Submitted to: Insect Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2014
Publication Date: 4/24/2015
Citation: Johnson, A.J., Shukle, R.H., Chen, M., Srivastava, S., Subramanyam, S., Schemerhorn, B.J., Weintraub, P.G., Moniem, H., Flanders, K.L., Williams, C.E. 2015. Differential expression of candidate salivary effector proteins in field collections of Hessian fly, Mayetiola destructor. Insect Molecular Biology. 24(2):191-202. DOI: 10.1111/imb.12148. Interpretive Summary: Hessian fly is a plant-parasitic insect pest of wheat that can cause significant yield reduction in all the production areas of the United States. Damage to wheat includes irreversible stunting, rapid increase in host-cell permeability, and failure of infested plants to head. The most effective control of Hessian fly is the deployment of genetically resistant wheat. However, deployment of resistant wheat places a selection pressure on field populations that leads to the appearance of biotypes that can overcome formerly resistant wheat. Evidence is emerging that proteins secreted by gall forming plant-parasites are the effectors responsible for damage to the host plant. A large number of secreted salivary gland proteins (SSGPs), thought to be the effectors responsible for damage to wheat by Hessian fly larvae, have been documented. However, no role has been identified for these SSGPs in the Hessian fly/wheat interactions, and there is no knowledge of possible variation in the abundance of these SSGPs among different field populations. Our study revealed significant variation in abundance of some SSGPs among field populations. From these results, we hypothesize the variation is correlated with adaptation to differences in agro-ecosystem practices among the geographic regions, and its impact on population structure and evolution. Knowledge gained from this study will help scientists understand Hessian fly/wheat interactions and devise novel control strategies to ensure durable resistance to prevent yield loss due to Hessian fly. This study will benefit the agricultural community and consumers by providing improved pest control that increases yield and quality without increasing cost.
Technical Abstract: Evidence is emerging that proteins secreted by gall forming plant-parasites are the effectors responsible for systemic changes in the host plant, such as galling and nutrient tissue formation. A large number of secreted salivary gland proteins (SSGPs) that are hypothesized to be the effectors responsible for the systemic physiological changes elicited in susceptible seedling wheat by Hessian fly, Mayetiola destructor (Say), larvae have been documented. However, how the genes encoding these candidate effectors might respond under field conditions is unknown. The goal of this study was to use microarray analysis to investigate variation in SSGP transcript abundance among field collections from different geographic regions (southeastern United States, Central United States, and the Middle East). Results revealed significant variation in SSGP transcript abundance among the field collections studied. The field collections under study separated into three groups that corresponded to recently described Hessian fly populations. Patterns of differential expression of SSGPs were shared within established populations with some local adaptation. These data support previously reported correlations relating population structure in Hessian fly with differences in agro-ecosystem parameters such as deployment of resistance genes, variation in climatic conditions, and cultivation of regionally adapted wheat cultivars.