Clonal propagation and antimicrobial activity of an endemic medicinal plant Stevia rebaudiana

Introduction

In ancient Indian traditional Ayurvedic system of mediine, Stevia rebaudiana has a long history of use by tribal people. Stevia rebaudiana Bertoni, belonging to the family Asteraceae, is a perennial and endemic, medicinal shrub. Medicinal plants constitute one of the most important groups of wild plants in terms of their contribution to the economy and wellbeing of farmers.

Stevia is a natural non-calorie sweetener and is indigenous to the northern regions of South America. The crop was first established in Japan in 1968. By mid-1970s, standardized extract and pure stevioside was utilized comercially in Japan for sweetening and flavoring foods and beverage as a substitute for several synthetic sweete-ners. The total market value of Stevia sweetener in Japan is established to be around 2 - 3 billion yen/year. It is being

cultivated in continental China, Taiwan, Thailand, Korea, Brazil, and Malaysia. Besides the above-mentioned countries, Stevia today is also grown in Israel, Ukraine, UK, Philippines, Canada, Hawaii, California, and all over South America. The leaves of Stevia contain diterpene glucosides viz. stevioside and rebaudioside with a sweet taste but which are not metabolized. The biggest part of the sweet glycosides consists of the stevioside molecule. The sweetener, stevioside extracted from the plants is 300 times sweeter than sugar. The fresh leaves have a nice liquorice taste. It is recommended for diabetes and has been extensively tested on animals and has been used by humans with no side effects. For anyone who suffers from diabetes, hypoglycemia, high blood pressure, obesity and chronic yeast infections, Stevia is the ideal sweetener.

The seeds of Stevia show a very low germination percenttage. Propagation by seeds does not allow the production of homogeneous populations, resulting in great variability in important features like sweetening levels and composition.