Microbial inoculation and fertilizer application on growth of cowpea and spore-based assemblages of arbuscular mycorrhizal fungi in its rhizophere.

In this study, the effect of microbial inoculants and fertilizer application on cowpea (BRS Pujante) growth and on the structure and composition of arbuscular mycorrhizal fungi (AMF) assemblages were evaluated. A completely randomized experiment was set up involving 17 treatments: four with AMF, three with nodulating bacteria, six with AMF + nodulating bacteria, two with phosphorus, one with nitrogen and one control (reference) in five replicates. Plant growth and nutritional content, mycorrhizal colonization, glomerospores number, spore-based AMF assemblages and ecological indices were evaluated. Mycorrhizal inoculants associated with Bradyrhizobium BR3267 strain were more effective than the Microvirga BR3296 strain. Multidimensional scaling analysis showed that Acaulospora longula treatments were more similar among themselves, and distinct from the other treatments. A difference was observed in the structure of AMF community assemblage between treatments with G. albida + Bradyrhizobium BR 3267 and A. longula, with greater Shannon diversity and Pielou equitability indices in the first treatment and greater dominance in the treatment with A. longula only. Long-term studies are required to determine if the successful establishment of A. longula among indigenous species persists over time and if its dominant behavior is not deleterious to the AMF native community.

The Importance of Biodiversity E-infrastructures for Megadiverse Countries.

Addressing the challenges of biodiversity conservation and sustainable development requires global cooperation, support structures, and new governance models to integrate diverse initiatives and achieve massive, open exchange of data, tools, and technology. The traditional paradigm of sharing scientific knowledge through publications is not sufficient to meet contemporary demands that require not only the results but also data, knowledge, and skills to analyze the data. E-infrastructures are key in facilitating access to data and providing the framework for collaboration. Here we discuss the importance of e-infrastructures of public interest and the lack of long-term funding policies. We present the example of Brazil's speciesLink network, an e-infrastructure that provides free and open access to biodiversity primary data and associated tools. SpeciesLink currently integrates 382 datasets from 135 national institutions and 13 institutions from abroad, openly sharing ~7.4 million records, 94% of which are associated to voucher specimens. Just as important as the data is the network of data providers and users. In 2014, more than 95% of its users were from Brazil, demonstrating the importance of local e-infrastructures in enabling and promoting local use of biodiversity data and knowledge. From the outset, speciesLink has been sustained through project-based funding, normally public grants for 2-4-year periods. In between projects, there are short-term crises in trying to keep the system operational, a fact that has also been observed in global biodiversity portals, as well as in social and physical sciences platforms and even in computing services portals. In the last decade, the open access movement propelled the development of many web platforms for sharing data. Adequate policies unfortunately did not follow the same tempo, and now many initiatives may perish.

Predictors of Arbuscular Mycorrhizal Fungal Communities in the Brazilian Tropical Dry Forest.

Arbuscular mycorrhizal fungi (AMF) are symbiotic fungi with a broad distribution, and many taxa have physiological and ecological adaptations to specific environments, including semiarid ecosystems. Our aim was to address regional distribution patterns of AMF communities in such semiarid environments based on spore morphological techniques. We assessed AMF spores at the bottom and top of inselbergs distributed throughout the tropical dry forest in the Northeast region of Brazil. Across 10 replicate inselbergs and the surrounding area, spanning a range of altitude between 140 and 2000 m, we scored the AMF soil diversity and properties in 52 plots. We fitted parsimonious ordination analyses and variance partitioning models to determine the environmental factors which explained the variation in AMF community, based on morphological spore analysis. The diversity of AMF was similar at the bottom and top of inselbergs; however, we detected high variation in abundance and richness across sites. We formulated a parsimonious richness model that used physical soil factors as predictors. The AMF community structure could be best explained through the variables coarse and total sand, iron, organic matter, potassium, silt, and sodium which together accounted for 17.8% of total variance. Several AMF species were indicators of either deficiency or high values of specific soil properties. We demonstrated that habitat isolation of the inselbergs compared with surrounding areas did not trigger differences in AMF communities in semiarid regions of Brazil. At the regional scale, soil predictors across sites drove the distribution of symbiotic mycorrhizal fungi.

Changes in Microbial Community Structure and Soil Biological Properties in Mined Dune Areas During Re-vegetation.

The aim of this study was to describe the impact of re-vegetation on the restoration of microbial community structure and soil microbiological properties in sand dunes that had been affected by mining activity. Soil samples were collected during the dry and rainy seasons from a chronosequence (1, 9, 21 years) of re-vegetated dunes using a single preserved dune as a reference. The composition of the fatty acid methyl esters and soil microbial properties were evaluated. The results showed that the changes in microbial community structure were related to seasonal variations: biomarkers of Gram-positive bacteria were higher than Gram-negative bacteria during the dry season, showing that this group of organisms is more tolerant to these stressful conditions. The microbial community structure in the natural dune was less affected by seasonal variation compared to the re-vegetated areas, whereas the opposite was observed for microbiological properties. Thus, in general, the proportion of saprobic fungi was higher in the natural dune, whereas Gram-negative bacteria were proportionally more common in the younger areas. Although over time the re-vegetation allows the recovery of the microbial community and the soil functions, these communities and functions are different from those found in the undisturbed areas.

Mycorrhizal technology and phosphorus in the production of primary and secondary metabolites in cebil (Anadenanthera colubrina (Vell.) Brenan) seedlings.

BACKGROUND: The application of arbuscular mycorrhizal fungi (AMF) can increase the growth and concentration of primary and secondary metabolites in several plant species. Cebil (Anadenanthera colubrina), a medicinal plant, benefits from mycorrhizal association, but the influence of the symbiosis on the production of its bioactive compounds is unknown. In this study the effect of mycorrhizal inoculation and phosphorus (P) supply on the production of primary and secondary metabolites in cebil seedlings was determined. RESULTS: The production of proteins and carbohydrates in terms of both concentration and content was enhanced by inoculation with AMF, but this benefit was mitigated at higher levels of P (30 and 50 mg dm(-3) soil). The concentration of phenols, flavonoids and total tannins was favoured by mycorrhizal inoculation even at the highest levels of P (30 and 50 mg dm(-3) soil). CONCLUSION: The production of primary and secondary metabolites in leaves of A. colubrina can be maximised by mycorrhization, with the benefit depending on supplementation of soil phosphate.

Use of plant residues on growth of mycorrhizal seedlings of neem (Azadirachta indica A. Juss.).

BACKGROUND: Owing to its multiple uses in veterinary medicine, biofertilizers, pest control, etc., the commercial cultivation of neem (Azadirachta indica) has been increasing in various countries. The use of arbuscular mycorrhizal fungi (AMF) and plant by-products (composted leaves and residues of neem and sugarcane) for the propagation of seedlings can be an efficient alternative to stimulate plant growth, reducing the propagation time and conferring increased tolerance of plants to biotic and abiotic stresses. Therefore this study aimed to evaluate the effect of plant substrates and inoculation with AMF on the production of neem seedlings. RESULTS: Beneficial effects of the application of neem by-products to neem seedlings were observed on most of the variables analysed. However, the treatment with sugarcane cake did not improve the growth of neem seedlings. In general, the inoculation treatments using Glomus etunicatum in the composted neem substrates improved seedling growth. CONCLUSION: Neem by-products benefit the growth of seedlings of this plant under greenhouse conditions. Inoculation with G. etunicatum enhances plants growth mainly in substrates with residues of neem leaves, providing an alternative for the production of seedlings of this crop under nursery conditions, which can reduce the need for chemical fertilizers that impact the environment.

Microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants in lead contaminated soil.

The goals of this study were to evaluate the microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants (Caesalpinia ferrea, Mimosa tenuiflora and Erythrina velutina) in lead contaminated soil from the semi-arid region of northeastern of Brazil (Belo Jardim, Pernambuco). Dilutions were prepared by adding lead contaminated soil (270 mg Kg(-1)) to uncontaminated soil (37 mg Pb Kg soil(-1)) in the proportions of 7.5%, 15%, and 30% (v:v). The increase of lead contamination in the soil negatively influenced the amount of carbon in the microbial biomass of the samples from both the dry and rainy seasons and the metabolic quotient only differed between the collection seasons in the 30% contaminated soil. The average value of the acid phosphatase activity in the dry season was 2.3 times higher than observed during the rainy season. There was no significant difference in the number of glomerospores observed between soils and periods studied. The most probable number of infective propagules was reduced for both seasons due to the excess lead in soil. The mycorrhizal colonization rate was reduced for the three plant species assayed. The inoculation with arbuscular mycorrhizal fungi benefited the growth of Erythrina velutina in lead contaminated soil.

Fungal transcript pattern during the preinfection stage (12 h) of ectomycorrhiza formed between Pisolithus tinctorius and Castanea sativa roots, identified using cDNA microarrays.

Transcriptional changes in Pisolithus tinctorius leading to ectomycorrhizal formation in P. tinctorius- Castanea sativa were investigated using a 12-h fungal interaction in vitro system. Using a 3107-cDNA clone microarray, 34 unique expressed sequence tags (ESTs) were found to be differentially expressed. These ESTs represent 14 known genes, 5 upregulated and 9 downregulated, and 20 orphan sequences. Some transcripts of upregulated genes (with unknown function) were previously identified in other mycorrhizal Pisolithus spp. associations. ESTs for S-adenosyl-L-homocysteine hydrolase and several orphan sequences were identified in our system. The identified transcript of downregulated genes involved hydrophobins, 5S, 18S, and 28S ribosomal RNA genes, large subunits of ribosomal RNA (mitochondrial gene), and two types of heat shock proteins. This study demonstrates the high complexity of molecular events involved in the preinfection steps and suggests the utilization of different fungal gene repertories before ectomycorrhizal formation. These data constitute a first contribution for the molecular understanding of early signaling events between P. tinctorius and C. sativa roots during ectomycorrhizal formation.

Symbiosis with AMF and leaf Pi supply increases water deficit tolerance of woody species from seasonal dry tropical forest.

In seasonal dry tropical forests, plants are subjected to severe water deficit, and the arbuscular mycorrhizal fungi (AMF) or inorganic phosphorus supply (Pi) can mitigate the effects of water deficit. This study aimed to assess the physiological performance of Poincianella pyramidalis subjected to water deficit in combination with arbuscular mycorrhizal fungi (AMF) and leaf inorganic phosphorus (Pi) supply. The experiment was conducted in a factorial arrangement of 2 water levels (+H2O and -H2O), 2 AMF levels (+AMF and -AMF) and 2Pi levels (+Pi and -Pi). Leaf primary metabolism, dry shoot biomass and leaf mineral nutrients were evaluated. Inoculated AMF plants under well-watered and drought conditions had higher photosynthesis and higher shoot biomass. Under drought, AMF, Pi or AMF+Pi plants showed metabolic improvements in photosynthesis, leaf biochemistry and higher biomass compared to the plants under water deficit without AMF or Pi. After rehydration, those plants submitted to drought with AMF, Pi or AMF+Pi showed a faster recovery of photosynthesis compared to treatment under water deficit without AMF or Pi. However, plants under the drought condition with AMF showed a higher net photosynthesis rate. These findings suggest that AMF, Pi or AMF+Pi increase the drought tolerance in P. pyramidalis, and AMF associations under well-watered conditions increase shoot biomass and, under drought, promoted faster recovery of photosynthesis.

Optimization of the production of mycorrhizal inoculum on substrate with organic fertilizer.

The system for production of inoculum of arbuscular mycorrhizal fungi (AMF) using sand and vermiculite irrigated with nutrient solution is promising. However, organic amendments added to the substrate can stimulate sporulation of AMF and replace the nutrient solution. The aim of this study was to maximize the production of AMF (Acaulospora longula, Claroideoglomus etunicatum, Dentiscutata heterogama and Gigaspora albida) using selected organic substrates (vermicompost, coir dust and Tropstrato) together with sand and vermiculite. The production of spores varied among the tested AMF and according to the organic source added to the substrate. The vermicompost promoted higher sporulation of A. longula in relation to the other AMF and substrates. The Tropstrato inhibited the sporulation of D. heterogama while the reproduction of C. etunicatum was not affected by the organic compounds. The inoculum of A. longula also showed a high number of infective propagules and promoted biomass accumulation in maize plants. The system of inoculum production using sand and vermiculite + 10% vermicompost favors the production of infective inoculum of A. longula with the fungus benefiting growth of corn plants.

Optimization of the production of mycorrhizal inoculum on substrate with organic fertilizer

The system for production of inoculum of arbuscular mycorrhizal fungi (AMF) using sand and vermiculite irrigated with nutrient solution is promising. However, organic amendments added to the substrate can stimulate sporulation of AMF and replace the nutrient solution. The aim of this study was to maximize the production of AMF (Acaulospora longula, Claroideoglomus etunicatum, Dentiscutata heterogama and Gigaspora albida) using selected organic substrates (vermicompost, coir dust and Tropstrato) together with sand and vermiculite. The production of spores varied among the tested AMF and according to the organic source added to the substrate. The vermicompost promoted higher sporulation of A. longula in relation to the other AMF and substrates. The Tropstrato® inhibited the sporulation of D. heterogama while the reproduction of C. etunicatum was not affected by the organic compounds. The inoculum of A. longula also showed a high number of infective propagules and promoted biomass accumulation in maize plants. The system of inoculum production using sand and vermiculite + 10% vermicompost favors the production of infective inoculum of A. longula with the fungus benefiting growth of corn plants.

Microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants in lead contaminated soil

The goals of this study were to evaluate the microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants (Caesalpinia ferrea, Mimosa tenuiflora and Erythrina velutina) in lead contaminated soil from the semi-arid region of northeastern of Brazil (Belo Jardim, Pernambuco). Dilutions were prepared by adding lead contaminated soil (270 mg Kg-1) to uncontaminated soil (37 mg Pb Kg soil-1) in the proportions of 7.5 percent, 15 percent, and 30 percent (v:v). The increase of lead contamination in the soil negatively influenced the amount of carbon in the microbial biomass of the samples from both the dry and rainy seasons and the metabolic quotient only differed between the collection seasons in the 30 percent contaminated soil. The average value of the acid phosphatase activity in the dry season was 2.3 times higher than observed during the rainy season. There was no significant difference in the number of glomerospores observed between soils and periods studied. The most probable number of infective propagules was reduced for both seasons due to the excess lead in soil. The mycorrhizal colonization rate was reduced for the three plant species assayed. The inoculation with arbuscular mycorrhizal fungi benefited the growth of Erythrina velutina in lead contaminated soil.

Sporulation of arbuscular mycorrhizal fungi using Tris-CHl buffer in addition to nutrient solutions

A produção de inóculo é um dos entraves na aplicação de fungos micorrízicos arbusculares (FMA) em larga escala. O objetivo deste trabalho foi avaliar o efeito de soluções nutritivas associadas a tampão Tris-HCl sobre a esporulação dos FMA. Foram conduzidos dois experimentos em casa de vegetação, um para cada hospedeiro, painço (Panicum miliaceum) e sorgo (Sorghum vulgare), usando como substrato areia:vermiculita (1:1 v/v), onde foram aplicados cinqüenta esporos de Gigaspora margarita, Scutellospora heterogama e Glomus etunicatum. O substrato foi irrigado com as seguintes soluções nutritivas: Hoagland com 3 mM P (S1), Long Ashton II com 15,9 mM P (S2) e Hoagland com 20 mM P (S3), com ou sem 50 mM de tampão Tris-HCl (pH 6,5); o tratamento controle, que consistiu de solo: areia:vermiculita (2:1:1 v/v) recebeu água deionizada. Após 10 semanas não houve diferença na esporulação, nos tratamentos com sorgo, exceto para G. etunicatum. Porém, no experimento com painço os tratamentos com solução nutritiva diferiram significativamente. A esporulação de S. heterogama aumentou após adição do tampão nas soluções S1 e S2, enquanto a de G. etunicatum foi incrementada no substrato irrigado com S1 + tampão e S3, independente da presença do tampão. A produção de esporos de G. margarita foi maior nas soluções S1 e S3, ambas com tampão, porém diferenças significativas foram observadas somente em relação à solução S2, sem tampão. A utilização de soluções nutritivas e a adição de tampão podem contribuir para o aumento da esporulação de FMA; porém, como demonstrado, cada sistema substrato, FMA e hospedeiro deve ser avaliado separadamente, para estabelecimento das condições mais favoráveis para produção de inóculo em larga escala.

Germination and germ tube growth of the arbuscular mycorrhizal fungi Gigaspora albida in different substrates

The role of substrate on germination of Gigaspora Albida Schenck & Smith was investigated, Spores were desinfested with 0.5(per cent) sodium hypochlorite (20 min.) and placed on Petri dishes over a Millipore filter, with one of the following media: a- 1(per cent) water-agar; b- water-agar + aqueous extract of roots of Panicum miliaceum L.; c- salt medium of Murashige & Skoog (MS) or sterelized sand; and incubated in the dark at room temperature (28 C+-2). The experimental design was at random with four treatments and four replicates. Germination was evaluted every 7 days until the 28th day. The water-agar medium was the most feasible for spore germination at the 7th day, followed by the MS medium at the 14th day. Conversely, the sand and the root extract medium did not allow high germination. Spores maintained in water-agar also presented longer germ tubes than spores in the other treatments . Auxiliary cells were observed at the beginning of formation of hyphal branching in all treatments, however they were more numerous in the water-agar medium.

Ultrastructure of hyphae in gigaspora albida schenck & smith (glomales)

Se efectuaron estudios para determinar la ultraestructura de las hifas en gigaspora albida. Se observó una distribución regular de los organelos citoplasmáticos, con nucleos interespaciados con vacuolas y granos de polifosfato. Las evidencias indicaron que la condición nuclear cambia después de la formación del tubo germinativo. No se encontró ninguna prueba de procesos meióticos o mitóticos, pero se observó la presencia de núcleos alargados, una linea divisoria en la región central de algunos de éstos y organelos asociados al núcleo