Submitted to: Journal of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 3, 2010
Publication Date: March 1, 2011
Citation: Cilia, M., Tamborindeguy, C., Fish, T., Howe, K.J., Thannhauser, T.W., Gray, S.M. 2011. Genetics coupled to quantitative intact proteomics links heritable aphid and endosymbiont protein isoform expression to polerovirus transmission. Journal of Virology. 85(5):2148-2166. Interpretive Summary: Yellow dwarf viruses are responsible for significant economic disease loss in all major cereal crops and despite intensive efforts, there are few consumer accepted cultivars with effective virus resistance. Disease management options are limited to various cultural control practices that are aimed at controlling or avoiding aphid vector populations as a way to reduce the spread of the virus into and within the crop. The effectiveness of these cultural control strategies is dependent upon knowing when the potential vectors are present and which of the potential aphid vector species is responsible for the bulk of the virus transmission. Species and populations within a species of aphid can differ drastically in their ability to transmit a single virus. Our fundamental studies on how the virus is transmitted by aphids have identified the various virus and aphid genes and proteins that are involved in the transmission process. This manuscript describes the identification of a set of proteins present in the aphid that differ slightly depending on whether the aphid can or cannot transmit virus. We have shown that combining aphid genetic techniques with proteomic methods, we can identify multiple proteins in an aphid that are linked to efficient virus transmission. These proteins define specific tissues and biological pathways in the aphid that are targets for disruption of the normal virus-aphid interactions and prevention of virus transmission. These proteins are also potential markers to determine the risk that any aphid is a virus disease vector.
Technical Abstract: Yellow dwarf viruses in the family Luteoviridae, such as Cereal yellow dwarf virus-RPV (CYDV-RPV), are vectored by aphids and cause the most economically important virus disease of cereal crops worldwide. The identification of aphid proteins mediating virus transmission will better define transmission mechanisms and should facilitate the development of virus management strategies. Schizaphis graminum genotypes that differ in their ability to transmit CYDV-RPV were compared using 2-D difference gel electrophoresis (DIGE) and differentially expressed proteins were identified by mass spectrometry. Proteins from the aphid’s obligate and maternally-inherited bacterial endosymbiont, Buchnera, were identified and surprisingly, the isoelectric points of the Buchnera proteins varied according to transmission phenotype, not maternal lineage. Aphid proteins involved in energy metabolism, membrane trafficking and the cytoskeleton were also among those identified as differentially expressed between transmission competent and transmission refractive aphids. Our combined genetics and DIGE approach made it possible to predict where the proteins may be expressed in refractive aphids with different barriers to transmission. At least eight aphid proteins were expressed as heritable, isoelectric point isoform pairs, one derived from each parental lineage. In the F2 genotypes, the expression of isoforms derived from the competent parental lineage aligned with the virus transmission phenotype with high precision. Thus, these isoforms are candidate biomarkers for CYDV-RPV transmission in S. graminum.