Abstract:

To study the effect of genotypes on the efficiency of genetic transformation. The embryogenic calli of four cultivars YZ-1, Coker 312, Ym-4, and Em 23 were transformed by Agrobacterium strain A1 harbouring Psg 529 carrying isopentenyl transferase gene (ipt). The results showed that the transgenic efficiency was different in four cultivars under the same transgenic procedure. YZ-1 and Coker 201 showed higher genetic transformation and plant regeneration efficiencies than Ym-4 and Em 23. To optimize the procedure of somatic embryos germination, rooting and transplant, several factors were studied using somatic embryos of YZ-1 as material. The results showed that low concentration of inorganic salt in the embryo germination media, namely 1/2 MS inorganic salts, could increase the ratio of normal regenerated plant and help build stronger root systems. Phytagel was a better for solidifying the medium than Agar. Activated carbon added in rooting medium was proved to be helpful for root regeneration of somatic embryos. When the roots of some regenerated plantlets with 3–5 true leaves were brown due to a long culturing period in solid medium. They could rebuild stronger after the brown roots were removed and the plantlets were inoculated on fresh medium with low concentration of inorganic salt. The plantlets were stepwise opening the lids of culture bottles helped the regenerated plantlets accommodate the open circumstances.

Key words: Cotton (Gossypium hirsutum L.), Agrobacterium, Genetic transformation, Plant regeneration, Transplanting