RNA interference and nonviral targeted gene therapy of experimental brain cancer

According to isotopic labeling experiments, most of the carbon used by truffle (Tuber sp.) fruiting bodies to develop underground is provided by host trees, suggesting that trees and truffles are physically connected. However, such physical link between trees and truffle fruiting bodies has never been observed.We discovered fruiting bodies of Tuber aestivum adhering to the walls of a belowground quarry and we took advantage of this unique situation to analyze the physical structure that supported these fruiting bodies in the open air. Observation of transversal sections of the attachment structure indicated that it was organized in ducts made of gleba-like tissue and connected to a network of hyphae traveling across soil particles.Only one mating type was detected by PCR in the gleba and in the attachment structure, suggesting that these two organs are from maternal origin, leaving open the question of the location of the opposite paternal mating type

Two ectomycorrhizal truffles, Tuber melanosporum and T. aestivum , endophytically colonise roots of non‐ectomycorrhizal plants in natural environments

International audienceSerendipitous findings and studies on Tuber species suggest that some ectomycorrhizal fungi, beyond their complex interaction with ectomycorrhizal hosts, also colonise roots of nonectomycorrhizal plants in a loose way called endophytism. Here, we investigate endophytism of T. melanosporum and T. aestivum . We visualised endophytic T. melanosporum hyphae by fluorescent in situ hybridisation on nonectomycorrhizal plants. For the two Tuber species, microsatellite genotyping investigated the endophytic presence of the individuals whose mating produced nearby ascocarps. We quantified the expression of four T. aestivum genes in roots of endophyted, non‐ectomycorrhizal plants. Tuber melanosporum hyphae colonised the apoplast of healthy roots, confirming endophytism. Endophytic Tuber melanosporum and T. aestivum contributed to nearby ascocarps, but only as maternal parents (forming the flesh). Paternal individuals (giving only genes found in meiotic spores of ascocarps) were not detected. Gene expression of T. aestivum in non‐ectomycorrhizal plants confirmed a living status. Tuber species, and likely other ectomycorrhizal fungi found in nonectomycorrhizal plant roots in this study, can be root endophytes. This is relevant for the ecology (brûlé formation) and commercial production of truffles. Evolutionarily speaking, endophytism may be an ancestral trait in some ectomycorrhizal fungi that evolved from root endophytes

Five years of research revealed the Périgord black truffle (Tuber melanosporum Vittad.) sexual reproduction strategy

International audienc

Comparative genomics and population genetics provide new insights on the life cycle of the black truffle of Périgord (Tuber melanosporum Vittad.)

International audienceTruffles are ectomycorrhizal fungi living in symbiosis with many trees and shrubs. Inoculated seedlings with truffles are available since forty years and the interest in truffle cultivation is increasing worldwide. However, novel management guidelines for sustainable truffle orchards, in which the production is less unpredictable even in the climate change context, are needed. A better understanding of the biological and ecological mechanisms driving the truffle life cycle is one of the approaches to reach these goals. The genomic resources available for Tuber melanosporum allowed us to unravel its sexual reproduction mode by identifying mating type genes and to characterize new polymorphic markers allowing population genetics analyses. The study of genet distribution in truffle orchards showed a non-random spatial distribution of ectomycorrhizas formed by both T. melanosporum mating types, as well as a rapid yearly turnover of these genets. This analysis revealed a striking competition between genets based on their mating-type genes to colonize plant root system and questioned the localization of both parents in the initiation of the sexual cycle. To gain additional information on T. melanosporum genetic diversity, we re-sequenced the nuclear genome of six geographic accessions. A total of 442,326 single nucleotide polymorphisms (SNPs) corresponding to 3,540 SNPs/Mbps were identified. Based on their SNP density, samples clustered according to their geographic origin and the putative role of the last glaciation in T. melanosporum phylogeography is confirmed. Additionally, genomic regions and genes potentially subjected to positive or purifying selection were identified. Finally, a large-scale analysis of T. melanosporum populations at European scale using highly polymorphic simple sequence repeats (SSR) is also in progress

Comparative genomics and population genetics provide new insights on the life cycle of the black truffle of Périgord (Tuber melanosporum Vittad.)

International audienceTruffles are ectomycorrhizal fungi living in symbiosis with many trees and shrubs. Inoculated seedlings with truffles are available since forty years and the interest in truffle cultivation is increasing worldwide. However, novel management guidelines for sustainable truffle orchards, in which the production is less unpredictable even in the climate change context, are needed. A better understanding of the biological and ecological mechanisms driving the truffle life cycle is one of the approaches to reach these goals. The genomic resources available for Tuber melanosporum allowed us to unravel its sexual reproduction mode by identifying mating type genes and to characterize new polymorphic markers allowing population genetics analyses. The study of genet distribution in truffle orchards showed a non-random spatial distribution of ectomycorrhizas formed by both T. melanosporum mating types, as well as a rapid yearly turnover of these genets. This analysis revealed a striking competition between genets based on their mating-type genes to colonize plant root system and questioned the localization of both parents in the initiation of the sexual cycle. To gain additional information on T. melanosporum genetic diversity, we re-sequenced the nuclear genome of six geographic accessions. A total of 442,326 single nucleotide polymorphisms (SNPs) corresponding to 3,540 SNPs/Mbps were identified. Based on their SNP density, samples clustered according to their geographic origin and the putative role of the last glaciation in T. melanosporum phylogeography is confirmed. Additionally, genomic regions and genes potentially subjected to positive or purifying selection were identified. Finally, a large-scale analysis of T. melanosporum populations at European scale using highly polymorphic simple sequence repeats (SSR) is also in progress

Five years investigation of female and male genotypes in périgord black truffle (Tuber melanosporum Vittad.) revealed contrasted reproduction strategies

The Périgord black truffle (Tuber melanosporum Vittad.) is a heterothallic ascomycete that establishes ectomycorrhizal symbiosis with trees and shrubs. Small-scale genetic structures of female genotypes in truffle orchards are known, but it has not yet been studied in male genotypes. In this study, our aim was to characterize the small-scale genetic structure of both male and female genotypes over five years in an orchard to better understand the T. melanosporum sexual reproduction strategy, male genotype dynamics, and origins. Two-hundred forty-one ascocarps, 475 ectomycorrhizas, and 20 soil cores were harvested and genotyped using microsatellites and mating type genes. Isolation by distance analysis revealed pronounced small-scale genetic structures for both female and male genotypes. The genotypic diversity was higher for male than female genotypes with numerous small size genotypes suggesting an important turnover due to ascospore recruitment. Larger and perennial female and male genotypes were also detected. Only three genotypes (1.5%) were found as both female and male genotypes (hermaphrodites) while most were detected only as female or male genotype (dioecy). Our results suggest that germinating ascospores act as male genotypes, but we also proposed that soil mycelium could be a reservoir of male genotypes

Le trufficulteur : Un trait d’union indispensable entre trufficulteurs et scientifiques

Prod 2017-339 équipe SPE IPM UBNational audienc

Report of the Task Force on the Incident of 19th September 2008 at the LHC

This report summarizes the findings and recommendations of the AT department Task Force established to investigate the 19th September 2008 incident which occurred in sector 3-4 of the LHC. It includes a number of annexes where specific analyses are detailed