Cryopreservation-Practical considerations

Abstract

Over the past 40 years individual scientists developed and tested a range of cryopreservation techniques for preserving plant cells and tissues, but routine storage of plant germplasm other than seeds in liquid nitrogen (LN) is a relatively new practice (Engelmann 2004). Controlled rate cooling, vitrification, encapsulation dehydration, dormant bud preservation, and combinations of these techniques are now directly applicable for plant genotypes representing hundreds of species. An increasing number of laboratories are instituting these techniques for secondary genetic resource preservation. Cryopreservation is commonly used for storage of suspension and callus cultures, and is now becoming more useful for organized tissues. Many protocols are available in the literature; however they are often difficult to interpret for everyday use (Towill 2002). The procedures themselves are not difficult, but initial implementation of cryopreservation procedures can be daunting where financial and human resources are limited. Often the initial steps to define protocols and set up procedures for testing, screening, and ultimately storing the range of genotypes in each collection are beyond the scope of many plant laboratories (Reed et al. 1998b). Cryopreserved storage is now in place for many important collections of algae, cell cultures, and organized plant tissues, and techniques are now available for many more. The aim of this book is to provide starting points for a wide range of plant types and to make cryopreservation an easier technique to use for long-term storage by providing step-by-step instructions. The experimental protocols presented here were developed for, and in some cases already used with a range of genotypes. They will provide a starting point for application to additional germplasm such as that available in national or breeder collections. The protocols were provided by the scientists who developed them, and the underlying literature was reviewed by expert scientists working with each particular plant system.