BACKGROUND: Panax japonicus C. A. Mey. is a rare traditional Chinese herbal medicine that uses ginsenosides as its main active ingredient. Rice does not produce ginsenosides because it lacks a key rate-limiting enzyme ($β$-amyrin synthase, $β$AS); however, it produces a secondary metabolite, 2,3-oxidosqualene, which is a precursor for ginsenoside biosynthesis.$\$n$\$nRESULTS: In the present study, the P. japonicus $β$AS gene was transformed into the rice cultivar 'Taijing 9' using an Agrobacterium-mediated approach, resulting in 68 rice transgenic plants of the T0 generation. Transfer-DNA (T-DNA) insertion sites in homozygous lines of the T2 generation were determined by using high-efficiency thermal asymmetric interlaced PCR (hiTAIL-PCR) and were found to vary among the tested lines. Approximately 1-2 copies of the $β$AS gene were detected in transgenic rice plants. Real-time PCR and Western blotting analyses showed that the transformed $β$AS gene could be overexpressed and $β$-amyrin synthase could be expressed in rice. HPLC analysis showed that the concentration of oleanane-type sapogenin oleanolic acid in transgenic rice was 8.3-11.5 mg/100 g dw.$\$n$\$nCONCLUSIONS: The current study is the first report on the transformation of P. japonicus $β$AS gene into rice. We have successfully produced a new rice germplasm, "ginseng rice", which produces oleanane-type sapogenin.
Huang, Z., Lin, J., Cheng, Z., Xu, M., Guo, M., Huang, X., … Zheng, J. (2015). Production of oleanane-type sapogenin in transgenic rice via expression of β-amyrin synthase gene from Panax japonicus C. A. Mey. BMC Biotechnology, 15(1). https://doi.org/10.1186/s12896-015-0166-4