Coleus spp.: Micropropagation and In Vitro Production of Secondary Metabolites

Coleus spp. have long been prized for their colorful foliage, which may combine shades of green, yellow, pink, red and maroon. They are plants for all locations. Besides their ornamental nature, Coleus spp. are also valued in folk medicine. C. blumei Benth., a natural hybrid of several Coleus spp. is an ornamental plant growing all over the world in an enormous number of different cultivars that vary in color and shape of the leaves, and is also known for its medicinal properties, in particular rosmarinic acid, one of its most important secondary compounds. Rosmarinic acid has been shown to exhibit antioxidative, anti-inflammatory and antiallergic activities in mammalian systems. C. forskohlii Briq. is a medicinally important plant valued for the production of forskolin, a diterpenoid, present in root tubers of the plant and known to lower blood pressure and intraocular pressure. C. parviflorus Benth. (country potato) has the potential of developing into a crop similar to potato. An ample amount of work has been reported on micropropagation of different Coleus spp. from different explants like shoot tips, leaf segments, nodal and internodal segments, etc. Furthermore, large-scale production of rosmarinic acid and forskolin from cell cultures of C. blumei and C. forskohlii, respectively, has also been reported. Genetic transformation using Agrobacterium has been reported to enhance rosmarinic acid and forskolin production in transformed cultures of C. blumei and C. forskohlii. _____________________________________________________________________________________________________________