High efficiency shoot regeneration from calluses of strawberry (Fragaria X ananassa Duch.) stipules of in vitro shoot cultures |
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| Authors: | E Rugini R Orlando |
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| Institution: | Istituto di Ortofloroarboricoltura, Università della Tuscia, Facoltà di Agraria, Via S. Camillo de Lellis, 01100 Viterbo, Italy |
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| Abstract: | A highly efficient method of shoot regeneration was developed from calluses of four culti- vars of strawberries (Fragaria x ananassa Duch.), ‘Addie’, ‘Dana’, ‘Gea’ and ‘Santana’, grown in vitro. Optimum shoot regeneration (84-96% of the explants), with four to eight shoots was obtained from calluses developed from stipules near the internal zone between petiole and stipule, on Murashige and Skoog (1962) or Gamborg et al. (1968) media, supplemented with 3% (w/v) glucose, 10 iM BAP and 2.5 IBA and 0.8% agar. The calluses continued to produce shoots for at least six subsequent subcultures. This has been reported, up to now, only in juvenile explants. Microscopic observation showed no preformed buds or meristematic groups of cells in the connecting zone of petiole and stipule prior to culture. However, there were several layers of cells in this area containing higher amounts of starch, which were not observed in the cells of the bottom or in the external side of the stipule. Regeneration from stipules occurred five to six days earlier in whole leaves (stipule + petiole + lamina) than in leaves without laminae, but the final percentage was the same in the cases of all explants. The percentage of regenerating calli from the other explant sources (leaf lamina, petiole and root) was low and dependent on cultivar. Cv. Gea, which showed the highest regeneration capacity, regenerated 32% from leaf laminae, 16% from petiole and root calluses, followed by cv. Addie with 12% from leaf laminae only; the others failed to regenerate from calluses derived from these tissues. The regenerated shoots were successfully rooted and hardened for further observations on eventual somaclonal variation. |
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