In vitro organogenesis and genetic transformation in popular Cucumis sativus L. through Agrobacterium tumefaciens

The effect of growth regulators and culture conditions on the morphogenetic response of cotyledonary leaf discs was studied in popular cucumber variety (Cucumis sativus cv. Sheetal). Organogenesis was induced directly without any intervening callus phase on Murashige and Skoog medium supplemented with different concentrations of benzyladenine and indole propionic acid. Best results (93%) were obtained in the presence of the 4 mg/L benzyladenine and 1 mg/L IPA. The elongated shoots were rooted in basal medium with 1 mg/L indole butyric acid, hardened and transferred to the field conditions. Genetic transformation system has been established for Cucumis sativus cv. Sheetal, plants by infecting cotyledonary explants with Agrobacterium tumefaciens strain LBA4404 carrying binary plasmid pBI121, which contains scorable marker, beta-glucuronidase and selectable marker nptII under the CaMV 35S promoter. Infection was most effective when explants were infected with Agrobacterium for 15 min and co-cultivated for 2 days in the co-cultivation medium. Shoots were regenerated directly from cotyledonary leaf explants in the presence of kanamycin (50 microg/ml) and analysed. Southern blot analysis confirmed that transformation had occurred. This method will allow genetic improvement of this crop by the introduction of agronomically important genes.