Genome of crop pest reveals nature of a complex symbiosis
24 February 2010
New research into the genome sequence of a major feed pest, funded in part by a joint BBSRC/ANR initiative, is providing an unprecedented opportunity both to understand its biology and to help to develop biological methods of control - with significant implications for food security.
Researchers at the Department of Biology at the University of York, led by Dr Gavin Thomas, were involved in the community-based annotation of the genome of the pea aphid, Acyrthosiphon pisum, focusing on its metabolism.
The genome sequence has been completed by a team headed by Stephen Richards at Baylor College of Medicine Human Genome Sequencing Center in Houston Texas. The findings are published in the latest edition of PLoS Biology and in two companion papers in a special issue of Insect Molecular Biology dedicated to interpretation of the aphid genome.
All aphids live on a single foodstuff - the phloem sap of plants, even though it is nutritionally poor in amino acids. The aphid overcomes this through the formation of an obligate symbiotic association with a bacterium called Buchnera aphidicola. The aphid develops special cells to host the bacteria and feeds them with sugars, producing the essential amino acids.
Dr Thomas said: "During annotation of the aphid genome, it became apparent that the symbiosis was potentially more complex than previously thought. The aphid, uniquely for an animal, lacks particular genes that are required for the recycling and excretion of excess nitrogen during metabolism."
Analysis of the genes and computational modelling of the combined metabolic functions of these two components of the organism revealed that it is likely that the bacterium also functions as a sink for the excess nitrogen. It is able to recycle some of this nitrogen and return it to the aphid in a useable form.
Dr Thomas added: "This unexpected finding extends the complexity of the interactions between the two partners in the symbiosis. It provides a route by which potential biological controls of the aphid may be developed."
The collaborative study involved Dr. Sandy Macdonald, Peter Ashton and Dr Thomas at York working with colleagues in INRA Lyon, Cornell University and University of Miami.
The York and Lyon component of the research was funded through the BBSRC/ANR Systems Biology initiative.
Notes for editors
The paper in PLoS Biology is: The International Aphid Genomics Consortium (2010) Genome Sequence of the Pea Aphid Acyrthosiphon pisum. PLoS Biol 8(2):e1000313. doi:10.1371/journal.pbio.1000313.
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