Stevia rebaudiana produces sweet-tasting steviol glycosides (SGs) in its leaves which can be used as natural sweeteners. Metabolic engineering of Stevia would offer an alternative approach to conventional breeding for enhanced production of SGs. However, an effective protocol for Stevia transformation is lacking. | Overexpression of SrDXS1 and SrKAH enhances steviol glycosides content in transgenic Stevia plants .den color inherit .ttnd ol .ttnd ul .ttnd dl padding 0 0px 0 20px .ttnd hr margin 10px 0px .ttnd a href javascript void 0 .ttnd a href color inherit dtextscript p text-align left dtextscript img vertical-align middle Zheng et al. BMC Plant Biology 2019 19 1 lt br gt https s12870-018-1600-2 lt br gt lt br gt lt br gt lt br gt lt br gt RESEARCH ARTICLE Open Access lt br gt lt br gt Overexpression of SrDXS1 and SrKAH lt br gt enhances steviol glycosides content in lt br gt transgenic Stevia plants lt br gt Junshi Zheng1 2 Yan Zhuang1 Hui-Zhu Mao1 and In-Cheol Jang1 2 lt br gt lt br gt lt br gt Abstract lt br gt Background Stevia rebaudiana produces sweet-tasting steviol glycosides SGs in its leaves which can be used as lt br gt natural sweeteners. Metabolic engineering of Stevia would offer an alternative approach to conventional breeding lt br gt for enhanced production of SGs. However an effective protocol for Stevia transformation is lacking. lt br gt Results Here we present an efficient and reproducible method for Agrobacterium-mediated transformation of Stevia. lt br gt In our attempts to produce transgenic Stevia plants we found that prolonged dark incubation is critical for increasing lt br gt shoot regeneration. Etiolated shoots regenerated in the dark also facilitated subsequent visual selection of lt br gt transformants by green fluorescent protein during Stevia transformation. Using this newly established transformation lt br gt method we overexpressed the Stevia 1-deoxy-d-xylulose-5-phosphate synthase 1 SrDXS1 and kaurenoic acid hydroxylase lt br gt SrKAH both of which are required for SGs biosynthesis. Compared to control plants the total SGs content in SrDXS1- lt br gt and SrKAH-overexpressing transgenic lines were enhanced by up to 42 54 and 67 88 respectively showing a lt br gt positive correlation with the expression levels of SrDXS1 .
