Plant cell culture. Basic principles pf freezing injury to plant cells: natural tolerance and approaches to cryopreservation. Cryobiology of isolated protoplasts: application to plant cell cryopreservation. Biophysical and ultrastructural studies of membrane alterations in plant cells during extracellular freezing: molecular mechanisms of membrane injury. Cryoprotective compounds in the viable freezing of plant tissues. Meristem culture and germplasm preservation. Cryopreservation of shoot-tips of fruit trees and herbaceous plants. Cryopreservation of potato meristems.