I want to know whether callus derived from seeds can sustain desiccation tolerance just like that of seed?
1. First of all, the seed has seed coat, a layer of 'skin' to protect the seed from many things including the prevention of structure dry out in the seed. The calluses (or calli) don't have the layer.
2. Seed is an organ. Unlike seed, calli is a group of un-differentiate or less-differentiated cells (see attachment 1). A lot of important proteins and compounds which contribute to seed's toleration to desiccation may not be there in calli (see attachment 2: Seed Desiccation Tolerance ).
3. So, in geneeral, seed can be store in a dry place, but we have to grow/culture callus in a high-humility environment such as in a tissue-culturing plate or a box.
This is an interesting question. The seeds, during dessication period shows a peak of ABA and this is genetically controlled within seed tissue. This is why other parts of plant can not be dehydrated to the extent of seed. However, as Yuan said, during callus induction we turn the cells into undifferentiated state. By adding ABA to media, we can induce desiccation tolerance to any callus tissue, not only those derived from seeds. However, I suspect that if you initiate the callus at the time of the ABA peak, there may be a chance to induce desiccation tolerance without external ABA. Give it a try. I have added some classical papers on membrane stability/dessication tolerance and a patent which explains the phenomenon partly. At least, we can now induce dessication tolerance to somatic embryos by mimicking (adding ABA at the right time of development) the true embryo development in culture media, but I haven't come across any studies on callus.
If your reason to induce desiccation tolerance in callus in order to store them over long period, you can encapsulate the callus in Sodium alginate beads and further desiccate them. These can then be stored in vitro using slow growth method (medium term) or cryopreservation (long term). Journals like CryoLetters and Cryobiology do contain articles related to this topic.
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