Biology subjects

Lebeis, S. L.

Publications and source records attributed to Lebeis, S. L..

5 recordsLinked to original sources

bioRxiv2026

A Caulobacter hub taxon in the soybean root endosphere has a distinctive biofilm and engages in riboflavin-mediated mutualism with Bradyrhizobium

While it is well established that communities of microbes colonize the surfaces of plants as epiphytes and the interior plant tissues as endophytes, their ecological roles and colonization mechanisms remain under characterized. Members of the genus Caulobacter have emerged as hub taxa in epiphytic and endophytic microbiomes of diverse plant hosts, but the factors that support their colonization and community interactions have not been defined. Here, we characterize Caulobacter sp. RL271, a non-canonical member of the genus recently identified as a hub taxon in the soybean root endosphere. We demonstrate that the surface attachment strategies and biofilm architecture of Caulobacter sp. RL271 are determined by a matrix of capsular polysaccharide and cellulose rather than a polar holdfast adhesin, a classical defining feature of the genus. Both polysaccharide components influence the kinetics of plant root colonization in the model plant Arabidopsis thaliana. We further demonstrate that the ecology of Caulobacter sp. RL271 is shaped by its nutritional dependence on exogenous riboflavin and by interactions with Bradyrhizobium diazoefficiens, the nitrogen-fixing symbiont of soybean roots. This work advances understanding of Caulobacter biology and establishes RL271 as a tractable model for dissecting the functional role of hub taxa in root endophyte communities.

microbiology↗

bioRxiv2026

A beneficial bacteria influences myo-inositol homeostasis to protect plants during drought

Exposure to abiotic stress is one of the primary factors limiting crop productivity with drought stress is the most prevalent. Under drought, plants can produce osmolytes that increase water retention and prevent severe drought symptoms. Plant responses by extension also impact their associated root microbiomes through altered root metabolite concentrations and exudation. For example, myo-inositol (MI) serves as a precursor to osmolytes and also serves as a mediator for plant-microbe interactions in Arabidopsis thaliana (Arabidopsis). Here, we inoculated plants with Pantoea sp. R4 (R4), an isolate that can catabolize MI, and subjected them to drought. We observed that R4 colonized plants experiencing drought maintained their leaf relative water content while uninoculated planted did not, and that this colonization coincided with enrichment of MI in the shoots and depletion of MI in the roots. Interestingly, exogenous MI alone rescued water retention in wild-type Col-0, but not in int1 mutants, which lack the tonoplast MI transporter. Together, our results show that R4 colonization under drought conditions increases MI in the shoots, that this accumulation is associated with increased leaf water retention, and that INT1-mediated MI transport is required for this protection. Our results suggest that microbial colonization can alter how MI is localized in plants, which can inform future development of treatments to protect plants from drought.

microbiology↗

bioRxiv2025

Microbiome responses to natural Fusarium infection in field-grown soybean plants

The rhizosphere microbiome influences plant health by mediating plant-pathogen interactions. Plants can recruit protective microbes in response to disease, but the consistency of this process in field conditions is unclear. We examined the rhizosphere microbiome of field-grown soybean (Glycine max L.) naturally infected with root pathogens across three commercial fields in Kentucky, USA. Symptomatic and asymptomatic plants were sampled to assess disease-associated shifts in the rhizosphere microbiome. Amplicon sequencing identified a diverse Fusarium community, with one Fusarium solani amplicon sequence variant (ASV) consistently enriched in diseased plants, identifying it as the likely pathogen. While microbial communities differed between diseased and healthy plants, these shifts were largely field-specific. Several fungal ASVs with known biocontrol potential (Clonostachys rosea, Penicillium, and Trichoderma) were enriched in healthy plants, implying a role in disease suppression. A Sphingomonas ASV, a genus previously linked to plant protection, was more abundant in diseased plant rhizospheres in two fields, suggesting pathogen-triggered recruitment. Conversely, Macrophomina phaseolina, a generalist root pathogen, was enriched in the rhizosphere of diseased plants in all fields, indicating possible co-infection with F. solani. These findings reveal complex pathogen-microbe interactions in field conditions and emphasize the need for field-specific microbiome research to inform sustainable disease management strategies.

plant biology↗

bioRxiv2023

Plant inositol transport influences bacterial colonization phenotypes

Plant microbiomes are assembled and modified through a complex milieu of biotic and abiotic factors. Despite dynamic and fluctuating contributing variables, specific host metabolites are consistently identified as important mediators of microbial interactions. We combine information from a large-scale metatranscriptomic dataset from natural poplar trees and experimental genetic manipulation assays in model Arabidopsis seedlings to converge on a conserved role for transport of the plant metabolite myo-inositol in mediating host-microbe interactions. While microbial catabolism of this compound is often linked to increased host colonization, we identify motility phenotypes that occur independently of catabolism, suggesting that inositol may additionally serve as a eukaryotic-derived signaling molecule to modulate microbial activities. Our data suggests host control of this compound and resulting microbial behavior are important mechanisms at play surrounding the host metabolite inositol.

microbiology↗

bioRxiv2022

Additive genetic effects in interacting species jointly determine the outcome of caterpillar herbivory

Plant-insect interactions are common and important in basic and applied biology. Trait and genetic variation can affect the outcome and evolution of these interactions, but the relative contributions of plant and insect genetic variation and how these interact remain unclear and are rarely subject to assessment in the same experimental context. Here we address this knowledge gap using a recent host range expansion onto alfalfa by the Melissa blue butterfly. Common garden rearing experiments and genomic data show that caterpillar performance depends on plant and insect genetic variation, with insect genetics contributing to performance earlier in development and plant genetics later. Our models of performance based on caterpillar genetics retained predictive power when applied to a second common garden. Much of the plant genetic effect could be explained by heritable variation in plant phytochemicals, especially saponins, peptides, and phosphatidyl cholines, providing a mechanistic understanding of variation in the species interaction. We find evidence of polygenic, mostly additive effects within and between species, with consistent effects of plant genotype on growth and development across multiple butterfly species. Our results inform theories of plant-insect coevolution and the evolution of diet breadth in herbivorous insects and other host-specific parasites. Teaser summaryThe combined, additive effects of plant and insect genetic variation explain Melissa blue caterpillar growth and development on alfalfa plants.

genomics↗