Fig. 1. Regeneration of multiple shoots from shoot tip explants of Exacum travancoricum. (A). Initiation
of shoot from shoot tip explants after two weeks of culture. (B). Multiple shoot initiation after
three weeks on MS containing 4.44 µM BAP and 1.34 µM NAA. (C, D). Proliferation of multiple
shoots from shoot tip explants after four weeks. (E). Proliferation of multiple shoots from shoot tip
explants at 35 days. (F). Rooted plants on MS containing 2.46 µM IBA after 30 days ready for
transplantation. (G). A well established rooted plant. (H). Well established plants successfully
transplanted to the plastic cups.
In the present study, development of shootlets from shoot tip explants were
observed on MS medium containing BAP 4.44 μM and 1.34 µM NAA after 35
days in culture. In earlier study, the production of shoot buds from nodal
explants of E. travancoricum showed the development of shoots (25.5, 26.9 and
15.8 and 17.1) both in second, third and fifth subcultures on MS supplemented
with two different hormones BAP (13.32 µM) and Kn (13.8 µM) (Elangomathavan
et al. 2006). The use of BAP and NAA for shoot development from shoot tip
explants observed in this study is in agreement with earlier reports on
organogenesis of dicotyledonous plants (Asamenew and Narayanaswamy 2000,
Dhar and Joshi 2005).
Individual shoots from a multiple shoot complex were separated after 28
days of culture and transferred to half strength of MS supplemented with IBA
(0.49 ‐ 12.30 µM). The root induction was initiated after two weeks of culture, and
In vitro Plant Regeneration from Shoot tip Explants 117
after four weeks, the root system was well developed (Fig. 1F,G). The maximum
rooting response (80%) was achieved on medium supplemented with IBA (2.46
μM), with an average of 5.3 roots per shoot explant (Table 2). Earlier studies
reported the use of higher concentration of IBA (14.7µM) for effective rooting in
E. travancoricum (Elangomathavan et al. 2006). In the present study root
induction was obtained with lower concentration of IBA.