Chemical and genetic stability of methyl chavicol-rich Indian basil (Ocimum basilicum var. CIM-Saumya) micropropagated in vitro

Indian basil i.e. Ocimum basilicum L., an important essential oil yielding plant, is used in high-grade perfumes, flavoring, dental and oral products. A methyl chavicol-rich, high essential oil yielding variety of Indian basil CIM-Saumya, released by the Central Institute of Medicinal and Aromatic Plants, India, has immense industrial potential due to the occurrence of two important aromatic components, i.e. methyl chavicol (62.5-77.6%) and linalool (14.4-34.1%). The Ocimum being highly cross-pollinated and seed propagated, produce heterogeneous progeny thereby restricting its commercial application. In the present investigation, an attempt has been made to produce a large number of genetically and chemically uniform plants of this improved variety CIM-Saumya for the first time using nodal explants. Multiple shoot cultures developed on Murashige and Skoog's medium (MS) supplemented with BA (N6-benzyladenine, 2.67 μM) and these shoots were further transferred to half strength MS medium supplemented with NAA (α-naphthalene acetic acid, 0.27 μM) for rhizogenesis. These plantlets were maintained under in vitro conditions for more than three years. The established plantlets were successfully shifted in a glasshouse and finally in the field. Flow cytometry, inter simple sequence repeat (ISSR) and random amplified polymorphic DNA (RAPD) markers, were employed to evaluate genetic similarity amongst micro-clones and the mother plant. In all, 28 primers (18 RAPD and 10 ISSR) generated 178 distinct, monomorphic and reproducible bands. Head space gas chromatography showed the similarity in the qualitative profile of 11 major volatile constituents. These results clearly demonstrated that the developed protocol can be efficiently utilized to generate genetically and chemically uniform population of an industrially important variety CIM-Saumya.