Endophytes in woody plants are much less understood. Pantoea strain FBS135 is an endophytic bacterium isolated from Pinus massoniana with the ability to promote pine growth significantly. In this study, we demonstrated that FBS135 has the astonishing ability of low nitrogen tolerance but no ability of nitrogen fixation. To exactly determine the phylogenetic status of FBS135, we sequenced the whole genomes of P. eucalypti LMG 24197T and P. vagans 24199T, type strains of two Pantoea species, which are evolutionarily closest to FBS135. P. eucalypti LMG 24197T contained a single chromosome of 4,035,995 bp (C+G, 54.6%) plus three circular plasmids while LMG 24199T comprises a single circular chromosome of 4,050,173 bp (C+G, 55.6%) and two circular plasmids. With the genomic information, FBS135 was finally identified as a P. eucalypti strain, although it showed some different physiological traits from the two type strains. Comparative genomic analyses were performed for the three strains, revealing their common molecular basis associated with plant lifecycle as well as the differences in their gene arrangements relating to nitrogen utilization.
Keywords: Pantoea eucalypti FBS135; collinearity analysis; endophyte; nitrogen fixation; phylogenetic analysis; stable isotope.