In vitro Culture of Grapevine Infected by Closterovirus Type III*

Herbaceous cuttings collected in autumn from a closterovirus type III infected grapevine plant (cv. Merlot) were micropropagated in vitro. Results showed thai cultured plants did not present any leaf symptoms even if they grow slower than healthy control plants by a ratio of about 1/2. The virus concentration, as estimated by electron microscopy, was found constant when observed fortnightly over a period of 75 days. The number of particles was about 30 times higher than in viral preparations obtained from infected material collected in the field.