which were previously reported in high concentrations of metal contamination. Interestingly, we found a strong phylogenetic signal in OTU associations with host plant species identity, biotopes (roots or soils), and contamination concentrations (lowest, intermediate and highest). The genus Rhizophagus was the most dominant taxon representing 74.4% of all sequences analyzed in this study and showed clear association with the highest contamination level. The clear association of Rhizophagus with high contamination levels suggests the importance of the genus for the use of AMF in bioremediation, as well as for the survey of key AMF genes related to petroleum hydrocarbon resistance. By favoring plant fitness and mediating its soil microbial interactions, Rhizophagus spp. could enhance petroleum hydrocarbon pollutant degradation by both plants and their microbiota in contaminated sites. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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21 pages, 2114 KiB

Open AccessArticle

Arbuscular Mycorrhizal Fungal Assemblages Significantly Shifted upon Bacterial Inoculation in Non-Contaminated and Petroleum-Contaminated Environments

by Dimitri J. Dagher, Ivan E. de la Providencia, Frédéric E. Pitre, Marc St-Arnaud and Mohamed Hijri

Microorganisms 2020, 8(4), 602; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8040602 - 21 Apr 2020

Cited by 17 | Viewed by 3783

Abstract

Arbuscular mycorrhizal fungi (AMF) have been shown to reduce plant stress and improve their health and growth, making them important components of the plant-root associated microbiome, especially in stressful conditions such as petroleum hydrocarbons (PHs) contaminated environments. Purposely manipulating the root-associated AMF assemblages in order to improve plant health and modulate their interaction with the rhizosphere microbes could lead to increased agricultural crop yields and phytoremediation performance by the host plant and its root-associated microbiota. In this study, we tested whether repeated inoculations with a Proteobacteria consortium influenced plant productivity and the AMF assemblages associated with the root and rhizosphere of four plant species growing either in non-contaminated natural soil or in sediments contaminated with petroleum hydrocarbons. A mesocosm experiment was performed in a randomized complete block design in four blocks with two factors: (1) substrate contamination (contaminated or not contaminated), and (2) inoculation (or not) with a bacterial consortium composed of ten isolates of Proteobacteria. Plants were grown in a greenhouse over four months, after which the effect of treatments on plant biomass and petroleum hydrocarbon concentrations in the substrate were determined. MiSeq amplicon sequencing, targeting the 18S rRNA gene, was used to assess AMF community structures in the roots and rhizosphere of plants growing in both contaminated and non-contaminated substrates. We also investigated the contribution of plant identity and biotope (plant roots and rhizospheric soil) in shaping the associated AMF assemblages. Our results showed that while inoculation caused a significant shift in AMF communities, the substrate contamination had a much stronger influence on their structure, followed by the biotope and plant identity to a lesser extent. Moreover, inoculation significantly increased plant biomass production and was associated with a decreased petroleum hydrocarbons dissipation in the contaminated soil. The outcome of this study provides knowledge on the factors influencing the diversity and community structure of AMF associated with indigenous plants following repeated inoculation of a bacterial consortium. It highlights the dominance of soil chemical properties, such as petroleum hydrocarbon presence, over biotic factors and inputs, such as plant species and microbial inoculations, in determining the plant-associated arbuscular mycorrhizal fungi communities. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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17 pages, 2601 KiB

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Formation of Common Mycorrhizal Networks Significantly Affects Plant Biomass and Soil Properties of the Neighboring Plants under Various Nitrogen Levels

by Muhammad Atif Muneer, Ping Wang, Jing Zhang, Yaoming Li, Muhammad Zeeshan Munir and Baoming Ji

Microorganisms 2020, 8(2), 230; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8020230 - 08 Feb 2020

Cited by 30 | Viewed by 5872

Abstract

Common mycorrhizal networks (CMNs) allow the transfer of nutrients between plants, influencing the growth of the neighboring plants and soil properties. Cleistogene squarrosa (C. squarrosa) is one of the most common grass species in the steppe ecosystem of Inner Mongolia, where nitrogen (N) is often a key limiting nutrient for plant growth, but little is known about whether CMNs exist between neighboring individuals of C. squarrosa or play any roles in the N acquisition of the C. squarrosa population. In this study, two C. squarrosa individuals, one as a donor plant and the other as a recipient plant, were planted in separate compartments in a partitioned root-box. Adjacent compartments were separated by 37 µm nylon mesh, in which mycorrhizal hyphae can go through but not roots. The donor plant was inoculated with arbuscular mycorrhizal (AM) fungi, and their hyphae potentially passed through nylon mesh to colonize the roots of the recipient plant, resulting in the establishment of CMNs. The formation of CMNs was verified by microscopic examination and ¹⁵N tracer techniques. Moreover, different levels of N fertilization (N0 = 0, N1 = 7.06, N2 = 14.15, N3 = 21.19 mg/kg) were applied to evaluate the CMNs’ functioning under different soil nutrient conditions. Our results showed that when C. squarrosa–C. squarrosa was the association, the extraradical mycelium transferred the ¹⁵N in the range of 45–55% at different N levels. Moreover, AM fungal colonization of the recipient plant by the extraradical hyphae from the donor plant significantly increased the plant biomass and the chlorophyll content in the recipient plant. The extraradical hyphae released the highest content of glomalin-related soil protein into the rhizosphere upon N2 treatment, and a significant positive correlation was found between hyphal length and glomalin-related soil proteins (GRSPs). GRSPs and soil organic carbon (SOC) were significantly correlated with mean weight diameter (MWD) and helped in the aggregation of soil particles, resulting in improved soil structure. In short, the formation of CMNs in this root-box experiment supposes the existence of CMNs in the typical steppe plants, and CMNs-mediated N transfer and root colonization increased the plant growth and soil properties of the recipient plant. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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16 pages, 2746 KiB

Open AccessArticle

Impact of Phosphorus Fertilization on Tomato Growth and Arbuscular Mycorrhizal Fungal Communities

by Masao Higo, Mirai Azuma, Yusuke Kamiyoshihara, Akari Kanda, Yuya Tatewaki and Katsunori Isobe

Microorganisms 2020, 8(2), 178; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8020178 - 25 Jan 2020

Cited by 42 | Viewed by 6017

Abstract

Understanding the impact of phosphorus (P) addition on arbuscular mycorrhizal fungi (AMF) is crucial to understanding tomato (Solanum lycopersicum L.) P nutrition. However, it remains unknown how P fertilization is associated with the structure of AMF communities on tomato plants. Thus, we investigated whether levels of P fertilizer interacted with the colonization and structure of AMF in tomato roots in a field trial. In this study, we established three different amounts of P fertilizer treatments (0 kg ha⁻¹, 50 kg ha⁻¹, and 100 kg ha⁻¹). We investigated AMF root colonization and community structure, as well as plant growth in tomatoes at seven weeks following transplantation. The structure of the AMF communities in the roots of tomato were determined by MiSeq amplicon sequencing. As expected, P fertilizer input enhanced the P uptake and plant biomass. In contrast, the P fertilizer level did not affect the AMF root colonization and diversity or the structure of the AMF communities in the tomato. However, we found a negative correlation between AMF colonization and richness in the roots of the tomato plants. Therefore, we need to investigate whether and how AMF communities and P fertilization develop more effective P management for tomato plants. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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14 pages, 2408 KiB

Open AccessArticle

Inoculation with Rhizophagus irregularis Does Not Alter Arbuscular Mycorrhizal Fungal Community Structure within the Roots of Corn, Wheat, and Soybean Crops

by Sébastien Renaut, Rachid Daoud, Jacynthe Masse, Agathe Vialle and Mohamed Hijri

Microorganisms 2020, 8(1), 83; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8010083 - 07 Jan 2020

Cited by 26 | Viewed by 4689

Abstract

Little is known about establishment success of the arbuscular mycorrhizal fungal (AMF) inocula and their effects on a soil-indigenous community of AMF. In this study, we assessed the effect of introducing Rhizophagus irregularis DAOM-197198 in soil under field condition on the community composition of indigenous AMF in the roots of corn (Zea mays), soybean (Glycine max), and wheat (Triticum aestivum). Three field trials were conducted with inoculated and non-inoculated plots. Four to ten roots and their rhizosphere soil samples of two growth stages for corn and wheat, and one growing stage of soybean, were collected, totalling 122 root and soil samples. Root colonization was measured microscopically, and the fungal communities were determined by paired-end Illumina MiSeq amplicon sequencing using 18S rDNA marker. After quality trimming and merging of paired ends, 6.7 million sequences could be assigned to 414 different operational taxonomic units. These could be assigned to 68 virtual taxa (VT) using the AMF reference sequence database MaarjAM. The most abundant VT corresponded to R. irregularis. The inoculation treatment did not influence the presence of R. irregularis, or AMF community diversity in roots. This seems to indicate that inoculation with R. irregularis DAOM-197198 does not change the indigenous AMF community composition, probably because it is already present in high abundance naturally. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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18 pages, 853 KiB

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Aided Phytoremediation to Clean Up Dioxins/Furans-Aged Contaminated Soil: Correlation between Microbial Communities and Pollutant Dissipation

by Hacène Meglouli, Joël Fontaine, Anthony Verdin, Maryline Magnin-Robert, Benoît Tisserant, Mohamed Hijri and Anissa Lounès-Hadj Sahraoui

Microorganisms 2019, 7(11), 523; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms7110523 - 03 Nov 2019

Cited by 11 | Viewed by 2853

Abstract

To restore and clean up polluted soils, aided phytoremediation was found to be an effective, eco-friendly, and feasible approach in the case of many organic pollutants. However, little is known about its potential efficiency regarding polychlorinated dibenzo-p-dioxins and furans-contaminated soils. Thus, phytoremediation of aged dioxins/furans-contaminated soil was carried out through microcosm experiments vegetated with alfalfa combined with different amendments: an arbuscular mycorrhizal fungal inoculum (Funneliformis mosseae), a biosurfactant (rhamnolipids), a dioxins/furans degrading-bacterium (Sphingomonas wittichii RW1), and native microbiota. The total dioxins/furans dissipation was estimated to 23%, which corresponds to 48 ng.kg⁻¹ of soil, after six months of culture in the vegetated soil combined with the four amendments compared to the non-vegetated soil. Our findings showed that the dioxins/furans dissipation resulted from the stimulation of soil microbial enzyme activities (fluorescein diacetate hydrolase and dehydrogenase) and the increase of bacterial abundance, richness, and diversity, as well as fungal diversity. Amplicon sequencing using Illumina MiSeq analysis led to identification of several bacterial (Bacillaceae, Sphingomonadaceae) and fungal (Chaetomium) groups known to be involved in dioxins/furans degradation. Furthermore, concomitant cytotoxicity and dioxins/furans concentration decreases were pointed out in the phytoremediated soil. The current study demonstrated the usefulness of combining different types of amendments to improve phytoremediation efficacy of aged dioxins/furans-contaminated soils. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi)

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