RESULT AND DISCUSSION In recent yea

RESULT AND DISCUSSION In recent years, it has become difficult to maintain an ample supply of medicinal plants due to several factors, such as ruthless exploitation from natural habitat, lack of conservation of the environment, increasing labor costs and economical or technical problems associated with the cultivation of medicinal plants. The use of tissue culture technique for biosynthesis of secondary metabolites, particularly in plants of pharmaceutical significance, holds promise for the controlled production of plant constituents (Kokate et al., 2008). In spite of recent development in synthetic chemistry, higher plants are still an important source of medicinal compounds (Debnath et al., 2010). Formation of callus is the outcome of cell division and cell expansion under the influence of exogenously supplied plant growth regulator (Pierik, 1987). Calli like organs and cells are seats of metabolism and metabolic gradients. Despite changes in the physical form, they are capable of continued production of secondary metabolites e.g. Anthraquinone from Ophiorrhiza pumila tissue and cell cultures (Kitajima et al., 1998). Physical, chemical or biological stress leads to alteration in the concentration of secondary metabolites (Yeoman and Yeoman, 1996). Tissue culture media and controlled conditions reported to enhance callus growth along with secondary metabolite production of isoflavonoid in soyabean (Tuominen and Musgrave, 2006); Anthraquinones from Ophiorrhiza pumila tissue and cell cultures (Kitajima et al., 1998). Compact cell aggregates (Fu et al., 2005) and Methyl Jasmonate is reported to produce hispidulin in Saussurea medusa (Fu et al., 2006). Optimization of the hormonal concentration and combination are often effective. High auxin levels, although good for cell growth, are often deleterious to secondary metabolite production. Alteration in the environmental factors such as nutrient levels, light and temperature may also affect in increasing the productivity (Zenk et al, 1975). Plant growth regulators were tested in combinations of auxins, namely 2,4-D and IAA; along with cytokinins Kinetin and BAP. Amongst the combination of growth regulators tested, IAA: Kin (5:5) produced upto 1600 mg of callus from explants of 40-60 mg initial (Fig.1A) fresh weight in a period of 6 weeks (Fig.1E), The callus induced gradually covered the explants (Fig 1B, Fig 1C). Browning of callus was initiated at the contact region with the medium at the end of 4 weeks (Fig. 1D). Proliferation of callus continued till the end of 9 weeks (Fig. 1F) (Table 1). When BAP was used singly the amount of callus produced was less than 600mg/explants which is comparable to the control treatment devoid of plant growth regulators.