Scientists sequence Tulsi genome for medicinal value

New Delhi: A team of researchers from the National Centre for Biological Sciences (NCBS), Bangalore, has succeeded in sequencing the genome of Tulsi, a step which will help identify the genes responsible for production of compounds with potential medicinal benefits.

The team which included researchers from NCBS, inStem and CCAMP (Centre for Cellular and Molecular Platforms), all members of the Bangalore Life Sciences Cluster, used five different types of Tulsi, (Ocimum tenuflorium subtype Rama, O tenuflorium subtype Krishna, O Gratissimum, O Saccharicum and O Kilmund) to collect the genomic data.

They then compared the results with well-studied species like Arabidopsis thaliana, a Eurasian plant which was first to have its genome sequenced, and is a popular tool for understanding the molecular biology of many plant traits. This helped them identify the unique compounds found in Tulsi Krishna subtype.

As part of Ministry of Science and Technology initiative, they also investigated an important metabolic pathway producing Urosolic acid, which revealed that such specialised metabolites are synthesised in the young tissues and carried onto the matured parts, while retaining their medicinal properties.

The medicinal properties of Tulsi are attributed to specialised compounds produced as a part of its defence mechanism. These compounds are called 'metabolites' because they are a by-product of the plant's metabolism.

"The sequence reveals the interesting pathways used by Tulsi to make Ursolic acid, a medically important compound. If one could now use modern synthetic biology techniques to synthesise Urosolic acid --- a compound with multiple chiral centers ---- it would be of great benefit," Prof S Ramaswamy, from inStem said.

Tulsi or Ocimum tenuiflorum, is assumed to be of Indian origin and has been under cultivation for almost 3000 years now. It has a variety of medicinal properties, anti-bacterial, anti-fungal, anti-pyretic and anti-cancer, to name a few. The herb has been widely used in the Ayurvedic system of medicine.

Despite its historical importance and extensive use in traditional Indian medicine, there is a poor understanding of the bioactive compounds produced by Tulsi. "There are more than 40 secondary metabolites in Ocimum species, which are exploited by humans to treat diseases including Apigenin, Citral, Eugenol, Taxol and Urosolic acid", said Prof Sowdhamini Ramanathan, who led the research.

"Apigenin, Taxol and Urosolic acid are anti-cancer properties of the plant, Citral is useful for its anti-septic nature and Eugenol for its anti-infective properties and so on," said Atul Updadhyay, the first author of the paper.