Properties of cell cultures containing the citrus exocortis viroid

Cell and protoplast-derived callus and suspension cultures from healthy and citrus exocortis viroid (CEV)-infected tomato tissue have been established. The growth rates of CEV-containing cells is not affected by the presence of the viroid. In addition, the viroid-containing cells demonstrate a higher temperature tolerance for growth. The cell wall structure of infected tissue apparently differs from healthy cells as suggested by the differential release of protoplasts and the increased yields of protoplasts from infected cells in the presence of beta-1,3-glucanase. This biochemical distinction also persists in cell suspension cultures. The relationship between the cell wall anomaly and the increased frequency of plasmalemmasomes in CEV-containing callus cells is discussed.