Résumé
We have recently shown that cauliflower mosaic virus (CaMV) forms precisely at the aphid vectors' arrival on its host plant specific transmission morphs. Artificial inhibition and induction of their formation decreases and increases transmission rates, respectively. Such a behavior suggests that CaMV perceives – probable via the plant's sensory systems – the presence of the vector and uses it to control its own transmission. One important question emerging from these results is whether other vector-transmitted viruses also control their transmission by sensing arrival of their vector. To investigate this question, we started to explore transmission of turnip mosaic virus (TuMV), which is also aphid-vectored, but entirely unrelated to CaMV. Using protoplasts purified from infected plants, we found that calcium channel inhibitors decreased aphid transmission of both viruses. On the other hand, azide treatment increased transmission of CaMV, but not of TuMV. Finally, incubation of protoplasts with the reactive oxygen species (ROS) hydrogen peroxide increased dramatically transmission of TuMV, but not of CaMV. Thus it seems that calcium signaling is involved in transmission activation of both viruses, but ROS signaling only in activation of TuMV transmission. This might indicate that reaction pathways diverge after a common calcium-mediated step. Taken together, our results indicate that with TuMV another virus is able to react on the presence of the vector on the host plant. This is a first step towards generalization of real-time “vector-sensing” and prompt coordination of transmission by viruses.