Species composition of arbuscular mycorrhizal communities changes with elevation in the Andes of South Ecuador.

Arbuscular mycorrhizal fungi (AMF) are the most prominent mycobionts of plants in the tropics, yet little is known about their diversity, species compositions and factors driving AMF distribution patterns. To investigate whether elevation and associated vegetation type affect species composition, we sampled 646 mycorrhizal samples in locations between 1000 and 4000 m above sea level (masl) in the South of Ecuador. We estimated diversity, distribution and species compositions of AMF by cloning and Sanger sequencing the 18S rDNA (the section between AML1 and AML2) and subsequent derivation of fungal OTUs based on 99% sequence similarity. In addition, we analyzed the phylogenetic structure of the sites by computing the mean pairwise distance (MPD) and the mean nearest taxon difference (MNTD) for each elevation level. It revealed that AMF species compositions at 1000 and 2000 masl differ from 3000 and 4000 masl. Lower elevations (1000 and 2000 masl) were dominated by members of Glomeraceae, whereas Acaulosporaceae were more abundant in higher elevations (3000 and 4000 masl). Ordination of OTUs with respect to study sites revealed a correlation to elevation with a continuous turnover of species from lower to higher elevations. Most of the abundant OTUs are not endemic to South Ecuador. We also found a high proportion of rare OTUs at all elevations: 79-85% of OTUs occurred in less than 5% of the samples. Phylogenetic community analysis indicated clustering and evenness for most elevation levels indicating that both, stochastic processes and habitat filtering are driving factors of AMF community compositions.

Arbuscular mycorrhizal fungal communities in the rhizosphere of a continuous cropping soybean system at the seedling stage

Abstract Arbuscular mycorrhizae (AM) fungi play a crucial role in the growth of soybean; however, the planting system employed is thought to have an effect on AM fungal communities in the rhizosphere. This study was performed to explore the influence of continuous soybean cropping on the diversity of Arbuscular mycorrhizal (AM) fungi, and to identify the dominant AM fungus during the seedling stage. Three soybean cultivars were planted under two and three years continuous cropping, respectively. The diversity of AM fungi in the rhizosphere soil at the seedling stage was subsequently analyzed using polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). The results showed that an increase in cropping years improved the colonization rate of AM in all three soybean cultivars. Moreover, the dominant species were found to be Funneliformis mosseae and Glomus species. The results of cluster analysis further confirmed that the number of years of continuous cropping significantly affected the composition of rhizospheric AM fungal communities in different soybean cultivars.

Effectiveness of Arbuscular Mycorrhizal Fungal Isolates from the Land Uses of Amazon Region in Symbiosis with Cowpea

ABSTRACT Arbuscular mycorrhizal fungi provide several ecosystem services, including increase in plant growth and nutrition. The occurrence, richness, and structure of arbuscular mycorrhizal fungi communities are influenced by human activities, which may affect the functional benefits of these components of the soil biota. In this study, 13 arbuscular mycorrhizal fungi isolates originating from soils with different land uses in the Alto Solimões-Amazon region were evaluated regarding their effect on growth, nutrition, and cowpea yield in controlled conditions using two soils. Comparisons with reference isolates and a mixture of isolates were also performed. Fungal isolates exhibited a wide variability associated with colonization, sporulation, production of aboveground biomass, nitrogen and phosphorus uptake, and grain yield, indicating high functional diversity within and among fungal species. A generalized effect of isolates in promoting phosphorus uptake, increase in biomass, and cowpea yield was observed in both soils. The isolates of Glomus were the most efficient and are promising isolates for practical inoculation programs. No relationship was found between the origin of fungal isolate (i.e. land use) and their symbiotic performance in cowpea.

Physiological response of Cucurbita pepo var. pepo mycorrhized by Sonoran desert native arbuscular fungi to drought and salinity stresses

ABSTRACT Plants response to symbiosis with arbuscular mycorrhizal fungi (AMF) under water stress is important to agriculture. Under abiotic stress conditions native fungi are more effective than exotics in improving plant growth and water status. Mycorrhization efficiency is related to soil fungi development and energy cost-benefit ratio. In this study, we assessed the effect on growth, water status and energy metabolism of Cucurbita pepo var. pepo when inoculated with native AMF from the Sonoran desert Mexico (mixed isolate and field consortium), and compared with an exotic species from a temperate region, under drought, low and high salinity conditions. Dry weights, leaf water content, water and osmotic potentials, construction costs, photochemistry and mycorrhization features were quantified. Under drought and low salinity conditions, the mixed isolate increased plant growth and leaf water content. Leaf water potential was increased only by the field consortium under drought conditions (0.5-0.9 MPa). Under high salinity, the field consortium increased aerial dry weight (more than 1 g) and osmotic potential (0.54 MPa), as compared to non-mycorrhized controls. Plants inoculated with native AMF, which supposedly diminish the effects of stress, exhibited low construction costs, increased photochemical capacity, and grew larger external mycelia in comparison to the exotic inoculum.

Tripartite symbiosis of Sophora tomentosa, rhizobia and arbuscular mycorhizal fungi

ABSTRACT Sophora tomentosa is a pantropical legume species with potential for recovery of areas degraded by salinization, and for stabilization of sand dunes. However, few studies on this species have been carried out, and none regarding its symbiotic relationship with beneficial soil microorganisms. Therefore, this study aimed to evaluate the diversity of nitrogen-fixing bacteria isolated from nodules of Sophora tomentosa, and to analyze the occurrence of colonization of arbuscular mycorrhizal fungi on the roots of this legume in seafront soil. Thus, seeds, root nodules, and soil from the rhizosphere of Sophora tomentosa were collected. From the soil samples, trap cultures with this species were established to extract spores and to evaluate arbuscular mycorhizal fungi colonization in legume roots, as well as to capture rhizobia. Rhizobia strains were isolated from nodules collected in the field or from the trap cultures. Representative isolates of the groups obtained in the similarity dendrogram, based on phenotypic characteristics, had their 16S rRNA genes sequenced. The legume species showed nodules with indeterminate growth, and reddish color, distributed throughout the root. Fifty-one strains of these nodules were isolated, of which 21 were classified in the genus Bacillus, Brevibacillus, Paenibacillus, Rhizobium and especially Sinorhizobium. Strains closely related to Sinorhizobium adhaerens were the predominant bacteria in nodules. The other genera found, with the exception of Rhizobium, are probably endophytic bacteria in the nodules. Arbuscular mycorrhizal fungi was observed colonizing the roots, but arbuscular mycorhizal fungi spores were not found in the trap cultures. Therefore Sophora tomentosa is associated with both arbuscular mycorhizal fungi and nodulating nitrogen-fixing bacteria.

Arbuscular mycorrhizal fungi in Mimosa tenuiflora (Willd. ) Poir from Brazilian semi-arid

Abstract Many plant species from Brazilian semi-arid present arbuscular mycorrhizal fungi (AMF) in their rhizosphere. These microorganisms play a key role in the establishment, growth, survival of plants and protection against drought, pathogenic fungi and nematodes. This study presents a quantitative analysis of the AMF species associated with Mimosa tenuiflora, an important native plant of the Caatinga flora. AMF diversity, spore abundance and root colonization were estimated in seven sampling locations in the Ceará and Paraíba States, during September of 2012. There were significant differences in soil properties, spore abundance, percentage of root colonization, and AMF diversity among sites. Altogether, 18 AMF species were identified, and spores of the genera Acaulospora, Claroideoglomus, Dentiscutata, Entrophospora, Funneliformis, Gigaspora, Glomus, Racocetra, Rhizoglomus and Scutellospora were observed. AMF species diversity and their spore abundance found in M. tenuiflora rhizosphere shown that this native plant species is an important host plant to AMF communities from Brazilian semi-arid region. We concluded that: (a) during the dry period and in semi-arid conditions, there is a high spore production in M. tenuiflora root zone; and (b) soil properties, as soil pH and available phosphorous, affect AMF species diversity, thus constituting key factors for the similarity/dissimilarity of AMF communities in the M. tenuiflora root zone among sites.

Molecular characterization of a new monopartite dsRNA mycovirus from mycorrhizal Thelephora terrestris (Ehrh.) and its detection in soil oribatid mites (Acari: Oribatida).

A novel dsRNA virus was identified in the mycorrhizal fungus Thelephora terrestris (Ehrh.) and sequenced. This virus, named Thelephora terrestris virus 1 (TtV1), contains two reading frames in different frames but with the possibility that ORF2 could be translated as a fusion polyprotein after ribosomal -1 frameshifting. Picornavirus 2A-like motif, nudix hydrolase, phytoreovirus S7, and RdRp domains were found in a unique arrangement on the polyprotein. A new genus named Phlegivirus and containing TtV1, PgLV1, RfV1 and LeV is therefore proposed. Twenty species of oribatid mites were identified in soil material in the vicinity of T. terrestris. TtV1 was detected in large amounts in Steganacarus (Tropacarus) carinatus (C.L. Koch, 1841) and in much smaller amounts in Nothrus silvestris (Nicolet). This is the first description of mycovirus presence in oribatid mites.

Comparison of different PCR primers on detecting arbuscular mycorrhizal communities inside plant roots.

OBJECTIVE: Communities of arbuscular mycorrhizal fungi (AMF) colonizing roots have been increasingly investigated by molecular approaches with AMF-specific PCR primers. However, it is difficult to compare the species diversity and species compositions of AMF communities across various studies due to the PCR primers used differently, and also little is known if significant difference of community compositions is characterized by different primers. We aim to compare the difference of efficiency of four primers for AMF. METHODS: We chose four commonly used AMF-specific primer combinations (NS31-AM1, AMLl-AML2, NS31-AML2 and SSUmCf-LSUmBr), and used 18S rDNA clone libraries to describe the AMF diversity and community. RESULTS: Our results showed that the specificity and coverage varied among the tested primers, different primer combinations would yield distinct patterns of species diversity and composition of AMF community. SSUmCf-LSUmBr had the best specificity and coverage in amplifying AMF sequences, followed by NS31-AML2 and NS31-AM1, and AML1-AML2 showed the lowest specificity towards AMF sequences. CONCLUSION: SSUmCf-LSUmBr is not the optimal primer pair for AMF community study in current stage due to limited reference sequences and large DNA size. As an alternative, NS31-AML2 is more suitable in AMF community study, because its target rDNA region could well match the increasingly used virtual taxonomy database (http://maarjam. botany.ut.ee) and also its suitable DNA size could be efficiently used in high-throughput sequencing.

Expression profiles of defence related cDNAs in oil palm (Elaeis guineensis Jacq.) inoculated with mycorrhizae and Trichoderma harzianum Rifai T32.

Basal stem rot is one of the major diseases of oil palm (Elaies guineensis Jacq.) caused by pathogenic Ganoderma species. Trichoderma and mycorrhizae were proposed to be able to reduce the disease severity. However, their roles in improving oil palm defence system by possibly inducing defence-related genes in the host are not well characterized. To better understand that, transcript profiles of eleven putative defence-related cDNAs in the roots of oil palm inoculated with Trichoderma harzianum T32 and mycorrhizae at different time points were studied. Transcripts encoding putative Bowman-Birk protease inhibitor (EgBBI2) and defensin (EgDFS) increased more than 2 fold in mycorrhizae-treated roots at 6 weeks post inoculation (wpi) compared to those in controls. Transcripts encoding putative dehydrin (EgDHN), glycine-rich RNA binding protein (EgGRRBP), isoflavone reductase (EgIFR), type 2 ribosome inactivating protein (EgT2RIP), and EgDFS increased in the oil palm roots treated with T. harzianum at 6 and/or 12 wpi compared to those in the controls. Some of these genes were also expressed in oil palm roots treated with Ganoderma boninense. This study provides an insight of some defence-related genes induced by Trichoderma and mycorrhizae, and their roles as potential agents to boost the plant defence system.

[Photosynthetic parameters and physiological indexes of Paris polyphylla var. yunnanensis influenced by arbuscular mycorrhizal fungi].

Through potted inoculation test at room temperature and indoor analysis, the photosynthetic parameters and physiological and biochemical indexes of Paris polyphylla var. yunnanensis were observed after 28 arbuscular mycorrhizal (AM) fungi were injected into the P. polyphylla var. yunnanensis growing in a sterile soil environment. The results showed that AM fungi established a good symbiosis with P. polyphylla var. yunnanensis. The AM fungi influenced the photosynthetic parameters and physiological and biochemical indexes of P. polyphylla var. yunnanensis. And the influences were varied depending on different AM fungi. The application of AM fungi improved photosynthesis intensity of P. polyphylla var. yunnanensis mesophyll cells, the contents of soluble protein and soluble sugar, protective enzyme activity of P. polyphylla var. yunnanensis leaf, which was beneficial to resist the adverse environment and promote the growth of P. polyphylla var. yunnanensis. Otherwise, there was a certain mutual selectivity between P. polyphylla var. yunnanensis and AM fungi. From the comprehensive effect of inoculation, Racocetra coralloidea, Scutellospora calospora, Claroideoglomus claroideum, S. pellucida and Rhizophagus clarus were the most suitable AM fungi to P. polyphylla var. yunnanensis when P. polyphylla var. yunnanensis was planted in the field.

Evaluation of six primer pairs targeting the nuclear rRNA operon for characterization of arbuscular mycorrhizal fungal (AMF) communities using 454 pyrosequencing.

In the last few years, 454 pyrosequencing-based analysis of arbuscular mycorrhizal fungal (AMF; Glomeromycota) communities has tremendously increased our knowledge of the distribution and diversity of AMF. Nonetheless, comparing results between different studies is difficult, as different target genes (or regions thereof) and primer combinations, with potentially dissimilar specificities and efficacies, are being utilized. In this study we evaluated six primer pairs that have previously been used in AMF studies (NS31-AM1, AMV4.5NF-AMDGR, AML1-AML2, NS31-AML2, FLR3-LSUmBr and Glo454-NDL22) for their use in 454 pyrosequencing based on both an in silico approach and 454 pyrosequencing of AMF communities from apple tree roots. Primers were evaluated in terms of (i) in silico coverage of Glomeromycota fungi, (ii) the number of high-quality sequences obtained, (iii) selectivity for AMF species, (iv) reproducibility and (v) ability to accurately describe AMF communities. We show that primer pairs AMV4.5NF-AMDGR, AML1-AML2 and NS31-AML2 outperformed the other tested primer pairs in terms of number of Glomeromycota reads (AMF specificity and coverage). Additionally, these primer pairs were found to have no or only few mismatches to AMF sequences and were able to consistently describe AMF communities from apple roots. However, whereas most high-quality AMF sequences were obtained for AMV4.5NF-AMDGR, our results also suggest that this primer pair favored amplification of Glomeraceae sequences at the expense of Ambisporaceae, Claroideoglomeraceae and Paraglomeraceae sequences. Furthermore, we demonstrate the complementary specificity of AMV4.5NF-AMDGR with AML1-AML2, and of AMV4.5NF-AMDGR with NS31-AML2, making these primer combinations highly suitable for tandem use in covering the diversity of AMF communities.

Early changes in arbuscular mycorrhiza development in sugarcane under two harvest management systems

Sugarcane (Saccharum spp.) is grown on over 8 million ha in Brazil and is used to produce ethanol and sugar. Some sugarcane fields are burned to facilitate harvesting, which can affect the soil microbial community. However, whether sugarcane pre-harvest burning affects the community of arbuscular mycorrhizal fungi (AMF) and symbioses development is not known. In this study, we investigated the early impacts of harvest management on AMF spore communities and root colonization in three sugarcane varieties, under two harvest management systems (no-burning and pre-harvest burning). Soil and root samples were collected in the field after the first harvest of sugarcane varieties SP813250, SP801842, and RB72454, and AMF species were identified based on spore morphology. Diversity indices were determined based on spore populations and root colonization determined as an indicator of symbioses development. Based on the diversity indices, spore number and species occurrence in soil, no significant differences were observed among the AMF communities, regardless of harvest management type, sugarcane variety or interactions between harvest management type and sugarcane variety. However, mycorrhiza development was stimulated in sugarcane under the no-burning management system. Our data suggest that the sugarcane harvest management system may cause early changes in arbuscular mycorrhiza development.

Arbuscular mycorrhizal fungi in saline soils: vertical distribution at different soil depth

Arbuscular mycorrhizal fungi (AMF) colonize land plants in every ecosystem, even extreme conditions such as saline soils. In the present work we report for the first time the mycorrhizal status and the vertical fungal distribution of AMF spores present in the rhizospheric soil samples of four species of Chenopodiaceae (Allenrolfea patagonica, Atriplex argentina, Heterostachys ritteriana and Suaeda divaricata) at five different depths in two saline of central Argentina. Roots showed medium, low or no colonization (0-50%). Nineteen morphologically distinctive AMF species were recovered. The number of AMF spores ranged between 3 and 1162 per 100 g dry soil, and AMF spore number decreased as depth increased at both sites. The highest spore number was recorded in the upper soil depth (0-10 cm) and in S. divaricata. Depending of the host plant, some AMF species sporulated mainly in the deep soil layers (Glomus magnicaule in Allenrolfea patagonica, Septoglomus aff. constrictum in Atriplex argentina), others mainly in the top layers (G. brohultti in Atriplex argentina and Septoglomus aff. constrictum in Allenrolfea patagonica). Although the low percentages of colonization or lack of it, our results show a moderate diversity of AMF associated to the species of Chenopodiaceae investigated in this study. The taxonomical diversity reveals that AMF are adapted to extreme environmental conditions from saline soils of central Argentina.

Evidence of nickel (Ni) efflux in Ni-tolerant ectomycorhizal Pisolithus albus isolated from ultramafic soil.

Nickel (Ni)-tolerant ectomycorrhizal Pisolithus albus was isolated from extreme ultramafic soils that are naturally rich in heavy metals. This study aimed to identify the specific molecular mechanisms associated with the response of P. albus to nickel. In presence of high concentration of nickel, P. albus Ni-tolerant isolate showed a low basal accumulation of nickel in its fungal tissues and was able to perform a metal efflux mechanism. Three genes putatively involved in metal efflux were identified from the P. albus transcriptome, and their overexpression was confirmed in the mycelium that was cultivated in vitro in the presence of nickel and in fungal tissues that were sampled in situ. Cloning these genes in yeast provided significant advantages in terms of nickel tolerance (+ 31% Ni EC50) and growth (+ 83% µ) compared with controls. Furthermore, nickel efflux was also detected in the transformed yeast cells. Protein sequence analysis indicated that the genes encoded a P-type-ATPase, an ABC transporter and a major facilitator superfamily permease (MFS). This study sheds light on a global mechanism of metal efflux by P. albus cells that supports nickel tolerance. These specific responses to nickel might contribute to the fungal adaptation in ultramafic soil.

Efeito de fungos micorrízicos arbusculares na bioprodução de fenóis totais e no crescimento de Passiflora alata Curtis / Total phenols in Passiflora alata Curtis inoculated with mycorrhizal fungi

Os compostos fenólicos encontrados no extrato das folhas de maracujazeiro doce (Passiflora alata Curtis) são os principais responsáveis pelos efeitos terapêuticos, incluindo a atividade ansiolítica. O presente trabalho avaliou o efeito de diferentes espécies de fungo micorrízicos arbusculares (FMAs) e doses de fósforo sobre a bioprodução de fenóis totais, bem como, o crescimento vegetal e os conteúdos de nitrogênio, fósforo e potássio na massa da matéria seca da parte aérea do maracujazeiro doce. O experimento, fatorial 4x2, foi conduzido em um telado com quatro tratamentos microbiológicos: Glomus etunicatum, Glomus intraradices, inóculo misto (Glomus clarum e Gigaspora margarita) e o controle sem fungo, e duas doses de fósforo: 0 e 50 mg kg-1 de solo. O delineamento experimental foi de blocos casualizados com quatro repetições. As plantas foram colhidas 90 dias após a semeadura. Na ausência da adubação fosfatada, o conteúdo de fenóis totais, a massa da matéria seca da parte aérea e o número de folhas foram maiores nos tratamentos inoculados com FMAs, quando comparados ao tratamento sem fungo. Plantas com inóculo misto apresentaram maior altura com ou sem adubação fosfatada. Os tratamentos inoculados com FMAs, tanto na dose 0 quanto na dose 50 mg kg-1 de P incrementaram os conteúdos de N, P e K na parte aérea do maracujazeiro doce, evidenciando a capacidade dos FMAs em promover o melhor estado nutricional das plantas.

The phenolic compounds found in extracts from leaves of sweet passion fruit (Passiflora alata) are mainly responsible for its therapeutic effects, such as the anxiolytic activity. This study evaluated the effects of different species of mycorrhizal fungi (AMF) and phosphorus levels on the bioproduction of total phenols, as well as plant growth and the contents of nitrogen, phosphorus and potassium in the dry mass of shoots of sweet passion fruit. The experiment was conducted in a greenhouse. The factors were arranged in a :[(microbiological treatments: Glomus etunicatum, Glomus intraradices, mixed inoculum (Glomus clarum and Gigaspora margarita) and without fungus] x 2 (doses of phosphorus: 0 and 50 mg kg-1 soil) factorial arrangement, in a randomized block experimental design with four replications. The plants were harvested 90 days after seeding. In the absence of phosphate fertilization, the total phenol content, dry mass of shoot and leaf number were greater in treatments inoculated with AMF compared to the treatments without fungus. Mixed inoculum plants had higher plant height with or without phosphate fertilization. Treatments inoculated with AMF in both the 0 and 50 mg kg-1 doses of P increased the content of N, P and K in the shoots of sweet passion fruit, demonstrating the ability of AMF to promote better nutritional statusfin plants.

Communities of arbuscular mycorrhizal fungi in Pyrus pyrifolia var. culta (Japanese pear) and an understory herbaceous plant Plantago asiatica.

We investigated communities of arbuscular mycorrhizal fungi (AMF) in the fine roots of Pyrus pyrifolia var. culta, and Plantago asiatica to consider the relationship between orchard trees and herbaceous plants in AMF symbioses. The AMF communities were analyzed on the basis of the partial fungal DNA sequences of the nuclear small subunit ribosomal RNA gene (SSU rDNA), which were amplified using the AMF-specific primers AML1 and AML2. Phylogenetic analysis showed that the obtained AMF sequences were divided into 23 phylotypes. Among them, 12 phylotypes included AMF from both host plants, and most of the obtained sequences (689/811) were affiliated to them. Canonical correspondence analysis showed that the host plant species did not have a significant effect on the distribution of AMF phylotypes, whereas the effects of sampling site, soil total C, soil total N and soil-available P were significant. It was also found that the mean observed overlaps of AMF phylotypes between the paired host plants in the same soil cores (27.1% of phylotypes shared) were significantly higher than the mean 1,000 simulated overlaps (14.2%). Furthermore, the same AMF sequences (100% sequence identity) were detected from both host plants in 8/12 soil cores having both roots. Accordingly, we concluded that Py. pyrifolia and Pl. asiatica examined shared some AMF communities, which suggested that understory herbaceous plants may function as AMF inoculum sources for orchard trees.

Arbuscular mycorrhizal fungi in a wetland constructed for benzene-, methyl tert-butyl ether- and ammonia-contaminated groundwater bioremediation.

Arbuscular mycorrhizal fungi (AMF), which are present in most natural environments, have demonstrated capacity to promote biodegradation of organic pollutants in the greenhouse. However, it is not certain whether AMF can spontaneously establish in phytoremediation systems constructed to decontaminate groundwater, because of the unusual conditions during the construction and operation of such systems. To assess this possibility, root samples from a wetland constructed for the phytoremediation of groundwater contaminated with benzene, methyl tert-butyl ether and ammonia were analysed. Substantial AMF colonization was observed in plant roots sampled close to the inlet of a basin filled with fine gravel and planted with Phragmites australis. In addition, analysis of a fragment of the nuclear large ribosomal subunit, amplified by nested PCR, revealed the presence of AMF molecular operational taxonomic units closely related to Funneliformis mosseae and Rhizophagus irregularis in the samples. These findings demonstrate the capacity of generalist AMF strains to establish spontaneously, rapidly and extensively in groundwater bioremediation technical installations.

Molecular approach to characterize ectomycorrhizae fungi from Mediterranean pine stands in Portugal

Stone pine (Pinus pinea L.), like other conifers, forms ectomycorrhizas (ECM), which have beneficial impact on plant growth in natural environments and forest ecosystems. An in vitro co-culture of stone pine microshoots with pure mycelia of isolated ECM sporocarps was used to overcome the root growth cessation not only in vitro but also to improve root development during acclimation phase. Pisolithus arhizus (Scop.) Rauschert and Lactarius deliciosus (L. ex Fr.) S.F. Gray fungi, were collected, pure cultured and used in in vitro co-culture with stone pine microshoots. Samples of P. arhizus and L. deliciosus for the in vitro co-cultures were collected from the pine stands southwest Portugal. The in situ characterization was based on their morphotypes. To confirm the identity of the collected material, ITS amplification was applied using the pure cultures derived from the sporocarps. Additionally, a molecular profile using PCR based genomic fingerprinting comparison was executed with other genera of Basidiomycetes and Ascomycetes. Our results showed the effectiveness of the techniques used to amplify DNA polymorphic sequences, which enhances the ­characte­rization of the genetic profile of ECM fungi and also provides an option to verify the fungus identity at any stage of plant mycorrhization.

Ocorrência de fungos micorrízicos em catuaba (Anemopaegma arvense (Vell. ) Stell. ex de Souza - Bignoniaceae), uma planta medicinal do Cerrado em risco de extinção / Michorrizical funghi studies in catuaba (Anemopaegma arvense (Vell. ) Stell. ex de Souza), a medicinal plant from the Cerrado region at risk of extinction

Este trabalho foi realizado com o objetivo de verificar a ocorrência de fungos micorrízicos, identificar suas espécies, e avaliar a colonização em raízes de plantas de diferentes populações e variedades de Anemopaegma arvense, uma planta medicinal do Cerrado em risco de extinção. As avaliações da colonização micorrízica e identificação de espécies de fungos micorrízicos arbusculares (FMAs) foram realizadas no Laboratório de Microbiologia do Solo da Universidade Federal de Lavras (UFLA). Foram utilizadas raízes de 10 plantas coletadas em diferentes locais juntamente com as amostras de solo próximo ao sistema radicular de populações naturais das variedades: glabra, puberula e petiolata. Os esporos foram extraídos do solo por meio da metodologia de peneiramento úmido e, para a avaliação e observação da colonização radicular, as raízes coradas foram observadas em microscópio estereoscópico (ampliação 10 a 40x). Em todas as amostras analisadas foi possível identificar espécies de FMAs, exceto para a variedade puberula, coletada no município de Mogi Guaçu-SP. O número de esporos variou de maneira significativa entre as amostras e os locais amostrados, não havendo distribuição regular. Acaulospora scrubiculata, A. spinosa, A. longula, Escustelospora heterogama, Paraglomus occultum, Gigaspora margarita, Gigaspora sp., dentre outros, encontram-se entre as espécies identificadas. Quanto à avaliação da colonização micorrízica nas raízes, observou-se que todas as variedades foram colonizadas no sitema radicular, verificada por meio da presença de hifas. No entanto, a colonização não foi constatada em todas as amostras avaliadas e também não foi observada a formação de arbúsculos e/ou vesículas.

This work was carried out to verify the occurrence, identify species of mycorrhizal fungi and to evaluate the colonization in roots of plants of different varieties and populations of Anemopaegma arvense, a medicinal plant from the Savannah, in danger of extinction. Assessments of mycorrhizal infection and identification of species of mycorrhizal fungi (AMF) were conducted at the Laboratory of Soil Microbiology, Federal University of Lavras (UFLA). We used roots from 10 plants collected at different sites, along with samples of soil near the root system of natural populations of the varieties glabra, puberula and petiolata. Spores were extracted from soil by the wet sifting methodology and, for the assessment and observation of the root colonization, the stained roots were observed under a stereomicroscope (magnification 10 to 40x), respectively. In all samples it was possible to identify AMF species, except for the variety puberula, collected in the municipality of Mogi Guaçu - SP. The number of spores varied significantly between samples and sampling sites, with no regular distribution. Acaulospora scrubiculata, A. spinosa, A. longula, Escustelospora heterogama, Paraglomus occultum, Gigaspora margarita, Gigaspora sp. among others, are some of the species identified. Regarding the assessment of mycorrhizal infection in the roots, we observed that all the varieties analyzed showed colonization by hyphae. However, not all samples assessed presented colonization and the formation of arbuscules and/or vesicles was not observed.

Tracking nickel-adaptive biomarkers in Pisolithus albus from New Caledonia using a transcriptomic approach.

The fungus Pisolithus albus forms ectomycorrhizal (ECM) associations with plants growing on extreme ultramafic soils, which are naturally rich in heavy metals such as nickel. Both nickel-tolerant and nickel-sensitive isolates of P. albus are found in ultramafic soils in New Caledonia, a biodiversity hotspot in the Southwest Pacific. The aim of this work was to monitor the expression of genes involved in the specific molecular response to nickel in a nickel-tolerant P. albus isolate. We used pyrosequencing and quantitative polymerase chain reaction (qPCR) approaches to investigate and compare the transcriptomes of the nickel-tolerant isolate MD06-337 in the presence and absence of nickel. A total of 1,071,375 sequencing reads were assembled to infer expression patterns of 19,518 putative genes. Comparison of expression levels revealed that 30% of the identified genes were modulated by nickel treatment. The genes, for which expression was induced most markedly by nickel, encoded products that were putatively involved in a variety of biological functions, such as the modification of cellular components (53%), regulation of biological processes (27%) and molecular functions (20%). The 10 genes that pyrosequencing analysis indicated were induced the most by nickel were characterized further by qPCR analysis of both nickel-tolerant and nickel-sensitive P. albus isolates. Five of these genes were expressed exclusively in nickel-tolerant isolates as well as in ECM samples in situ, which identified them as potential biomarkers for nickel tolerance in this species. These results clearly suggest a positive transcriptomic response of the fungus to nickel-rich environments. The presence of both nickel-tolerant and nickel-sensitive fungal phenotypes in ultramafic soils might reflect environment-dependent phenotypic responses to variations in the effective concentrations of nickel in heterogeneous ultramafic habitats.