PLANT CELL BIOTECHNOLOGY AND MOLECULAR BIOLOGY

The effect of chitosan nanoparticles (Chs NPs; 50 and 200 mg/l) either individually or coated with coumarin (40 mg/l) and L-phenylalanine (40 mg/l) were tested for callus growth, silymarin, phenolic compounds and antioxidant activity in Silybum marianum callus. XRD pattern and particle distribution curves of the NPs treatments were assigned. Root explants of in vitro germinated seedlings gave the highest callus formation rate and biomass of healthy friable callus on Murashige and Skoog (MS) medium supplemented with 1.0 mg/l of both 2,4-dichlorophenoxy acetic acid and 6-benzyladenine. Chs NPs (50 mg/l) coated with coumarin (40 mg/l) recorded the maximum value of callus fresh weight (67.85 g), compared to the control and this treatment showed low lipid peroxidation product. However, the lowest malondialdehyde content was recorded when callus was treated with 50 mg/l Chs NPs coated with L-phenylalanine, which showed the maximum radical scavenging activity. Peroxidase activity of callus was superior by the treatment of 200 mg/l Chs NPs coated with coumarin. Overall, NPs treatments were superior in the production of silymarin isomers and phenolic compounds, except for isosilybin B, catechol and cinnamic acid, in comparison to the control. In addition, NPs triggered the accumulation of some silymarin isomers (taxifolin and silydianin) and some phenolics (P-OH-benzoic acid and protocatechuic acid), which were not detected in the control callus. These results confirm the potential of using NPs as elicitors for enhancing the in vitro production of bioactive compounds.