Searching for nature-based solutions: Molecular ecology of an endangered Himalayan medicinal herb shows roadmap for conservation and sustainable utilization

In recent times, to meet the surging demand of the herbal industry, overharvesting of medicinal herbs from their natural habitats has accelerated. This has posed severe extinction risks to plant species worldwide and therefore requires urgent conservation efforts and long-term sustainable solutions. By employing a molecular ecology approach, here we showcase a sustainable solution model for an endemic Himalayan medicinal herb, Trillium govanianum. The herb, being a rich source of diosgenin, is currently overharvested for its rhizome by extraction of the whole plant from the wild, leading to a drastic decline in its natural populations, and now declared Endangered. In the present study, we investigated whether there is an alternative sustainable source of diosgenin (i.e. leaves) other than rhizome in T. govanianum. We studied the spatial dynamics of diosgenin biosynthesis and accumulation using qRT-PCR-based targeted gene expression and High-Performance Liquid Chromatography-based diosgenin quantification in the leaf and rhizome samples of T. govanianum collected along the elevation gradients in Kashmir Himalaya. Our results revealed a higher diosgenin content in the leaf than in rhizome samples of T. govanianum. Expression analysis showed that, compared to the rhizome, the leaf samples exhibit relatively higher expression of all the seven genes of the diosgenin biosynthesis pathway. We also found a strong positive correlation between the expression of the targeted genes and diosgenin content in the leaf and rhizome samples. Overall, our findings offer a nature-based solution for the conservation and sustainable utilization of this imperiled endemic Himalayan herb, with lessons for elsewhere in the world.