Callus induction studies on Stevia rebaudiana and antibacterial screening of leaf extracts

Abstract

The medicinal plant

Stevia rebaudiana (Asteraceae family) produces sweet

steviol glycosides in the leaves which can be used as a natural alternative to

artificial sweetener. The propagation by seeds or other methods is not viable

due to the low rate of seed germination. The present study was focused on

induction and maintenance of callus from leaf explants of

Stevia by using

different concentrations of 2, 4 dichlorophenoxy acetic acid

. Surface sterilized

leaf explants were inoculated in MS medium with vitamins, sucrose (30

g l

–1), agar (0.8% w/v) and supplemented with various concentrations of 2, 4â€Â

D (0.5, 1.0, 1.5, 2.0, 2.5 and 3 mg l

–1). Medium supplemented with 2.5 mg l–1

2, 4

â€ÂD showed best callus induction. Leaf extracts in different solvent systems

were screened for antimicrobial activity against some Gram

â€Âpositive

and Gram

â€Ânegative bacteria by disc diffusion method. The chloroform and

methanol extract of leaves exhibited a concentration dependent antibacterial

inhibition.