Abstract

Genomics for Understanding Secondary Metabolism in Medicinal and Aromatic Plants

Sumit Gandhi, Sr. Scientist, Indian Institute of Integrative Medicine (CSIR-IIIM)

A variety of organic compounds are synthesized by plants, which are classified as primary or secondary metabolites. Secondary metabolites are phytochemicals that are not required for normal growth of the plant, but may provide unique survival advantages in a particular ecological niche.  Nearly 60% of all US-FDA approved drugs are natural products (mostly secondary metabolites), natural product analogues or their derivatives. Secondary metabolites are also useful as dyes, flavors, fragrances, insecticides etc.

Coleus forskohlii (Willd.)  Briq. (Lamiaceae) is an herb possessing antihypertensive activity by virtue of production of a labdane diterpene ‘forskolin’, which is a potent and reversible activator of adenylate cyclase.

Dysoxylum binectariferum (Roxb.) Hook. f. ex Bedd. (Meliaceae) is an evergreen tree, native to India, China and other parts of Asia. It is the richest reported source of ‘rohitukine’ a chromone alkaloid possessing anti-inflammatory and immunomodulatory properties. ‘Flavopiridol’, an analogue of rohitukine, has been shown to possess potent cytotoxic activity and has been approved for treatment of chronic lymphocytic leukemia.

We are employing various molecular tools, including transcriptome sequencing, to understand the biosynthetic pathways of forskolin and rohitukine. This information may in future be useful to generate these compounds in larger quantities in the host plants. It may also become possible to transfer the entire biosynthetic pathway into a microbe and produce these interesting phytochemicals using these microbes.