Regeneration and transformation of quince (Cydonia oblonga Mill.) and pear (Pyrus communis L.)
1997
Sumontip Bunnag | Mok, M.
Quince (Cydonia oblonga Mill.) is widely used as a dwarfing rootstock for pear (Pyrus communis L.). The disadvantage of this rootstock is its inefficient uptake of Fe, resulting in leaf chlorosis. Agrobacterium-mediated gene transfer for quince and pear were devised using leaves as explants. Efforts were directed at the following: improving the regeneration system, selecting the best antibiotic to eliminate Agrobacterium while maintaining a high regeneration frequency, and identifying a suitable selectable marker. Regeneration of quince was improved by replacement of agar with 1.6 g/l gelrete. The regeneration frequency of control leaf disc on a medium containing 32 micro metre thidiazuron (TDZ) and 0.3 micro mole alpha-naphhalene acetic acid (NAA) was closed to 100 percent Regeneration of the pear rootstock RV113 was enhanced by cold treatment of the shoot cultures used as explants. The antibiotic timentin, which consists of ticarcillin and a beta-lactamase inhibitor, was more effective in eliminating Agrobacterium and less inhibitory to regeneration than cefotaxime and carbenicillin. Vectors containing the bar gene (bialaphos resistance) were chosen for transformation experiments since bialaphos caused less damage to the leaf explants than kanamycin at effective concentrations for selection of transformants. GUS (beta-glucuronidase activity assays showed that under the proper conditions, transformed tissues were obtained.
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