Potato virus Y transmission and quantitative detection in the stylet of aphid species

Potato virus Y (PVY), the type species of potyviruses is a destructive and a worldwide distributed virus causing important damage in different crops, particularly in potato. PVY is transmitted in a non-persis-tent manner by more than 50 different aphid species and presumably, the distal part of the stylet plays an important role in the virus transmission by these aphids. Transmission efficiency is influenced by the aphid species, the aphid feeding behavior, the virus type, strain, or isolate and environmental factors. Moreover, the type of host plant on which the aphids are feeding is also a factor that can also affect transmission efficiency yet has not been studied well so far. In this respect, the quantity of potyvirus uptake by aphid species, through probing a specific infected host plant may be correlated with the transmission efficiency. Several reports have been published reporting on the presence or even the quantity of potyviruses in individual vectors. However, they mainly report on detection or quantitation in whole aphid bodies, and only very few studies focus on virus transmission efficiency, linked to virion concentration in the stylet. An even more precise index that correlates to vector efficiency in non-per-sistent transmitted viruses is the virion concentration in the stylet tip, which is in close contact with the host tissue during the probing process. In this study, the transmission efficiency of four aphid species was evaluated. Additionally, the influence of five different host plants for rearing aphids on PVY trans-mission was assessed. The correlation between these two bioassays and virus quantity in whole aphid bodies, stylets and stylet tips was assessed using a serial dilution of PVY transcripts in a one-step real-time RT-PCR. The results confirmed that Myzus persicae transmitted PVY most efficiently (39%) and that aphids which were reared on faba bean transmitted PVY less efficient than those which were reared on Brussels sprouts, Chinese cabbage, sweet pepper, or potato. qRT-PCR tests showed that quantity of virus in stylets are a better index to evaluate vector transmission efficiency