Substitution of Benzyladenine with meta-Topolin Improved Shoot Regeneration and Rooting in Wedelia chinensis (Osbeck) Merr. and Quantitative Estimation of Flavonoids

A successful regenerative method was developed for Wedelia chinensis by using nodal segments as explant. Nodal segments were implanted on Murashige and Skoog (MS) (Physiol Plant, 15: 473–497, 1962) medium augmented with different combinations (0.5, 1.5, 2.5, 5.0, or 7.5 μM) of benzyladenine (BA) and meta-Topolin (mT) singly as well as in combination with various auxins viz. Indole-3-acetic acid (IAA), indole-3 butyric acid (IBA), and α-naphthalene acetic acid (NAA) at various concentrations (0.1, 0.5, or 1.0 μM). MS medium supplemented with mT (2.5 μM) was most efficient in inducing axillary shoot induction and growth, producing 12.40 ± 0.22 average number of shoot with 5.39 ± 0.09 cm shoot length after 8 weeks of incubation. The highest regeneration frequency (90%) was achieved by the inclusion of low concentration of NAA (0.5 μM) with optimal mT (2.5 μM) in MS medium, as it produced 28.90 ± 0.27 mean number of shoots with an average of 6.01 ± 0.04 cm shoot length after 12 weeks of incubation. Further microshoots initiated rooting on ½ MS liquid medium containing 0.5 μM IBA which produced 3.60 ± 0.16 mean number of roots/shoot with 4.20 ± 0.08 cm root length after 4 weeks of incubation. In vitro raised plants with well-developed roots were acclimatized well in thermocol cups comprising sterile soilrite for 4 weeks under culture conditions. Significant enhancement in the pigment content (Chlorophyll a, b, and carotenoid) was observed during successive period (0, 7, 14, 21, and 28 days) of acclimatization. The total flavonoid content was highest in the cultures treated with mT (2.5 μM) + NAA (0.5 μM) producing 111.60 CE/g of flavonoid.