Rhizobium rhizogenes-Mediated Genetic Transformation of Antidiabetic Plants

Rhizobium rhizogenes induces a disease syndrome in infected plants commonly known as hairy roots (HR) production. These unique organs are considered of transgenic nature since they derived after horizontal gene transfer from the bacterial root-inducing (Ri) plasmid to the plant genome. The HR culture represents a major biotechnological tool facilitating the production of plant-derived compounds exhibiting interesting features for pharmaceutical, cosmetics and food industries. Moreover, HR cultures can be used for studying the biosynthetic pathways of plant-derived molecules or investigating interactions occurring during phytoremediation. Among this wide range of HR applications, it is important to point out the possibility to synthesize some antidiabetic compounds which are of special interest because diabetes is one of the major and frequently occurring debilitating diseases of the human body in the world. The use of available synthetic antidiabetic drugs has several limitations, including drug resistance, side effects, or toxicity. Therefore, the availability of new antidiabetic drugs from a natural source is of big importance. Stevia rebaudiana Bertoni is one of the promising plant species, constituting the source of desired plant molecules. This plant accumulates steviol glycosides (SGs), which are responsible for the sweet flavour of stevia leaves. These secondary metabolites are considered metabolically inert and therefore could be a safe substitute for sugar for diabetic people. In this chapter, we would like to present recent achievements in the range of antidiabetic substances production via genetic transformation of plants using R. rhizogenes strains. In this context, a key role of the so-called rol genes, carried by Ri plasmids, in the biosynthesis of various secondary metabolites is also discussed. Our aim is to bring closer the issue of HR cultures and their big potential in the pharmacognosy of antidiabetic plants.