In Vitro Micropropagation of Stevia rebaudiana Using Nodal Explants and Growth Regulator Combinations

Abstract

Stevia rebaudiana is grown for the intensely sweet steviol glycosides in its leaves, yet its seeds germinate poorly and give offspring that differ from one another, which is why tissue culture is so often proposed as a route to uniform planting material. This narrative review asks how far nodal explants and combinations of growth regulators can be relied upon for in vitro micropropagation of the species, and how much weight the published protocols can carry. It draws on literature about the plant, the principles of shoot multiplication and rooting, the behaviour of cytokinins and auxins in culture, and the practical problems of contamination, browning, hyperhydricity, somaclonal variation and acclimatisation, and it reports no new data. Nodal segments are an attractive starting point because they carry axillary buds and tend to preserve the parent genotype, and a cytokinin followed by an auxin is the usual sequence for multiplication and rooting. Reports differ in genotype, medium, vessel and the way results are scored, so the best combination of regulators cannot be named from the literature as it stands, and few papers follow plants into the field or measure glycoside content afterwards. The review closes with a short list of what a comparable, decision-grade protocol study should record.