A Caulobacter hub taxon in the soybean root endosphere has a distinctive biofilm and engages in riboflavin-mediated mutualism with Bradyrhizobium
- 1Michigan State University
Abstract
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.
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BibTeX
@misc{quinlan2026caulobacter,
title = {{A Caulobacter hub taxon in the soybean root endosphere has a distinctive biofilm and engages in riboflavin-mediated mutualism with Bradyrhizobium}},
author = {M. A. Quinlan and S. Crosson and S. L. Lebeis and G. Bonito and R. Longley and A. Fiebig},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.14.750808},
url = {https://www.biorxiv.org/content/10.64898/2026.09.14.750808v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - A Caulobacter hub taxon in the soybean root endosphere has a distinctive biofilm and engages in riboflavin-mediated mutualism with Bradyrhizobium
AU - M. A. Quinlan
AU - S. Crosson
AU - S. L. Lebeis
AU - G. Bonito
AU - R. Longley
AU - A. Fiebig
PY - 2026
DA - 2026/09/14
PB - bioRxiv
DO - 10.64898/2026.09.14.750808
UR - https://www.biorxiv.org/content/10.64898/2026.09.14.750808v1
AB - 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.
ER -