Submitted to: CryoLetters
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/15/2004
Publication Date: 12/1/2003
Citation: Towill, L.E., Bonnart, R.M. 2003. Cracking in a vitrification solution during cooling or warming does not effect growth of cryopreserved mint shoot tips. CryoLetters. 24:341-346. Interpretive Summary: Vitrification solutions are used for cryopreservation of shoot tips and are rapidly cooled in liquid nitrogen. The concentrated solution forms a glass upon cooling, but may also crack or fracture during the process. There is concern whether cracking, per se, can physically damage the shoot tip and reduce the ability to subsequently regenerate a shoot. We used shoot tips from mint for these studies and found that cracking of the glass did not reduce the viability of the shoot tips. No external, physical defects were apparent. Samples were cooled and warmed for three cycles, under conditions that either promoted cracking or avoided cracking. Viability was not reduced after the three cycles.
Technical Abstract: No obvious decrease in viability or in the ability of the shoot tip to develop into a shoot occurred during a PVS2 vitrification protocol when the external glass cracked upon either cooling or warming. Samples within semen straws did not show a decrease in survival over three cycles of cooling and warming either in the presence or absence of cracking. No physical defects were visible in treated shoot tips. In a practical sense, cracking might occur during cooling and/or warming or during handling of materials (dropping or jarring samples) stored within LN. Cracking of the external glass formed from PVS2 did not obviously influence shoot tip survival in mint species.