ABSTRACT
BACKGROUND: Plant Vitrification Solution 2 (PVS2) was reported to be a successful cryoprotectant solution in regenerating plantlets from sweet potato shoot tips after cryostorage. However, this was not the case for the South African sweet potato accessions. OBJECTIVE: This study assessed the responses of buds of sweet potato to different concentrations of the components of PVS2 both individually and in combination. MATERIALS AND METHODS: The percentage material that regenerated into plantlets was recorded against the total that was evaluated. RESULTS: Regeneration of buds after treatment with 5% dimethyl sulphoxide was significantly better (p<0.001) than 10-15% dimethyl sulphoxide while exposure to ethylene glycol concentrations of 5-10% were better than 15% for all but one accession. Significant difference (p<0.001) was observed in treatment with 30-40% glycerol. Combination of the components at 5% (PVS5%) was better than 10-15% dimethyl sulphoxide and ethylene glycol and 20% glycerol. CONCLUSION: It is recommended that PVS5% be used for further development of the cryopreservation protocol for the South African accessions.
ABSTRACT
Culture of cassava somatic embryos on media with an altered macro- and micro-nutrient salt concentration affected embryo development and germination capability. In the tests, quarter-, half-, full- or double-strength Murashige and Skoog (MS) media were compared. The maximum number of somatic embryos differentiated from a proliferative nodular embryogenic callus (NEC) on either half- or full-strength MS medium, and the greatest numbers of cotyledonary stage embryos were formed on full-strength MS medium. Developed somatic embryos were then desiccated above a saturated K2SO4 solution for 10 d. After transfer to germination medium, embryos that had developed on half- and full-strength MS medium yielded 8.3 and 8.6 germinants g(-1) NEC tissue, respectively. For this important but often disregarded culture factor, either half- or full-strength MS medium is recommended for both the differentiation and development of cassava somatic embryos that are capable of germination.
Subject(s)
Cell Differentiation/drug effects , Cotyledon/drug effects , Manihot/drug effects , Salts/pharmacology , Seeds/drug effects , Cotyledon/growth & development , Culture Media/pharmacology , Culture Techniques/methods , Desiccation/methods , Dose-Response Relationship, Drug , Germination/drug effects , Manihot/cytology , Manihot/embryology , Seeds/growth & development , Water/physiologyABSTRACT
Low-temperature scanning electron microscopy cannot be used as a general approach when resolution of definitive surface features is required for fungal characterization, because of the production of a pervading exudate by some of the species, strains or varieties. As the resolution of the light microscope is obviously limiting, scanning electron microscopy remains the best microscopical mode. Results are presented for four species within the Aspergillus flavus group which indicate that minimal (if any) distortion or collapse can be achieved with concomitant preservation of surface morphology, when particular precautions are taken during fixation and critical-point drying. Details of the steps pertaining to preparation for scanning electron microscopy following critical-point drying that are considered collectively to contribute to the success of the approach are discussed.
