Effect of cesium ions on the mycelium growth and zoospores motility in the oomycete Phytophthora infestans

Summary Oomycetes are a group of parasitic eukaryotic microorganisms infecting plant and animal hosts worldwide. Many of those, for example, the crop parasite Phytophthora infestans , have a considerable economic impact. Previously we revealed the unexpected diversity of ion channels that could participate in the potassium transport in oomycetes. In the present study, we investigated the effects of cesium ions, which are known to nonspecifically block the activity of membrane proteins involved in the potassium transport, on the growth of Ph. infestans mycelium and motility of its zoospores. We showed that the addition of 3–24 mM cesium chloride to the culturing medium inhibited the oomycete growth on agar plates. Moreover, the application of 6 and 12 mM CsCl to zoospores substantially reduced the velocity of their movement in a liquid medium. The results indicate an important role of potassium transport at the different stages of Ph. infestans life cycle.