Efficient regeneration of Stevia rebaudiana Bertoni transformants through hairy root culture technique

Abstract

Stevia rebaudiana is a small herb from the Asteraceae family. The plant produces tetracyclic diterpenes, steviol glycosides (SGs) that makes it Stevia sweet. Stevia can act as a natural sweetener as it does not interfere with insulin metabolism in humans when consumed. Amid the prevailing paradigm of health-focused living, Stevia can be produced and used worldwide by individuals and plant breeders. Yet, it is frequently challenging to cultivate stevia conventionally due to low germinating rate and viability of its seeds. Hence, raising plants through tissue culture becomes a viable option. The present study aims to regenerate transformed Stevia lines through Rhizobium rhizogenes mediated hairy root culture for investigating the possibility of increasing SGs. This study also focuses on increasing Stevia plant lines through an efficient and cost-effective micropropagation technique. For micropropagation, MS media supplied with 1 mg L-1 BAP in combination with 0.2 mg L -1 NAA gave the best result for shooting with nodal segments as explants. MS medium supplemented with IBA at a concentration of 1 mg L-1 was most effective in promoting the highest number of roots, while 2 mg L-1 IBA was optimal for achieving the longest root length. The highest number and frequency of hairy roots were observed with co-culture period of 48 h. Growth of transformed plantlets was observed best with 1 mg L-1 BAP + 0.3 mg L-1 NAA after 8 weeks of micro-shoots placed on solid MS media. Stevia plants raised through these biotechnological approaches will be a boon to plant breeders and researchers as these are efficient and easy methods to raise Stevia plants. The growing demand for natural sweeteners will be met at lower cost to pharmacology industries and individuals suffering from various life style diseases such as diabetes, hypertension and obesity.