Articles
Sixty years of plant cryopreservation: from freezing hardy mulberry twigs to establishing reference crop collections for future generations
Article number
1234_1
Pages
1 – 8
Language
English
Abstract
In this presentation, 60 years of plant cryopreservation research will be highlighted.
It is generally accepted that plant cryopreservation really started in 1956 when Prof.
Akira Sakai (Sakai, 1956) reported the survival of cold hardened and prefrozen mulberry twigs that were exposed to liquid nitrogen.
He already found out that hardening on the one hand and dehydration on the other were essential for survival.
In a next phase, in vitro plant cultures were tested for their resistance towards cryopreservation.
This posed an extra challenge since it is difficult to cool down freeze such fully hydrated tissues to the temperature of liquid nitrogen with the formation of lethal intracellular ice-crystals.
Therefore, slow freezing protocols, often in the presence of DMSO were developed.
These proved to be a very efficient system for non-organized tissues like callus and suspension cells but organized tissues remained problematic.
But it was only with the development of fast freezing protocols, such as droplet freezing, encapsulation dehydration and droplet-vitrification that the large scale application of cryopreservation to reference crop germplasm collections became possible.
Currently, over 10,000 accessions starting from in vitro cultures are safely preserved for the long term through cryopreservation.
More than 80% of these belong to 5 crops; potato, cassava, bananas, mulberry and garlic.
Other important cryopreservation collections representing thousands of accessions are those of dormant apple buds.
It is generally accepted that plant cryopreservation really started in 1956 when Prof.
Akira Sakai (Sakai, 1956) reported the survival of cold hardened and prefrozen mulberry twigs that were exposed to liquid nitrogen.
He already found out that hardening on the one hand and dehydration on the other were essential for survival.
In a next phase, in vitro plant cultures were tested for their resistance towards cryopreservation.
This posed an extra challenge since it is difficult to cool down freeze such fully hydrated tissues to the temperature of liquid nitrogen with the formation of lethal intracellular ice-crystals.
Therefore, slow freezing protocols, often in the presence of DMSO were developed.
These proved to be a very efficient system for non-organized tissues like callus and suspension cells but organized tissues remained problematic.
But it was only with the development of fast freezing protocols, such as droplet freezing, encapsulation dehydration and droplet-vitrification that the large scale application of cryopreservation to reference crop germplasm collections became possible.
Currently, over 10,000 accessions starting from in vitro cultures are safely preserved for the long term through cryopreservation.
More than 80% of these belong to 5 crops; potato, cassava, bananas, mulberry and garlic.
Other important cryopreservation collections representing thousands of accessions are those of dormant apple buds.
Authors
B. Panis
Keywords
cryopreservation, vitrification, meristems, dormant buds
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