Traditional medicine in South Africa could face severe shortages of raw materials because of stubborn seeds.
It is estimated that 70% of the South African population relies on traditional medication and a large number of the plants used have what is referred to as ‘recalcitrant seeds”.
They exhibit traits such as being unable to survive dehydration.
Not only are these seeds unable to be stored effectively, but the traditional medicine market is causing these plants to be over-utilised and this could lead to extinction.
Professor Patricia Berjak of the University of KwaZulu-Natal is currently researching a solution to the storage of these seeds. Berjak and her colleagues began experimenting with cryogenically freezing the seeds to store them for future use. ‘You cannot freeze large wet structures, so we had to cut the embryonic axis from the seed, separating it from the cotyledon.” The axis is then placed in a germination medium on a grid and are subjected to flash-drying.
‘If you let seeds dry slowly, you can unbalance them and cause injury, which will kill the seed.”
After the maximum amount of water that can be removed without causing damage, the freezing process has to be a quick one, as ice-crystal formations could destroy the axis cells and tissues. ‘Once frozen, theoretically they can last for ever. Then we had to test whether they could be defrosted successfully,” said Berjak.
These plants need to be gradually acclimatised, ‘just like a newborn baby”, said Berjak.
Berjak and her companions are now working on producing synthetic seeds. In this ‘synthetic seed” form they should be able to be transported without damage.
‘All that is necessary is a relatively short survival period of the encapsulated axes to let us get them to their destination where they can be planted.”
On March 21, at the Monument Guy Butler Theatre, Professor Patricia Berjak will talk about The Case of Obstinately Disobedient Seeds from 12pm to 1pm. Entrance fee: R7,50