A. Mello - Academia.edu (original) (raw)

Papers by A. Mello

Purpose: Madagascar is worldwide recognized as one of the top biodiversity hotspots. Our purpose ... more Purpose: Madagascar is worldwide recognized as one of the top biodiversity hotspots. Our purpose was to investigate a fungal species found in Madagascar as a sclerotial mass. Methods: A fungal sample consisting of a sclerotium was collected on a Raphia farinifera log in Antsohihy (North Madagascar) and sent to our lab for characterization. Morphological and molecular analyses were carried out and small pieces of sclerotium tissue were inoculated in agar in order to isolate mycelium. Results: light and scanning electron microscope observations of the sclerotium revealed a carpet of thick-walled hyphae whereas light microscope observations of mycelium showed nematode-trapping structures. The nrITS sequence obtained from the sclerotium was compared with the GeneBank database showing high similarity with Pleurotus tuber-regium . A phylogenetic analysis clearly revealed two clades in this species: one of mainly African origin, the other one of Asian and Australasian origin. Whether these...

FEMS Microbiology Ecology, 2010

Truffles are hypogeous ectomycorrhizal fungi. They belong to the genus Tuber and are currently co... more Truffles are hypogeous ectomycorrhizal fungi. They belong to the genus Tuber and are currently considered a hot spot in fungal biology due to their ecological and economic relevance. Among all the species, Tuber magnatum is the most appreciated because of its special taste and aroma. The aim of this work was to set up a protocol to detect T. magnatum in soil and to assess its distribution in a natural truffle-ground. We used the b-tubulin gene as a marker to identify T. magnatum in the soil. This gene allowed us to trace the distribution of the fungus over the entire truffle-ground. Tuber magnatum was found, in one case, 100 m from the productive host plant. This study highlights that T. magnatum mycelium is more widespread than can be inferred from the distribution of truffles and ectomycorrhizas. Interestingly, a new haplotype-never described from fruiting body material-was identified. The specific detection of T. magnatum in the soil will allow to unravel the ecology of this fungus, following its mycelial network. Moreover, this new tool may have practical importance in projects aimed to increase large-scale truffle production, checking for T. magnatum persistence in plantations.

In order to link microbial community composition to ecological processes happening in the brule, ... more In order to link microbial community composition to ecological processes happening in the brule, a metaproteomics analysis was applied to a brule previously characterized by metagenomics. The metagenomics data had showed a reduced fungal biodiversity, a dominance of Tuber melanosporum and a reduced presence both of ectomycorrhizal Basidiomycota and of bacteria belonged to Pseudomon as and Flavobacteriaceae inside the brule. By metaproteomics analysis, the identified proteins revealed which biological processes were more represented or only present in the brule, and, among them, processes related to multiple stresses were identified in herbaceous plants. This study demonstrates that combining the data of metagenomics and metaproteomics gives the opportunity to potentially reveal the functioning of any environment.

iForest - Biogeosciences and Forestry, 2016

Biogeosciences and Forestry Biogeosciences and Forestry Arbuscular mycorrhizal colonization in bl... more Biogeosciences and Forestry Biogeosciences and Forestry Arbuscular mycorrhizal colonization in black poplar roots after defoliation by a non-native and a native insect Elisa Zampieri (1) , Edoardo Petrucco Toffolo (2) , Antonietta Mello (3) , Achille Giorcelli (4) , Massimo Faccoli (2) , Raffaella Balestrini (3) , Paolo Gonthier (1) A major goal in ecology is to understand how interactions among organisms influence ecosystem services. This work compares the effects of two Lepidoptera defoliators, one non-native (Hyphantria cunea) and one native (Lymantria dispar) to Europe, on the colonization of black poplar (the Populus nigra clone "Jean Pourtet") roots by an arbuscular mycorrhizal (AM) symbiotic fungus (Funneliformis mosseae) in a pot experiment. The effects of defoliation have also been assessed on the expression of fungal and plant genes playing a role during symbiosis. Both control and defoliated poplars have shown a low level of mycorrhization. Additionally, neither the non-native nor the native insect seem to strongly affect the AM colonization, at least at the time of observation (eight days from the end of the defoliation). Concerning the gene expression analysis, our results suggest that defoliation does not influence neither the expression of genes coding for a fungal and a plant phosphate transporter nor that of a gene coding for a fungal ATPase, and that there were no differences between defoliation carried out by the non-native and the native insect.

Current Genetics, 2014

Questa è la versione dell'autore dell'opera: [Gene expression and metabolite changes during Tuber... more Questa è la versione dell'autore dell'opera: [Gene expression and metabolite changes during Tuber magnatum fruiting body storage,

Diversity, 2013

Identifying a soil core microbiome is crucial to appreciate the established microbial consortium,... more Identifying a soil core microbiome is crucial to appreciate the established microbial consortium, which is not usually subjected to change and, hence, possibly resistant/resilient to disturbances and a varying soil context. Fungi are a major part of soil biodiversity, yet the mechanisms driving their large-scale ecological ranges and distribution are poorly understood. The degree of fungal community overlap among 16 soil samples from distinct ecosystems and distant geographic localities (truffle grounds, a Mediterranean agro-silvo-pastoral system, serpentine substrates and a contaminated industrial area) was assessed by examining the distribution of fungal ITS1 and ITS2 sequences in a dataset of 454 libraries. ITS1 and ITS2 sequences were assigned to 1,660 and 1,393 Operational

Mycologia, 2011

In a recent study pyrosequencing of the ribosomal internal transcribed spacer-1 (ITS-1) has valid... more In a recent study pyrosequencing of the ribosomal internal transcribed spacer-1 (ITS-1) has validated the effectiveness of such technology in the survey of soil fungal diversity. Here we compare the two ITS regions, ITS-1 and ITS-2, of the fungal populations occurring in Tuber melanosporum/Quercus pubescens truffle grounds and sampled in two areas, one devoid of vegetation (''burned'', brulé in French) where T. melanosporum fruiting bodies are usually collected, and outside the brulé. TS1F/ITS2 and ITS3/ITS4 were used respectively for the amplification of the ITS-1 and ITS-2 regions. Two amplicon libraries were built, one for inside and the other for outside. A set of 15.788 reads was obtained. After the removal of low quality sequences, 3568 and 3156 sequences were obtained from inside the brulé with the ITS-1 and ITS-2 primers respectively. The sequences obtained from outside the brulé were 4490 with the ITS-1 primers and 2432 with the ITS-2 primers. Most of the sequences obtained for both ITS fragments could be attributed to fungal organisms. The pair of primers, ITS1-F/ITS2, was more selective, producing fewer non-fungal sequences (1% inside, 3% outside), in addition to a higher number of sequences, than the pair ITS3/ITS4 (6% inside, 11% outside). Although differences are present in the taxa percentages between ITS-1 and ITS-2, both reveal that Ascomycota were the dominant fungal phylum and that their number decreased moving from inside the brulé to outside, while the number of Basidiomycota increased. Taken together, both the short ITS-1 and ITS-2 reads obtained by the high throughput 454 sequencing provide adequate information for taxon assignment and are suitable to correlate the dynamics of the fungal populations to specific environments.

FEMS Microbiology Letters, 2009

Truffles are hypogeous Ascomycete fungi belonging to the genus Tuber and forming fruiting bodies ... more Truffles are hypogeous Ascomycete fungi belonging to the genus Tuber and forming fruiting bodies highly prized for their taste and aroma. The identification of the genus Tuber and its species is important to investigate their ecology and avoid fraud in the food market. As genus-specific primers are not available, the aims of this work were (1) to assess the usefulness of the b-tubulin gene as a DNA barcoding region for designing Tuber genus-specific primers, (2) to test the primers on a range of fruiting bodies, representing a large part of truffle biodiversity and (3) to check their ecological usefulness, applying them to truffleground soil. The new primers designed on the b-tubulin gene were specific to the Tuber genus in nested PCR. When applied to DNA from soils, they gave a positive signal for 23 of 32 soils. Phylogenetic analysis confirmed that the bands corresponded to Tuber and that at least five Tuber species were present in the truffle-ground. b-tubulin was found to be a good barcoding region for designing Tuber genus-specific primers, detecting a high Tuber diversity in a natural environment. These primers will be useful for understanding truffle ecology and for practical needs in plantation management.

Environmental Microbiology, 2005

The aim of this work was to clarify the genetic structure of the ectomycorrhizal fungus, Tuber ma... more The aim of this work was to clarify the genetic structure of the ectomycorrhizal fungus, Tuber magnatum Pico, in a natural truffle ground located in north Italy. Ascomata of this population of T. magnatum were collected over a period of up to 5 years. For comparative analysis, T. magnatum fruit bodies of different geographical origin were also considered. We used single locus markers, such as the variable region of ribosomal genes (ITS), the beta-tubulin gene and sequence-characterized amplified regions (SCAR), as tools to identify single-nucleotide polymorphisms (SNPs). On the basis of the molecular results, which were indirectly supported by a karyological analysis, a self-fertilization mechanism is suggested. A SCAR region was polymorphic within the samples of the truffle ground, leading to the identification of two genotypes. In addition, both the SCAR and the ITS proved to be polymorphic among samples coming from different geographical regions, revealing a genetic differentiation in T. magnatum.

New Phytologist, 2009

 • The fruiting bodies of the ectomycorrhizal (ECM) fungus Tuber melanosporum are usually collec... more  • The fruiting bodies of the ectomycorrhizal (ECM) fungus Tuber melanosporum are usually collected in an area devoid of vegetation which is defined as a 'burnt area' (brulé in French).  • Here, the soil fungal populations of inside and outside brulé were compared in order to understand whether the scanty plant cover was related to a change in fungal biodiversity. Both denaturing gradient gel electrophoresis (DGGE) and molecular cloning of the internal transcribed spacer (ITS) marker were employed on soil DNA to obtain profiles from nine truffle grounds and fungal sequences from one selected truffle ground sampled in two years.  • Denaturant gradient gel electrophoresis profiles from the two areas formed two distinct clusters while molecular cloning allowed 417 fungal sequences to be identified. T. melanosporum was the dominant fungus within the brulé. There were nine new haplotypes, which had never been detected in fruiting bodies. The Basidiomycota ECM fungi decreased within the brulé, indicating a competitive effect of T. melanosporum on the other ECM fungi.  • Among other factors, the dynamics of fungal populations seems to be correlated to brulé formation. 2006). T. melanosporum grows in symbiosis with several oak species and hazelnut trees in Mediterranean conditions, in France, Italy and the Iberian Peninsula (Ceruti et al., 2003). Truffle plantations have, however, been introduced in New Zealand, Australia, Israel and North America (Bonet et al., 2006). The development of mycorrhizal symbiosis in some Tuber species is associated with the production of a burnt area (commonly referred to by the French word brulé) around their symbiotic plants. This brulé is usually circular, characterized by scanty vegetation and typical of T. melanosporum and T. aestivum (Pacioni, 1991). Explanations for the formation of the brulé have been proposed. Plattner & Hall (1995) hypothesized parasitism of the Tuber spp. on the nonhost herbaceous plants, whereas Delmas (1983) thought that Tuber ectomycorrhizas may compete for nutrients or water. A phytotoxic effect by truffle metabolites was highlighted by Pacioni (1991) and Lanza et al. (2004). Recently, Splivallo et al. (2007) showed that truffle volatiles inhibit growth and induce an oxidative burst in Arabidopsis thaliana, indicating that fungal volatiles are molecules that can mediate fungal-plant interactions, at least in in vitro conditions. However, the mechanisms are still unknown, as is its ecological meaning. To our knowledge, only two studies, limited to cultivable fungi, have tested the hypothesis that the presence of Tuber spp. could affect fungal biodiversity (Luppi-Mosca, 1972; Luppi & Fontana, 1977). On the basis of this knowledge, we have focused attention on the fungal composition in the brulé associated with T. melanosporum, where the fruiting bodies of this species are usually collected in late autumn and winter.

iForest - Biogeosciences and Forestry, 2017

Invasive fungal pathogens and pests of sweet chestnut (Castanea sativa Mill.) forests drastically... more Invasive fungal pathogens and pests of sweet chestnut (Castanea sativa Mill.) forests drastically reduce their productivity. The recently described Gnomoniopsis castaneae is one of the main agents involved in the epidemic of brown rot of chestnut nuts worldwide. In 2014, during an investigation aimed at evaluating the health status of chestnut forests in Sardinia, a high incidence of necrotic galls induced by the Asian gall wasp Dryocosmus kuriphilus Yasumatsu (Hymenoptera, Cynipidae) was observed. Several fungal isolates were consistently isolated from necrotic gall tissues. Based on their morphological characters and analyses of both the ITS and EF1-α-coding gene sequences, all isolates were identified as Gnomoniopsis castaneae.

Plant Microbes Symbiosis: Applied Facets, 2014

Ectomycorrhizal (ECM) fungi form association with relatively small number of plants that dominate... more Ectomycorrhizal (ECM) fungi form association with relatively small number of plants that dominate boreal, temperate, Mediterranean, and some subtropical forest ecosystems. These plant species have been able to acquire metabolic capabilities through symbioses with ECM fungi, thus improving their mineral nutrition and growth in several ecological niches. Mycorrhizal fungi can also play several other important ecological roles, including the protection of plants from abiotic and biotic stresses. Several "targeted" metagenomic projects have been carried out, or are now in progress, in order to identify the fungal communities in soil, including ECM fungi, which are present in various habitats (e.g., forest and truffl eground soils, etc.). ECM fungi, which are important both because of their economic value as edible fungi (i.e., truffl es, boletes) and because of their application in reforestation projects, are the subject of this chapter, in which the recent advances in ECM fungal communities are reviewed, focusing mainly on the applicative aspects related to the use of these fungi.

Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 2013

Mycorrhiza, 1996

DNA analyses were developed to type mycorrhizas of two Tuber species of commercial value (T. mela... more DNA analyses were developed to type mycorrhizas of two Tuber species of commercial value (T. melanosporum, T. borchii) and a competitive fungus (Sphaerosporella brunnea) which forms ectomycorrhizas with plants usually considered hosts for truffles. Polymerase chain reaction (PCR) amplification of DNA isolated from fruitbodies, mycelia, mycorrhizas and leaves of host plants, was performed with a primer pair for an internal transcribed spacer ITS1-4. ITS amplification followed by restriction fragment length polymorphism (RFLP) analysis of the amplified products clearly distinguished the two Tuber species at the fruitbody, mycorrhiza and mycelium levels.

Mycologia, 2000

Two similar truffle species described by Vittadini, Tuber borchii and T. maculatum, were compared... more Two similar truffle species described by Vittadini, Tuber borchii and T. maculatum, were compared. We designate neotypes for both species, which were described microscopically and compared with fresh samples both morphologically and by DNA analysis. The results show that the collections, originally described by Vittadini on macroscopic characters and taste and smell, indeed represent distinct species that can be differentiated by peridial anatomy and DNA analysis.

FEMS Microbiology Letters, 2006

Truffles are hypogeous fungi which live in symbiosis with plant host roots in order to accomplish... more Truffles are hypogeous fungi which live in symbiosis with plant host roots in order to accomplish their life cycle. Some species, such as Tuber magnatum Pico, the 'white truffle' , and Tuber melanosporum Vittad., the 'black truffle' , are highly appreciated in many countries because of their special taste and smell. The great demand for the black and white truffles, the increasing attention towards other species of local interest for the rural economy (such as T. aestivum) together with a drop in productivity, have stimulated researchers to develop projects for a better understanding of the ecology of truffles by exploiting the new approaches of environmental microbiology and molecular ecology. Specific primers have been developed to identify many morphologically similar species, the distribution of T. magnatum has been followed in a selected truffle-ground, the phylogeography of T. melanosporum and T. magnatum has been traced, and the microorganisms associated with the truffles and their habitats have been identified.

Environmental Microbiology, 2002

RENDICONTI LINCEI, 2008

The word Rhizosphere describes the part of the soil which is immediately adjacent to and affected... more The word Rhizosphere describes the part of the soil which is immediately adjacent to and affected by plant roots. This is a very dynamic environment where plants, soil and microorganisms interact. The plant releases, in addition to biologically active substances, nutritive substances (exudates), which create a privileged habitat for many microbial populations. The same microbes that live in the rhizosphere