alt="Illustration of tautomeric structures of Daucosterol and Epitaraxerol."/> 2.4.2 Culture Conditions
Plant growth hormones influence the growth of cell biomass and production of secondary metabolites in cell cultures of plants. The optimized culture conditions can induce the biosynthesis and accumulation of plant secondary metabolites (Bhojwani and Razdan 1996; Subathra and Mohana 2011). The cell culture studies of A. vasica were established on Murashige and Skoog culture medium (Murashige and Skoog 1962; Singh and Sharma 2013). Elicitation is being exploited as important technique and has opened new avenues for the enhancement of production of secondary metabolites (Pirian and Piri 2012). Salicylic acid and methyl jasmonate are plant growth hormones that induce the production of secondary plant products (Jirage et al. 1999). Several types of elicitors were used to increase the synthesis of phenolic compounds in cell cultures of Vitis vinifera (Riedel et al. 2012; Kauss et al. 1993). Polysaccharides also elicited manifold increase in the production of anthraquinones and other compounds in suspension cultures of Rubia as well as other plant species (Jin et al. 1999; Karuppusamy 2009; Rao and Ravishankar 2002; Wong 2003). The amino acids were added in cell cultures to enhance the production of terpenoid indole alkaloids in Catharanthus roseus (Gaviraj and Veerasham 2006). The effect of salts on the accumulation of secondary metabolites at 50 mM concentration was assessed, and it is found that NaCl increased the production of alkaloids in Rauvolfia tetraphylla (Mohana Priya et al. 2011; Anitha and Kumari 2006).
Amino acids play significant roles in catalyzing the reactions of secondary metabolism in plants (Pratelli and Pilot 2014). It has been reported that methyl jasmonate increases the accumulation of amino acids in suspension cultures of Scrophularia striata (Sadeghnezhad et al. 2016). Methionine and aspartic acid were added as elicitors in the cell suspension cultures of Nicotiana tabacum and showed twofold increase (serine, glutamic acid, aspartic acid) in accumulation of free amino acids (Dougall 1965). With feeding of NaCl and CoCl2, the cell cultures of Mesembryanthemum crystallinum and Zea mays maintained 5% extra synthesis of proline as well as total amino acids (Thomas et al. 1992; Jaleel et al. 2009).
The anthranilate synthase (AS) is a complex enzyme and having two subunits known as ASα and ASβ (Poulsen et al. 1993). The anthranilate synthase catalyzes the biosynthesis of anthranilate from chorismate via amination of C-2 and removal of hydroxyl group (Delmer and Mills 1968; Tamir and Srinivasan 1971). Oligo-N-acetylchitooligosaccharide and D-tryptophan were used to increase the anthranilate synthase activity in oats (Matsukawa et al. 2002). The biosynthesis of anthranilate synthase was induced by D-tryptophan in cell cultures of C. roseus (Moreno et al. 1991).
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