Low and Homogeneous Copy Number of Plasmid-Borne Symbiont Genes Affecting Host Nutrition in Buchnera Aphidicola of the Aphid Uroleucon Ambrosiae

Mol Ecol. 2003 Apr;12(4):1095-100. doi: 10.1046/j.1365-294x.2003.01782.x.


The bacterial endosymbiont of aphids, Buchnera aphidicola, often provides amino acids to its hosts. Plasmid amplification of leucine (leuABCD) and tryptophan (trpEG) biosynthesis genes may be a mechanism by which some Buchnera over-produce these nutrients. We used quantitative polymerase chain reaction to assess the leuABCD/trpEG copy variability within Uroleucon ambrosiae, an aphid with a wide diet breadth and range. Both leuABCD and trpEG abundances are: (i) similar for aphids across 15 populations, and (ii) low compared to Buchnera from other aphid species (particularly trpEG). Consequently, the plasmid location of trpEG combined with Buchnera's chromosomal polyploidy may functionally limit, rather than increase, tryptophan production within Uroleucon ambrosiae.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Aphids / microbiology*
  • Buchnera / genetics*
  • DNA Primers
  • Genetic Variation*
  • Leucine / biosynthesis
  • Leucine / genetics*
  • Polymerase Chain Reaction
  • Symbiosis*
  • Tryptophan / biosynthesis
  • Tryptophan / genetics*
  • United States


  • DNA Primers
  • Tryptophan
  • Leucine