Four single-sporangium isolates of were inoculated on 14 different plant species to determine their ability to infect and reproduce in each host and their ability to transmit two tobacco necrosis virus isolates. Two isolates, one from lettuce and one from tomato, were able to reproduce in most hosts and transmitted both tobacco necrosis virus isolates to all hosts. By contrast, a mustard isolate reproduced in only six species and was not a vector of tobacco necrosis virus. An oat isolate reproduced in six species (three in common with the mustard) and was a poor vector, transmitting one tobacco necrosis virus isolate to only two hosts and not transmitting the other tobacco necrosis virus isolate to any host.

Zoospores of the different fungus isolates were mixed with suspensions of virus, washed, negatively stained, and examined in the electron microscope. Virus adsorbed tightly to the surface membranes (plasmalemma of the body and axonemal sheath) of zoospores of isolates that transmitted it, but not to those of the non-vector (mustard) isolate. Zoospores of the poor vector (oat) isolate adsorbed fewer particles of the tobacco necrosis virus isolate they transmitted than did those of good vectors and did not adsorb the other tobacco necrosis virus isolate. Most, but not all, of the observed specificity of transmission of tobacco necrosis virus seems to be associated with the ability or inability of zoospores to adsorb the virus on their surfaces. None of these isolates adsorbed particles of turnip yellow mosaic, tomato bushy stunt or cucumber necrosis viruses. zoospores also adsorbed satellite virus particles. Zoospores of adsorbed particles of cucumber necrosis virus, but not of tobacco necrosis virus, to their surfaces. Thus, acquisition consisted of a tight adsorption of virus to the zoospore surface membranes in each of the three known instances of this type of relationship.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error