In vitro Rapid Regeneration of Bitter Melon (Momordica charantia L.) Using Direct Organogenesis in Kenya

Abstract

Bitter melon is a traditional therapeutic vegetable in tropical and subtropical countries due to its carotenoid content, which provides health advantages. However, the production is significantly impacted by the poor seed germination rate and variability of progenies associated with the cultivation of this plant. Clonal propagation would increase the yield and usefulness of bitter melon. Momordica charantia was micropropagated using nodal explants in a modified MS medium containing vitamins (Glycine, myo-inositol, nicotinic acid pyridoxine HCl). Nodal explants were obtained from in vivo seedlings grown for 30 days in a greenhouse and then cultured on MS media with a range of BAP or KIN concentrations (0.50 - 2.5 mg/L), either alone or in combination. Shoots were induced within a minimum (6.33±0.58) day when 0.5 mg/L BAP was coupled with 0.50 mg/L KIN, resulting in the maximum shoot induction frequency (72.17±2.83%), 4.40±0.17 shoots/explant and 4.13±0.98 cm shoot length. Then, shoots were inoculated on 1/2 strength MS media either without growth regulator or with a supplement of IBA, NAA, and IAA in various concentrations (0.5 - 1.5 mg/L) to promote root induction. MS medium without growth regulator induced maximum rooting rates (93.33±2.66%) with 12.33 roots/shoot and 23.33 cm of root length. Rooted plantlets were successfully established in greenhouses after undergoing a hardening period in a regulated environment. The combination of BAP and KIN (0.50 mg/L and 0.50 mg/L) was most suitable for bitter melon shoot formation, whereas MS medium without growth regulator was optimal for rooting. This reproducible protocol for the regeneration of bitter melon plantlets would allow for rapid mass multiplication, conservation, and genetic manipulation for its agronomic improvement.