A comprehensive review of in vitro precursor feeding strategies for the overproduction of high-value plant secondary metabolites

Plant tissue culture techniques have revolutionized various aspects of modern agriculture, horticulture, and pharmaceutical industries. This method contributes to enhancing the production of plant secondary metabolites, which have noteworthy applications in pharmaceuticals, agriculture, and industry. Presently, over 50,000 plant metabolites have been identified and categorized into three primary groups: terpenoids, flavonoids, and alkaloids. Numerous studies have elucidated the metabolic pathways involved in the biosynthesis of plant compounds to better understand the metabolic flux, with the aim of identifying and engineering the production of valuable constituents. In vitro precursor feeding is one phytochemical strategy that helps increase the accumulation of plant compounds. Therefore, this review focuses on investigating the application of in vitro precursor feedings to the overproduction of a high-value phytochemicals. Moreover, it evaluates the influence of type and concentration of precursors, plant species and culture conditions as well as the phytochemical products providing insights into optimization strategies. Additionally, the potential application of accumulated terpenoids, flavonoids, and alkaloid-derived compounds for agricultural, pharmaceutical, and industrial purposes are discussed. Finally, perspective challenges and limitations related to in vitro precursor feeding strategy are addressed, including production stability, cytotoxicity effect, and uptake efficiency. The overall data presented might serve as an up-to-date report on the application of in vitro precursor feedings for enhancing plant secondary metabolite production.