Genetic transformation of green-colored cotton

Summary This study reports an Agrobacterium-mediated transformation of green-colored cotton (Gossypium hirsutum L.). A tissue culture procedure was optimized to induce callus formation from hypocotyl explants and subsequent differentiation into the embryogenic type. Callus formation could be induced by growing explants on Murashige and Skoog medium containing 2,4-dichlorophenoxyacetic acid and kinetin. Among the four genotypes studied, embryogenic calli and plant regeneration were observed only in var. G9803. Agrobacterium-mediated transformation of G9803 with the fiber-specific expansin gene GhExpl was achieved based on the establishment of these tissue culture methods. A total of 32 individual regenerants resistant to kanamycin were generated within 7 mo., with a transformation frequency of 17.8%. Transformation was confirmed by Southern blot analysis and RT-PCR. These results represent the first step towards genetic manipulation of the colors and fiber quality of green-colored cottons by biotechnology. These authors contributed equally to this work