| This work has taken advantage of the availability of cell and hairy root culture systems for S. medusa previously established in our laboratory. S. medusa is best known as a medicinal plant, but its natural populations are diminishing and endangered. The major bioactive compounds in S. medusa are flavonoids and syringin.The main objective of the thesis has been to enhance production of flavonoids and syringin in cell and hairy root cultures of S. medusa by elicitors. A few key enzymes in the phenylpropanoid pathway were examined. A cDNA encoding S. medusa chalcone synthase, the first enzyme in the flavonoid biosynthesis pathway, was cloned.The first project involved salicylic acid (SA) and yeast extract (YE) as elicitors. It was shown that SA was more efficient than YE for increasing cell growth and/or flavonoid accumulation. Treatment with SA at low dosages not only increased cell growth, but also flavonoid and syringin contents in the cells. SA added at 20μM on day 6 was found to be optimal, which led to flavonoid and syringin production up to 532 mg/l and 630 mg/l, or 130% and 150% increases, respectively, compared with the control.The second project was concerned with hairy root growth and flavonoid production in the presence of YE and SA. Application of SA or YE in early growth phases inhibited hairy root growth but, overall, unlike for cell cultures, YE proved better than SA in stimulating hairy root growth. The best result was achieved using YE at 40μg/ml added on day 10; with 741 mg total flavonoids and 303 mg syringin per liter culture obtained. These values were about 2.8- and 2.5-times higher than from the control.The third project dealt with time course changes of enzymatic activities in flavonoid biosynthetic pathway in cell cultures with SA. With 20μM SA, activities of chalcone synthase and chalcone isomerase were elevated within 1 h. For phenylalanine ammonia-lyase, its activity increased to up to 6.5-fold higher than in untreated cells...
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