Location: Hard Winter Wheat Genetics ResearchTitle: Transcriptomic analyses of the secreted proteins from the salivary glands of the wheat midge larvae
|AL-JBORY, ZAINAB ALI - Kansas State University|
|ANDERSON, KIRK - North Dakota State University|
|HARRIS, MARION - North Dakota State University|
|MITTAPALLI, OMPRAKASH - The Ohio State University|
|WHITWORTH, R. JEFF - Kansas State University|
Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/22/2018
Publication Date: 4/5/2018
Citation: Al-Jbory, Z., Anderson, K.M., Harris, M.O., Mittapalli, O., Whitworth, R., Chen, M. 2018. Transcriptomic analyses of the secreted proteins from the salivary glands of the wheat midge larvae. Journal of Insect Science. 18(1):17. https://doi.org/10.1093/jisesa/iey009.
Interpretive Summary: The wheat midge is a destructive insect pest that attacks wheat kernels during the grain filling stage of growth. Wheat midge larvae inject saliva into plant tissues during feeding. Some of the components in the saliva are thought to reprogram host metabolic pathways and facilitate parasitism by the larvae. In this study, we did an analysis of genes expressed in the salivary glands of larvae during feeding. We found that ~25% of genes encode proteins with a typical secretion signal peptide. These secreted salivary gland proteins (SSGPs) can be classified into 97 groups based on their sequence similarity. The identification of the genes encoding SSGPs provides a foundation for further studies on the biological and biochemical functions of these proteins as well as for comparative analyses among different insects that share similar feeding mechanisms.
Technical Abstract: Both the wheat midge (Sitodiplosis mosellana) and the Hessian fly (Mayetiola destructor) belong to a group of insects called gall midges (Diptera: Cecidomyiidae) and both are destructive pests of wheat. From Hessian fly larvae, a large number of genes have been identified to encode Secreted Salivary Gland proteins (SSGPs), which are presumably critical for the insect to feed on and manipulate host plants. For comparison, we conducted an analysis on transcripts encoding SSGPs from the first instar larvae of the wheat midge. We discovered that approximately 25% of ~3,500 cDNA clones obtained from dissected salivary glands encoded SSGPs. The SSGPs were grouped into 97 groups based on sequence homology. Among the SSGP-encoding transcripts, 235 encoded unique proteins with no sequence similarity to any known protein. Most SSGP-encoding genes appear under strong selection for mutations that generate amino acid changes within the coding region. Identification and characterization of SSGPs in wheat midge larvae provide a foundation for future work to reveal molecular mechanisms behind wheat midge - wheat interactions and the role of these putative effector proteins in insect virulence. Availability of the SSGP transcripts will also facilitate comparative analyses of insect effectors from related species.