A small microbial genome: the end of a long symbiotic relationship?

Science. 2006 Oct 13;314(5797):312-3. doi: 10.1126/science.1130441.


Intracellular bacteria are characterized by genome reduction. The 422,434-base pair genome of Buchnera aphidicola BCc, primary endosymbiont of the aphid Cinara cedri, is approximately 200 kilobases smaller than the previously sequenced B. aphidicola genomes. B. aphidicola BCc has lost most metabolic functions, including the ability to synthesize the essential amino acid tryptophan and riboflavin. In addition, most retained genes are evolving rapidly. Possibly, B. aphidicola BCc is losing its symbiotic capacity and is being complemented (and might be replaced) by the highly abundant coexisting secondary symbiont.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / biosynthesis
  • Animals
  • Aphids / microbiology*
  • Aphids / physiology
  • Base Pairing
  • Buchnera / genetics*
  • Buchnera / metabolism
  • Buchnera / physiology
  • Chromosomes, Bacterial / genetics
  • Evolution, Molecular
  • Genes, Bacterial
  • Genome, Bacterial*
  • Molecular Sequence Data
  • Sequence Analysis, DNA
  • Serratia / genetics
  • Serratia / metabolism
  • Serratia / physiology
  • Symbiosis*
  • Tryptophan / biosynthesis


  • Amino Acids
  • Tryptophan

Associated data

  • GENBANK/AY438025
  • GENBANK/CP000263