In Vitro Techniques to Improve the Germplasm Preservation—Case Studies for Three Temperate Crops and Some General Remarks

摘要

Crops, which cannot be maintained as seeds, need high input, thus requiring development of alternative methods. In vitro culture is used for maintenance and pathogen cleaning, Cryopreservation is increasingly effective in long-term conservation. Whereas most vegetative crops are tropical, potato, Allium, and mint are examples of temperate crops. Potato is maintained for long periods by shoot tip or microtuber storage. Combinations of thermotherapy with meristem culture are used for virus elimination.Several methods work for potato Cryopreservation; droplet method is applied in Germany. The main vegetative Allium species, garlic, is virus-cleaned by meristem culture. Slow growth storage works well, whereas only some organs of in vivo plants can be used for Cryopreservation. Mint, an important medicinal herb, is maintained by slow growth storage. Vitrification protocols exist for Cryopreservation. Important are the physiological state of donor plants prior to explant excision and the cellular watercontent. Cold hardening may improve storability. For germplasm preservation, contamination and hyperhydration are of increasing influence. Genebanks are often challenged with respect to genetic stability of plant material. However, proof of genetic stability or demonstration of instability are difficult and cannot be established beyond doubt.