Transcriptome analysis of the salivary glands of potato leafhopper, Empoasca fabae
The potato leafhopper, Empoasca fabae, is a destructive pest of economic crops in the United States and Canada, where it causes damage known as hopperburn (tip yellowing of leaves). The saliva injected into leaves leads to decrease in photosynthetic rate, stunting and chlorosis associated with hopperburn. Although E. fabae saliva is known to induce plant responses, little to no knowledge exists of saliva composition at the molecular level.   Results  We subjected the sialtranscriptome of E. fabae to Roche 454-pyrosequencing.  Our effort yielded 255,491 transcriptomic reads, which were assembled into 34,689 high quality expressed sequence tags (ESTs). Of these ESTs A Hhigh number of sequences,( 77.94%)  showed high similarity to other insect species in GenBank. The majority of sequences showed similarity with T. castaneum (33.7%), D. melanogaster (30%) and A. pisum (30%). KEGG analysis predicted the presence of pathways for purine and thiamine metabolism, T cell receptor signalling, biosynthesis of secondary metabolites, drug metabolism, and lysine degradation. Pfam analysis showed a high number of  cellulase and carboxylesterase protein domains to be present in the sialotranscriptome. Sequences with homology to endo-beta-glucanase, alpha-amylase and chitinase were also detected; these enzymes are known to be present in insect saliva.  Conclusions  This is the first study to characterize the sialotranscriptome of E. fabae.  Due to the status of this insect as an economic pest, knowledge of which genes are active in the salivary glands is important for understanding the impact that E. fabae has on its host plants.