The weekly seminar will be given by Sophie Mieszkin (IAM) next Friday at 1.30 pm . Sophie will present the results of her work during her last post-doc.
7th of octobre, 1.30pm (conference room INRA): Sophie Mieszkin (IAM)
“Action mechanisms involved in the bioprotective effect of Lactobacillus harbinensis K.V9.3.1.Np against Yarrowia lipolytica in yogurt“
Root-endophytic fungi cause morphological and functional differences in Scots pine roots in contrast to ectomycorrhizal fungi. J Heinonsalo, M Buée, LM Vaario. Botany
Endophytic fungi and ectomycorrhizal fungi co-exist in the mycorrhizal root tips of boreal forest trees. However, very little is known about the functional role they play in their host’s biology. The activity of enzymes responsible for important biochemical processes is used to unravel the functional role of root-associated mycorrhizal fungi. However, enzyme activity is never studied in the presence of endophytic fungi in planta. The aims of the present study were to investigate the effect of Scots pine root-isolated fungal endophytes on the host plant root morphology, to determine their functional effect using host root-excreted enzyme activity measurements and to compare them to roots colonized by decomposer and ectomycorrhizal fungal strains and non-colonised Scots pine root tips. Our results show that endophytic fungi did not damage the pine roots in contrast to the decomposer fungi. The endophytic fungi penetrated the cortical cells of the host plant. The roots colonised by endophytic fungi produce different exo-enzymes compared to those produced by roots colonized by other fungal groups or non-colonized control root tips. Our results indicate that endophytic fungi are clearly a distinctive ecological group of fungi that have functional traits different from those of ectomycorrhizal and decomposer fungi.
Esther Galbrun, researcher from the Institute of Applied Informatics of Nancy, will visit us next Thursday and give a talk at 1.30pm in the Conference room of INRA Center. Esther is visiting us to build collaborative research with INRA teams. Her research focuses on redescription mining (see abstract below) and it could be applied to many fields of research in which large data sets with multiple variable are used (e.g for IAM: genomics, transcriptomics, metagenomics).
Investigation of the sexual reproduction strategy of the Perigord black truffle (tuber melanosporum Vittad.) revealed trioecy. H De la Varga, F Le Tacon, M Lagoguet, F Todesco, T Varga, I Miquel, …Bio-archive
Fungi display a rich variety of sexual reproduction systems and are therefore good models to investigate sex evolution. Moreover, understanding the investment in sexual reproduction of edible fungi is a critical challenge for improving their cultivation. The Perigord black truffle (Tuber melanosporum Vittad.) is a heterothallic ascomycete associated with trees through ectomycorrhizas and forming highly prized ascocarps. The aim of this study was to unravel the sexual reproduction strategy (hermaphroditic versus male/female specialization) of T. melanosporum in a truffle orchard by disentangling the contribution of female and male genotypes to the formation of ascocarps in a five-year investigation. Few genotypes were hermaphrodites, co-occurring with numerous genotypes behaving only as female or male, revealing trioecy. The genetic diversity of the male genotypes was higher than female diversity, suggesting for male elements a higher recruitment from ascospores. Most of the female and male genotypes were transitory (present only one year), whereas some genotypes persisted for several years: female-fertile genotypes as mycorrhizas, and male-fertile genotypes as soil free-living mycelium. Contrary to other ascomycetes, a high number of female-fertile only genotypes was found. We hypothesized that the mycorrhizal life style favours female-fertile strains and therefore that the life strategy influences fungal sexual strategy.
Global geographic distribution and host range of Dothistroma species: a comprehensive review R Drenkhan, V Tomešová‐Haataja, S Fraser, RE Bradshaw, P Vahalík, … Forest Pathology
Dothistroma needle blight (DNB) is one of the most important diseases of pine. Although its notoriety stems from Southern Hemisphere epidemics in Pinus radiataplantations, the disease has increased in prevalence and severity in areas of the Northern Hemisphere, including Europe, during the last two decades. This increase has largely been attributed to expanded planting of susceptible hosts, anthropogenic dispersal of the causative pathogens and changes in climate conducive to disease development. The last comprehensive review of DNB was published in 2004, with updates on geographic distribution and host species in 2009. Importantly, the recognition that two species, Dothistroma septosporum and D. pini, cause DNB emerged only relatively recently in 2004. These two species are morphologically very similar, and DNA-based techniques are needed to distinguish between them. Consequently, many records of host species affected or geographic location of DNB prior to 2004 are inconclusive or even misleading. The objectives of this review were (i) to provide a new database in which detailed records of DNB from 62 countries are collated; (ii) to chart the current global distribution of D. septosporum and D. pini; (iii) to list all known host species and to consider their susceptibility globally; (iv) to collate the published results of provenance trials; and (v) to consider the effects of site factors on disease incidence and severity. The review shows that DNB occurs in 76 countries, with D. septosporum confirmed to occur in 44 and D. pini in 13. There are now 109 documented Pinaceae host taxa for Dothistroma species, spanning six genera (Abies, Cedrus, Larix, Picea, Pinus and Pseudotsuga), with Pinus being the dominant host genus, accounting for 95 host taxa. The relative susceptibilities of these hosts to Dothistroma species are reported, providing a resource to inform species choice in forest planting. Country records show that most DNB outbreaks in Europe occur on Pinus nigra and its subspecies. It is anticipated that the collaborative work described in this review will both underpin a broader global research strategy to manage DNB in the future and provide a model for the study of other forest pathogens.
Diversity and Structure of Fungal Communities in Neotropical Rainforest Soils: The Effect of Host Recurrence H Schimann, C Bach, J Lengelle, E Louisanna, S Barantal, C Murat, … Microbial Ecology, 1-11
The patterns of the distribution of fungal species and their potential interactions with trees remain understudied in Neotropical rainforests, which harbor more than 16,000 tree species, mostly dominated by endomycorrhizal trees. Our hypothesis was that tree species shape the non-mycorrhizal fungal assemblages in soil and litter and that the diversity of fungal communities in these two compartments is partly dependent on the coverage of trees in the Neotropical rainforest. In French Guiana, a long-term plantation and a natural forest were selected to test this hypothesis. Fungal ITS1 regions were sequenced from soil and litter samples from within the vicinity of tree species. A broad range of fungal taxa was found, with 42 orders and 14 classes. Significant spatial heterogeneity in the fungal communities was found without strong variation in the species richness and evenness among the tree plots. However, tree species shaped the fungal assemblages in the soil and litter, explaining up to 18 % of the variation among the communities in the natural forest. These results demonstrate that vegetation cover has an important effect on the structure of fungal assemblages inhabiting the soil and litter in Amazonian forests, illustrating the relative impact of deterministic processes on fungal community structures in these highly diverse ecosystems.
Ectomycorrhizal ecology is imprinted in the genome of the dominant symbiotic fungus Cenococcum geophilum M Peter, A Kohler, RA Ohm, A Kuo, J Krützmann, E Morin, M Arend, … Nature Communications 7, 12662
The most frequently encountered symbiont on tree roots is the ascomycete Cenococcum geophilum,the only mycorrhizal species within the largest fungal class Dothideomycetes, a class known for devastating plant pathogens. Here we show that the symbiotic genomic idiosyncrasies of ectomycorrhizal basidiomycetes are also present in C. geophilum with symbiosis-induced, taxon-specific genes of unknown function and reduced numbers of plant cell wall-degrading enzymes. C. geophilum still holds a significant set of genes in categories known to be involved in pathogenesis and shows an increased genome size due to transposable elements proliferation. Transcript profiling revealed a striking upregulation of membrane transporters, including aquaporin water channels and sugar transporters, and mycorrhiza-induced small secreted proteins (MiSSPs) in ectomycorrhiza compared with free-living mycelium. The frequency with which this symbiont is found on tree roots and its possible role in water and nutrient transport in symbiosis calls for further studies on mechanisms of host and environmental adaptation.
Improving the design of long-term monitoring experiments in forests: a new method for the assessment of local soil variability by combining infrared spectroscopy and dendrometric data E Akroume, B Zeller, M Buée, P Santenoise, L Saint-André Annals of Forest Science, 1-9
Near- and mid-infrared spectroscopy allows for the detection of local patterns of forest soil properties. In combination with dendrometric data, it may be used as a prospective tool for determining soil heterogeneity before setting up long-term forest monitoring experiments.
Forest soils and stands generally exhibit higher spatial heterogeneity than other terrestrial ecosystems. This variability needs be taken into account before setting up long-term forest monitoring experiments to avoid multiple interactions between local heterogeneity and the factors tested in the experiment.
We hypothesized that raw near- and mid-infrared spectra can be used as an integrated proxy of a large set of soil properties. The use of this method, in combination with dendrometric data, should provide a quick and cost-effective tool for optimizing the design of experimental forest sites.
We assessed the local soil heterogeneity at 11 experimental sites in oak and beech stands, which belong to a new forest long-term ecological research (LTER) network. We used near- and mid-infrared spectroscopy in soil and litter samples. The spectra were subjected to principal components analyses (PCA) to determine the intra-site variability of the soil and litter layers.
Based on mapped PCA coordinates and basic dendrometric data, it was possible to design the experiment and minimize the interactions between the treatment layout and the tested variables. The method was validated with chemical analyses of the soil. No interaction was detected at the set-up of the experiment between the treatment layout and chemical soil properties (C, N, C/N ratio, pH, CEC, Al, Mg, P2O5, Fe, Mn, Na, and K).
Near-infrared (NIR) and mid-infrared (MIR) spectroscopy is a useful tool for characterizing the overall heterogeneity of soil chemical properties. It can be used without any preliminary calibration. In combination with dendrometric data, it provides a reliable method for optimizing LTER plots in different types of ecosystems.
Genetic signatures of a range expansion in natura: when clones play leapfrog R Becheler, C Xhaard, EK Klein, KJ Hayden, P Frey, S De Mita, F Hackett. Ecology and Evolution
