Genetic engineering of cabbage for resistance to diamondback moth

Genetic transformation studies were carried out to standardize a protocol for insect resistance gene (cry IAb) transfer in cabbage using Agrobacterium-mediated gene transfer technique. Agrobacterium tumefaciens strain containing npt-II and cryIAb genes in binary vector pBin Bt1 was used for genetic transformation. Both hypocotyls and cotyledon explants were used for transformation studies. Hypocotyl explants showed better shoot regeneration as compared to cotyledon. For shoot regeneration from cotyledon and hypocotyl explants the best medium was found to be MS + 2.0 mg/l BAP + 0.25 mg/l IAA and MS + 1.5 mg/l BAP + 0.5 mg/l NAA, respectively. MS medium supplemented with 0.1 mg/l IBA was found best for root regeneration. Kanamycin sensitivity experiment revealed that the kanamycin concentration as low as 10 mg/l is toxic to the explants. Preincubation of 72 hours and cocultivation of 48 hours was found optimum as it gave maximum transgenic shoot regeneration on selective medium. Several putative cabbage transformants were selected on kanamycin selective media. Positive and stable Bt gene transformants were selected based on polymerase chain reaction analysis.