Biology subjects

Mommer, L.

Publications and source records attributed to Mommer, L..

10 recordsLinked to original sources

bioRxiv2026

Scale matters: the arbuscular mycorrhiza - root hair trade-off from individual plants to communities

1. Plant roots employ multiple strategies to acquire soil resources, including the outgrowth of root hairs and the association with arbuscular mycorrhizal fungi (AMF). These structures represent alternative pathways to access soil resources. Evidence is derived mostly from studies within single species or multi-species experiments under controlled conditions. It remains unclear whether this trade-off holds under natural conditions and whether it manifests consistently across different scales of biological organization. 2. We analysed 81 grassland species representing grasses, forbs and legumes, sampled under heterogeneous field conditions in three regions across Germany, allowing for analyses (i) across different species (interspecific), (ii) across communities (intercommunity), (iii) within plant species (intraspecific) and (iv) within root systems of individual plants (intra-individual). Fine root traits related to AMF colonization (including scoring of fungal hyphae and arbuscules) and root hair growth (including length and incidence) were quantified. 3. Comparing plant species, we observed a strong negative correlation between mycorrhizal colonization and root hair traits, confirming previous studies working under controlled conditions. The negative relationship between root hair length and mycorrhization was also evident when comparing mean trait values at the plant community scale. Among different individuals of the same species (i.e. intraspecific scale), there was no consistent pattern of trait-trait relationship. When comparing within roots of the same plant (i.e. intra-individual scale), co-occurrence of root hairs and mycorrhiza was less likely than what would be expected by chance, with forbs showing the most consistent negative pattern. 4. Our study demonstrates that the hypothesized trade-off between AMF and root hairs is a robust pattern under field conditions at the community and interspecific scale. At the intraspecific scale, no uniform trade-off pattern can be discerned, and within single root systems the negative trade-off pattern is widespread but weak. This indicates that ecological and evolutionary constraints shape trait-trait relationships at higher scale, whereas physiological limits do not restrict trait co-occurrence at lower scales.

ecology↗

bioRxiv2026

Still standing: persistence traits capture belowground plant functions beyond resource exploration and acquisition

Belowground plant trait research has predominantly focused on trade-offs in fine root traits via the root economics space. Yet, this fine root framework captures only a fraction of the functional strategies plants employ beneath the soil surface. Here, we broaden the perspective on belowground plant functioning by integrating traits related to root system extent, clonality and bud banks, using data from the new UNDERPLOT database. This integration links measurable traits to key belowground functions: resource acquisition, spatial exploration, and persistence. Our analysis shows that the fine root economics space explains less than 5% of the variation in traits related to root system extent, clonality, and bud banks. Instead, an expanded trait analysis reveals three significant dimensions, explaining 62% of total trait variation. The third dimension, represents an independent, persistence-related gradient, not captured by existing root economics frameworks. We propose that understanding belowground plant strategies requires embracing additional functional gradients. The strategy of persistence, in particular, varies significantly across growth forms and is a critical dimension of plant response to resource limitation and stress, becoming increasingly important as global change shifts disturbance regimes.

plant biology↗

bioRxiv2025

Predicting Rhizosphere Competence Related Catabolic Gene Clusters in plant-associated bacteria with RhizoSMASH

Plants release a substantial fraction of their photosynthesized carbon into the rhizosphere as root exudates, a mix of chemically diverse compounds that drive microbiome assembly. Deciphering how plants modulate the composition and activities of rhizosphere microbiota through root exudates is challenging, as no dedicated computational methods exist to systematically identify microbial root exudate catabolic pathways. Here we used and integrated published information on catabolic genes in bacterial taxa that contribute to their rhizosphere competence. We developed the RhizoSMASH algorithm for genome-synteny-based annotation of rhizosphere-competence-related catabolic gene clusters (rCGCs) in bacteria by means of a set of 58 knowledge-based logic detection rules carefully curated through sequence similarity network analysis. Our analysis revealed large heterogeneity of rCGC prevalence both across and within plant-associated bacterial taxa, indicating extensive niche specialization. Furthermore, we validated that the presence or absence of rCGCs in bacterial genomes reflects their catabolic capacity and is predictive for their rhizosphere competence by aligning rhizoSMASH results with paired genome/metabolome datasets of rhizobacterial taxa. RhizoSMASH provides an extensible framework for studying rhizosphere bacterial catabolism, allowing targeted selection of beneficial bacterial taxa for microbiome-assisted breeding approaches for sustainable agriculture.

bioinformatics↗

bioRxiv2024

On the diversity of nematode antagonists in an agricultural soil, and their steerability by root-knot nematode density and cover crops

Plant-parasitic nematodes are harmful pathogens for many agricultural crops. Within this category, root-knot nematodes (RKN, Meloidogyne spp.) are worldwide regarded as the most impactful because of their wide geographical distribution and their polyphagous nature. Host plant resistances against RKN have been successfully introduced in a few crops only. As the use of nematicides is becoming increasingly restricted because of environmental and human health concerns, there is a need for alternative strategies to control RKN. One such approach is the stimulation of local nematode antagonists. We investigated this in an experimental field setting with two main variables: density of the Columbia root-knot nematode Meloidogyne chitwoodi, and the type of cover of crop. For each of the three M. chitwoodi densities, the effects of ten cover crop treatments were tested on both the resident (DNA) and the active (RNA) fractions of the bacterial and fungal communities. In our analyses, we focussed on changes in the abundance of plant-parasitic nematode antagonists. From the eight bacterial and 26 fungal genera known from global literature to harbour potential antagonists of plant-parasitic nematodes, we detected respectively five and 14 genera in our agricultural field. Among the bacterial genera, four included bacterial species for which nematode antagonism has been documented. The fungal genera included facultative nematode parasites (e.g., Arthrobotrys spp.), endophytes strengthening host defences (e.g., Acremonium spp.), as well as multiple obligatory nematophagous species. This study revealed that conventionally managed arable fields may harbour an unexpectedly high diversity of nematode antagonists. Multiple antagonists were stimulated by cover crops in a cover crop-specific manner, and, to a lesser extent, by increased RKN densities. The richness in putative nematode antagonists did not translate into M. chitwoodi suppression probably because most antagonists have a facultative nematophagous lifestyle and will only predate nematodes under poorer nutritional conditions.

ecology↗

bioRxiv2024

Plant species richness and the root economics space drive soil fungal communities

Trait-based approaches have been increasingly used to relate plants to soil microbial communities. However, the plant organs mediating this plant-microbe interaction - the roots - have been largely overlooked. The recent discovery of the root economics space offers a predictive framework for the structure of soil microbial communities, and specifically soil-borne fungal communities. Applying this novel approach, our study in a grassland plant diversity experiment reveals distinct root trait strategies at the level of the plant community. In addition to significant effects of plant species richness, we show that both axes of the root economics space - the collaboration and conservation gradient - are strong drivers of the composition of the different guilds of soil fungi, including saprotrophic, plant pathogenic, and mycorrhizal fungi. Our results illustrate that the root economics space and plant species richness jointly determine the effects of plants on fungal communities and their potential role in plant health and ecosystem functioning.

ecology↗

bioRxiv2022

Pinpointing the distinctive impacts of ten cover crop species on the resident and active fractions of the soil microbiome

Cover crops are used in agriculture to minimise soil erosion, prevent nutrient leaching and increase soil organic matter content. Cover crops can also be grown to stimulate the soil microbial community to improve soil biological conditions. Despite their widespread use, little is known about the impact of different cover crop species on the composition and activity of the soil microbiome. Here we investigate the effect of distinct cover crop species on the rhizosphere microbiome and to characterise both the resident (DNA-based) and the active (RNA-based) fractions of the bacterial, fungal, protist and metazoan communities in the cover crops rhizosphere. We conducted a field experiment using 70-litre bottomless containers in which we grew ten monocultures of commonly used cover crop species belonging to five plant families, and an unplanted control treatment (fallow). The total DNA and RNA were extracted from soil and the bacterial, fungal, protistan and metazoan communities were characterized using Illumina MiSeq sequencing. We found that all cover crop species significantly impacted the resident and active microbial community composition. Moreover, cover crops showed distinct selection strengths on their rhizospheres. Together with borage (Boraginaceae), oilseed radish (Brassicaceae) was shown to provoke the strongest microbial shifts, in part attributable to a promotion of the bacterial family Pseudomonadaceae and a repression of Microascaceae in the rhizosphere. Lentil (Fabaceae) showed enrichment in fungal taxa, including Trichocomaceae and fungal members of the Glomerales order, whereas black oat, hybrid ryegrass (both Poaceae) and marigold (Asteraceae) induced relatively mild changes in the soil microbial communities. Predominantly, differences in selection strengths were consistent among the four organismal groups under investigation and were observed in both the active and resident communities. Our work provides a broad baseline for the effects of cover crops on four organismal groups, which may facilitate future cover crop selection to advance soil health.

ecology↗

bioRxiv2020

Global Root Traits (GRooT) Database

MotivationTrait data are fundamental to quantitatively describe plant form and function. Although root traits capture key dimensions related to plant responses to changing environmental conditions and effects on ecosystem processes, they have rarely been included in large-scale comparative studies and global models. For instance, root traits remain absent from nearly all studies that define the global spectrum of plant form and function. Thus, to overcome conceptual and methodological roadblocks preventing a widespread integration of root trait data into large-scale analyses we created the Global Root Trait (GRooT) Database. GRooT provides ready-to-use data by combining the expertise of root ecologists with data mobilization and curation. Specifically, we (i) determined a set of core root traits relevant to the description of plant form and function based on an assessment by experts, (ii) maximized species coverage through data standardization within and among traits, and (iii) implemented data quality checks. Main types of variables containedGRooT contains 114,222 trait records on 38 continuous root traits. Spatial location and grainGlobal coverage with data from arid, continental, polar, temperate, and tropical biomes. Data on root traits derived from experimental studies and field studies. Time period and grainData recorded between 1911 and 2019 Major taxa and level of measurementGRooT includes root trait data for which taxonomic information is available. Trait records vary in their taxonomic resolution, with sub-species or varieties being the highest and genera the lowest taxonomic resolution available. It contains information for 184 sub-species or varieties, 6,214 species, 1,967 genera and 254 families. Due to variation in data sources, trait records in the database include both individual observations and mean values. Software formatGRooT includes two csv file. A GitHub repository contains the csv files and a script in R to query the database.

ecology↗

bioRxiv2020

The fungal collaboration gradient dominates the root economics space in plants

Plant economics run on carbon and nutrients instead of money. Leaf strategies aboveground span an economic spectrum from live fast and die young to slow and steady, but the economy defined by root strategies belowground remains unclear. Here we take a holistic view of the belowground economy, and show that root-mycorrhizal collaboration can short circuit a one-dimensional economic spectrum, providing an entire space of economic possibilities. Root trait data from 1,781 species across the globe confirm a classical fast-slow conservation gradient but show that most variation is explained by an orthogonal collaboration gradient, ranging from do-it-yourself resource uptake to outsourcing of resource uptake to mycorrhizal fungi. This broadened root economics space provides a solid foundation for predictive understanding of belowground responses to changing environmental conditions. One Sentence SummaryCollaboration broadens the root economics space ranging from do-it-yourself resource acquisition to outsourcing to mycorrhizal partners.

ecology↗

bioRxiv2019

Plant traits are poor predictors of long-term ecosystem functioning

Earth is home to over 350,000 vascular plant species1 that differ in their traits in innumerable ways. Yet, a handful of functional traits can help explaining major differences among species in photosynthetic rate, growth rate, reproductive output and other aspects of plant performance2-6. A key challenge, coined "the Holy Grail" in ecology, is to upscale this understanding in order to predict how natural or anthropogenically driven changes in the identity and diversity of co-occurring plant species drive the functioning of ecosystems7, 8. Here, we analyze the extent to which 42 different ecosystem functions can be predicted by 41 plant traits in 78 experimentally manipulated grassland plots over 10 years. Despite the unprecedented number of traits analyzed, the average percentage of variation in ecosystem functioning that they jointly explained was only moderate (32.6%) within individual years, and even much lower (12.7%) across years. Most other studies linking ecosystem functioning to plant traits analyzed no more than six traits, and when including either only six random or the six most frequently studied traits in our analysis, the average percentage of explained variation in across-year ecosystem functioning dropped to 4.8%. Furthermore, different ecosystem functions were driven by different traits, with on average only 12.2% overlap in significant predictors. Thus, we did not find evidence for the existence of a small set of key traits able to explain variation in multiple ecosystem functions across years. Our results therefore suggest that there are strong limits in the extent to which we can predict the long-term functional consequences of the ongoing, rapid changes in the composition and diversity of plant communities that humanity is currently facing.

ecology↗

bioRxiv2019

The results of biodiversity-ecosystem functioning experiments are realistic

A large body of research shows that biodiversity loss can reduce ecosystem functioning, thus providing support for the conservation of biological diversity1-4. Much of the evidence for this relationship is drawn from biodiversity-ecosystem functioning experiments (hereafter: biodiversity experiments), in which biodiversity loss is simulated by randomly assembling communities of varying species diversity, and ecosystem functions are measured5-9. This random assembly has led some ecologists to question the relevance of biodiversity experiments to real-world ecosystems, where community assembly may often be non-random and influenced by external drivers, such as climate or land-use intensification10-18. Despite these repeated criticisms, there has been no comprehensive, quantitative assessment of how experimental and real-world plant communities really differ, and whether these differences invalidate the experimental results. Here, we compare data from two of the largest and longest-running grassland biodiversity experiments globally (Jena Experiment, Germany; BioDIV, USA) to related real-world grassland plant communities in terms of their taxonomic, functional, and phylogenetic diversity and functional-trait composition. We found that plant communities of biodiversity experiments have greater variance in these compositional features than their real-world counterparts, covering almost all of the variation of the real-world communities (82-96%) while also containing community types that are not currently observed in the real world. We then re-analysed a subset of experimental data that included only ecologically-realistic communities, i.e. those comparable to real-world communities. For ten out of twelve biodiversity-ecosystem functioning relationships, biodiversity effects did not differ significantly between the full dataset of biodiversity experiments and the ecologically-realistic subset of experimental communities. This demonstrates that the results of biodiversity experiments are largely insensitive to the inclusion/exclusion of unrealistic communities. By bridging the gap between experimental and real-world studies, these results demonstrate the validity of inferences from biodiversity experiments, a key step in translating their results into specific recommendations for real-world biodiversity management.

ecology↗