A novel method to induce direct somatic embryogenesis,secondary embryogenesis and regeneration of fertile green cereal plants

A direct somatic embryogenesis and secondary embryogenesis protocol was developed for seven cereal species, thus providing a new vista for in vitro plant genetic transformation or propagation. This paper describes a novel process that has been successfully developed for efficient regeneration of a wide range of cereal species and genotypes. This tissue culture and regeneration system does not require formation of callus tissues and takes approximately 2 months to complete, shorter than any of the currently available systems requiring 3-4 months. Rapid induction of direct somatic embryogenesis in barley (Hordeum vulgare), common wheat (Triticum aestivum), durum wheat (T. durum) and derived amphiploids, wild wheat (T. monococcum and T. urartu), rye (Secale cereale) and oats (Avena sativa) was induced from excised immature scutellum on DSEM medium. Newly developed globular embryos were cultured on SEM medium for a second cycle of embryogenesis followed by germination (GEM medium) and regeneration of embryos into normally growing green and fertile plants. In vitro techniques to induce direct somatic embryogenesis, secondary embryogenesis and plant regeneration from these cereals require a specific sequence of defined media and controlled environments. The sequence and the timing of the media used, as well as their hormonal composition and balance are critical aspects of this process. The organic and mineral compositions of these media are not new but are important for supporting and sustaining rapid growth of the tissues.