The role of 2,4-D and auxin-binding proteins during the induction of embryogenic and non-embryogenic callus in Zea mays (L.)

This thesis deals with the influence of the growth regulator 2,4-dichlorophenoxyacetic acid (2,4-D) on the induction of callus in cultured immature embryos of <em>Zea mays</em> (L). In maize, two types of embryogenic callus can be induced in immature zygotic embryos.<br/>Type I callus, which is compact in appearance and hard to subculture, and type II callus, which is friable, and is well suited for subculture without loosing its capability to produce somatic embryos. The somatic embryos mature on growth regulator free medium with 6% sucrose and grow out into normal fertile plants on regeneration medium. This process of somatic embryogenesis is important for large scale manipulation in biotechnological procedures.<br/>Friable embryogenic callus can be used for the production of suspension cultures or protoplasts with regeneration capacity. It is also well suited for particle gun experiments in which foreign DNA is transferred in the cells of the callus. The influence of the 2,4-D was studied in two inbred lines