Influence of NH4NO3 in the pre-freeze and post-freeze culture medium and 2 or 30 day preconditioning in the presence of 0.5 M sucrose on regeneration of shoot tips of Holostemma annulare following cryopreservation using an encapsulation-dehydration protocol was studied. A long preconditioning phase of 30 days significantly reduced tissue water and improved post-freeze recovery of shoot tips. Under the long preconditioning treatment, Murashige & Skoog (MS) medium free of NH4NO3 (MS-3) allowed maximum regeneration (59%) of liquid nitrogen (LN) exposed shoot tips with less frequency of callusing (10.4%) after 45 days of post-freeze culture. Corresponding desiccated control shoot tips showed 8590% regeneration. A 3.75 mM NH4NO3 concentration (MS-4) favoured 72-89% and 43-47% regeneration after desiccation and LN exposure respectively. The standard MS medium with 20.6 mM NH4NO3 (MS-1) allowed poor regeneration after desiccation (39-53%) as well as LN exposure (8-23%). The study reveals the importance of reducing ammonium nitrate in the culture medium to get maximum recovery of cryopreserved shoot tips of Holostemma annulare.
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Document Type: Research Article
Publication date: January 1, 2002
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CryoLetters is a bimonthly international journal for low temperature sciences, including cryobiology, cryopreservation or vitrification of cells and tissues, chemical and physical aspects of freezing and drying, and studies involving ecology of cold environments, and cold adaptation
The journal publishes original research reports, authoritative reviews, technical developments and commissioned book reviews of studies of the effects produced by low temperatures on a wide variety of scientific and technical processes, or those involving low temperature techniques in the investigation of physical, chemical, biological and ecological problems.