Biology subjects

Rothballer, M.

Publications and source records attributed to Rothballer, M..

4 recordsLinked to original sources

bioRxiv2025

Improving Seedling Survival for Forest Restorations: A Novel Screening Method to Identify Microbial Allies Against Drought Stress

Improving drought tolerance of tree seedlings by plant growth-promoting microorganisms (PGPMs) is a promising approach for nature-based forest restoration. Identifying suitable microorganisms requires a robust selection, including efficient in planta screenings. We sampled at two forest sites in southern Germany with drought legacies and within a dry period to enhance the probability of isolating drought-tolerant microbes. Metabarcoding of the resident soil community revealed a broad on-site diversity with the potential for diverse plant growth-promoting and stress-resistance traits. We isolated 1,292 bacteria and 59 fungi from fine roots of Norway spruce and European beech. 429 isolates were identified on genus level. The most abundant genera were Paraburkholderia (121) and Bacillus (43) in bacteria and Penicillium (8) and Umbelopsis (8) in fungi. Isolates were scored in vitro for abiotic stress tolerance and plant growth-promoting traits, revealing diverse plant growth-promoting abilities for 31 bacteria and a particularly high stress tolerance for 8 fungi. Importantly, an axenic 24-well-plate system was developed to test the most promising bacteria on spruce seedlings under drought. The system allowed direct comparison of inoculation effects on seedling growth and survival with or without drought application. Two strains improved survival and root length under drought, while six strains significantly promoted plant growth under well-watered conditions. This study represents one of the first larger scale screenings for PGPMs isolated from forest soils on tree seedlings under drought and may contribute to finding nature-based drought mitigation strategies.

microbiology↗

bioRxiv2023

A gut meta-interactome map reveals modulation of human immunity by microbiome effectors

The molecular mechanisms by which the gut microbiome influences human health remain largely unknown. Pseudomonadota is the third most abundant phylum in normal gut microbiomes. Several pathogens in this phylum can inject so-called virulence effector proteins into host cells. We report the identification of intact type 3 secretion systems (T3SS) in 5 - 20% of commensal Pseudomonadota in normal human gut microbiomes. To understand their functions, we experimentally generated a high-quality protein-protein meta-interactome map consisting of 1,263 interactions between 289 bacterial effectors and 430 human proteins. Effector targets are enriched for metabolic and immune functions and for genetic variation of microbiome-influenced traits including autoimmune diseases. We demonstrate that effectors modulate NF-{kappa}B signaling, cytokine secretion, and adhesion molecule expression. Finally, effectors are enriched in metagenomes of Crohns disease, but not ulcerative colitis patients pointing toward complex contributions to the etiology of inflammatory bowel diseases. Our results suggest that effector-host protein interactions are an important regulatory layer by which the microbiome impacts human health.

microbiology↗

bioRxiv2023

Microbe-induced plant resistance against insect pests depends on timing of inoculation, but is consistent across climatic conditions

O_LITo cope with abiotic and biotic stressors, plants have developed mutualistic associations with beneficial soil microbes, but little is known about how (extreme) abiotic conditions impact on microbe-induce resistance to insect herbivores. C_LIO_LIExtreme temperatures are often accompanied by extremes in plant water availability, which together reduce plant growth and change plant physiology. There are potential consequences for increasing plant susceptibility to biotic stresses, and this poses a real challenge for plant productivity. C_LIO_LIWe evaluated how the effects of beneficial soil bacteria (Acidovorax radicis) on barley plant growth and resultant resistance against aphid infestation (Sitobion avenae) were impacted by a single heatwave event across a plant water availability gradient. We also tested if timing of bacterial inoculation (before or after the heatwave) affected bacteria-plant interactions on aphids. C_LIO_LIWe found that heatwaves affected plant biomass allocation from aboveground to belowground tissues. Inoculation with A. radicis led to reduction of aphid numbers, but depended on timing of inoculation, and led to stronger resistance when inoculations occurred closer to aphid infestation. Remarkably, microbe-induced resistance against aphids was consistent across heatwave and water availability treatments. C_LIO_LIThis study provides evidence that beneficial plant-bacteria interactions may represent a potential solution for sustainable agricultural practices to enhance plant growth and response to insect pests under climate change. Future field trials should investigate the consistency of beneficial effects reported here for a better understanding of multispecies interactions in the context of global change. C_LI

ecology↗

bioRxiv2019

Climate change alters beneficial crop-microbe-invertebrate interactions

Increasing levels of CO2 and tropospheric ozone (O3) due to climate change are contributing to reduced plant health and unstable crop yield production1. The inoculation of plant roots with beneficial fungi or bacteria can increase plant health2. However, this is often studied under very controlled conditions and it is unknown how climate change or interactions with other species can alter the resulting benefits. Here we show that the rhizosphere bacterium Acidovorax radicis N35 can increase plant growth and reduce insect growth - with increased impact in a high-stress elevated O3 environment, but reduced impact under elevated CO2. In a fully-factorial climate chamber experiment we disentangled the impacts of climate factors (elevated CO2 and elevated O3) and biotic interactions (plant cultivar, sap-feeding insects and earthworms) on cereal growth and insect suppression mediated by A. radicis N35. Earthworms promoted plant aboveground growth, whereas A. radicis N35 promoted root growth, and overall plant growth was higher when both species were present. However, earthworms also promoted insect growth and therefore increased plant damage through herbivory. While A. radicis N35 inoculation was able to mitigate these negative effects to some extent under an ambient environment this was lost under climate change conditions. Our results show that knowledge-based solutions for sustainable agriculture should include biotic interactions and must be tested across variable climate change scenarios in order to build resilient cropping systems.

ecology↗