Tuber spp. are filamentous ascomycetes which establish symbiosis with the roots of trees and shrub species. By virtue of this symbiosis they produce hypogeous ascocarps, known as truffles. Filamentous ascomycetes can reproduce by homothallism or heterothallism depending on the structure and organization of their mating type locus. The first mating type locus in a truffle species has been recently characterized in Tuber melanosporum and it has been shown that this fungus, endemic in Europe, is heterothallic. The availability of sequence information for T. melanosporum mating type genes is seminal to cloning their orthologs from other Tuber species and assessing their reproductive mode. Here we report on the organization of the mating type region in T. indicum, the black truffle species present in Asia, which is the closest relative to T. melanosporum and is characterized by an high level of morphological and genetic variability. The present study shows that T. indicum is also heterothallic. Examination of Asiatic black truffles belonging to different genetic classes, sorted according to the sequence polymorphism of the internal transcribed spacer rDNA region, has revealed sequence variations and rearrangements in both coding and non-coding regions of the mating type locus, to suggest the existence of cryptic species within the T. indicum complex. The presence of transposable elements within or linked to the mating type region suggests a role of these elements in generating the genotypic diversity present among T. indicum strains. Overall, comparative analyses of the mating type locus have thus allowed us to tackle taxonomical and phylogenetic issues within black truffles and make inferences about the evolution of T. melanosporum-T. indicum lineage. Our results are not only of fundamental but also of applied relevance as T. indicum produces edible fruit bodies that are imported also into Europe and thus may represent a biological threat for T. melanosporum.

Crocus sativus is an important crop for the production of saffron and bioactive compounds. Plant endophytic fungi are a source of secondary metabolites additional to those produced by the plant itself. We analysed the biodiversity of endophytic fungi present in corms, stems, leaves, tepals, and stigmas of C. sativus from ten Italian sites; furthermore, we isolated putative pathogenic fungi from rotten plants. We used an in vitro isolation approach followed by molecular analysis of the internal transcribed spacer (ITS rDNA) region. We obtained 165 strains belonging to 39 OTUs, spreading over 26 genera and 29 species. Dark septate endophytes of the genus Cadophora and the species Talaromyces pinophilus dominated in corms, while Alternaria alternata, Epicoccum spp., T. pinophilus, Mucor fragilis, and Stemphylium vesicarium dominated in other tissues. The most frequently isolated pathogens were Fusarium oxysporum and Rhizopus oryzae. Endophytic communities significantly differed among tissues and life stages, whereas differences among cultivation sites were not statistically supported. Several endophytes were hypothesized to have changing trophic modes and/or to be latent pathogens in C. sativus. All strains were conserved ex-situ for future bioactivity tests and production of metabolites.

The ectomycorrhizal fungus Tuber magnatum produces the white truffle appreciated worldwide for its unique aroma. With respect to other Tuber spp. of economic interest, T. magnatum presents a narrower geographical range. This species has, in fact, long been considered endemic to Italy. However, over the last few decades several reports have documented the presence of white truffles in different Mediterranean countries and in particular in various areas of south-east Europe. In this study, samples from several Pannonian and Balkan countries such as Hungary, Serbia, Romania, Bulgaria and Greece have been collected and genotyped with microsatellite markers and the data merged with those available for Italian populations. Our objectives were to test whether Italian and south-east European populations are differentiated and to evaluate the genetic diversity of T. magnatum all over its distributional range. We show the genetic structure of T. magnatum populations with the differentiation of four main groups: northern Italy, central-northern Italy, southern Italy and the Balkan/Pannonian region. The present study allowed us to refine the evolutionary history of T. magnatum and track the possible post-glacial expansion route of this species. The assessment of T. magnatum’s genetic structure is not only of scientific relevance, but it is also important for the conservation and market traceability of this prestigious fungus.

Ectomycorrhizal ascomycetes belonging to the genus Tuber produce edible fruiting bodies known as truffles. Tuber aestivum, in particular, is a fungus appreciated worldwide and has a natural distribution throughout Europe. Most of the molecular studies conducted on this species have been focused on the question as to whether or not T. aestivum and the morphologically similar T. uncinatum are conspecific. Conversely, only a handful of studies have assessed the level and distribution of genetic diversity and occurrence of phylogeographic patterns in this species. Here, we analyzed the genetic diversity of T. aestivum over a wide geographic range, performing an extensive sampling of specimens from Turkey, which is novel, to the best of our knowledge. We compared the internal transcribed spacer (ITS) profiles of 45 samples collected in different Turkish areas with those of 144 samples from all over Europe. We identified 63 haplotypes, 32 of which were exclusively present in Turkey. The majority of these haplotyes were also population specific. Haplotype network analysis and statistical tests highlighted the presence of a genetic structure and phylogeographic pattern, with three spatially distinct genetic clusters (northeastern Europe, southern Europe, and Turkey), with Turkey representing a diversity hotspot. Based on these results, we hypothesize the presence of glacial refugia for T. aestivum in Turkey, whereas European populations likely experienced a population bottleneck. The possible occurrence of cryptic species among Turkish T. aestivum samples also emerged. Our results are of practical relevance for the marketing of T. aestivum truffles and mycorrhizal seedlings and the preservation of the biodiversity of this species.