Micropropagation and bioreactor studies of the medicinally important plant Lessertia (Sutherlandia) frutescens L.

Abstract

This study describes a protocol for rapid and efficient in vitro propagation of Lessertia frutescens (cancer bush), a medicinally important plant species native to southern Africa. Single node explants were grown in various culture regimes of MS medium containing 30g/l sucrose supplemented with various concentrations of cytokinins and auxins and solidified with 8g/l agar. These were (a) 2.22, 4.44, 13.32 and 22.19µM BA; 2.32, 4.65, 13.95 and 23.23µMK and 0.45, 2.27, 4.54 and 13.62µM TDZ (b) a combination of 2.22µM BA with 0.57, 2.85, 5.71 and 11.42µM IAA, 0.49, 2.46, 4.9 and 9.8µM IBA or 0.54, 2.69, 5.37 and 10.74µM NAA and (c) different media types viz. MS, SH basal salt medium and WPM at 1, ½ and ¼ salt strength which were each supplemented with 2.22µM BA and 0.54µM NAA. Single node explants were also grown in MS liquid medium supplemented with 2.22µM BA and 0.54µM NAA in temporary and continuous immersion bioreactors. Maximum number of shoots (12.9) per single node explant was obtained in the temporary immersion bioreactor but 50% of these shoots showed symptoms of hyperhydricity. In solid culture the best shoot multiplication response (10 shoots) was obtained in full strength MS. Roots were induced using shoot tips cultured in ½ MS solid medium supplemented with various concentrations of IBA or NAA. The highest rooting percentage (78%) was achieved in 19.6µM IBA. Rooted plantlets were cultured in a mixture of perlite and vermiculite (1:1; v/v) and successfully acclimatized in a growth chamber with an 85% survival rate.