Genome Sequence of Azospirillum brasilense CBG497 and Comparative Analyses of Azospirillum Core and Accessory Genomes provide Insight into Niche Adaptation.
Bacteria of the genus Azospirillum colonize roots of important cereals and grasses, and promote plant growth by several mechanisms, notably phytohormone synthesis. The genomes of several Azospirillum strains belonging to different species, isolated from various host plants and locations, were recently sequenced and published. In this study, an additional genome of an A. brasilense strain, isolated from maize grown on an alkaline soil in the northeast of Mexico, strain CBG497, was obtained. Comparative genomic analyses were performed on this new genome and three other genomes (A. brasilense Sp245, A. lipoferum 4B and Azospirillum sp. B510). The Azospirillum core genome was established and consists of 2,328 proteins, representing between 30% to 38% of the total encoded proteins within a genome. It is mainly chromosomally-encoded and contains 74% of genes of ancestral origin shared with some aquatic relatives. The non-ancestral part of the core genome is enriched in genes involved in signal transduction, in transport and in metabolism of carbohydrates and amino-acids, and in surface properties features linked to adaptation in fluctuating environments, such as soil and rhizosphere. Many genes involved in colonization of plant roots, plant-growth promotion (such as those involved in phytohormone biosynthesis), and properties involved in rhizosphere adaptation (such as catabolism of phenolic compounds, uptake of iron) are restricted to a particular strain and/or species, strongly suggesting niche-specific adaptation.
Université de Lyon, UMR 5557 CNRS, USC 1193 INRA, VetAgro Sup Ecologie Microbienne, Villeurbanne 69622, France. florence.wisniewski@univ-lyon1.fr.
Florence
F
Wisniewski-Dyé
Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, AP565-A Cuernavaca, Morelos 62210, México. llozano@ccg.unam.mx.
Luis
L
Lozano
Université de Lyon, UMR 5557 CNRS, USC 1193 INRA, VetAgro Sup Ecologie Microbienne, Villeurbanne 69622, France. eyacosta@yahoo.com.
Erika
E
Acosta-Cruz
Université de Lyon, UMR 5557 CNRS, USC 1193 INRA, VetAgro Sup Ecologie Microbienne, Villeurbanne 69622, France. stephanie.borland@hotmail.fr.
Stéphanie
S
Borland
Université de Lyon, UMR 5557 CNRS, USC 1193 INRA, VetAgro Sup Ecologie Microbienne, Villeurbanne 69622, France. benoit.drogue@gmail.com.
Benoît
B
Drogue
Université de Lyon, UMR 5557 CNRS, USC 1193 INRA, VetAgro Sup Ecologie Microbienne, Villeurbanne 69622, France. claire.prigent-combaret@univ-lyon1.fr.
Claire
C
Prigent-Combaret
Laboratoire d'Analyse Bioinformatique en Génomique et Métabolisme CNRS UMR8030, France. zrouy@genoscope.cns.fr.
Zoé
Z
Rouy
Institut de Génomique, CEA, Génoscope, 2 rue Gaston Crémieux, 91057 Evry, France. vbarbe@genoscope.cns.fr.
Valérie
V
Barbe
Centro de Biotecnología Genómica, Instituto politécnico Nacional, 88710 Reynosa, Tamaulipas, México. amendozah@ipn.mx.
Alberto Mendoza
AM
Herrera
Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, AP565-A Cuernavaca, Morelos 62210, México. vgonzal@ccg.unam.mx.
Victor
V
González
Université de Lyon, UMR 5557 CNRS, USC 1193 INRA, VetAgro Sup Ecologie Microbienne, Villeurbanne 69622, France. patrick.mavingui@univ-lyon1.fr.
Patrick
P
Mavingui