Agrobacterium rhizogenes -Mediated Transformation Enhances Steviol Glycosides Production and Growth in Stevia rebaudiana Plantlets

Stevia rebaudiana accumulates steviol glycosides (SGs) that are used as noncaloric, natural sweeteners in food industry. The most important SGs are rebaudioside A (Reb A) and stevioside (St), and they are markers of the quality of S. rebaudiana lines. In this work, the production and physiology of SGs in Agrobacterium rhizogenes -transformed plantlets were analyzed. By means of HPLC–DAD, the production of St and Reb A was quantified, resulting in a 1.4- and 1.5-fold production increase of St and Reb A, respectively, in transformed compared to wild-type plantlets. Superior phenotype of transformed plantlets was observed in comparison with wild type, represented as an increase of 25% in biomass of aerial parts, 43% in biomass of roots, 20–30% of leaf area and 24% of chlorophylls content. Moreover, the SG production profiles evaluated in a 20-d period showed higher yield in the transformed line. The results of this work demonstrated the usefulness of S. rebaudiana transformation via A. rhizogenes as a strategy to explore new approaches for the improvement of SGs production.