Mycorrhizal Occurrence Research Articles

The influence of bioproducts on mycorrhizal occurrence in the vegetable roots

In plant cultivation, it is very important to reduce the negative effects of biotic and abiotic environmental stresses in order to produce high-quality crops (Wu 2017). Biotic factors include stresses caused by pathogenic fungi, bacteria, nematodes, viruses, and pests, while abiotic factors include drought, mineral deficiency/excess, salinity, thermal stresses, and heavy metal contamination (Inculet et al. 2019 ). Among abiotic stresses, the most serious losses in horticultural and agricultural crops are caused by water shortage, especially long-term. Plants grown in field conditions are of-ten exposed to the simultaneous effects of several stresses, a typical example of which is the occurrence of drought and high temperature, common in many agricultural areas not only in Poland but also throughout the world (Duc et al. 2018) . Crop losses caused by stress factors can reach up to 50-82% (Inculet et al. 2019) . These are the most significant threats to the cultivation and yielding of plants, and constitute serious limitations in plant production (Abewoy 2017). For this reason, a key role in plant production is played by sustainable plant cultivation technologies with the use of beneficial

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The intense exploitation of coal deposits in Southern Brazil has caused severe degradation problems in extensive areas. In order to recover such areas, the use of revegetation with species adapted to disturbed environments and with the capacity to establish mutual relationships with microorganisms have been of great value. The objective of this study is to characterize plant-root symbioses in two grass-legume (Calopogonium mucunoides with Brachiaria decumbens and Vicia sativa with Brachiaria decumbens) consortia inoculated with soil of the Carboniferous Basin in the state of Santa Catarina. Areas evaluated were at different stages of land reclamation and the influence of those consortia on the occurrence of rhizobia, arbuscular mycorrhizal fungi, and in the community of endophytic bacteria were evaluated. The study was done in two independent experiments in a completely randomized design, with five replications; done under greenhouse condition. There were seven treatments - five inoculated (with soil obtained from areas of 2, 4, 6 and 12 years of recovery, and a reference area) and two control treatments without inoculation (with low and high concentrations of mineral nitrogen). After 50 days of implantation, soil and plant material were collected to characterize root symbioses by nodule counting, nitrogen fixing bacteria isolation, mycorrhizal occurrence (%), and characterization of root endophytic bacterial communities. Only the calopogonium-brachiaria consortium was able to nodulate with rhizobia from the recovering coal mining areas. Arbuscular mycorrhizal fungi (AMF) and endophytic bacteria occur in the vetch-brachiaria and calopogonium-brachiaria consortia regardless of the time of recovery. The microbial communities present in soils with different stages of recovery are more efficient in promoting plant growth in the calopogonium-brachiaria consortium and this behavior may be associated with the calopogonium's ability to associate with autochthonous rhizobia. Key words: Environmental recovery, revegetation, plant-growth-promoting, rhizobia, arbuscular mycorrhiza.

Morphology, anatomy and mycotrophy of pseudobulb and subterranean organs in Eulophia epidendraea and Malaxis acuminata (Epidendroideae, Orchidaceae)

Morphology, anatomy and mycotrophy of pseudobulb and subterranean organs in Eulophia epidendraea and Malaxis acuminata (Epidendroideae, Orchidaceae)

Presencia de micorrizas en orquídeas de un jardín botánico neotropical

Mycorrhizal occurrence was tested in roots of 24 terrestrial and epiphytic orchid species growing at the Lankester Botanical Gardens (Cartago, Costa Rica). Standard staining and light microscopy were used to search for pelotons. Roots in contact with the substrate harbor extensive mycorrhyzal fungi. There may be a wide distribution and density of the fungal flora in the secondary forests of the site, this could explain the high natural regeneration of orchids on the garden.

The Influence of Bioproducts on Mycorrhizal Occurrence and Diversity in the Rhizosphere of Strawberry Plants under Controlled Conditions

The new products obtained from natural resources are an alternative to methods based on traditional mineral fertilizers, which are destructive for soil mycorrhizal communities. Our experiment was carried out to evaluate the effect of organic fertilizers and amendments of very diverse composition on mycorrhizal abundance and diversity, as well as on root growth, in strawberry plants cv. “Honeoye”. The plants were grown in rhizoboxes filled with a podsolic soil. The plants were treated with granulated bovine manure, vermicompost extract, humates extract, plant extract, extract from seaweed species reinforced with humic and fulvic acids, a consortium of beneficial soil organisms, a stillage from yeast production and a solution of titanium. Plants treated with products and the microorganisms consortium also received half dose of manure. A standard mineral fertilization (NPK) and an unfertilized control were also included. The bioproducts based on humus-like substances and the yeast stillage had the greatest positive influence on the colonization of roots by arbuscular mycorrhizal fungi (AMF). The different treatments affected the diversity of AMF species present in the rhizospheric soil. All organic products, even though providing a significantly low amount of nutrients, enhanced root growth characteristics in comparison to the mineral fertilization.

Mycorrhizal occurrence and responsiveness of tall fescue and wheatgrass are affected by the source of phosphorus fertilizer and fungal inoculation

We assessed colonization and mycorrhizal growth responses (MR) of wheatgrass and tall fescue growing with and without indigenous soil microorganisms (from Argentinean Pampas) as affected for inoculation with the non-indigenous arbuscular mycorrhizal fungi (AMF) Acaulospora longula or Glomus claroideum and for fertilization with superphosphate (SP) or rock phosphate (RP). Inoculation increased growth, P uptake and MR in plants growing without indigenous microorganisms. The highest MR was determined in non-fertilized tall fescue plants inoculated with G. claroideum. When inoculation and RP were added together to the fumigated soil, plant growth, mycorrhiza and MR were significantly stimulated over the single treatments. When plants were grown in non-fumigated soil, no treatment effects were detected. The introduction of G. claroideum or A. longula under like-field conditions would not cause plant growth increments under field conditions. Emphasis could be put to select an effective indigenous AMF, and reinforcing the mycorrhizal population in soils supplied with RP.

The effect of ground cover or initial organic carbon on soil fungi, aggregation, moisture and organic carbon in one season with oat ( Avena sativa) plots

The effect of ground cover or initial organic carbon on soil fungi, aggregation, moisture and organic carbon in one season with oat ( Avena sativa) plots

Phylogenetic distribution and evolution of mycorrhizas in land plants

A survey of 659 papers mostly published since 1987 was conducted to compile a checklist of mycorrhizal occurrence among 3,617 species (263 families) of land plants. A plant phylogeny was then used to map the mycorrhizal information to examine evolutionary patterns. Several findings from this survey enhance our understanding of the roles of mycorrhizas in the origin and subsequent diversification of land plants. First, 80 and 92% of surveyed land plant species and families are mycorrhizal. Second, arbuscular mycorrhiza (AM) is the predominant and ancestral type of mycorrhiza in land plants. Its occurrence in a vast majority of land plants and early-diverging lineages of liverworts suggests that the origin of AM probably coincided with the origin of land plants. Third, ectomycorrhiza (ECM) and its derived types independently evolved from AM many times through parallel evolution. Coevolution between plant and fungal partners in ECM and its derived types has probably contributed to diversification of both plant hosts and fungal symbionts. Fourth, mycoheterotrophy and loss of the mycorrhizal condition also evolved many times independently in land plants through parallel evolution.

Interactions between arbuscular mycorrhizal fungi and intraspecific competition affect size, and size inequality, of Plantago lanceolata L.

Summary 1 Intraspecific competition causes decreases in plant size and increases in size inequality. Arbuscular mycorrhizas usually increase the size and inequality of non-competing plants, but mycorrhizal effects often disappear when plants begin competing. We hypothesized that mycorrhizal effects on size inequality would be determined by the experimental conditions, and conducted simultaneous field and glasshouse experiments to investigate how AM fungi and intraspecific competition determine size inequality in Plantago lanceolata . 2 As predicted, plant size was reduced when plants were competing, in both field and controlled conditions. However, size inequality was unexpectedly reduced by competition. Plants may have competed in a symmetric fashion, probably for nutrients, rather than the more common situation, in which plant competition is strongly asymmetric. 3 Mycorrhizas had no effect on plant size or size inequality in competing plants in either field or controlled conditions, possibly because competition for nutrients was intense and negated any benefit the fungi could provide. 4 The effects of mycorrhizas on non-competing plants were also unexpected. In field-grown plants, AM fungi increased plant size, but decreased size inequality: mycorrhizal plants were more even in size, with few very small individuals. In glasshouse conditions, mycorrhizal colonization was extremely high, and was generally antagonistic, causing a reduction in plant size. Here, however, mycorrhizas caused an increase in size inequality, supporting our original hypothesis. This was because most plants were heavily colonized and small, but a few had low levels of colonization and grew relatively large. 5 This study has important implications for understanding the forces that structure plant communities. AM fungi can have a variety of effects on size inequality and thus potentially important influences on long-term plant population dynamics, by affecting the genetic contribution of individuals to the next generation. However, these effects differ, depending on whether plants are competing or not, the degree of mycorrhizal colonization and the responsiveness of the plant to different colonization densities.

Vesicular-arbuscular mycorrhizal status of various crops in different agricultural soils of northern Greece

This paper reports the results of a survey of the occurrence of vesicular-arbuscular mycorrhizas and spores of the associated fungi in a variety of soils in Northern Greece. The roots of several crop species were examined for the presence of mycorrhizal structures and all samples showed evidence of infection, though to varying degrees. Cotton plants, in particular, had heavy arbuscular infection. Intact and presumably viable spores were relatively infrequent and empty non-viable spores were much more common. Soil characteristics at each sample site are reported also, but only broad generalizations are made at this stage with respect to correlations between mycorrhizal occurrence and edaphic factors.

Vesicular-arbuscular mycorrhizal associations with barley on sewage-amended plots

Vesicular-arbuscular mycorrhizal associations with barley on sewage-amended plots

Mycorrhizal occurrence in willows in a northern freshwater wetland

Willows growing in a north central Michigan wetland were found to be ectomycorrhizal throughout the 1978 growing season on each of two sites (one water-saturated, one relatively drier). Each site was dominated by a mix of sedges (Carex spp.) and willows (Salix spp.). On both sites, phosphorus was added at two levels (20 or 200 kg P ha−1) to simulate potential inputs from the disposal of secondarily-treated municipal wastewater. The intensity of willow root infection was determined by scoring root tips on a 0 to 4 scale based on mantle-, intercellular hyphae-, and root epidermal cell characteristics. Infection on the wet site remained uniformly heavy in July and August when P was added, but it declined significantly during August for control plants at both sites. When water levels increased during September, the intensity of mycorrhizal infection increased on control plants on the wet site. On the drier site, mycorrhizal intensity decreased on controls and on plants exposed to the highest P levels. Between August and September samplings, mycorrhizal intensity increased considerably on dry-site controls but did not change on plants exposed to added P.

Toward Development of Optimal Alnus glutinosa Symbioses

Field observations and a literature review indicate a broad range of Frankia spp. associations with Alnus glutinosa. A study of three A. glutinosa seedling populations and one of A. rubra inoculated with four different selections of inoculum showed significant host genotype/actinomycete strain interaction. Mycorrhizal occurrence was observed, and an unidentified Basidiomycete associate was isolated. Because mycorrhizae increase the uptake efficiency of minerals, determining the A. glutinosa mycorrhizal association that provides the most efficient nutrient status should also contribute to increased nitrogen fixation.