2.4.2. Elicitation
Methyl jasmonate (MeJA), a plant-specific endogenous phytohormone, regulates the biosynthesis of specialized plant metabolites (Rahnamaie-Tajadod et al., 2017).
MeJA (100-200µM) not only triggers the biosynthetic pathway but also, stimulates specific gene expression that leads to a higher yield of many anticancer compounds such as by elicitation of cell suspension cultures of L. album cell line 2-5aH with MeJA, accumulation of PPT reached 7 mg/g, DW (Wasternack and Hause, 2013; van Fürden et al., 2005). Salicylic acid is a potent signaling molecule present in plants that are actively involved in providing resistance against pathogens and growth responses. Salicylic acid has a profound role in plant defense systems via the production of plant defense compounds. It has also been used in the production of various biologically active compounds in plant cell culture systems (Nadeem et al., 2019). Salicylic acid in the L. album produces 333µg/g PPT; it also increases the expression of three genes involving in the first step of the PPT biosynthetic pathway. However, genes involved in the last biosynthetic steps were not affected by salicylic acid (Yousefzadi et al., 2010). Biotechnological production of anticancer compound PPT inL. album cell cultures shows a seven-fold increase in compound production than control by fungal elicitor Fusarium graminearum . Extracts of Fusarium graminearum in cell cultures of L. album produce 140µg/g DW of PPT. Besides, the up-regulation of lignan biosynthesis pathway genes was also observed in fungal elicitor cultures (Bahabadi et al., 2012).