Cryopreservation of protoplasts from sporidia of Ustilago maydis

Abstract

Protoplasts isolated from sporidia of Ustilago maydis were stored by freezing for more than two months. After thawing, the survival of protoplasts was estimated using the vital stain phenosafranine. In a buffered and osmotically stabilized medium containing polyvinyl-pyrrolidone (15% (w/v), PVP) as cryoprotectant, nearly 100% of the protoplasts remained viable, if cooled slowly to − 80 °C. Cell-wall regeneration and reversion frequency of the protoplasts after storage was investigated to further prove cell viability. No significant difference was detected comparing freshly isolated and stored protoplasts. © 1992, British Mycological Society. All rights reserved.