Bioloistic-mediated Transformation of Cotton (Gossypium hirsutum L.): Embryogenic Calli as Explant

Genetic transformation was carried out by using biolistic gun method. The hypocotyl derived embryogenic calli (explants) of cotton (Gossypium hirsutum L.) cv. Cocker-312 were transformed with a recombinant pGreen II plasmid, in which both, bar (selection marker) and GUS (${\beta}$-glucuronidase) reporter genes were incorporated. Explants were arranged on osmoticum-containing medium (0.5M mannitol) 4 hours prior to and 16 hours after bombardment that was resulted into an increase about >80% for GUS stable expression. 3 days after bombardment, GUS assay was performed, which exhibited, $18.36{\pm}1.00$ calli showed blue spots. The transformed embryogenic calli were cultured on selection medium (@ 6 mg/L basta) for 3 months. The putative transgenic plants were developed via selective somatic embryogenesis (@1.50 mg/L basta); maximum $27.58{\pm}1.25$ somatic embryos were obtained while $17.47{\pm}1.00$ embryos developed into plantlets (@ 0.75mg/L basta). In five independent experiments, up to 7.24% transformation efficiency was recorded. The presence of the transgenes was analyzed by using PCR and southern hybridization analysis. The transgenic plants were developed with in 6-7 months, but mostly transformants were abnormal in morphology.