Bacterial and fungal communities associated with Tuber magnatum‐productive niches

Abstract

Truffles are hypogeous ectomycorrhizal fungi of ecological interest for forestry in soils of the northern hemisphere, and of economical relevance for food markets worldwide. The molecular mechanisms that control truffle body formation are largely unknown, as well as the environmental factors that are likely involved. Among the latter, it has been hypothesized that soil‐borne communities may have an impact on truffle production. To address this question, we investigated bacterial and fungal communities resident in productive versus adjacent non‐productive grounds of the white truffle Tuber magnatum by using PCR‐DGGE. Although bacterial communities were generally highly similar across all samples within the grounds, profiles did cluster according to the productivity of circumscribed niches, and a Moraxella osloensis population appeared to be associated with productive sites. Fungal communities revealed several populations, yet showed no obvious patterns in relation to productivity, although Mortierella and Fusarium oxysporum appeared to be more abundant in the productive area. Our results offer a first glimpse into microbial communities thriving in truffle productive niches, and open the question as to whether microbe‐mediated mechanisms may facilitate/inhibit truffle fruiting‐body production or, vice versa, i.e. whether truffle sporocarps have an impact on the microbes living in the rhizosphere.     

Isolation of a trans-acting factor involved in localization of Paracentrotus lividus maternal mRNAs

Localization of Paracentrotus lividus bep maternal mRNAs at the animal pole occurs by association with the cytoskeleton and involves a 54-kDa protein, called LP54, that is able to bind to the 3' untranslated regions (UTRs) of bep mRNAs. We describe here the isolation and purification of this protein. Antibodies raised against purified LP54 allowed us to establish its localization in P. lividus eggs and embryos. This localization coincides with the mRNAs with which it is associated, that is, the animal pole in the egg, and, after fertilization, the regions derived from this part of the egg, and finally the oral ectoderm of the pluteus. Association with the cytoskeleton was shown by the copurification of LP54 in a microtubule preparation. Involvement in bep mRNA localization was demonstrated by microinjection of anti-LP54 antibodies in P. lividus eggs, which caused alteration of spatial distribution of bep3 mRNA.     

Inflamed adult pharynx tissues and swimming larva of Ciona intestinalis share CiTNFα-producing cells

In situ hybridisation and immunohistochemistry analyses have shown that the Ciona intestinalis tumour necrosis factor alpha gene (CiTNFα), which has been previously cloned and sequenced, is expressed either during the inflammatory pharynx response to lipopolysaccharide (LPS) or during the swimming larval phase of development. Granulocytes with large granules and compartment/morula cells are CiTNFα-producing cells in both inflamed pharynx and larvae. Pharynx vessel endothelium also takes part in the inflammatory response. Haemocyte nodules in the vessel lumen or associated with the endothelium suggest the involvement of CiTNFα in recruiting lymphocyte-like cells and promoting the differentiation of inflammatory haemocytes. Specific antibodies against a CiTNFα peptide have identified a 43-kDa cell-bound form of the protein. Observations of pharynx histological sections (at 4 and 8 h post-LPS inoculation) from naive and medium-inoculated ascidians have confirmed the CiTNFα-positive tissue response. Larval histological sections and whole-mount preparations have revealed that CiTNFα is expressed by trunk mesenchyme, preoral lobe and tunic cells, indicating CiTNFα-expressing cell immigration events and an ontogenetic role.     

Molecular validation of Sarcodon quercinofibulatus, a species of the S. imbricatus complex associated with Fagaceae, and notes on Sarcodon

Morphological and molecular phylogenetic analyses revealed that Italian and Mexican collections of an unknown Sarcodon species of the S. imbricatus complex associated with Fagaceae (Castanea and Quercus), were assignable to Sarcodon quercinofibulatus, a species recently described from Spain. The species, characterized by a light brown-hazelnut coloured pileus surface eventually breaking into large and coarse scales, was recognized as independent from Sarcodon imbricatus and S. squamosus. S. aspratus, usually synonymized with S. imbricatus, is a different species. S. squamosus collections from montane and Mediterranean pine woodlands were shown to be conspecific. Four sections of Sarcodon (Sarcodon, Violacei, Squamiceps and Scabrosi) established by Maas Geesteranus (Verh K ned Akad Wet III, 65: 1–127, 1975) only on morphological basis, are here confirmed as monophyletic.     

A new taxon in the Infundibulicybe gibba complex (Basidiomycota, Agaricales, Tricholomataceae) from Sardinia (Italy)

A new species of Infundibulicybe (viz. I. mediterranea sp. nov.) is described from Sardinia based both on morphological and molecular ITS data. The species, a close ally of I. gibba, differs from the latter in the darker tinges of the basidiomata, the stipe, which is nearly concolorous with the pileus, and smaller basidiospores. Drawings of the main micro-morphological features as well as a color photograph of fresh basidiomata in situ are provided.     

Paxillus orientalis sp. nov. (Paxillaceae,Boletales) from south-western China based on morphological and molecular data and proposal of the new subgenus Alnopaxillus

The new species Paxillus orientalis is reported from Yunnan Province (south-western China). Based on morphological and molecular characters the novel taxon belongs to the sibling, holarctic alder-associated P. rubicundulus complex. Colour pictures of fresh basidiomes and line drawings are provided, accompanied by notes concerning its taxonomic and phylogenetic relationships within the genus. The new subgenus Alnopaxillus is established to accommodate P. rubicundulus and allied undescribed taxa characterized by basidiomes usually associated with Alnus and with a distinctly areolate–squamulose pileal surface.     

Alien fungal species distribution: the study case of Favolaschia calocera

Invasive organisms (especially plants and animal species) are considered to be one of the main causes of global biodiversity loss. Up to now, few papers have dealt with the spreading of fungi. The establishment of the geographic origin of alien organisms could be useful to assess their impact on the environment. Favolaschia calocera is a basidiomycete species which was first described from Madagascar, and successively observed in New Zealand in 1969, where it has currently been recorded in more than 200 stands. It has recently also been reported in Australia, Thailand, China, Kenya, and Reunion Island. F. calocera was found in Genoa, Italy, in 1999: this recording represented the first in Europe. Till now, Favolaschia specimens have been collected in six areas around Genoa. F. calocera was observed growing on debris of various vascular plant species (Pteridophytes, Conifers, Mono- and Dicotyledons), thus showing to be a polyphagous species. Because it is spreading, it needs to be monitored. The main goal of our research is to investigate, through molecular phylogeographic analysis, the origin of the Italian strains. The sequencing of the ribosomal DNA ITS region of the Italian specimens followed by Neighbour-joining analysis showed that they cluster with the specimens from New Zealand, Kenya, Norfolk Island and Réunion Island. Hypotheses on the origin and introduction way as well as on its mechanisms of spreading are provided.     

Enhanced expression of a cloned and sequenced Ciona intestinalis TNFα-like (CiTNFα) gene during the LPS-induced inflammatory response

A tumor necrosis factor-alpha (TNFα)-like gene from Ciona intestinalis (CiTNFα-like) body wall challenged with bacterial lipopolysaccharide (LPS) was cloned and sequenced 4 h after LPS inoculation. An open reading frame of 936 bp encoding a propeptide of 312 amino acids (35.4 kDa) displaying a transmembrane domain from positions 7 to 29, a TACE cleavage site, and a mature peptide domain of 185 amino acids (20.9 kDa), was determined with a predicted isoelectric point of 9.4. The phylogenetic tree based on deduced amino acid sequences of invertebrate TNF-like protein and vertebrate TNFs supported the divergence between the ascidian and vertebrate TNF families, whereas D. melanogaster Eiger A and B TNF-like sequences were distinctly separated from the chordate TNFs. Thus, the ascidian TNFα-like cytokine was upregulated by in vivo LPS challenge supporting its pro-inflammatory role. In the pharynx, increased expression levels were found following analysis by real-time polymerase chain reaction, whereas in situ hybridization assay showed positive hemocytes both in the tissue and in circulating hemocytes. Finally, Western blot with monoclonal antibodies disclosed human TNFα epitopes in a 15-kDa protein component of the hemolymph serum and in a 43-kDa protein contained in the hemocyte lysate supernatant prepared in the presence of detergents. Both soluble and hemocyte-bound CiTNFα-like protein therefore appeared to be modulated by the LPS challenge. This work was supported by a research grant from the Italian Ministry of University and Scientific Research (PRIN 2006 to N. Parrinello), co-funded by the University of Palermo.     

Crinipellis pedemontana sp. nov. (Agaricomycetes), a new basidiomycete from Italy

Crinipellis pedemontana, a new agaric growing on stems of dead grasses in an Italian urban park, is described and illustrated. It fits in sect. Grisentinae on account of the green reaction with KOH and ammonia and its bright colored pileus. The unique combination of purple-violaceous tinges in the pileus and the presence of chlamydospores in the pileipellis characterize this species as new. Its taxonomic position within Crinipellis and the related genus Moniliophthora is discussed.