Production of transgenic plants and their early seed set in Japanese soybean variety, Kariyutaka

Abstract

A soybean variety, Kariyutaka was found to form much more precocious flower buds than those of the other six genotypes used in this study when in vitro cultured at 26°C with 16/8 h light/dark regime (fluorescent tubes at an intensity of about 100 μmols s−1 m−2). In addition, it was a suitable genotype for soybean transformation because it was highly sensitive to Agrobacterium and it exhibited excellent shoot regeneration. Its transformation frequency (about 1%) was comparable to that of a variety Thorne, which is known as one of the suitable cultivars for Agrobacterium-mediated transformation. Because transgenic shoots of Kariyutaka formed in vitro precocious flower buds, T1 seeds were obtained in only six months after co-cultivation with Agrobacterium. A few copy numbers of transgenes were inheritable to T1 generations. T1 plants also produced seed within 2–3 months when grown at the same regime as in vitro culture. Hence Agrobacterium-mediated transformation using Kariyutaka can be recommended as a model method for the rapid development of transgenic soybean lines.