Project description: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.
Project description:The short-term, reversible process that allows plants to cope with immediate environmental fluctuations is often referred to as acclimation. Plant acclimation help maintain the balance of natural systems, supporting biodiversity and the services that ecosystems provide, such as carbon sequestration and water regulation. With climate change modifying the distribution area of plants and causing more frequent and severe weather events, knowledge of how plants acclimate can inform strategies to manage ecosystems and agriculture. Analyses of plant immune responses under abiotic constraints generally focus on pathogen inoculation under prolonged and stable abiotic conditions. Daily fluctuations of the environment may alter plant metabolism, growth and flowering as well as gene regulation and invasive growth of fungal pathogens. Yet, how plant immunity acclimates to daily temperature fluctuations remains largely unexplored. To study the molecular bases of quantitative disease resistance acclimation, we performed a global transcriptome analysis of Arabidopsis thaliana accessions Col-0, Rld-2 and Sha grown in temperate, continental and Mediterranean climates, followed or not by Sclerotinia sclerotiorum inoculation.