New glomeromycotan taxa, Dominikia glomerocarpica sp. nov. and Epigeocarpum crypticum gen. nov. et sp. nov. from Brazil, and Silvaspora gen. nov. from New Caledonia

Examination of fungal specimens collected in the Atlantic rain forest ecosystems of Northeast Brazil revealed many potentially new epigeous and semihypogeous glomerocarp-producing species of the phylum Glomeromycota. Among them were two fungi that formed unorganized epigeous glomerocarps with glomoid spores of almost identical morphology. The sole structure that distinguished the two fungi was the laminate layer 2 of their three-layered spore wall, which in spores of the second fungus crushed in PVLG-based mountants contracted and, consequently, transferred into a crown-like structure. Surprisingly, phylogenetic analyses of sequences of the 18SITS- 28S nuc rDNA and the rpb1 gene indicated that these glomerocarps represent two strongly divergent undescribed species in the family Glomeraceae. The analyses placed the first in the genus Dominikia, and the second in a sister clade to the monospecific generic clade Kamienskia with Kamienskia bistrata. The first species was described here as Dominikia glomerocarpica sp. nov. Because D. glomerocarpica is the first glomerocarp-forming species in Dominikia, the generic description of this genus was emended. The very large phylogenetic distance and the fundamental morphological differences between the second species and K. bistrata suggested us to introduce a new genus, here named as Epigeocarpum gen. nov., and name the new species Epigeocarpum crypticum sp. nov. In addition, our analyses also focused on an arbuscular mycorrhizal fungus originally described as Rhizophagus neocaledonicus, later transferred to the genus Rhizoglomus. The analyses indicated that this species does not belong to any of these two genera but represents a new clade at the rank of genus in the Glomeraceae, here described as Silvaspora gen. nov

Caractérisation taxonomique des champignons mycorhiziens à arbuscules natifs des sols ultramafiques de Nouvelle-Calédonie ; analyse de leur synergie permettant l’adaptation des plantes à ces milieux extrêmes

Plant arbuscular mycorrhizal fungi (AMF) symbiosis can be critically important in the development of sustainable agriculture, remediation of polluted lands and ecological restoration of degraded sites, such as mines. Indeed, AMF symbioses improve plant growth and tolerance to biotic and abiotic stresses from the environment. This study based on the hypothesis, that in environments facing different stress factors, inoculation with several species from different AMF taxa may be essential to promote growth and to withstand stresses of plant in ultramafic soils of mine-degraded areas. The aims of the present study were to characterize taxonomically (isolate, describe, and identify) and functionally (plant growth and adaptation) AMF from ultramafic soil. Five new species of AMF from ultramafic soil were described (Blaszkowski et al. 2017; Crossay et al. 2018). Taxonomic identification of AMF need considerable expertise and is not well-adapted for “routine” identification. Therefore, we developed a fast, accurate and efficient method for AMF identification using MALDI-TOF MS proteomic-based biotyping approach (Crossay et al. 2017). Finally, we analyzed the effects of six species of AMF from a New Caledonian ultramafic soil on plant growth and nutrition, using mono-inoculations and mixtures comprising different numbers of AMF species, in a greenhouse experiment. Our results suggest that, co-inoculation of native AMF was very efficient in improving growth and tolerance to heavy metals of plants in ultramafic soil (Crossay et al. 2019).Une des solutions les plus prometteuses pour la restauration écologique des milieux dégradés, mais aussi pour l’agriculture, est l’utilisation des champignons mycorhiziens à arbuscules (CMA). En effet, ces champignons permettent de conférer aux plantes une meilleure nutrition minérale et une tolérance aux stress biotiques et abiotiques du milieu. L’étude réalisée ici part de l’hypothèse que les effets simultanés de plusieurs CMA taxonomiquement bien différents pourraient permettre de réduire la majorité des contraintes et permettre ainsi à la plante de s’adapter et se développer de façon optimale dans les sols extrêmes (ultramafiques) dégradés par l’activité minière. Les objectifs de cette thèse sont de caractériser les CMA isolés de ces milieux ultramafiques d’un point de vue taxonomique et fonctionnel (croissance et d’adaptation de la plante hôte). Ce travail a permis la découverte de cinq espèces nouvelles de CMA (Błaszkowski et al. 2017 ; Crossay et al. 2018). La complexité des méthodes d’identification de ces symbiotes, a suscité une réflexion scientifique qui a permis d’aboutir à la mise au point d’une méthode d’identification par MALDI-TOF MS précise et routinière pour l’identification des CMA (Crossay et al. 2017). Les différents isolats identifiés et cultivés en laboratoire ont ensuite été testés en conditions expérimentales afin d’évaluer leurs fonctions individuelles et collectives au sein des plantes hôtes (Crossay et al. 2019). En conclusion, la co-inoculation de ces différentes nouvelles espèces de CMA natives des sols ultramafiques de Nouvelle-Calédonie permet une grande amélioration de la croissance des plantes et de leur adaptation à ces milieux extrêmes

Taxonomic characterization of native arbuscular mycorrhizal fungi from ultramafic soils of New Caledonia; analysis of their functional complementarity for plant growth and adaptation in ultramafic soil

Une des solutions les plus prometteuses pour la restauration écologique des milieux dégradés, mais aussi pour l’agriculture, est l’utilisation des champignons mycorhiziens à arbuscules (CMA). En effet, ces champignons permettent de conférer aux plantes une meilleure nutrition minérale et une tolérance aux stress biotiques et abiotiques du milieu. L’étude réalisée ici part de l’hypothèse que les effets simultanés de plusieurs CMA taxonomiquement bien différents pourraient permettre de réduire la majorité des contraintes et permettre ainsi à la plante de s’adapter et se développer de façon optimale dans les sols extrêmes (ultramafiques) dégradés par l’activité minière. Les objectifs de cette thèse sont de caractériser les CMA isolés de ces milieux ultramafiques d’un point de vue taxonomique et fonctionnel (croissance et d’adaptation de la plante hôte). Ce travail a permis la découverte de cinq espèces nouvelles de CMA (Błaszkowski et al. 2017 ; Crossay et al. 2018). La complexité des méthodes d’identification de ces symbiotes, a suscité une réflexion scientifique qui a permis d’aboutir à la mise au point d’une méthode d’identification par MALDI-TOF MS précise et routinière pour l’identification des CMA (Crossay et al. 2017). Les différents isolats identifiés et cultivés en laboratoire ont ensuite été testés en conditions expérimentales afin d’évaluer leurs fonctions individuelles et collectives au sein des plantes hôtes (Crossay et al. 2019). En conclusion, la co-inoculation de ces différentes nouvelles espèces de CMA natives des sols ultramafiques de Nouvelle-Calédonie permet une grande amélioration de la croissance des plantes et de leur adaptation à ces milieux extrêmes.Plant arbuscular mycorrhizal fungi (AMF) symbiosis can be critically important in the development of sustainable agriculture, remediation of polluted lands and ecological restoration of degraded sites, such as mines. Indeed, AMF symbioses improve plant growth and tolerance to biotic and abiotic stresses from the environment. This study based on the hypothesis, that in environments facing different stress factors, inoculation with several species from different AMF taxa may be essential to promote growth and to withstand stresses of plant in ultramafic soils of mine-degraded areas. The aims of the present study were to characterize taxonomically (isolate, describe, and identify) and functionally (plant growth and adaptation) AMF from ultramafic soil. Five new species of AMF from ultramafic soil were described (Blaszkowski et al. 2017; Crossay et al. 2018). Taxonomic identification of AMF need considerable expertise and is not well-adapted for “routine” identification. Therefore, we developed a fast, accurate and efficient method for AMF identification using MALDI-TOF MS proteomic-based biotyping approach (Crossay et al. 2017). Finally, we analyzed the effects of six species of AMF from a New Caledonian ultramafic soil on plant growth and nutrition, using mono-inoculations and mixtures comprising different numbers of AMF species, in a greenhouse experiment. Our results suggest that, co-inoculation of native AMF was very efficient in improving growth and tolerance to heavy metals of plants in ultramafic soil (Crossay et al. 2019)

Four new species of arbuscular mycorrhizal fungi (Glomeromycota) associated with endemic plants from ultramafic soils of New Caledonia

International audienceFour new species of arbuscular mycorrhizal (AM) fungi (Glomeromycota) were isolated from the rhizosphere of endemic metallophytic plants in ultramafic soils in New Caledonia (South Pacific) and propagated on Sorghum vulgare. Acaulospora saccata and A. fragilissima are placed in the Acaulosporaceae, Scutellospora ovalis in the Gigasporaceae, and Rhizophagus neocaledonicus in the Glomeraceae. The novelty of these species is supported by morphological characters of spores and phylogenetic analyses of sequences of the rDNA region, comprising partial small subunit rRNA gene, the internal transcribed spacers, 5.8S rRNA gene, and the partial large subunit rRNA gene. New Caledonia is known for its high degree of endemism in plants, which is due to its geographic position and geological history. This is the first taxonomic study exploring local Glomeromycota of this island, which may help to address the question of possible AMF endemism in future studies

Evaluation of the performance of MALDI-TOF-MS biotyping to identify Gigasporaceae

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A new family, Pervetustaceae with a new genus, Pervetustus, and P. simplex sp. nov. (Paraglomerales), and a new genus, Innospora with I. majewskii comb. nov. (Paraglomeraceae) in the Glomeromycotina

A new arbuscular mycorrhizal, Paraglomus-like, fungal species (Glomeromycotina) was found and propagated in single-species cultures established from spores coming from Oman, Greece, Tunisia, and New Caledonia. The hyaline spores of the fungus are small, 17–67 μm diam. when globose. Their spore wall consists of an evanescent, 1.0–2.3 μm thick, short-lived outer layer and a laminate, smooth, 3.8–7.3 μm thick inner layer, of which none shows amyloid or dextrinoid reaction in Melzer's reagent. Mycorrhizal structures (arbuscules and hyphae without vesicles) of the fungus stained slightly in Trypan blue, thus like those of the formerly described Paraglomus spp., in which the histochemical feature has been recognized. However, in the phylogenies gained from analyses of nrDNA sequences, the fungus formed a distinct lineage in a basal position relative to and highly diverged from that with P. majewskii and that with the other Paraglomus spp. of known molecular phylogeny. Comparisons of similarity of sequences and the spore wall structure of the new fungus with those of P. majewskii and the other Paraglomus spp. and the positions of clades of the three taxa relative to those of the other taxa of the Glomeromycotina suggested transferring P. majewskii to a new genus in the Paraglomeraceae and describing the new fungus as a new species of a new genus in a new family of the order Paraglomerales

Combinations of different arbuscular mycorrhizal fungi improve fitness and metal tolerance of sorghum in ultramafic soil

International audienceResearch on arbuscular mycorrhizal fungi (AMF) in ultramafic soils has principally focused on ecological restorationwhereas little attention has been given to agriculture. The present study aims at understanding ifmixtures of different AMF species from a New Caledonian ultramafic soil induced a better plant fitness and lowercontents of potentially toxic metals in aerial parts of a crop plant than single species inoculants. Sorghum vulgareplants were inoculated using six AMF species separately and in different mixtures of these species in a glasshouseexperiment in ultramafic soil. The tested inocula showed very different effects on plant fitness. Results highlightthat, when sorghum is grown in ultramafic soil, AMF mixes were more efficient than single species inoculation inalleviating abiotic stresses by reducing translocation of potentially toxic metals to the aerial part of the plant andthereby improving the fitness of the plants. Our findings point out the utility of arbuscular mycorrhizal biotechnologyfor agricultural ultramafic soils

Importance and roles of arbuscular mycorrhizal fungi in new Caledonian ultramafic soils

International audienceOur knowledge about New Caledonian serpentine ecosystems has increased greatly during the past half-century, mainly thanks to Jaffré's group. However, research on soil microflora and plant symbionts started only in the nineties and was mainly published during the last two decades. We aim to synthesize these studies, focusing particularly on arbuscular mycorrhizal fungi (AMF). Research on AMF consists firstly of a global and inventory approach aiming to produce a basic but essential lacking knowledge. These studies showed that AMF are abundant in ultramafic soils and concerned nearly all plant species of these ecosystems. Even Nihyperaccumulator plants and sedges, generally considered non-mycorrhizal, were found to be functionally colonized by AMF in New Caledonian ultramafic soils. The adaptation of AMF communities to the extreme conditions of these soils led to high levels of metal tolerance (particularly to Ni) and noticeable originality of the taxa. The influence of these symbionts on plant growth and adaptation was assessed in greenhouse and field conditions. An accurate selection of AMF isolates that improve plant growth, and plant metal tolerance was performed. It was demonstrated that combinations of AMF isolates with complementary functional traits showed highly synergistic effects on plant development. Finally, a partnership with a biotechnological company led to the production of an efficient commercial inoculant now used in the ecological restoration of mine-degraded areas. Today studies are focused mainly on the additive effects of AMF and mycorrhiza-helper bacteria

Prediction of photovoltaic p-n device short circuit current by photoelectrochemical analysis of p-type CIGSe films

The quality control of individual semiconductor thin films during fabrication of multiple layers is important for industry and academia. The ultimate aim of this research is to predict the efficiency of p-–n junction solar cells by photoelectrochemical analysis of the bare p-type semiconductor. A linear correlation between the photocurrent measured electrochemically on Cu(In,Ga)Se2 absorber layers through a Eu3+ electrolyte junction and short circuit current and efficiency of the corresponding solid state devices is found. However, the correlation is complicated by pronounced recombination at the semiconductor/electrolyte interface, while the solid state interface behaves more ideally

Is a mixture of arbuscular mycorrhizal fungi better for plant growth than single-species inoculants

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