Abstract
•meta-Topolin, a new aromatic cytokinin enhances shoot proliferation of A. cathartica.•Adjuvant ammonium nitrate accelerates shoot multiplication.•Plant growth regulators have enhanced the secondary metabolites in the leaf tissues of regenerants.
An efficient micropropagation protocol has been optimized through nodal explant in Allamanda cathartica, a potential woody climber using a new aromatic cytokinin, meta-Topolin. Of the different cytokinin tested, higher number of shoots (10.5 ± 0.16) with higher shoot length (6.1 ± 0.09 cm) was observed on Murashige and Skoog (MS, 1962) medium supplemented with 3.0 μM meta-Topolin (mT). The combined effect of cytokinin-auxin (3.0 μM mT + 0.5 μM α-naphthalene acetic acid (NAA)) resulted in the production of 26.2 ± 0.32 mean shoots per explant. The inclusion of 5.0 μM ammonium nitrate (NH4NO3) to the optimized (MS + 3.0 μM mT + 0.5 μM NAA) significantly influenced the shoot procreation rate by producing 58.8 ± 0.46 mean shoots per explant in 96.80 % culture after 12 weeks of incubation. The higher rooting response in the microshoots (6 cm) was obtained on ½ MS medium containing 0.5 μM indole-3-butyric acid (IBA) which yielded a higher of 6.5 ± 0.16 mean roots with an average of 5.4 ± 0.16 cm root length in 97.80 % cultures. Among the various treated samples, higher flavonoids and quercetin content was recorded in the leaves of plantlets raised on 3.0 μM mT + 0.5 μM NAA + 5.0 μM NH4NO3, yielding 174.32 mg QE/g and 55.2 mg/g flavonoid and quercetin per gram of extract respectively. The protocol assures a speedy production of plantlets that can be used for isolation of biologically active compounds to be utilized by the pharmaceutical industries for the treatment of various diseases.