Aphid transmission of a Potexvirus, Foxtail mosaic virus, in the presence of the Potyvirus helper component proteinase

To establish successful infections, plant viruses compete with the host plants for limited resources and thus alter the physiological state of the plants. After successful infection, insect vectors are required for the transmission of some plant viruses to the next host plant. One of the largest groups of plant viruses, the potyvirus, can be transmitted by aphids. During transmission, the potyvirus protein helper component proteinase (HC-Pro) binds to the yet-to-be-defined aphid receptor on the stylet, as well as to the virus particles through the Asp-Ala-Gly (DAG) motif of the viral coat protein. Previously it was determined that a naturally occurring DAG motif in the non-aphid transmissible potexvirus, Potato aucuba mosaic potexvirus (PAMV), is functional when the HC-Pro is provided through co-infection with a potyvirus. Further, the DAG motif of PAMV can be successfully transferred to another non-aphid transmissible potexvirus, Potato virus X (PVX), to convey aphid transmission capabilities. We expand on this previous work by demonstrating, the DAG motif from two different potyviruses, Sugarcane mosaic virus and Turnip mosaic virus, as well as the DAG motif from the previous potexvirus PAMV, can be added to another non-aphid transmissible potexvirus, Foxtail mosaic virus (FoMV), to make it aphid transmissible. Transmission efficiency varied from less than 10% to over 80% depending on the DAG motif and host plant used in transmission, suggesting not all DAG motifs are equal for engineering aphid transmission. The underlying mechanisms mediating this variation still need to be explored.