Transmission of tobacco stunt virus by Olpidium brassicae

Abstract

When tobacco ( Nicotiana tabacum L. var. Bright Yellow) was seeded in stunt-in-fested soil which had dried for 9–12 years, the plants became infected with stunt. Stunt resulted when zoospores or resting sporangia of Olpidium brassicae (Wor.) Dang. were transferred from stunt-infected to healthy tobacco, but not when tobacco stunt virus (TSV) alone was added to roots of tobacco seedlings. Stunt did not result if viruliferous zoospores were killed by 10 minutes at 55°C, 24 hours at −10°, 1-phenylthiosemicarbazide, sodium dithiosemicarbazide, oxine, or salicylaldoxime. None of these treatments inactivated virus used as inoculum. A TSV-free strain of Olpidium from tobacco became viruliferous when added to roots of tobacco mechanically inoculated with TSV on the leaves. Drainage water from tobacco plants with TSV and Olpidium contained Olpidium and virus and was infective to healthy tobacco, but the drainage water from plants with TSV without Olpidium was not.