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The mycobiome (fungal microbiome) influences plants—from seed germination to full maturation. While many studies on fungal‐plant interaction studies have focused on known mutualistic and pathogenic fungi, the functional role of ubiquitous endophytic fungi remains little explored.We examined how root‐inhabiting fungi (endophytes) influence range‐expanding plant species. We isolated endophytes from three European intra‐continental range‐expanders and three congenerics that are native both in the range expander's original (southern Europe) and new (northern Europe) range. To standardize our collection, endophytes were obtained from all six plant species growing under controlled conditions in northern (new range of the range expander) and southern (native range of the range expander) soils. We cultivated, molecularly identified and tested the effects of all isolates on seed germination, and growth of seedlings and older plants.Most of the 34 isolates could not be functionally characterized based on their taxonomic identity and literature information on functions. Endophytes affected plant growth in a plant species–endophyte‐specific manner, but overall differed between range‐expanders and natives. While endophytes reduced germination and growth of range‐expanders compared to natives, they reduced seedling growth of natives more than of range‐expanders.Synthesis. We conclude that endophytic fungi have a direct effect on plant growth in a plant growth stage‐dependent manner. While these effects differed between range expanders and natives, the effect strength and significance varied among the plant genera included in the present study. Nevertheless, endophytes likely influence the establishment of newly arriving plants and influence vegetation dynamics. [ABSTRACT FROM AUTHOR]

Current climate change has led to latitudinal and altitudinal range expansions of numerous species. During such range expansions, plant species are expected to experience changes in interactions with other organisms, especially with belowground biota that have a limited dispersal capacity. Nematodes form a key component of the belowground food web as they include bacterivores, fungivores, omnivores and root herbivores. However, their community composition under climate change-driven intracontinental range-expanding plants has been studied almost exclusively under controlled conditions, whereas little is known about actual patterns in the field. Here, we use novel molecular sequencing techniques combined with morphological quantification in order to examine nematode communities in the rhizospheres of four range-expanding and four congeneric native species along a 2,000 km latitudinal transect from South-Eastern to North-Western Europe. We tested the hypotheses that latitudinal shifts in nematode community composition are stronger in range-expanding plant species than in congeneric natives and that in their new range, range-expanding plant species accumulate fewest root-feeding nematodes. Our results show latitudinal variation in nematode community composition of both range expanders and native plant species, while operational taxonomic unit richness remained the same across ranges. Therefore, range-expanding plant species face different nematode communities at higher latitudes, but this is also the case for widespread native plant species. Only one of the four range-expanding plant species showed a stronger shift in nematode community composition than its congeneric native and accumulated fewer root-feeding nematodes in its new range. We conclude that variation in nematode community composition with increasing latitude occurs for both range-expanding and native plant species and that some range-expanding plant species may become released from root-feeding nematodes in the new range., (© 2019 The Authors Global Change Biology Published by John Wiley & Sons Ltd.)

Plant range expansion is occurring at a rapid pace, largely in response to human-induced climate warming. Although the movement of plants along latitudinal and altitudinal gradients is well-documented, effects on belowground microbial communities remain largely unknown. Furthermore, for range expansion, not all plant species are equal: in a new range, the relatedness between range-expanding plant species and native flora can influence plant-microorganism interactions. Here we use a latitudinal gradient spanning 3,000 km across Europe to examine bacterial and fungal communities in the rhizosphere and surrounding soils of range-expanding plant species. We selected range-expanding plants with and without congeneric native species in the new range and, as a control, the congeneric native species, totalling 382 plant individuals collected across Europe. In general, the status of a plant as a range-expanding plant was a weak predictor of the composition of bacterial and fungal communities. However, microbial communities of range-expanding plant species became more similar to each other further from their original range. Range-expanding plants that were unrelated to the native community also experienced a decrease in the ratio of plant pathogens to symbionts, giving weak support to the enemy release hypothesis. Even at a continental scale, the effects of plant range expansion on the belowground microbiome are detectable, although changes to specific taxa remain difficult to decipher.