Analysis of transgenic rice for animal feed with high amino acid content generated by direct co-transformation using silicon carbide whiskers

Abstract

We reported previously that the genetically modified rice lines expressing OASA1D, a feedback-insensitive anthranilate synthase (AS) α subunit gene of rice, showed remarkable increase of free tryptophan (Trp) in leaves and seeds. For the purpose of practical use of this gene, we tried to develop the direct co-transformation system with linear transgene cassette and selectable maker gene cassette lacking vector backbone sequence. To avoid the integration of any vector backbone sequence in the rice genome, the cassette fragments (pRbcAc::OASA1D-asa1T and p35S::HPT-nosT) were introduced into rice cells by the use of silicon carbide whiskers. This system produced fertile transgenic rice plants with a low copy of transgene, and those contained high level of free Trp in leaves and seeds. In addition, we will show some results of frequency in appearance of selectable maker lacking lines by genetic segregation in the progenies.