title: A novel symbiovar (aegeanense) of the genus Ensifer nodulates Vigna unguiculata.
abstract: BACKGROUND
  Cowpea (Vigna unguiculata) forms nitrogen-fixing root nodules with diverse symbiotic bacteria, mainly slow-growing rhizobial species belonging to the genus Bradyrhizobium, although a few studies have reported the isolation of fast-growing rhizobia under laboratory and field conditions. Although much research has been done on cowpea-nodulating bacteria in various countries around the world, very limited information is available on cowpea rhizobia in European soils. The aim of this study was to study the genetic and phenotypic diversity of indigenous cowpea-nodulating rhizobia in Greece.
  
  
  RESULTS
  The genetic diversity of indigenous rhizobia associated with cowpea was investigated through a polyphasic approach. ERIC-PCR based fingerprinting analysis grouped the isolates into three groups. Based on the analysis of the 16S rRNA genes, IGS and on the concatenation of six housekeeping genes (recA, glnII, gyrB, truA, thrA and SMc00019), rhizobial isolates were classified within the species Ensifer fredii. However, symbiotic gene phylogenies, based on nodC, nifH and rhcRST genes, showed that the Ensifer isolates are markedly diverged from type and reference strains of E. fredii and formed one clearly separate cluster. The E. fredii strains were able to nodulate and fix nitrogen in cowpea but not in soybean and common bean.
  
  
  CONCLUSIONS
  The present study showed that cowpea is nodulated under field conditions by fast-growing rhizobia belonging to the species E. fredii. Based on the phylogenies, similarity levels of symbiotic genes and the host range, the Ensifer isolates may constitute a new symbiovar for which the name 'aegeanense' is proposed. © 2017 Society of Chemical Industry.
authors.affiliation: Laboratory of General and Agricultural Microbiology, Department of Crop Science, Agricultural University of Athens, Athens, Greece.
authors.forename: Anastasia P
authors.initials: AP
authors.lastname: Tampakaki
authors.affiliation: Laboratory of General and Agricultural Microbiology, Department of Crop Science, Agricultural University of Athens, Athens, Greece.
authors.forename: Christos T
authors.initials: CT
authors.lastname: Fotiadis
authors.affiliation: Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, Athens, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Ntatsi
authors.affiliation: Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, Athens, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Savvas
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D006115:Greece; D010802:Phylogeny; D053204:Root Nodules, Plant / Q000382:microbiology*; D042181:Sinorhizobium fredii / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D012988:Soil Microbiology; D013559:Symbiosis; D000070658:Vigna / Q000382:microbiology* / Q000502:physiology
chemical_list: D001426:Bacterial Proteins
keywords: Ensifer/Sinorhizobium; MLSA; T3SS; cowpea; phylogeny; symbiovar