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Tree root-associated microbiomes are shaped by geographic, soil physico-chemical, and host tree parameters. However, their respective impacts on microbiome variations in soils across larger spatial scales remain weakly studied. We out-planted saplings of oak clone DF159 (Quercus robur L.) as phytometer in four grassland field sites along a European North–South transect. After four years, we first compared the soil microbiomes of the tree root zone (RZ) and the tree root-free zone (RFZ). Then, we separately considered the total microbiomes of both zones, besides the microbiome with significant affinity to the RZ and compared their variability along the transect. Variations within the microbiome of the tree RFZ were shaped by geographic and soil physico-chemical changes, whereby bacteria responded more than fungi. Variations within both microbiomes of the tree RZ depended on the host tree and abiotic parameters. Based on perMANOVA and Mantel correlation tests, impacts of site specificities and geographic distance strongly decreased for the tree RZ affine microbiome. This pattern was more pronounced for fungi than bacteria. Shaping the microbiome of the soil zones in root proximity might be a mechanism mediating the acclimation of oaks to a wide range of environmental conditions across geographic regions.

The role of microorganisms and other factors in the process of autoimmune uveitis Abstract The aim of this work was to gain new knowledge about the influence and the mechanisms of the effect of microorganisms in the process of autoimmune uveitis. A mouse model of experimental autoimmune uveitis (EAU) was used and the influence of oral broad-spectrum antibiotic, i.e. metronidazole, as well as probiotic bacteria Escherichia coli O83:K24:H31 (EcO) nad Escherichia coli Nissle 1917 (EcN) were tested in preventive and therapeutic regimens. The grade of inflammation was assessed clinically in vivo and histologically post mortem. Immunological analysis of lymph nodes and Peyer's patches were performed. Evaluation of the effect of metronidazole proved significant reduction of inflammatory activity in both regimes - intitiation 1 week or 2 weeks before the EAU induction. In case of probiotics, protective effect was proved only in case of live EcN administered 2 weeks before or from the time of EAU induction. Its protective effect was accompanied with decreased interphotoreceptor retinoid-binding protein (IRBP)-specific T-lymphocyte response in the sentinel lymph nodes of the site of immunization 7 days after the induction of EAU and cervical lymph nodes as soon as there were apparent clinical signs of intraocular...