Studies on the virus-vector relationships of different isolates of Potato Virus Y strains and their three aphid vectors on potato

PVY is transmitted by different aphid species in a non-persistent manner. Green peach aphid (Myzus persicae Sulzer) is the most efficient PVY vector but bird cherry oat aphid (Rhopalosiphum padi L.) and potato aphid (Macrosiphum euphorbiae Thomas) also contribute to PVY transmission in many potato production areas. We conducted transmission studies with the three above mentioned aphid species to assess transmission efficiency for different isolates of the same strain of PVY. Transmission efficiency was defined as percentage of infected plants following inoculation. Nineteen treatments included three PVY strains (PVY^O, PVY^N:O, PVY^NTN), two isolates for each strains (Oz and NY31 for O; Alt and NY4 for N:O; N4 and NY29 for NTN), 3 aphid species and sham inoculation. We used 10 test plants per treatment, 10 aphids per plant and the experiment was repeated five times. Five weeks after aphid inoculation, we tested recipient plants with quantitative DAS-ELISA to assess infection percentage as well as to measure virus titer. In addition, subsamples of ELISA-positive recipient plants were tested with RT-PCR using a multiplex primer to confirm desired strains. Transmission efficiency varied according to aphid species and different isolates of strains. Isolates of NTN were transmitted with highest efficiency followed by isolates of O and N:O. In addition, bird cherry oat aphid transmitted PVY with high efficiency which is not consistent with previous literature. Implications of our finding will be discussed.