Submitted to: Journal of Insect Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/2004
Publication Date: 5/15/2004
Citation: Liu, X., Fellers, J.P., Wilde, G.E., Chen, M. 2004. Characterization of genes expressed in the salivary glands of the hessian fly, mayetiola destructor (say)#. Journal of Insect Biochemistry and Molecular Biology. 34(3), 229-237. Interpretive Summary: Fluid-sucking insects including the Hessian fly inject substances through salivary glands into host plants to partially digest food before sucking the juice up, and/or to manipulate host metabolic pathways for the advantage of the insect survival. This paper reports two new genes isolated from Hessian fly salivary glands. These genes encode proteins with a special sequence called secretion signal. The secretion signal can guide a protein to move out of the salivary glands, a necessary condition in order for a protein to be injected into host plants. Therefore, the proteins encoded by the genes reported in this manuscript are likely injected into host plants by the Hessian fly and could play important roles in Hessian fly development in wheat plants.
Technical Abstract: Two genes, Hfsp-31 and Hfsp-35, and several related cDNAs were cloned and characterized from the salivary glands of Hessian fly [Mayetiola destructor (Say)] larvae. The Hfsp-31 gene contains one small intron (89 bp) and encodes a putative protein with 79 amino acids. The first 18 amino acids constitute a putative secretion signal peptide. Thus, this gene can encode a mature protein of 7.1 KD with an isoelectric point of 9.63. The Hfsp-35 gene contains 3 small introns and encodes a putative protein with 234 amino acids. The first 19 amino acids constitute a putative secretion signal peptide. Therefore, the Hfsp-35 gene can encode a mature protein of 23.4 KD with an isoelectric point of 5.91. Each gene encodes a protein with a secretion signal at the N-terminal. Blot analysis revealed that both of the genes are primarily expressed in the salivary glands of Hessian fly larvae, the feeding stage of the insect. These observations are consistent with the possibility that the proteins encoded by them are secreted into host plants during feeding. Even though both of the genes were mainly expressed in salivary glands, the expression profiles between them were quite different in insects at different developmental stages. The Hfsp-31 gene was expressed in all larvae of different instars while the Hfsp-35 gene was almost exclusively expressed in the first instar larvae, suggesting that the proteins encoded by these two genes may perform very different functions.