Effect of Genotype and Methyl Jasmonate on Silymarin Content of Silybum marianum (L.) Gaertn. Hairy Roots Culture

Milk thistle is a valuable medicinal plant, and obtaining silymarin (SLM) is the main reason for the cultivation of this plant. Due to the non-agricultural properties of milk thistle, its cultivation and harvesting are accompanied by difficulties. In vitro producing SLM by hairy root culture can overcome these problems. Various factors such as plant genotype, Agrobacterium rhizogenes strain used for infection, type and concentration of elicitor and, etc., can significantly enhance SLM production. The impact of various genotypes on SLM production in milk thistle hairy root culture has yet to be investigated. In this study examined the effect of five different genotypes of milk thistle and methyl jasmonate (MeJA) on the amount of SLM in milk thistle hairy roots based on completely randomized design. HPLC was used to quantify the amount of SLM in the hairy root samples. Based on the results, SLM production showed a considerable difference among ecotypes, with levels ranging from 109.8 to 648.7 ppm. MeJA increased the amount of SLM in all genotypes except for Mashhad ecotype. Due to the approximately 5.9-fold difference in SLM levels among different genotypes and the opposite responses of genotypes to MeJA indicate a high variation in this trait among different milk thistle ecotypes. Based on these results, screening milk thistle germplasm to find ecotypes with the highest levels of SLM in hairy root culture and also considering the strong mutual effect between elicitor and ecotype can be fruitful for increasing SLM content.