Arbuscular mycorrhizal fungi (AMF, Glomeromycota) are globally distributed symbionts of plant roots. Relationships with arbuscular mycorrhizae can provide crucial support for the establishment of any plant in an unfavorable environment. We hypothesized that invasions of neophytes are associated with changes in the colonization of native plants and early invaders (archeophytes) by AMF. We examined changes in AMF colonization in yarrow (Achillea millefolium L.) and wild carrot (Daucus carota L.) (native plants) and tansy (Tanacetum vulgare L.) and false oatgrass [Arrhenatherum elatius (L.) P. Beauv. ex J. Presl & C. Presl] (archeophytes) in response to the invasion of four neophytes from the Asteraceae family, namely great globethistle (Echinops sphaerocephalus L.), New York aster [Symphyotrichum novi-belgii (L.) G. L. Nesom agg.], annual fleabane [Erigeron annuus (L.) Pers.], and Canada goldenrod (Solidago canadensis L.). We found that the AMF colonization of the Asteraceae neophytes was high in the studied monodominant invasions, and the AMF colonization of the neophytes was higher than or equal to that of the studied native plants and archeophytes. Changes in plant dominance did not serve as predictors of the extent of AMF colonization of the native plants and archeophytes despite the invaded plots being associated with strong changes in the availability of primary and secondary mineral nutrients. The absence of a response of AMF colonization of native and archeophyte plant species to the invasion of neophytes suggests that AMF are passengers, rather than drivers, in the course of Asteraceae invasions in central European environments.

Arbuscular mycorrhizal fungi (AMF) can increase plant nutrient uptake and chemical defense production, both of which can improve plants’ ability to resist insect herbivory. Cover crops—non-commercial species planted in between cash crops in a crop rotation—can naturally alter both soil nutrients and AMF. We tested whether different cover crop species alter AMF colonization, plant nutrient status and plant–insect interactions in a subsequent maize crop. Cover crop species were either non-mycorrhizal, non-leguminous (canola, forage radish), mycorrhizal non-leguminous (cereal rye, oats), mycorrhizal leguminous (clover, pea) or absent (fallow). We measured the cascading consequences of cover crop treatment on maize root AMF colonization, maize growth and performance of an herbivorous insect (European corn borer) feeding on the maize. Maize AMF colonization was greater in plots previously planted with mycorrhizal (rye, oats) than non-mycorrhizal (canola, radish) cover crops or no cover crop (fallow). AMF colonization was linked to increased plant phosphorous and nitrogen, and maize growth increased with low plant N:P. Induced jasmonic acid pathway plant defenses increased with increasing maize growth and AMF colonization. European corn borer survivorship decreased with lower plant N:P, and insect development rate decreased with increased induced plant defenses. Our data describe a cascade in which cover crop species selection can increase or decrease mycorrhizal colonization of subsequent maize crop roots, which in turn impacts phosphorus uptake and may affect herbivory resistance in the maize. These results suggest that farmers could select cover crop species to manage nutrient uptake and pest resistance, in order to amend or limit fertilizer and pesticide use.

We used a growth chamber experiment with first-year garlic mustard plants to explore the effects of three garlic mustard removal techniques (treatment with glyphosate, pulling out the entire plant, and clipping the shoot) on growth of the native herb pale jewelweed and its associated mycorrhizal fungi. We also explored the effects of activated carbon and mycorrhizal inocula amendments. We monitored plant height, intra- and extraradical mycorrhizal structures, root growth, and the fractal dimension of the root system. Removing as much garlic mustard root tissue as possible by hand pulling plants led to larger jewelweed plants than other removal methods. Activated carbon and mycorrhizal inocula did not improve plant growth.

Introduction. Tamarind (Tamarindus indica L.) belongs to the Fabaceae family; it is a multipurpose tree with slow growth. In order to help improve its growth and development, we assessed mycorrhizal diversity of tamarind parklands in Senegal. Materials and methods. Three sites of tamarind populations were sampled for each agro-ecological zone in Senegal: the Sahelian zone (i), Sahelo-Sudan zone (ii) and Sudan zone (iii). Soil and root samples were collected in each site and used for arbuscular mycorrhizal (AM) spore isolation and root colonization assessment. We identified the mycorrhizal fungi from spore collections and evaluated the root mycorrhization rate, defined as percentage of roots colonized according to agro-ecological zones. Results and discussion. The results did not reveal a specific AM fungal strain associated with tamarind plants. Three arbuscular mycorrhizal fungi (AMF) were identified from spores on the genus level: Glomus, Scutellospora and Acaulospora. Tamarind sites with sandy soil texture (70–90%) and located in dry areas (Sahel and Sudano-Sahel zones) were shown to be rich in mycorrhizal propagules. High densities of soil AM propagules evaluated with the Most Probable Number method (MPN) were found in Niokhoul (1100 propagules per 50 g of soil), Sakal (790 propagules per 50 g of soil) and Mbassis (780 propagules per 50 g of soil). However, higher mycorrhizal colonization (11%) was observed in the Sahel agro-ecological zone compared with the Sudano-Sahelian and Sahelian zones (3%) of Senegal. Conclusion. Our study explored natural AMF diversity as a starting point to develop inocula to be used in commercial nursery production of tamarinds.

Introduction. Arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) can be considered important rhizospheric beneficial microorganisms. Their use as biocontrol strategies against soilborne pathogens such as nematodes should be taken into account. However, optimal management of soil microbiota communities is not easy because of the high specificity involved in these types of interactions. The aim of our study was to determine whether the combined inoculation of two AMF species and a Bacillus consortium based on three strains previously described as PGPR in other crops were able to reduce nematode infection and damage on papaya. Materials and methods. Papaya seedlings were inoculated with two AMF isolates (Glomus mosseae or G. manihotis) at the beginning of the nursery phase. Once the mycorrhizal symbiosis was established, a Bacillus consortium was applied. Nematode inoculum was applied 20 d after transplanting to individual pots. Plants were harvested 160 d after nematode inoculation. Results. In terms of plant development and nutrition, benefits due to AMF inoculation persisted in the presence of PGPR. However, the effect of dual inoculation was different, depending on the Glomus species. This positive effect was also evident in plants with nematode. Meloidogyne infection was significantly reduced in mycorrhizal plants. However, the addition of PGPR does not seem to improve the results of AMF single treatments in terms of nematode infection. Conclusion. Dual application of AMF and PGPR must be considered for papaya threatened by the root-knot nematode, although a previous screening should be done in order to select the best microbe combination to optimise results.

Introduction. Arbuscular Mycorrhizal Fungi (AMF) can promote host growth and, among other benefits, alleviate the stress produced by transplanting seedlings from the nursery to the field. The objective of this work was to evaluate the effect of the amount of AMF inoculum on growth of Hancornia speciosa (Mangaba tree). Materials and methods. A greenhouse experiment was performed using a randomized experimental design in a factorial arrangement of 3 × 3 corresponding to: two AMF (Gigaspora albida Schenck & Smith andGlomus etunicatum Becker & Gerdeman) treatments plus one control with plants without AMF three inoculum densities [(50, 100 and 300) spores per plant], with five replicates, in a methyl bromide sterilized soil. Results. After 120 d, seedlings associated with G. albida had greater height, shoot diameter and dry biomass of the aerial part and leaf area than those associated with G. tunicatum, independent of inoculum density. G. etunicatum did not influence growth of H. speciosa. Positive correlations occurred between plant growth parameters and root colonization promoted by G. albida. Regression analysis showed interaction between the inoculum density of G. albida and plant growth parameters. Discussion and conclusion. Increments in growth of H. speciosa can be obtained with inoculation of approximately 180 spores of G. albida per plant, which could reduce the necessary period of time for the transplanting of seedlings from the nursery to the field.

Introduction. Le jujubier, Zizyphus mauritiana Lam., est un arbre fruitier forestier très recherché pour ses fruits par les populations du Sahel. La domestication de cette espèce a été abordée à partir de techniques sylvicoles comme la mycorhization contrôlée et la fertilisation phosphatée avec des phosphates naturels (PN). Le document présente une synthèse des résultats acquis sur ces sujets. Matériel et méthodes. La dépendance mycorhizienne du jujubier et de douze autres espèces d'arbres fruitiers forestiers vis-à-vis de deux champignons mycorhiziens à arbuscules Glomus aggregatum et G. intraradices a été étudiée. Par ailleurs, la capacité de l'arbre à mobiliser du phosphore à partir de PN d'Afrique de l'Ouest a été évaluée dans un sol sableux, pauvre en phosphore assimilable et à pH faiblement acide. Des jujubiers inoculés avec G. aggregatum ont été ensuite mis au champ afin de suivre des paramètres de croissance. Résultats et discussion. Parmi les treize espèces d'arbres fruitiers forestiers étudiés, le jujubier s'est révélé être le plus dépendant de la symbiose mycorhizienne avec G. aggregatum qui agit sur sa croissance et son alimentation en phosphore assimilable. Les jujubiers mycorhizés mobilisent plus efficacement le phosphore des PN de Tilemsi (Mali) que celui des PN de Taïba (Sénégal) et de Kodjari (Burkina Faso). En pépinières, la mycorhization contrôlée a des effets bénéfiques sur la croissance de jujubiers de différentes provenances. Cet effet bénéfique de l'inoculation a aussi été observé en plantation sur des arbres de 20 mois. Conclusion. Les techniques de mycorhization contrôlée et de fertilisation avec des PN sont aptes à améliorer la croissance et la nutrition phosphatée des jujubiers en pépinières et au champ. Cependant, elles devront être testées dans d'autres sites forestiers afin d'évaluer leurs effets sur la production fourragère et fruitière des jujubiers.