AUTHOR=Fu Benzhong , Yan Qing 

TITLE=Exopolysaccharide is required for motility, stress tolerance, and plant colonization by the endophytic bacterium Paraburkholderia phytofirmans PsJN

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1218653

DOI=10.3389/fmicb.2023.1218653

ISSN=1664-302X

ABSTRACT=<p><italic>Paraburkholderia phytofirmans</italic> PsJN is an endophytic bacterium and has been shown to promote the growth and health of many different plants. Exopolysaccharide (EPS) plays important roles in plant-bacteria interaction and tolerance to environmental stresses. However, the function of EPS in PsJN and its interaction with plants remain largely unknown. In this study, a deletion mutation of <italic>bceQ</italic> gene, encoding a putative flippase for the EPS biosynthesis, was introduced in the genome of PsJN. The Δ<italic>bceQ</italic> mutant produced a significantly lower level of EPS than the wild type strain in culture media. Compared to the wild type PsJN, the Δ<italic>bceQ</italic> mutant was more sensitive to desiccation, UV damage, salt (NaCl) and iron (FeCl<sub>3</sub>) stresses, and bacteriophage infection. More importantly, the mutation of <italic>bceQ</italic> decreased the endophytic colonization of PsJN in camelina (<italic>Camelina sativa</italic>) and pea (<italic>Camelina sativa</italic>) under plant drought stress conditions. To the best of our knowledge, this is the first report that EPS production is required for the maximal colonization of an endophytic bacterium in the plant tissues under stress conditions.</p>