TY - JOUR

T1 - Search for ancestral features in genomes of Rhizobium leguminosarum bv. Viciae strains isolated from the relict legume Vavilovia formosa

AU - Chirak, Elizaveta R.

AU - Kimeklis, Anastasiia K.

AU - Karasev, Evgenii S.

AU - Kopat, Vladimir V.

AU - Safronova, Vera I.

AU - Belimov, Andrey A.

AU - Aksenova, Tatiana S.

AU - Kabilov, Marsel R.

AU - Provorov, Nikolay A.

AU - Andronov, Evgeny E.

N1 - Publisher Copyright: © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2019/12

Y1 - 2019/12

N2 - Vavilovia formosa is a relict leguminous plant growing in hard-to-reach habitats in the rocky highlands of the Caucasus and Middle East, and it is considered as the putative closest living relative of the last common ancestor (LCA) of the Fabeae tribe. Symbionts of Vavilovia belonging to Rhizobium leguminosarum bv. viciae compose a discrete group that differs from the other strains, especially in the nucleotide sequences of the symbiotically specialised (sym) genes. Comparison of the genomes of Vavilovia strains with the reference group composed of R. leguminosarum bv. viciae strains isolated from Pisum and Vicia demonstrated that the vavilovia strains have a set of genomic features, probably indicating the important stages of microevolution of the symbiotic system. Specifically, symbionts of Vavilovia (considered as an ancestral group) demonstrated a scattered arrangement of sym genes (>90 kb cluster on pSym), with the location of nodT gene outside of the other nod operons, the presence of nodX and fixW, and the absence of chromosomal fixNOPQ copies. In contrast, the reference (derived) group harboured sym genes as a compact cluster (<60 kb) on a single pSym, lacking nodX and fixW, with nodT between nodN and nodO, and possessing chromosomal fixNOPQ copies. The TOM strain, obtained from nodules of the primitive “Afghan” peas, occupied an intermediate position because it has the chromosomal fixNOPQ copy, while the other features, the most important of which is presence of nodX and fixW, were similar to the Vavilovia strains. We suggest that genome evolution from the ancestral to the derived R. leguminosarum bv. viciae groups follows the “gain-and-loss of sym genes” and the “compaction of sym cluster” strategies, which are common for the macro-evolutionary and micro-evolutionary processes. The revealed genomic features are in concordance with a relict status of the vavilovia strains, indicating that V. formosa coexists with ancestral microsymbionts, which are presumably close to the LCA of R. leguminosarum bv. viciae.

AB - Vavilovia formosa is a relict leguminous plant growing in hard-to-reach habitats in the rocky highlands of the Caucasus and Middle East, and it is considered as the putative closest living relative of the last common ancestor (LCA) of the Fabeae tribe. Symbionts of Vavilovia belonging to Rhizobium leguminosarum bv. viciae compose a discrete group that differs from the other strains, especially in the nucleotide sequences of the symbiotically specialised (sym) genes. Comparison of the genomes of Vavilovia strains with the reference group composed of R. leguminosarum bv. viciae strains isolated from Pisum and Vicia demonstrated that the vavilovia strains have a set of genomic features, probably indicating the important stages of microevolution of the symbiotic system. Specifically, symbionts of Vavilovia (considered as an ancestral group) demonstrated a scattered arrangement of sym genes (>90 kb cluster on pSym), with the location of nodT gene outside of the other nod operons, the presence of nodX and fixW, and the absence of chromosomal fixNOPQ copies. In contrast, the reference (derived) group harboured sym genes as a compact cluster (<60 kb) on a single pSym, lacking nodX and fixW, with nodT between nodN and nodO, and possessing chromosomal fixNOPQ copies. The TOM strain, obtained from nodules of the primitive “Afghan” peas, occupied an intermediate position because it has the chromosomal fixNOPQ copy, while the other features, the most important of which is presence of nodX and fixW, were similar to the Vavilovia strains. We suggest that genome evolution from the ancestral to the derived R. leguminosarum bv. viciae groups follows the “gain-and-loss of sym genes” and the “compaction of sym cluster” strategies, which are common for the macro-evolutionary and micro-evolutionary processes. The revealed genomic features are in concordance with a relict status of the vavilovia strains, indicating that V. formosa coexists with ancestral microsymbionts, which are presumably close to the LCA of R. leguminosarum bv. viciae.

KW - Evolution of symbiosis

KW - Genomic rearrangements

KW - Horizontal gene transfer

KW - Last common ancestor (LCA)

KW - Rhizobium leguminosarum biovar viciae

KW - Symbiotic and housekeeping genes

KW - Vavilovia formosa

UR - http://www.scopus.com/inward/record.url?scp=85076276506&partnerID=8YFLogxK

U2 - 10.3390/genes10120990

DO - 10.3390/genes10120990

M3 - Article

C2 - 31805640

AN - SCOPUS:85076276506

VL - 10

JO - Genes

JF - Genes

SN - 2073-4425

IS - 12

M1 - 990

ER -