Host plant selection and virus transmission by Rhopalosiphum maidis are conditioned by potyvirus infection in Sorghum bicolor

Many plant viruses are significant pathogens that are able to utilize arthropod vectors to infect a vast range of host plants, resulting in serious economic damage to world food crops. One such crop is Sorghum bicolor, grain sorghum, which is the fifth most important global cereal crop, it is grown for human consumption, animal feed, and biofuel. In this study, the Potyviruses Johnsongrass mosaic virus (JGMV), Maize dwarf mosaic virus (MDMV), Sugarcane mosaic virus (SCMV), and Sorghum mosaic virus (SRMV) were tested for their rates of transmission into tissues of S. bicolor by the corn leaf aphid, Rhopalosiphum maidis . In addition, virus infected and non-infected S. bicolor plants were assessed for their effects on R. maidis host plant selection behavior. Further, the propagation of each virus (viral ssRNA copy number) in infected plants was determined using qPCR amplification of viral coating protein gene fragments. The mean rate of JGMV transmission into S. bicolor plants by R. maidis was significantly lower than transmission of MDMV, SCMV, and/or SRMV. Sorghum bicolor plants infected with MDMV, SCMV or SRMV also attract significantly more R. maidis than non-infected plants. JGMV-infected plants do not effect a similar change in R. maidis plant choice preference. The preference of non-viruliferous R. maidis toward S. bicolor plants infected with MDMV, SCMV or SRMV, and lack of such attraction by JGMV-infected plants may play a role in virus transmission strategy and efficiency by the vector.