ARS | Publication request: Expression and RNA interference of salivary polygalacturonase genes in Lygus lineolaris (Miridae: Hemiptera)

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 13, 2009
Publication Date: October 6, 2010
Citation: Walker III, W.B., Allen, M.L. 2010. Expression and RNA interference of salivary polygalacturonase genes in Lygus lineolaris (Miridae: Hemiptera). Journal of Insect Science. 173(10):1-13.

Interpretive Summary: Three genes responsible for digestive salivary enzymes were identified from the tarnished plant bug, Lygus lineolaris. This insect damages plants when it injects saliva into the growing leaves, stems, flowers, and fruits or seeds. The research described shows that the genes are active in the salivary glands and not other insect parts. Unexpectedly, the enzymes seem to be less active when the insects feed on cotton plants than when they eat artificial rearing diet. When a recently described method for decreasing gene activity, RNA interference, was performed on tarnished plant bugs using the saliva enzyme genes, one of the three genes exhibited decreased activity levels. This is the first use of RNA interference in Lygus, and additional experiments may identify genes that can be used to develop insect control strategies.

Technical Abstract: Three genes encoding polygalacturonase (PG) have been identified in Lygus lineolaris (Palisot de Beauvois). Earlier studies showed that the three PG gene transcripts are only expressed in the feeding stages of Lygus. In this report, we show that all three transcripts are specifically expressed in salivary glands indicating that PGs are salivary enzymes. Transcriptional profiles of the three PGs were evaluated with respect to diet, comparing live cotton plant material to artificial diet. PG2 transcript levels were consistently lower in cotton-fed insects than those reared on artificial diet. RNA interference was used to knock down expression of PG1 mRNA in adult salivary glands providing the first demonstration of the use of this method in the non-model insect, L. lineolaris.