Somatic embryogenesis and in vitro plant regeneration are fundamental processes in the obtainment of transgenic maize plants. Explant, genotype and culture medium are determining factors in these processes. Immature embryo explants and the American Hi-II genotype have been widely employed to acquire genetically modified plants in this species. However, the use of more readily available explants is desired as well as the development of genetic transformation protocols for productive genotypes adapted to local conditions. This study provides an evaluation of immature tassel explants in relation to embryogenic callus production and plant regeneration in South Brazilian maize genotypes for their use in genetic transformation experiments. Immature tassels from 5 hybrids were cultivated in different callus-induction media. The frequency and the fresh mass of embryogenic calli were evaluated. The frequency was influenced by genotype, and the fresh mass was influenced by genotype and culture medium. In plant regeneration, shoots, complete seedlings and acclimatized and fertile plants were quantified. Treatments producing long term embryogenic calli from immature tassels of South Brazilian genotypes with the capacity to regenerate were identified.
embryogenic callus; tissue culture; explants; Zea mays
