Bangalore Scientists Decode Genome and Mysteries of Tulsi plant

Unraveling the mysteries of Tulsi


Tulsi, a plant that denotes a Hindu home is a common sight in India and researchers have decoded the first draft genome.

Tulsi (Ocimum tenuiflorum), queen of all herbs, is used for therapeutic purposes, especially in Ayurveda and has been mentioned in ancient Indian scriptures.

A pan-India team led by Sowdhamini Ramanathan from National Centre for Biological Sciences (NCBS), Bangalore, have mapped the genome of Tulsi, in collaboration with inStem and CCAMP, all members of the Bangalore Life Sciences Cluster.

Tulsi grows extensively in tropical climates, and is familiar in Asia, Africa and Central and South America. The plant is known for its anti-bacterial, anti-fungal, anti-pyretic and anti-cancer properties. Its compounds are metabolites, a by-product of plant metabolism, typically used for plant self-defence. These metabolites are not fully understood due to lack of genomic information.

Sowdhamini and team have produced the first draft genome of O. tenuiflorum Krishna subtype, identifying the genes responsible for production of metabolites with medicinal properties.

Focusing on the important metabolite genes, the team used five different types of Tulsi, (Ocimum tenuflorium subtype Rama, O. tenufloriumsubtype Krishna, O. gratissimum, O. saccharicum and O. kilmund) to collect the genomic data and compare it with species likeArabidopsis thaliana, about which enough information is available.

“The genome sequencing projects involved generation of huge amounts of data. The genes were identified from this enormous amount of data using complex prediction models and were then numbered for easy identification. This assembled genome and the set of genes served as a starting point for all downstream analysis”, said Adwait Joshi, one of the team members.

Apigenin, Taxol and Ursolic acid are implicated in anti-cancer properties of the plant, Citral for its anti-septic nature and Eugenol for its anti-infective properties.

Some metabolites have been used in the perfume and cosmetic industries, while others have been exploited in curing human ailments like malaria, bronchitis, diarrhea and dysentery.

“Like many other plants, Tulsi also produces specialized metabolites as a part of its defence mechanism. Linalool, Linalyl, Geraniol, Camphor, Thymol, Safrol, Apigenin, Citral, Eugenol, Taxol and Ursolic acid are few examples among the important secondary metabolites of Ocimum species” says Harini, a team member.

Studying mature roots, leaves, flowers, seeds and other parts of the plant, the team found that the precursors of these metabolites are synthesized in young tissues, and retain their specific medicinal properties when transported to their mature counterparts.

“Owing to the 3000 years of cultivation of Krishna Tulsi and extensive descriptions in ancient Indian texts, it is assumed to be of Indian origin. The findings of the experiments reinstate the household knowledge passed on for generations, even when prodded by modern scientific techniques”, said Nitish Sathyanarayana, one of the authors of the research paper.’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 Ursolic acid – a compound with multiple chiral centers –   it would be of great benefit. “, says Prof. S. Ramaswamy, from inStem.

Prof. Sowdhamini added that this is the first report of draft genome sequencing of a plant species from NCBS and hopes to do more genome sequencing in the future. Convinced of the huge array of genes and their respective downstream compounds yet to be unraveled in further research, the team hopes to  provide the next version of the Tulsi genome.

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