Submitted to: BioMed Central (BMC) Cell Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/8/2006
Publication Date: 3/10/2006
Citation: Sabater-Munoz, B., Legeai, R., Rispe, C., Bonhomme, J., Dossat, C., Duclert, A., Gauthier, J.P., Giblot-Ducray, D., Hunter, W.B., Dang, P.M., Martinez-Torres, D., Moya, A., Nakabachi, A., Prunier-Leterme, N., Rahbe, Y., Simon, J.C., Stern, D., Wincker, P., Tagu, D. 2006. Large-scale gene discovery in the pea aphid Acyrthosiphon Pisum (Hemiptera). BioMed Central Genome Biology. 7:R21. doi:10.1186/gb-2006-7-3-r21 Interpretive Summary: Genetic analyses, which identify genes and proteins, their functions, and the biological pathways they build have greatly advanced human medicine, genetics, and a basic understanding of the relatedness of all living organisms. The need to identify a model organism with ancient ancestry within the insects resulted in the selection of the Pea aphid, by the International Aphid Genomics Consortium. The Pea aphid is used in lab research around the world and has unique biology and physiology that will permit researchers to increase our understanding of insect, animal, and human genetics. Using a large-scale approach researchers produced over 40,000 sequences from different life stages, (nymphs and adults), as well as from various organs, (antennae, brain, alimentary tract) and have identified thousands of genes and proteins. Approximately a third of all the genes being expressed in pea aphid were identified. Advanced studies in aphids, such as this, will also aid studies of other Hemipterans (ie. aphids, leafhoppers, whiteflies, psyllids, mealybugs) all of which are important agricultural pests. These findings will also aid the development of newer, more environmentally friendly management strategies. The unified, international effort, demonstrates the importance of this approach and highlights the fact that the benefits which will emerge from this project will be important for many programs around the world.
Technical Abstract: Aphids are the leading pest in agricultural crops spreading numerous plant diseases. To obtain a working overview of the genes controlling aphid survival and reproduction we chose to analyze aphid gene expression by conducting large-scale expressed sequence tag (EST) analysis using the model aphid species, Acyrthosiphon pisum. Sequencing was performed from six different biological sources representing a broad range of tissues and organs involved in trophic adaptation, dispersal, disease transmission and reproduction. A catalogue of 12,082 unique transcripts was derived from the 40,904 high quality annotated ESTs and characterized for codon bias, tissue-specific expression, and potential functions. A strong A/T bias was found mostly at the 3rd codon position, indicating a major compositional shift between Diptera and Hemiptera (Drosophila are G/C rich at the third codon position). An in silico profiling pattern allowed the characterization of 135 transcripts specific to different pea aphid tissues, mainly for bacteriocytes (specialized aphid cells involved in symbiosis with the bacteria Buchnera) and for parthenogenetic embryos. These two tissues fulfil specific cellular functions involved in symbiotic interaction and embryogenesis respectively. Sequence comparisons demonstrated that the pea aphid unique transcript catalogue represents an efficient genomic resource for other aphid species belonging to different tribes, like the plant pests Toxoptera citricida or Rhopalosiphum padi. However, a high proportion of the pea aphid unique transcripts still correspond to orphan genes, and are of unknown function. This reflects the lack of genomic knowledge for Hemipteran species. This international project is one of the first to address the genetics of the Hemiptera, one of the more ancient lineages of insects, and begins to fill the gap towards a better understanding of these important agricultural pests.