Secondary metabolite production and related biosynthetic genes expression in response to methyl jasmonate in Castilleja tenuiflora Benth. in vitro plants

Castilleja tenuiflora Benth. (Orobanchaceae) is a medicinal plant that synthetizes terpenes and phenolic compounds of therapeutic value. This study aimed to analyze the effect of methyl jasmonate (MeJA) at different concentrations on growth and content of total phenolic compounds (TPC) in C. tenuiflora in vitro plants. Changes in the concentration of secondary metabolites and gene expression patterns of four enzymes (DXS, G10H, PAL, and CHS) involved in metabolite biosynthesis were carried out under MeJA elicitation. MeJA did not decrease growth and 100 µM MeJA caused greater production of TPC. The increase in TPC was accompanied by an increase in PAL activity and in H₂O₂ content. MeJA elicitation had a greater effect on phenolic compounds than on iridoids, increasing the contents of verbascoside and aucubin to 82.1 ± 0.8 mg g⁻¹ dry matter and 14.6 ± 0.2 mg g⁻¹ dry matter, respectively. The highest accumulation of aucubin occurred after short exposure to the elicitor. MeJA treatment up-regulated the expression of metabolite biosynthesis related genes Cte-PAL1, Cte-CHS1, Cte-DXS1, and Cte-G10H when compared to control plants. The present work contributes to the understanding of the molecular basis of secondary metabolite biosynthesis in C. tenuiflora.