Hairy roots: A biotechnological strategy to increase metabolite synthesis in Salvia species

Salvia is the largest genus in the Lamiaceae family, with around 1000 species of shrubs, perennials, and annuals. The current research sought to cultivate the hairy roots of various Salvia species to enhance the production of secondary metabolites with pharmacological activity. Hairy root cultures are made by utilizing the special ability of the soil-dwelling bacterium Agrobacterium rhizogenes to produce hairy roots at infection sites. Transformed roots are potential biotechnological systems that generate large amounts of secondary metabolites due to their quick growth and genetic and metabolic stability. Salvia karwinskii and Salvia oxyphora hairy root lines were created by co-cultivating explants with a suspension of two different Agrobacterium rhizogenes strains (ATCC and LB9402). The formation of hairy roots was observed 3-4 weeks following inoculation in both nodal and leaf explants under dark conditions. When compared to the ATCC strain, the LB9402 strain grown on Yeast/Mannitol/Broth (YMB) medium supplemented with acetosyringone developed noticeably more roots on each explant. These roots showed strong development and an abundance of lateral branching in Murashige and Skoog media free of phytohormones. Cefotaxime was added at decreasing concentrations from 300 μg/l to 50 μg/l to totally eradicate the bacterium. We continued the research using various clones to establish biomass for the examination of secondary metabolites (diterpenoids, triterpenoids and phenolic acids) from the developed roots. Examining the virC1 and rolC genes using the polymerase chain reaction allowed us to confirm the transformation.