Metabolite bioprospection and expression analysis of patchoulol synthase gene in different in vitro systems of Pogostemon cablin: An important medicinal aromatic plant

Abstract

Pogostemon cablin (patchouli) is one of the most prized medicinal herbs cultivated worldwide. However, with changes in the bioclimatic patterns and nematode infections in its root, the availability of quality planting material for essential oil extraction has become a challenging task in recent times. In the present research, a synergistic effort based on the identification of the optimal gene expression level of the patchoulol synthase (PS) along with fresh weight (FW), an effective strategy was formulated for the bioprospection of specialized metabolites of patchouli via plant tissue culture based in vitro approaches. The comparative expression levels of the PS gene in various tissues grown in semisolid as well as suspension cultures provided vital insights into its role in the biosynthesis of patchoulol and its associated compounds. Comparatively, cell suspension derived biomass exhibited better efficacy in terms of antioxidant activity (IC50 = 27.88 μg/ml), sun protection factor (SPF = 4.49–20.20), accumulation of both volatile and non-volatile metabolites profiled through ultra performance liquid chromatography and gas chromatography-mass spectrometry (GC-MS) along with up regulated PS gene activity (5.01 FC). Interestingly, semisolid culture media derived callus extract also exhibited potent activities establishing the novelty of the approach. The findings illustrate the utilization of aromatic cytokinin – meta-Topolin as a potent elicitor in synergy with conventional elicitors like methyl jasmonate and synthetic growth regulators such as thidiazuron. The current approach also provides vital, reproducible, sustainable and cost-effective method for the bioprospection of prized metabolites in the callus and cell suspension cultures with the goal of up-scaling to pilot scale via coordinated use of next generation bioreactor approaches.