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.

ENDS

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    Credit: Professor Angela Douglas, Cornell University (896KB)

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.

About the University of York's Department of Biology

It is one of the leading centres for biological teaching and research in the UK. In the recent Research Assessment Exercise, the Department was equal first among broad spectrum bioscience departments. The Department both teaches degree courses and undertakes research across the whole spectrum of modern Biology, from molecular genetics and biochemistry to ecology.

About BBSRC

BBSRC is the UK funding agency for research in the life sciences. Sponsored by Government, BBSRC annually invests around £450 million in a wide range of research that makes a significant contribution to the quality of life in the UK  and beyond and supports a number of important industrial stakeholders, including the agriculture, food, chemical, healthcare and pharmaceutical sectors.

BBSRC provides institute strategic research grants to the following:

The Babraham Institute, Institute for Animal Health, Institute for Biological, Environmental and Rural Studies (Aberystwyth University), Institute of Food Research, John Innes Centre, The Genome Analysis Centre, The Roslin Institute (University of Edinburgh) and Rothamsted Research. The Institutes conduct long-term, mission-oriented research using specialist facilities. They have strong interactions with industry, Government departments and other end-users of their research.

For more information see: www.bbsrc.ac.uk

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