| چکیده انگلیسی مقاله |
Introduction: St. John's Wort, scientifically known as Hypericum perforatum L., belongs to the family Hypericaceae and is an important medicinal plant widely used today for the treatment of depression. It is one of the best-selling herbal products worldwide. Its medicinal properties are attributed to the secondary metabolites present in its extract, including hypericin, hyperforin, flavonoids, xanthones, and other valuable compounds. To meet the growing demands of the pharmaceutical industry and to obtain high-quality biomass, it is cultivated in various countries. However, plants grown under field conditions often face challenges that may affect their phytochemical composition. Plant tissue culture under controlled conditions can mitigate these issues and serve as an attractive alternative to field cultivation. Today, one of the key aspects of biotechnology in Hypericum perforatum is the enhancement of bioactive molecule content using various approaches, including elicitation in tissue culture.
Aim:This research aims to investigate the callogenesis optimization and morpho-physiological, phytochemical, and biochemical changes in the callus of Hypericum perforatum L. in response to chitosan elicitor under In Vitro culture conditions.
Materials and Methods: After obtaining Hypericum perforatum seeds, the effect of sterilization methods on seed contamination percentage was evaluated using a completely randomized design. Subsequently, a factorial experiment in a completely randomized design was conducted to optimize callus induction using hormonal treatments (E1 to E2), explants (E1, E2), and different light conditions (L1, L2). After preparing the chitosan elicitor at concentrations of 0 (control), 25, 50, and 75 mg, another experiment was carried out in a completely randomized design to apply the elicitor to the seeds. Finally, the effect of the chitosan elicitor on improving morphological, physiological, metabolic, and biochemical traits was examined.
Results: The results of the mean comparison for the effect of sterilization methods showed that treatment C (no sterilization) and S2 exhibited the lowest and highest levels of contamination percentage, respectively. The mean comparison results for the interaction effect of hormonal treatment explant type, and light conditions indicated that the best hormonal combination for callus induction was H1E1L1. The findings revealed a significant increase in traits such as fresh weight, dry weight, callus volume, flavonoids, phenols, antioxidant activity, anthocyanins, carotenoids, catalase, peroxidase, proline, and chlorophyll a and b at all chitosan concentrations compared to the control. The highest and lowest values for these traits were observed in the 50 mg/L chitosan treatment and the control, respectively. For malondialdehyde content, the highest and lowest levels were associated with the control treatment and the 50 mg/L chitosan treatment, respectively.
Conclusion: Overall, the results of this study demonstrated that the chitosan elicitor improved the growth, physiological, metabolic, and biochemical characteristics of Hypericum perforatum. Among all the concentrations used, the 50 mg/L concentration was the most effective in enhancing these traits.
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