Recalcitrant seeds brought into line
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CTA. 1994. Recalcitrant seeds brought into line. Spore 53. CTA, Wageningen, The Netherlands.
Permanent link to this item: http://hdl.handle.net/10568/49482
Exotic fruits growing in a Malaysian garden mark a break-through in the technology of preserving seeds. The success could help botanists to collect and store the genes of many important tropical plants whose seeds have proved impossible to preserve...
Exotic fruits growing in a Malaysian garden mark a break-through in the technology of preserving seeds. The success could help botanists to collect and store the genes of many important tropical plants whose seeds have proved impossible to preserve so far. The seeds of many economically important tropical species such as rubber, coconut, cocoa and coffee are described as 'recalcitrant' because they are unable to be dried slowly and frozen like 'orthodox' seeds which can survive in this state for many years. Carefully done, orthodox seeds can be dried down to 5% moisture which means there is little danger that on freezing ice will form in the tissue of the seed and kill it. Recalcitrant seeds have such a high water content that they have not been able to be dried enough to risk freezing them. A high proportion of tropical species produce recalcitrant seed which has meant that in order to preserve genetic diversity, that seed of each species has to be collected and then each successive generation grown: all of which takes time and space, which is not always available. Trials have been conducted on iackfruit by scientists at the Malaysian (University of Agriculture in Selangor. To overcome the problem of freezing seed they used instead just the embryo which contains much less moisture than the whole seed. Initially this was a difficult operation as the embryos of jackfruit and other recalcitrant species are only a few millimetres long. The embryos were coated with a solution of diethyl sulphoxide and proline to protect them from cold injury from water in the atmosphere. They were then blotted to remove excess moisture and dried carefully for one hour, before slowly being frozen and immersed in liquid nitrogen for permanent storage. After a month, 60% of the seeds were found to be viable. Jackfruit grown in the scientists' garden showed no abnormality, suggesting that the embryos were unharmed by this technique which has been described as an exceptionally important method by a scientist at the Royal Botanic Gardens, Kew, UK. 'New Scientist' (11 June 1994) IPC Specialist Group King's Reach Tower Stamford Street London SE1 9LS UK