Submitted to: Biomed Central (BMC) Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2006
Publication Date: 3/14/2006
Citation: Wilson, A.C., Dunbar, H.E., Davis, G.K., Hunter, W.B., Stern, D.L., Moran, N.A. 2006. A dual-genome microarray for the pea aphid, Acyrthosiphon Pisum, and its obligate bacterial symbiont, Buchnera Aphidicola. Biomed Central (BMC) Genomics. 7:50.(doi:10.1186/1471-2164-7-50). Interpretive Summary: Aphids are the number one vector of plant diseases causing huge economic losses to U.S. agriculture. These insects contain symbiotic bacteria, which are bacteria that co-exist in a beneficial way with the aphid. The best studied ‘insect-symbiont system’ is that of aphids and their primary bacterial endosymbiont Buchnera aphidicola. Buchnera inhabits specialized host cells, provides nutrients to the aphid and has co-speciated with its aphid hosts for the past 150 million years. This study examines gene expression in an aphid-symbiont system, that of the pea aphid and its resident bacteria. Very little is known of gene expression in aphids, and no study before has examined simultaneously the expression profiles of a host and its symbiont. Expression profiling of aphids, in studies such as this, will be critical for assigning newly discovered aphid genes to functional roles. In particular, because aphids possess many genes that have not been discovered, aphid genome efforts cannot rely entirely on the similarity of aphid genes to the other better-studied insect systems. Development of this dual-genome microarray represents a system that has allowed researchers to characterize genes by their expression under set conditions. Such analyses will advance efforts to identify critical pathways in aphid development. These pathways can then be targeted to reduce aphid populations and plant pathogens.
Technical Abstract: A dual-genome microarray, containing 1,862 genes, was constructed with 1,777 genes selected from the pea aphid, (Acyrthosiphon pisum), unigene set produced at the U.S. Horticultural Research Lab, Fort Pierce, Florida, gene sets from the International Aphid Genome Consortium, and 85 genes from the endosymbiotic bacterium, (Buchnera sp.), produced at University of Arizona. These arrays are the first to be used in a metagenomic approach to study gene expression under heat shock conditions in both the aphid and its endosymbiotic bacterium simultaneously. Our results showed similar heat shock responses for the same nine genes, (mopA, mopB, dnaJ, dnaK, grpE, ibpA, which function in recycling and refolding of degraded proteins in other bacteria. Plus fpr and the pseudogene yjeA, plus the aphid genes hsp70. Genes from Buchnera have been previously examined in the aphid, (Schizaphis graminum), however this is the first time heat shock responses have been examined in aphids. Additional analyses of the aphid transcripts showed significant responses of 16 fold by hsp70, plus seven other new genes with unknown functional identities. The study is the first to demonstrate the usefulness and application of using a single assay, dual-genome microarray to examine gene expression in an insect and its symbiont simultaneously. Dual microarrays such as this one are valuable tools for discovery and inferring functional roles of genes and will advance studies in identifying genes within specific biological pathways in multi-organism systems.