In vitro biomass accumulation of calli and root enhancement of Leucas aspera (Willed) Linn. under stress conditions

Abstract

Leucas aspera is a high value medicinal plant in India, Java, Mauritius and Philippines. The effects of plant growth regulators effects on in vitro callus biomass accumulation and root enhancement were assessed using leaf and stem explants. Leaf and stem explants were cultured on Murashige and Skoog basal medium supplemented with different concentrations of auxins and cytokinins. The highest amount of callus biomass accumulation was observed on leaf explants. Comparisons between stem and leaf explants indicated that leaf explants showed the greatest callus formation. Greatest callus formation was observed on NAA (2 mg L−1) (79.22%), followed by 2,4-D (2.0 mg L−1) (70.11%) and IBA (2.0 mg L−1) showed the least formation (36.42%). Maximum callus formation was observed on stem explants; these showed 60.70% from 2,4-D (2 mg L−1), NAA (2 mg L−1) showed 40.16%, and far less was obtained on IBA (31.60%). The greatest root formation (75.32%) was obtained on IBA (2 mg L−1) and the number of roots per shoot obtained was 26.55%; IAA (2 mg L−1) showed 66.82% root formation and the number of roots obtained was 21.22%; NAA (2 mg L−1) showed 54.33% root formation. In conclusion, root enhancement increased best under dark conditions, the conditions most suitable for regeneration of large numbers of high value clonal plants for commercial production and isolation of bioactive compounds.