Pathogenic Potential of Verticillium Albo-Atrum Protoplasts

ABSTRACT

A strepzyme lytic to Verticillium albo-atrum mycelium was obtained from a wild Streptomyces isolate cultured from local soil. Peak strepzyme production in a liquid mineral medium was 5 da. Treatment of 1-da-old V. albo-atrum mycelium with concentrated, desalted strepzyme stabilized in 0.7 m MgSO₄ yielded maximum (ca. 95%) protoplast release in 20 h. The sequence of protoplast release, observed by phase contrast microscopy, was similar to that reported for other fungi. Equal numbers of V. albo-atrum protoplasts or conidia introduced into root xylem of Verticillium-susceptible eggplants, tomatoes, and yellow-poplar seedlings resulted in vascular disease in eggplants and tomatoes only. Typical V. albo-atrum mycelium was recovered from diseased tissue by culture on a Verticillium-seleclive medium.

Key Words:

• Verticillium albo-atrum
• protoplast
• vascular disease
• lysis