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PLoS Biol. 2017 Sep 22;15(9):e2002860. doi: 10.1371/journal.pbio.2002860. eCollection 2017 Sep.

Genome-wide identification of bacterial plant colonization genes.

Author information

1
US Department of Energy Joint Genome Institute, Walnut Creek, California, United States of America.
2
Department of Biology, Department of Microbiology and Immunology, Curriculum in Genetics and Molecular Biology, Howard Hughes Medical Institute, Carolina Center for Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America.
3
Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
4
School of Natural Sciences, University of California Merced, Merced, California, United States of America.

Abstract

Diverse soil-resident bacteria can contribute to plant growth and health, but the molecular mechanisms enabling them to effectively colonize their plant hosts remain poorly understood. We used randomly barcoded transposon mutagenesis sequencing (RB-TnSeq) in Pseudomonas simiae, a model root-colonizing bacterium, to establish a genome-wide map of bacterial genes required for colonization of the Arabidopsis thaliana root system. We identified 115 genes (2% of all P. simiae genes) with functions that are required for maximal competitive colonization of the root system. Among the genes we identified were some with obvious colonization-related roles in motility and carbon metabolism, as well as 44 other genes that had no or vague functional predictions. Independent validation assays of individual genes confirmed colonization functions for 20 of 22 (91%) cases tested. To further characterize genes identified by our screen, we compared the functional contributions of P. simiae genes to growth in 90 distinct in vitro conditions by RB-TnSeq, highlighting specific metabolic functions associated with root colonization genes. Our analysis of bacterial genes by sequence-driven saturation mutagenesis revealed a genome-wide map of the genetic determinants of plant root colonization and offers a starting point for targeted improvement of the colonization capabilities of plant-beneficial microbes.

PMID:
28938018
PMCID:
PMC5627942
DOI:
10.1371/journal.pbio.2002860
[Indexed for MEDLINE]
Free PMC Article

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