Genome of crop pest reveals nature of a complex symbiosis
Posted on 24 February 2010
Researchers at the Department of Biology at 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.
This unexpected finding provides a route by which potential biological controls of the aphid may be developed
Dr Gavin Thomas
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 Biotechnology and Biological Sciences Research Council /ANR Systems Biology grant METNET4SysBio www.metnet4sysbio.org which is coordinated in York by Dr. Gavin Thomas and which includes the groups of Dr. Hubert Charles and Dr. Marie-France Sagot in Lyon. The project was initiated by Prof. Angela Douglas, a longstanding member of the Department of Biology at York, who is now at Cornell University, USA.
Notes to 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.
- The University of York’s Department of Biology 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.
- The Biotechnology and Biological Sciences Research Council (BBSRC) is the UK funding agency for research in the life sciences. Sponsored by Government, BBSRC annually invests around £420 million in a wide range of research that makes a significant contribution to the quality of life for UK citizens and supports a number of important industrial stakeholders including the agriculture, food, chemical, healthcare and pharmaceutical sectors. BBSRC carries out its mission by funding internationally competitive research, providing training in the biosciences, fostering opportunities for knowledge transfer and innovation and promoting interaction with the public and other stakeholders on issues of scientific interest in universities, centres and institutes.
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