Effect of antibiotic sensitivity on different cultured tissues and its signifi cance in genetic transformation of cabbage Brassica oleracea

Successful plant transformation requires highly effi cient regeneration protocol and suitable selection system. In this regard, the effect of kanamycin and cefotaxime was studied on cultured hypocotyl, cotyledon, leaf and petiole tissues of cabbage to look at the suitability of kanamycin resistance as a selectable marker and cefotaxime in controlling excessive bacterial growth during genetic transformation studies. Kanamycin sensitivity (0-60 mgL -1 ) was checked by fresh weight of the explants (leaf and petiole) which was measured at the interval of 7 days till 35 days. Explants showed decrease in fresh weight as concentration of the kanamycin increased resulting in full or partial inhibition of shoot regeneration. A negative correlation was observed between the concentration of kanamycin and fresh weight of the explants at different intervals of time. Effect of different concentrations of cefotaxime (0-500 mgL -1 ) was studied on the regeneration potential in cotyledon and hypocotyl explants of cabbage and found no much effect of cefotaxime on regeneration potential. Effect of different concentrations of cefotaxime and kanamycin (50 mgL -1 ) was studied on the growth of agrobacterial cells and regeneration potential of cotyledon and hypocotyl tissues after cocultivation. In both the explants, growth of agrobacterial cells were controlled at concentration of 400 mgL -1 cefotaxime and maximum per cent shoot regeneration in cotyledon (35.55 %) and hypocotyl (48.15 %) was obtained on the best MS shoot regeneration medium supplemented with 400 mgL -1 cefotaxime.The results indicate that kanamycin and cefotaxime act as an effective selective agents during genetic transformation studies.