Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/30/2004
Publication Date: 6/30/2004
Citation: Burrows, M.E., Smith, D., Benson, E., Gray, S.M. 2004. The genetics of luteovirus transmission in the aphid vector, schizaphis graminum. Phytopathology. 94:S12.
Technical Abstract: The circulative, persistent transmission of viruses that cause barley yellow dwarf is well described, but the genetics of transmission in aphids is not well understood. Clonal variants of Schizaphis graminum were identified that differ in transmission phenotype. Sexual forms of clone Sg-F, which transmits BYDY-SGV and CYDV-RPV, and clone Sg-SC, which does not transmit either virus, were used to generate 11 F1 hybrids. F1 hybrids segregated independently for their ability to transmit SGV (0% to 83%) and RPV (0% to 90%). Sexual forms of the F1 hybrids were randomly mated and 46 F2 hybrids obtained. The F2 hybrids also segregate independently for their ability to transmit SGV (0% to 100%) and RPV (0% to 94%). These data suggest transmission of RPV and SGV is not controlled by the same loci. Purified RPV was injected directly into the hemocoel of three F1 hybrids that do not transmit RPV. Transmission efficiency was not significantly improved, suggesting the gut is not a major barrier to transmission, although it may reduce efficiency. A real time PCR method was developed to quantify RPV in whole aphids and aphid tissues during the transmission process. Sg-F individuals ingested an average of 1.9 × 10(^8) copies of RNA while Sg-SC contained an average of 8.9 × 10(^8) copies of RNA during a 48 hour acquisition access period. Sg-SC aphids ingested and retained more virus than Sg-F aphids, but they were unable to transmit RPV to a susceptible host. Current efforts are focused on identifying and quantifying virus movement across the different barriers within the vector.