June 4th, 2015
Traditional knowledge in combination with modern scientific techniques could help unravel deep hidden mysteries. Scientists from NCBS, Bangalore, have revisited the age old knowledge of “Tulsi and its medicinal effects” in their labs, only to be overwhelmed by their scientific findings. Ocimum tenuiflorum or commonly known as Tulsi has been mentioned in ancient Indian scriptures and has found wide usage in the Indian traditional system of medicine, Ayurveda. Known for producing many aromatic compounds, Tulsi gained an informal name as the “Queen of Herbs”. It is considered sacred in Hindu households and mostly used for spiritual and religious purposes in India.
Tulsi grows extensively in tropical climate, hence found in most parts of Asia, Africa, Central and South America. It consists of a wide range of bioactive compounds which are known for their anti-bacterial, anti-fungal, anti-pyretic and anti-cancer properties. These compounds or plant metabolites are very poorly understood because of absolute lack of genomic information. Prof. Ramanathan Sowdhamini and team have produced the first draft genome of O. tenuiflorum Krishna subtype which is a huge leap in understanding and identifying the genes responsible for production of metabolites with medicinal properties. Focussing on the important metabolite genes, the team 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 and compare it with the nearest genetically related species. “The genome sequencing projects involved generation of huge quantity of data. The genes were identified from this enormous amount of data using complex prediction models and then they were numbered for easy identification. This assembled genome and the set of genes served as a start point for all downstream analysis”, said Adwait Joshi, one of the team members.
Like every other plant, Tulsi also produces specialized metabolites as a part of its defence mechanism. Linalool, Linalyl, Geraniol, Camphor, Thymol, Safrol, Apigenin, Citral, Eugenol, Taxol and Urosolic acid are few examples among the important secondary metabolites of Ocimum species. “Apigenin, Taxol and Urosolic acid are implicated in anti-cancer properties of the plant, Citral for its anti-septic nature and Eugenol for its anti-infective properties and so on”, says Prof. Sowdhamini. Few 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, etc. The metabolic pathway concerning the synthesis of Ursolic acid was investigated as a case study. 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 in their mature counterparts.
Owing to the 3000 years of cultivation of Krishna Tulsi and extensive descriptions in the Vedas and Puranas, it is assumed to be of Indian origin. The findings of the experiments at CCAMP, NCBS, reinstate the household knowledge passed on by grandma, even when prodded by the modern scientific techniques. Prof. Sowdhamini said, “This is the first report of draft genome sequencing of a plant species from NCBS and we hope to do more”. Convinced of the huge array of genes and their respective downstream compounds yet to be unraveled in further research, the team looks forward to working in collaboration with an independent parallel initiative by CAMP, Lucknow, to provide the next version of the draft of Tulsi genome.