Zea mays (L.) with capability of long term, highly efficient plant regeneration including fertile transgenic maize plants having a heterologous gene, and their preparation

摘要

Protoplasts which regenerate reproducibly in a short time to normal, fertile plants can be regenerated from an auxin-autotrophic genotype of Zea mays (L.). Starting from immature embryos on hormone-free media, an auxin-autotrophic, embryogenic callus is formed on the shoot basis of the seedlings, which callus retains its embryogenic potential over a substantial period of time when subcultured on hormone-free medium. In addition to fully-developed embryos, adventitious embryos are also formed under suitable culture conditions (6-9% of sucrose in the medium). When the sucrose content is reduced to 2-3% and 2,4-dichlorophenoxyacetic acid is added, soft, granular calli are formed which consist of embryogenic cell aggregates (type II callus). After subculturing the type II callus in the form of a cell suspension culture, totipotent protoplasts can be isolated. From these protoplasts, the maize plants according to the invention are regenerated.