Project description:Many trees form ectomycorrhizal symbiosis with fungi. During symbiosis, the tree roots supply sugar to the fungi in exchange for nitrogen, and this process is critical for the nitrogen and carbon cycles in forest ecosystems. However, the extents to which ectomycorrhizal fungi can liberate nitrogen and modify the soil organic matter and the mechanisms by which they do so remain unclear since they have lost many enzymes for litter decomposition that were present in their free-living, saprotrophic ancestors. Using time-series spectroscopy and transcriptomics, we examined the ability of two ectomycorrhizal fungi from two independently evolved ectomycorrhizal lineages to mobilize soil organic nitrogen. Both species oxidized the organic matter and accessed the organic nitrogen. The expression of those events was controlled by the availability of glucose and inorganic nitrogen. Despite those similarities, the decomposition mechanisms, including the type of genes involved as well as the patterns of their expression, differed markedly between the two species. Our results suggest that in agreement with their diverse evolutionary origins, ectomycorrhizal fungi use different decomposition mechanisms to access organic nitrogen entrapped in soil organic matter. The timing and magnitude of the expression of the decomposition activity can be controlled by the below-ground nitrogen quality and the above-ground carbon supply.
Project description:Illumina HiSeq2000 technology was used to generate mRNA profiles from the ectomycorrhizal fungi Laccaria bicolor colonizing roots of Populus trichocarpa. Samples were taken after 3 months of contact in order to identify mycorrhiza-regulated transcripts. 100bp reads were generated and aligned to the Populus trichocarpa (http://www.phytozome.net/poplar.php) reference genome.
Project description:Mycorrhiza helper bacteria (MHB) promote the formation of ectomycorrhizae between tree roots and ectomycorrhizal fungi. Despite the high relevance of MHB for forestry and for sustainable tree production in tree nurseries, little is known about the properties of the bacteria that contribute to their helper abilities. The MHB strain Pseudomonas fluorescens BBc6R8 is used as a model to study the mechanisms of the helper effect. We took advantage of new technologies to obtain, for the first time, the whole genome sequence of an MHB. Analyses reveal an important plasticity of the genome with numerous functions acquired by horizontal gene tranfer. Genome mining was combined with transcriptomic and mutagenesis approaches to reveal molecular determinants of the helper effect. The data suggest that the production of helper molecules is likely to be constitutive in vitro. The helper effect appears to be pleiotropic and to rely, for a substantial part, on trophic interactions. Despite its helper abilities, the bacterium is also able in specific conditions to outcompete ectomycorrhizal fungi and inhibit their growth. We conclude that the helper bacterium possess a broad range of properties whose expression depending on the biotic and abiotic conditions can result in either a beneficial, neutral or antagonistic interaction between the plant, the ectomycorrhizal fungus and the bacterium.
Project description:Populus×canescens inoculated with or without different ectomycorrhizal fungi, Paxillus involutus (MAJ) and Cenococcum geophilum Fr., were co-cultured in greeenhouse for 16 weeks, then exposed to different water conditions (well-watered, drought and re-watered) for 4 weeks. Poplar leaves and roots were harvest for RNA sequenceing.
Project description:In order to get insights into the ability of ectomycorrhizal fungi to perceive their biotic environment as well as into the mechanisms of the interactions between ectomycorrhizal fungi and soil bacteria, we analysed the transcriptomic response of the ectomycorrhizal fungus L. bicolor and one detrimental bacterial strain during their interactions in vitro.
Project description:In order to get insights into the ability of ectomycorrhizal fungi to perceive their biotic environment as well as into the mechanisms of the interactions between ectomycorrhizal fungi and soil bacteria, we analysed the transcriptomic response of the ectomycorrhizal fungus L. bicolor and one detrimental bacterial strain during their interactions in vitro.
Project description:In order to get insights into the ability of ectomycorrhizal fungi to perceive their biotic environment as well as into the mechanisms of the interactions between ectomycorrhizal fungi and soil bacteria, we analysed the transcriptomic response of the ectomycorrhizal fungus L. bicolor and the strain Pseudomonas fluorescens Pf29Arp during their interactions in vitro.
Project description:In order to get insights into the ability of ectomycorrhizal fungi to perceive their biotic environment as well as into the mechanisms of the interactions between ectomycorrhizal fungi and soil bacteria, we analysed the transcriptomic response of the ectomycorrhizal fungus L. bicolor and of two beneficial, and neutral soil bacteria during their interactions in vitro.
Project description:In order to get insights into the ability of ectomycorrhizal fungi to perceive their biotic environment as well as into the mechanisms of the interactions between ectomycorrhizal fungi and soil bacteria, we analysed the transcriptomic response of the ectomycorrhizal fungus L. bicolor and the strain Pseudomonas fluorescens Pf29Arp during their interactions in vitro. We performed six hybridizations (shotgun DNA microarray) with samples derived from Pseudomonas fluorescens Pf29Arp cultivated alone or with Laccaria bicolor S238N in vitro (3 control biological replicates and 3 biological replicates with L. bicolor)
