LOW TEMPERATURE STORAGE OF PLANT TISSUE CULTURES.

Plant tissue culture is a technique with massive potential for exploitation in the fields of plant physiology, horticulture and agriculture, somatic cell genetics, secondary metabolite production and genetic conservation. Important stock cultures for all of these applications can be maintained by serial subculture. However, to ensure the cessation of growth and therefore prevention of genetic change, it is necessary to store the stocks at ultra-low temperatures. Conveying plant material to and from the storage temperature (normally at or near minus 196 degree C) requires specific precautions to prevent damage. In this article, the current stage of expertise in the cryopreservation of cultured plant tissues is assessed and important areas for emphasis in future work are indicated. Protocols are offered for the preservation of specimens including suspension cultures, callus, somatic embryos and meristems. Limitations to the use of freeze-preservation for genome storage are discussed, with an evaluation of alternative storage methods.