Full text loading...
Abstract
A mutant (dm-1a) obtained from colonies of a diseased isolate (d-1a) of Helminthosporium victoriae carried the causal agent of disease but snowed almost no symptoms. Typical disease symptoms were produced in healthy H. victoriae after hyphal contact with the diseased mutant (dm-1a). Hence, the character responsible for suppression of severe disease symptoms in the mutant did not appear to be transmitted with the agent of disease. Healthy mutant cultures that did not carry the causal agent of disease were obtained by isolation of hyphal tips from the diseased mutant. Such cultures inoculated with a second diseased isolate (d-1 b) remained nearly symptomless but were capable of transmitting the disease to healthy cultures. The diseased mutant (dm-1 a) inoculated with diseased isolate d-1b usually transmitted only d-1 a to healthy cultures and the diseased mutant (dm-1 b) inoculated with d-1 a usually transmitted only d-1 b to healthy cultures. This indicates that the two agents tend to be mutually exclusive.
- Accepted:
- Published Online: