Ecological corridors homogenize plant root endospheric mycobiota

Ecological corridors promote species coexistence in fragmented habitats where dispersal limits species fluxes. The corridor concept was developed and investigated with macroorganisms in mind, while microorganisms, the invisible majority of biodiversity, were disregarded. We analyzed the effect of corridors on the dynamics of endospheric fungal assemblages associated with plant roots at the scale of 1 m over 2 years (i.e. at five time points) by combining an experimental corridor-mesocosm with high-throughput amplicon sequencing. We showed that plant root endospheric mycobiota were sensitive to corridor effects when the corridors were set up at a small spatial scale. The endospheric mycobiota of connected plants had higher species richness, lower beta-diversity, and more deterministic assembly than the mycobiota of isolated plants. These effects became more pronounced with the development of host plants. Biotic corridors composed of host plants may thus play a key role in the spatial dynamics of microbial communities and may influence microbial diversity and related ecological functions

Ecological corridors homogenize plant root endospheric mycobiota

Ecological corridors promote species coexistence in fragmented habitats where dispersal limits species fluxes. The corridor concept was developed and investigated with macroorganisms in mind, while microorganisms, the invisible majority of biodiversity, were disregarded. We analyzed the effect of corridors on the dynamics of endospheric fungal assemblages associated with plant roots at the scale of 1 m over 2 years (i.e. at five time points) by combining an experimental corridor-mesocosm with high-throughput amplicon sequencing. We showed that plant root endospheric mycobiota were sensitive to corridor effects when the corridors were set up at a small spatial scale. The endospheric mycobiota of connected plants had higher species richness, lower beta-diversity, and more deterministic assembly than the mycobiota of isolated plants. These effects became more pronounced with the development of host plants. Biotic corridors composed of host plants may thus play a key role in the spatial dynamics of microbial communities and may influence microbial diversity and related ecological functions

Intra- and inter-annual changes in root endospheric microbial communities of grapevine are mainly deterministic

International audienceBackground and aimsConsidering the plant microbiota, temporal changes are expected depending on plant development stages and environmental pressures because of modifications in plant requirements and available soil microbial reservoir.MethodsHerein, we analyzed the composition of root endosphere microbiota of grafted vine plants using two grapevine cultivars (Merlot and Cabernet-Sauvignon as scion grafted on rootstocks of different clones) as models both sampled in a single vineyard at three dates over a period of two growing years.ResultsHighly conserved temporal patterns were found in the two cultivars. Intra-annual changes in microbial community composition were recorded whereas convergent microbial communities were observed on the two September dates. In particular, the increase in Actinobacteria and decrease in Glomeromycota in September were interpreted as shifts in the microbiota community patterns related to plant physiological requirements (e.g. water supply). A high proportion of non-random assembly of the root endospheric bacterial community confirmed the deterministic influence of the plant or/and the environment in microbial recruitment over time. The modified normalized stochasticity ratio (MST) showed that deterministic processes of assembly (MST < 50%) were commonplace despite the changes in the root microbiota composition observed among sampling dates.ConclusionOur study suggests an intra-annual rhythm of microbiota shifts, marginally random, with a succession within the root-microbiota endosphere likely governed by active plant filtering. A better knowledge of microbial-recruitment at work, seems important for both fundamental and applied perspectives

Reproductive modes in populations of late-acting self-incompatible and self-compatible polyploid Ludwigia grandiflora subsp. hexapetala in western Europe

Reproductive mode, i.e., the proportion of individuals produced by clonality, selfing and outcrossing in populations, determines how hereditary material is transmitted through generations. It shapes genetic diversity and its structure over time and space, which can be used to infer reproductive modes. Ludwigia grandiflora subsp.hexapetala (Lgh) is a partially clonal, polyploid, hermaphroditic, and heteromorphic plant that recently colonized multiple countries worldwide. In western Europe, individuals are either self-incompatible caused by a late-acting self-incompatibility (LSI) system developing long-styled flowers, or self-compatible (SC), with short-styled flowers. In this study, we genotyped 53 long- and shortstyled populations newly colonizing France and northern Spain using SNPs to estimate rates of clonality, selfing and outcrossing. We found that populations reproduced mainly clonally but with a high diversity of genotypes along with rates of sexuality ranging from 10% up to 40%. We also found evidence for local admixture between long- and short-styled populations in a background of genetic structure between floral morphs that was twice the level found within morphs. Long- and short-styled populations showed similar rates of clonality, but short-styled populations presented significantly higher rates of selfing, as expected considering their breeding system and despite the small rates of failure of the LSI system. Within the 53 studied populations, the 13 short-styled populations had fewer effective alleles, lower observed heterozygosity, and higher inbreeding coefficients, linkage disequilibrium and estimates of selfing than whatwas found in long-styled populations. These results emphasize the necessity to consider the variation of reproductive modes when managing invasive plant species. The overall maintenance of higher genetic diversity with the possibility of maintaining populations clonally in the absence of compatible partners may explain why long-styled individuals seem to be more prevalent in all newly expanding populations worldwide. Beyond Lgh, our methodological approach may inspire future studies to assess the reproductive modes in other autopolyploid populations