Practical utility of genes responsible for the biosynthesis of a useful compound in a plant
You essentially gave the answer in your question. By identifying the biosynthetic pathway(s) required to create the compound in the plant, its natural host, those genes can then be cloned and transferred into an expression system like bacteria, yeast, or other plant cells like Arabidopsis thaliana to generate larger quantities of the compound of interest than would be possible from harvesting and processing the original plant itself.