Application Of Cryopreservation Techniques For Preservation Of Potato Germplasm
2005
Zarghami, Reza | Ja`far Zadeh, Mojtaba | Najafi, Puya | Dabir Ashrafi, Omid | Habashi, Ali Akbar
Cryopreservation is a very important method for conserving plant germplasm. Application of this method for each germplasm depends on optimizing its several successive stages. Effects of preculture-dehydration and vitrification techniques on Picasso and Agria cuiltivars were studied. Results showed that various potato cultivars react differently to application of this method, so that, often an unique protocol could not be used for several cultivars.(Agria showed better respond to treatments used). Results in relation to preculture stage showed that application of high sugar content in this stage (e.g. sucrose, 0.7 M) enhances the post-freeze recovery percentage. Although, there were some inter-relations between this factor and other factors (cultivar, for e.g.), but in most cases, short duration of preculture stage (e.g. one day) had better effect on regeneration. Application of ABA in this stage (0.5-3 mg/l depending on cultivars) had positive effects on post-thaw recovery and regeneration. But application of ABA on donor plants had no significant effect. In addition application of proline had significant positive effect (e.g. 5 g/l proline with one-day preculture period on cv. Agria). Results on dehydration step, showed that application of DMSO isn&rsquot proper for lowering free water of potato meristem tissues. Concentration of cryoprotectant solution must be about 7M and therefore, 2M isn&rsquot enough for vitrification process. Proper duration of dehydration solution, without and with application of loading solution was determined 50 and 40 min., respectively. Increasing the rate of freezing and thawing steps by application of aluminium vials instead of polypropylen vials improved the post-thaw recovery. Furthermore, results on post-thaw of stages, showed that application of activated charcoal (1g/l) in post-thaw medium, hasn&rsquot any significant effect on recovery and regeneration. Also, based on the results, some of freeze-induced damages in newly thawed tissues,were related to free radicals which are produced from photochemical reactions.
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