The effect of phenylalanine and salicylic acid facilitators on the production of secondary metabolites in the capillary roots of Silybum marianum L. under in vitro conditions

Although Silybum marianum as a member of the Asteraceae family, is most commonly acknowledged as a weed, extraction of its valuable secondary metabolite called silymarin has potentially-proved to become as a medicinal product for dealing with liver disease and heart and cancer diseases. The aim of this study was to induce capillary root in milk thistle plant in order to increase the production of secondary metabolite silymarin in transgenic roots and the use of allicitors to accelerate the production of this substance.

The objective of this study was to induce capillary root in milk thistle plant and investigating the effect of driving forces of salicylic acid and phenylalanine on enhancing the production of secondary metabolites in capillary root of milk thistle as well. This research was conducted in two distinct experiments at Zanjan University. The first experiment was performed in a completely- randomized design of 9 replications to evaluate the production of capillary roots and transgenics in this plant by three strains of Agrobacterium rhizogenesis including A7, R1000 and ATCC. Morphological traits Root number and root length were measured. The second experiment was a completely randomized design on salicylic acid treatment of three levels (0, 50 and 100 μM) and phenylalanine of three levels (0, 100 and 200 μM) in three replications. this aforementioned experiment was done to assess the impacts of these treatments on capillary roots lacking bacterial inoculation and who’s that derived from ATCC, A7 and R1000 bacteria with aim of measuring traits of total phenol, flavonoids, antioxidants and silymarin. Data were analyzed using SAS software.

According to the findings of analysis of variance, the length and number of capillary roots produced by ATCC strain were higher compared to other ones. The results also showed that all physiological and biochemical traits measured were significant at the level of 1% probability. The highest amount of total phenol was taken place in phenol content of capillary roots in the treatment of 200 μM phenylalanine with ATCC. The highest amount of silymarin was observed in capillary roots transgenic with R1000 bacteria and ATCC with phenylalanine at concentration levels of 200 μM.

The addition of elicitor along with the presence of bacteria as a transgenic agent improved the biochemical and physiological traits of marigold. Among them, the amount of silymarin secondary metabolite in capillary roots transfected with R1000 and ATCC along with phenylalanine treatment at the concentration of 200 μM showed the highest.