Potato leafhopper salivary gland Transcriptome or Gene expression. insect metagenome

The potato leafhopper, Empoasca fabae, is a pest of economic crops in the United States and Canada, where it causes damage known as hopperburn. Saliva, along with mechanical injury, leads to decreases in gas exchange rates, stunting and chlorosis. Although E. fabae saliva is known to induce plant responses, little knowledge exists of saliva composition at the molecular level. We subjected the salivary glands of E. fabae to Roche 454-pyrosequencing which resulted significant number (30,893) of expressed sequence tags including 2,805 contigs and 28,088 singletons. A high number of sequences (78%) showed similarity to other insect species in GenBank, including T. castaneum, D. melanogaster and A. pisum. KEGG analysis predicted the presence of pathways for purine and thiamine metabolic, biosynthesis of secondary metabolites, drug metabolism, and lysine degradation. Pfam analysis showed a high number of cellulase and carboxylesterase protein domains. Expression analysis of candidate genes (alpha amylase, lipase, pectin lyase, etc.) among different tissues revealed tissue-specific expression of digestive enzymes in E. fabae. This is the first study to characterize the sialotranscriptome of E. fabae and the first for any species in the family of Cicadellidae. Due to the status of these insects as economic pests, knowledge of which genes are active in the salivary glands is important for understanding their impact on host plants. Potato leafhoppers were collected on alfalfa from the Western Maryland Research and Education Center in Keedysville, Maryland on the morning of June 30, 2009. Leafhoppers were caught with sweep nets, and individual adult E. fabae were aspirated into cages containing excised alfalfa sprouts. The cages were then brought back to the laboratory for salivary gland dissection in the afternoon.