Bioinformatic analysis of pea aphid salivary gland transcripts

Abstract

Pea aphids (Acyrthosiphon pisum) are sap-sucking insects that feed on the phloem sap of some plants of the family Fabaceae (legumes). Aphids feed on host plants by inserting their stylets between plant cells to feed from phloem sap in sieve elements. Their feeding is of major agronomical importance, as aphids cause hundreds of millions of dollars in crop damage worldwide, annually. Salivary gland transcripts from plant-fed and diet-fed pea aphids were studied by RNASeq to analyze their expression. Most transcripts had higher expression in plant-fed pea aphids, likely due to the need for saliva protein in the aphid/plant interaction. Numerous salivary gland transcripts and saliva proteins have been identified in aphids, including a glutathione peroxidase. Glutathione peroxidases are a group of enzymes with the purpose of protecting organisms from oxidative damage. Here, I present a bioinformatic analysis of pea aphid expressed sequence tag libraries that identified four unique glutathione peroxidases in pea aphids. One glutathione peroxidase, ApGPx1 has high expression in the pea aphid salivary gland. Two glutathione peroxidase genes are present in the current annotation of the pea aphid genome. My work indicates that the two genes need to be revised.