Biology subjects

Selosse, M.-A.

Publications and source records attributed to Selosse, M.-A..

9 recordsLinked to original sources

bioRxiv2026

Kin discrimination in plants: competitive ability over kinship response

Numerous studies on plant-plant interactions aim to distinguish positive from negative effects, especially among related individuals. Most studies interpret a reduction in biomass when grown with related individuals as kin recognition. However, these interactions can shift from positive to negative depending on environmental or biotic factors. We investigated these interactions in Black poplar (Populus nigra L.), a riparian tree species growing in high densities and stressful habitats, by examining the effects of relatedness and water deficit during early developmental stages. We set up two experiments where seedlings from four kin groups were competing with related or unrelated individuals, in well-watered versus water deficit environment, and studied their response through growth, root nitrogen uptake and mycorrhizal diversity. The four kin groups exhibit similar intrinsic growth capacities. However, for two kin groups, we found differences in competitive ability. Thus, we found that individuals responded differently depending on whether they were grown with related or unrelated individuals. Water deficit did not change the outcomes of interactions. Differences in competitive ability between kin groups was the most parsimonious interpretation, thus eliminating kin recognition as an explanation. Our study suggests that results obtained in general in kin studies must be carefully analyzed and that alternative interpretations, such as differences in competitive ability, must be tested before conclude wrongly to kin recognition. Our study also suggests that mycorrhizal communities develop differently according to the kin groups considered and can potentially have impacts on the growth of individuals.

ecology↗

bioRxiv2024

Factors shaping the assembly of lichen holobionts in a tropical lichen community

Lichen thalli host complex microbial communities, which may foster the ecological stability and longevity of the lichen symbiosis. Yet, we lack a holistic understanding of the processes contributing to the assembly of the lichen holobiont. This study assessed the diversity and community structure in taxonomically diverse co-occurring lichens associated with Trebouxiophyceae algae from Bolivian forests. We focused on three components of the lichen holobiont: the lichenized fungus (mycobiont) and its associated algae (photobiome) and fungi (mycobiome). We specifically tested the influence of mycobiont identity, thallus morphological type, reproductive strategy, and lichen secondary metabolites on the lichen-associated photobiome and mycobiome. To understand the specialization patterns between holobiont components, we investigated interaction networks. We observed that co-occurring mycobiont taxa host diverse, taxon-specific, yet overlapping photobiome and mycobiome. In particular, these communities are significantly influenced by the hosts thallus morphological type and its secondary metabolites. Finally, we demonstrated that both photobiome and mycobiome are structured mainly by mycobiont identity, which results in modular networks with strong phylogenetic signals and high levels of specialization. In conclusion, the symbiotic interactions within lichen are structured mainly by the mycobiont, which appears to be the leading architect of the lichen holobiont.

microbiology↗

bioRxiv2024

Endophytic and ectomycorrhizal, an overlooked dual ecological niche? Insights from natural environments and Russula species

O_LIEctomycorrhizal (EcM) fungi play key roles in ecosystem functioning, in particular temperate ones. Recent findings suggest that they can endophytically colonize the roots of non-EcM plants. Here we aim at (i) providing new evidence of colonization of non-EcM hosts by EcM fungi, (ii) exploring factors driving such colonization (plant identity, site, root filter), and (iii) providing direct microscopical evidence for endophytism. C_LIO_LIUsing amplicon sequencing (ITS2), we described the root fungal communities of 42 plant species collected at nine locations in France. In two of those sites, we also compared rhizosphere and root fungal communities to identify a potential root filter. Finally, we investigated endophytism in Russula spp. at two Russula-rich sites using fluorescence in situ hybridization (FISH) paired with confocal microscopy. C_LIO_LIWe find a large but variable share of EcM sequences in roots of non-EcM plant species, in particular nearby EcM hosts, suggesting that endophytism is a secondary ecological niche. Though EcM fungi were more abundant in the rhizosphere compared to roots, their composition was similar to that of roots, suggesting a poor root filter. We observed metabolically active hyphae of Russula spp. endophytically colonizing the apoplast of two non-EcM plant species. C_LIO_LIAs shown for other EcM fungi (e.g., Tuber spp., Ascomycota) we demonstrate the dual EcM/endophyte niche for Russula (Basidiomycota). The ecological consequences of this duality still need to be addressed. The ability to colonize two ecological niches may be a trait kept by EcM fungi which evolved from endophytic fungi, as stipulated by the "waiting room hypothesis". C_LI

microbiology↗

bioRxiv2023

Seed or soil: tracing back the plant mycobiota primary sources.

Plants host diverse communities of fungi (collectively called the mycobiota) which play crucial roles in their development. The assembly processes of the mycobiota, however, remain poorly understood, in particular, whether it is transmitted by parents through the seeds (vertical transmission) or recruited in the environment (horizontal transmission). Here we attempt to quantify the relative contributions of horizontal and vertical transmission in the mycobiota assembly of a desert shrub, Haloxylon salicornicum, by comparing the mycobiota of in situ bulk soil and seeds to that of (i) in situ adult individuals and (ii) in vitro-germinated seedlings in soil collected in situ, either autoclaved or not. We show that the mycobiota is partially transmitted through the seeds to seedlings. In contrast, root mycobiota of adults are highly similar to that of bulk soil, whereas adult leaf mycobiota remain similar to that of seeds. Thus, the mycobiota is transmitted both horizontally and vertically depending on the plant tissue. Despite discrepancies between in situ and in vitro approaches, our result may also suggest a compositional turnover in plant mycobiota during plant development. Understanding the respective contribution of these transmission paths to the plant mycobiota is fundamental to deciphering potential coevolutionary processes between plants and fungi.

microbiology↗

bioRxiv2022

Structure and specialization of mycorrhizal networks in phylogenetically diverse tropical communities

BackgroundThe root mycobiome plays a fundamental role in plant nutrition and protection against biotic and abiotic stresses. In temperate forests or meadows dominated by angiosperms, the numerous fungi involved in root symbioses are often shared between neighboring plants, thus forming complex plant-fungus interaction networks of weak specialization. Whether this weak specialization also holds in rich tropical communities with more phylogenetically diverse sets of plant lineages remains unknown. We collected roots of 30 plant species in semi-natural tropical communities including angiosperms, ferns, and lycophytes, in three different habitat types on La Reunion island: a recent lava flow, a wet thicket, and an ericoid shrubland. We identified root-inhabiting fungi by sequencing both the 18S rRNA and the ITS2 variable regions. We assessed the diversity of mycorrhizal fungal taxa according to plant species and lineages, as well as the structure and specialization of the resulting plant-fungus networks. ResultsThe 18S and ITS2 datasets are highly complementary at revealing the root mycobiota. According to 18S, Glomeromycotina colonize all plant groups in all habitats forming the least specialized interactions, resulting in nested network structures, while Mucoromycotina (Endogonales) are more abundant in the wetland and show higher specialization and modularity compared to the former. According to ITS2, mycorrhizal fungi of Ericaceae and Orchidaceae, namely Helotiales, Sebacinales, and Cantharellales, also colonize the roots of most plant lineages, confirming that they are frequent endophytes. While Helotiales and Sebacinales present intermediate levels of specialization, Cantharellales are more specialized and more sporadic in their interactions with plants, resulting in highly modular networks. ConclusionsThis study of the root mycobiome in tropical environments reinforces the idea that mycorrhizal fungal taxa are locally shared between co-occurring plants, including phylogenetically distant plants (e.g. lycophytes and angiosperms), where they may form functional mycorrhizae or establish endophytic colonization. Yet, we demonstrate that, irrespectively of the environmental variations, the level of specialization significantly varies according to the fungal lineages, probably reflecting the different evolutionary origins of these plant-fungus symbioses. Frequent fungal sharing between plants questions the roles of the different fungi in community functioning and highlights the importance of considering networks of interactions rather than isolated hosts.

ecology↗

bioRxiv2021

Do closely related species interact with similar partners?Testing for phylogenetic signal in bipartite interaction networks

AO_SCPLOWBSTRACTC_SCPLOWWhether interactions between species are conserved on evolutionary time-scales has spurred the development of both correlative and process-based approaches for testing phylogenetic signal in interspecific interactions: do closely related species interact with similar partners? Here we use simulations to test the statistical performances of the two approaches that are the most widely used in the field: Mantel tests and the Phylogenetic Bipartite Linear Model (PBLM). Mantel tests investigate the correlation between phylogenetic distances and dissimilarities in sets of interacting partners, while PBLM is a process-based approach that relies on strong assumptions about how interactions evolve. We find that PBLM often detects a phylogenetic signal when it should not. Simple Mantel tests instead have infrequent false positives and moderate statistical power; however, they often artifactually detect that closely related species interact with dissimilar partners. Partial Mantel tests, which are used to partial out the phylogenetic signal in the number of partners, actually fail at correcting for this confounding effect, and we instead recommend evaluating the significance of Mantel tests with network permutations constraining the number of partners. We also explore the ability of simple Mantel tests to analyze clade-specific phylogenetic signals. We provide general guidelines and an application on an interaction network between orchids and mycorrhizal fungi.

ecology↗

bioRxiv2020

Diversification slowdown in an evolutionary cul-de-sac

Analyzing diversification dynamics is key to understanding the past evolutionary history of clades that led to present-day biodiversity patterns. While such analyses are widespread in well-characterized groups of species, they are much more challenging in groups which diversity is mostly known through molecular techniques. Here, we use the largest global database on the small subunit (SSU) rRNA gene of Glomeromycotina, a subphylum of microscopic arbuscular mycorrhizal fungi that provide mineral nutrients to most land plants by forming one of the oldest terrestrial symbioses, to analyze the diversification dynamics of this clade in the past 500 million years (Myr). We perform a range of sensitivity analyses and simulations to control for potential biases linked to the nature of the data. We find that Glomeromycotina tend to have low speciation rates compared to other eukaryotes. After a peak of speciations between 200 and 100 Myr ago, they experienced an important decline in speciation rates toward the present. Such a decline could be at least partially related to a shrinking of their mycorrhizal niches and to their limited ability to colonize new niches. Our analyses identify patterns of diversification in a group of obligate symbionts of major ecological and evolutionary importance and illustrate that short molecular markers combined with intensive sensitivity analyses can be useful for studying diversification dynamics in microbial groups.

evolutionary biology↗

bioRxiv2020

The genomic impact of mycoheterotrophy: targeted gene losses but extensive expression reprogramming.

ABSTRACTMycoheterotrophic plants have lost the ability to photosynthesize and they parasitize their associated fungus to get the mineral and organic nutrients they need. Despite involving radical changes in life history traits and ecological requirements, the transition from autotrophy to mycoheterotrophy occurred independently in almost all major lineages of land plants, but most often in Orchidaceae. Yet the molecular mechanisms underlying this shift are still poorly understood. The comparison of the transcriptomes of Epipogium aphyllum and Neottia nidus-avis, two mycoheterotrophic orchids, to other autotrophic and mycoheterotrophic orchids showed massive molecular function losses restricted to photosynthetic activities. In addition to these targeted losses, the analysis of their expression profiles showed that many orthologs had inverted root/shoot ratios compared to autotrophic species. Fatty acid and amino acid biosynthesis as well as primary cell wall metabolism were among the pathways most impacted by this expression reprogramming. Our study suggests that, while associated with function losses rather than metabolic innovations, the shift in nutritional mode from autotrophy to mycoheterotrophy remodeled the architecture of the plant metabolism.View Full Text

plant biology↗

bioRxiv2018

Constraints upon cheating emergence in mutualistic networks: evidence in the mycorrhizal symbiosis

O_LIWhile mutualisms are widespread and essential in ecosystem functioning, the emergence of uncooperative cheaters threatens their stability, unless there are functional or evolutionary mechanisms limiting cheaters interactions.\nC_LIO_LIHere, we evaluated the constraints upon mycoheterotrophic (MH) cheating plants in the mutualistic interaction network of autotrophic (AT) plants and arbuscular mycorrhizal fungi. For this purpose, we assembled a world-scale network of >25,000 interactions in order to investigate (i) the specialization and (ii) the phylogenetic distribution of MH or AT plants and their respective fungal partners.\nC_LIO_LIWe show that MH cheating repeatedly evolved in the vascular flora, suggesting low phylogenetic constraint for plants. However, MH cheaters are significantly more specialized than AT plants, and their fungi also appear more specialized and more closely related than fungi of AT plants, which suggest that cheaters are specifically isolated into modules by functional constraints\nC_LIO_LIThis unprecedented comparison of MH vs. AT plants thus reveals that MH cheating is most likely constrained by the specialization of phylogenetically conserved cheating-susceptible fungi, which suggests mechanisms for avoidance of these fungi. Beyond the mycorrhizal symbiosis, our approach highlights an empirical multiple-partners mutualistic system illustrating that the overall persistence of mutualism can be linked to functional constraints upon cheating emergences.\nC_LI

evolutionary biology↗