title: Phylogenetic lineages in Vanguerieae (Rubiaceae) associated with Burkholderia bacteria in sub-Saharan Africa.
abstract: OBJECTIVE
  It is well known that mutualistic bacteria can provide substantial benefits to their host plants. However, 'how,' 'why,' and the possible applications of such an interaction are only second to the questions 'who is involved?', and 'where does it occur?'. In the coffee family (Rubiaceae), certain species closely interact with endophytic leaf bacteria that are freely distributed among the mesophyll cells. This type of interaction was recently discovered in South Africa. Our aim is to document the bacterial diversity associated with Rubiaceae ('who') and to establish the geographic range of the interaction ('where').
  
  
  METHODS
  Representatives of the Vanguerieae tribe in Rubiaceae were investigated for the presence of endophytes with special emphasis on the distributional range of the plant-bacteria association by collecting specimens from different African regions.
  
  
  RESULTS
  The interaction is found in five genera and is restricted to three major host lineages. The endophytic bacteria belong to the genus Burkholderia and are part of the plant-associated beneficial and environmental group. Some endophytes are similar to B. caledonica, B. graminis, B. phenoliruptrix or B. phytofirmans, while others are classified in OTUs that show no similarity with any previously described Burkholderia species of bacteria.
  
  
  CONCLUSIONS
  The association is not obligate from the bacterial point of view and is considered a loose and recent interaction, which is demonstrated by the fact that there is no evidence for coevolution. The geographical distribution of the association is restricted by the distributional range of the host plants covering the whole of sub-Saharan Africa.
authors.affiliation: Plant Conservation and Population Biology, KU Leuven, Leuven, Belgium.
authors.forename: Brecht
authors.initials: B
authors.lastname: Verstraete
authors.forename: Steven
authors.initials: S
authors.lastname: Janssens
authors.forename: Benny
authors.initials: B
authors.lastname: Lemaire
authors.forename: Erik
authors.initials: E
authors.lastname: Smets
authors.forename: Steven
authors.initials: S
authors.lastname: Dessein
mesh_terms: D017954:Africa South of the Sahara; D019117:Burkholderia / Q000145:classification; D018744:DNA, Plant; D060026:Endophytes / Q000145:classification; D010802:Phylogeny; D018515:Plant Leaves / Q000382:microbiology; D019666:Rubiaceae / Q000235:genetics* / Q000382:microbiology; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013559:Symbiosis / Q000235:genetics*
chemical_list: D018744:DNA, Plant
keywords: Burkholderia; Rubiaceae; bacterial leaf symbiosis; diversity; endophyte; sub-Saharan Africa