| Callus induction in Origanum species . The present study was undertaken to determine the explant and media for callus induction of Origanum hirtum and O. onites . The explants (leaf-base, nodal, stem, cotyledon, hypocotyl, and root segments) were cultured onto Gamborg's B5 or Murashige and Skoog (MS) medium supplemented with 2,4-D, kinetin, NAA, and TDZ individually and in various combinations. The best explant for callus induction was leaf-base for both Origanum species. The best medium for callus formation and proliferation for O. hirtum was MS or B5 medium containing 0.01 mg/l TDZ. Also, the best callus formation and proliferation for O. onites was obtained with MS or B5 medium containing 1 mg/l 2,4-D + 0.5 mg/l kinetin. During subcultures of the calli, an apparent build-up of phenols caused brown necrotic areas on upper and lower sides of the callus. This browning of the cell inhibited callus growth, later it extended over the entire surface of the callus, and led to callus decline and death. In attempts to control phenols oxidation, ascorbic acid (vitamin C) and Polyvinyl-pyrrolidone (PVP) were added to liquid cultures. Callus growth of Origanum species was good in liquid culture. O. hirtum responded in liquid culture containing vitamin C at 5 or 10 mg/l a somewhat extended survival time. O. onites survival was insensitive to vitamin C and PVP, as was survival of O. hirtum to PVP.; Transient GUS expression in Origanum species . Callus of Origanum hirtum was used for gene transformation. Leaf-base explants grown on MS medium supplemented with 0.01 mg/l TDZ and 6 g/l agar were used. Transient GUS expression was observed at the cut edges of 63% of the calli. A mean of 1 to 1.5 of the GUS positive spots per callus were recorded. The transient expression of a GUS reporter gene transformation was achieved in Origanum hirtum for first time. The regeneration of the plant from callus culture must be completed before transformation studies can proceed.; Use of oregano oil as a surface disinfectant in plant tissue culture. The effect of oregano oil on surface sterilization of kalanchoe African violet, snake plant, miniature rose, begonia, and seeds of Turkish oregano, Greek oregano was evaluated. The oregano oil at 0.4, 0.5 and 1 g/l was effective in eliminating contamination in miniature rose, African violet and kalanchoe, respectively. Also all the oregano oil concentrations tested (1, 3, and 5 g/l) or 10% Clorox (0.525% NaOCl) eliminated contamination in snake plant, and seeds of Turkish oregano, or Greek oregano. |
