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Simple Summary: Truffle culture is a fairly profitable agricultural practice, yet there is a long waiting period to reach peak sporocarp production from the point when ectomycorrhizal truffle-oak seedlings are planted in the field. Adding a secondary crop, such as medicinal and aromatic plants, could enhance the sustainability of truffle agro-forest systems. In this work, we study the relationships between oaks and aromatic plants and their associated mycorrhizal fungi (either ectomycorrhizal or arbuscular mycorrhizal, respectively) under controlled conditions. A reciprocal competition effect is revealed between oaks and aromatic plant species, as well as between the different types of mycorrhizal fungi. Our results indicate that managing arbuscular mycorrhizal fungi in truffle plantations is a relevant factor to be considered when establishing the dual cultures of plant species and mycorrhizal types in intercropping systems. The high value of black truffle recompenses the slow growth of the fungus when established in the field. Adding a secondary crop, such as medicinal and aromatic plants (MAPs), could further enhance the sustainability of truffle production agro-forest systems. The dual cultures of ectomycorrhizal truffle-oak seedlings and MAPs (lavender, thyme, and sage) previously inoculated and non-inoculated with native arbuscular mycorrhizal fungi (AMF), were established to evaluate plant–fungi relationships. After 12 months in a shadehouse, plants' growth, mycorrhizal colonization, and extraradical soil mycelium (both of Tuber melanosporum and AMF) were measured. Overall, truffle-oaks' growth was negatively affected by the presence of MAPs, especially when inoculated with AMF. In turn, the presence of truffle-oaks barely affected the co-cultured MAPs, and only lavenders showed a significant growth reduction. All AMF-inoculated MAPs showed higher shoot and root biomass than non-inoculated ones. Compared to truffle-oaks growing alone, the presence of co-cultured MAPs, especially when they were AMF-inoculated, significantly decreased both the ectomycorrhizas and soil mycelium of T. melanosporum. These results reveal the strong competition between AMF and T. melanosporum and warn about the need for the protection of intercropping plants and their associated symbiotic fungi to avoid reciprocal counterproductive effects in mixed truffle-oak–AMF–MAP plantations. [ABSTRACT FROM AUTHOR]

Inoculum of arbuscular mycorrhizal fungi, with growing use in horticulture, is produced mainly in two technically different cultivation systems: in vivo culture in symbiosis with living host plants or in vitro culture in which the fungus life cycle develops in association with transformed roots. To evaluate the effectiveness and the infectivity of a defined isolate obtained by both production methods, a replicated comparative evaluation experiment was designed using different propagules of Rhizophagus irregularis produced in vivo on leek plants or in vitro in monoxenic culture on transformed carrot roots. The size of the spores obtained under both cultivation methods was first assessed and bulk inoculum, spores, sievings, and mycorrhizal root fragments were used to inoculate leek plantlets. Spores produced in vitro were significantly smaller than those produced in vivo. Although all mycorrhizal propagules used as a source of inoculum were able to colonize plants, in all cases, leek plants inoculated with propagules obtained in vivo achieved significantly higher mycorrhizal colonization rates than plants inoculated with in vitro inocula. Inoculation with in vivo bulk inoculum and in vivo mycorrhizal root fragments were the only treatments increasing plant growth. These results indicate that the production system of arbuscular mycorrhizal fungi itself can have implications in the stimulation of plant growth and in experimental results. [ABSTRACT FROM AUTHOR]

Eighteen Prunus rootstock cultivars were inoculated with three arbuscular mycorrhizal fungi under greenhouse conditions in order to evaluate their affinity for mycorrhizal colonization. The rootstocks were peach–almond hybrids, peaches, plums and cherries of Spanish, French and Italian origin. Mycorrhizal colonization was low in plants inoculated with Glomus mosseae (Nicol. and Gerd.) Gerdemann and Trappe, and Glomus etunicatum Becker and Gerdemann. In contrast, Glomus intraradices Schenck and Smith, proved to be the most infective endophyte, achieving the highest mycorrhizal colonization rate in most of the rootstocks evaluated. Species of Prunus insititia L. were the only botanical group to show a consistently high affinity for mycorrhizal colonization with G. intraradices. [Copyright &y& Elsevier]

Abstract: Psammophilic plants are characterized for their adaptability to the hard environmental conditions of the coastal sand dune habitats that limit the survival of most vegetation. Considering that mycorrhizal plants are known to be effective colonizers of degraded habitats, the influence of the arbuscular mycorrhizal (AM) symbiosis in plant growth was studied in fifteen psammophilic plant species: Lotus creticus, Dorycnium pentaphyllum, Otanthus maritimus, Thymbra capitata, Armeria maritima, Halimium halimifolium, Ononis natrix, Medicago marina, Genista umbellata, Crucinella maritima, Elymus farctus, Ammophila arenaria, Pancratium maritimum, Glaucium flavum and Limoniastrum monopetalum. Wild seeds were used in this study to compare the effect of plant inoculation with a consortium of native AM fungi isolated from a coastal sand dune and with the selected isolate Glomus intraradices BEG 72 versus non mycorrhizal plants. After six months growth, we found that eleven of the fifteen psammophilic species responded positively to AM fungi inoculation and both root and shoot development benefited considerably from the presence of the AM fungi. We can conclude that many of the psammophilic species produced after the germination of the wild seeds collected in their natural habitats show limited growth due in part to the lack of adequate AM fungal inoculum in the plants growing substrate. AM inoculation seems to be critical for their survival. [Copyright &y& Elsevier]

BACKGROUND: Rosemary forms an arbuscular mycorrhizal (AM) symbiosis with a group of soilborne fungi belonging to the phylum Glomeromycota, which can modify the plant metabolome responsible for the antioxidant capacity and other health beneficial properties of rosemary. RESULTS: The effect of inoculating rosemary plants with an AM fungus on their growth via their polyphenolic fingerprinting was evaluated after analyzing leaf extracts from non‐inoculated and inoculated rosemary plants by ultra‐high performance liquid chromatography‐high resolution mass spectrometry (UHPLC‐HRMS). Plant growth parameters indicated that mycorrhizal inoculation significantly increased plant height and biomass. Chemical modifications in the plant polyphenolic profile distribution were found after a principal components analysis (PCA) loading plots study. Four compounds hosting strong antioxidant properties – ferulic acid, asiatic acid, carnosol, and vanillin – were related to mycorrhizal rosemary plants while caffeic and chlorogenic acids had a higher influence on non‐mycorrhizal plants. CONCLUSION: Mycorrhization was found to stimulate growth to obtain a higher biomass of plant leaves in a short time, avoiding chemical fertilization, while analytical results demonstrate that there is an alteration in the distribution of polyphenols in plants colonized by the symbiotic fungus, which can be related to an improvement in nutritional properties with future industrial significance. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

• Mycorrhizas increased fruit yield, and quality with reduced fertilizer doses. • Deficit and optimized irrigation increased tomato yield and fruit size, but not quality. • Mycorrhiza-inoculated plants sustained yield levels with reduced fertigation. • Input efficiency should define mycorrhizal inoculant use and management. Viability of horticultural production requires high yields of high-value products, coupled with optimization of inputs. Rational fertilizer and water use are vital for the economic and environmental sustainability of vegetable production. Microbial resources are also used to increase yield, reduce inputs, and improve product quality. That includes arbuscular mycorrhizal fungi (AMF), symbionts associated with 80% of plant species, including many vegetable crops, such as tomato. To evaluate how AMF inoculation and reduced water and fertilizer affect tomato yield and quality, we carried out three independent experiments in commercial-production medium-technology (growth in soil, plastic cover, and no temperature control) greenhouses in Catalonia, Northern Spain. In the first experiment, AMF inoculation increased fruit number, total yield and improved fruit quality (soluble solids concentration or color) using lower fertilizer doses than those usually adopted on the farm. In a second assay, plants grew under three irrigation regimes: the farm usual regime, a managed-deficit regime (75% of the former), and an optimized dose using weather and plant-growth data. Deficit and optimized irrigation increased tomato yield and fruit size, but not fruit soluble solids concentration or color, and there was no effect of AMF inoculation. In the third experiment, fertigation was reduced by regulating irrigation doses according to soil moisture data. AM-inoculated plants sustained yield levels with 13% lower water and fertilizer rates. Reduced fertigation associated with AMF inoculation resulted in a 1.6% decrease in costs, which corresponds to at least six times the price of available commercial AMF inoculants. In all experiments, AMF inoculation was associated with increased water productivity, the ratio between product yield and the volume of irrigation water. Gains in input use efficiency, not only simple yield increase, should define commercial AMF inoculant use in vegetable production. We argue that researchers should estimate the financial incentive that AMF inoculation incurs so that farmers and inoculant producers have a base to test and adopt AMF inoculation technology. [ABSTRACT FROM AUTHOR]

Aims: Plants on coastal sand dunes are subjected to strong environmental fluctuations which affect their growth and survival. Sea water invasion of the dunar zone caused by storms is an important factor that determines the persistence of a plant community. In the present study, the benefits of arbuscular mycorrhiza on psammophilic plant species subjected to sea water flooding episodes were evaluated under controlled conditions and the effect of sea water on in vitro spore production was determined. Methods: In a greenhouse experiment, the growth response of nine plant species to inoculation with Glomus intraradices in beach sand was evaluated. A second experiment was designed in order to test if plant survival under sea water flooding was influenced by the symbiosis. A third experiment was conducted in vitro to quantify the effect of sea water on the production of G. intraradices spores. Results: Glomus intraradices was effective in promoting plant growth and survival in beach sand and promoted the survival of some species subjected to flooding events. Spore production was inhibited by 50% of sea water in the growth media, but not by 10% sea water. Conclusions: Results obtained under controlled conditions indicated that arbuscular mycorrhiza can improve the establishment of certain dune plant species in beach sand as the symbiosis contributes to enhanced plant tolerance against occasional sea water flooding. [ABSTRACT FROM AUTHOR]

A study was conducted with the vine rootstock Richter 110 ( Vitis berlandieri Planch. x Vitis rupestris L.) in order to assess whether the colonisation by the arbuscular mycorrhizal fungus (AMF) Glomus intraradices (BEG 72) can delay the disease development in plants inoculated with the root-rot fungus Armillaria mellea (Vahl:Fr) Kummer, and to elucidate if the levels of polyamines (PAs) are modified in response to G. intraradices, A. mellea or by the dual infection. Four treatments were considered: control and G. intraradices-inoculated plants infected or not with A. mellea. Plant growth, mycorrhizal colonisation and disease development were monitored throughout the experiment. High performance liquid chromatography (HPLC) in combination with fluorescence spectrophotometry was used to separate and quantify free root and leaf polyamines. The slower development of pathogenic symptoms and the higher plant biomass of mycorrhizal plants inoculated with A. mellea indicate an increase of tolerance due to the AMF inoculation. The variations in free PA levels detected at the beginning of the pathogenic infection suggest that PAs may have a potential role in the signalling mechanisms of the tolerance of mycorrhizal plants against A. mellea. [ABSTRACT FROM AUTHOR]

A greenhouse experiment was established with loquat plants to investigate the role of arbuscular mycorrhizal fungi (AMF) in the control of the white root rot fungus Armillaria mellea and to determine the changes produced in the plant metabolome. Plants inoculated with two AMF, Rhizoglomus irregulare and a native AMF isolate from loquat soils, were infected with Armillaria. Although mycorrhization failed to control the Armillaria root infection, the increased growth of infected plants following inoculation with the native mycorrhizal isolate suggests an initial tolerance towards Armillaria. Overall, metabolomics allowed highlighting the molecular basis of the improved plant growth in the presence of Armillaria following AMF colonization. In this regard, a wide and diverse metabolic response was involved in the initial tolerance to the pathogen. The AMF-mediated elicitation altered the hormone balance and modulated the production of reactive oxygen species (mainly via the reduction of chlorophyll intermediates), possibly interfering with the reactive oxygen species (ROS) signaling cascade. A complex modulation of fucose, ADP-glucose and UDP-glucose, as well as the down-accumulation of lipids and fatty acids, were observed in Armillaria-infected plants following AMF colonization. Nonetheless, secondary metabolites directly involved in plant defense, such as DIMBOA and conjugated isoflavone phytoalexins, were also involved in the AMF-mediated plant response to infection. [ABSTRACT FROM AUTHOR]