Improvement of Phenols Production by Amino Acids in Callus Cultures of <i>Verbascum thapsus</i> L.

Abstract

A great mullein ( Verbascum thapsus L.) was a famous species in Scrophulariaceae family. It was generally used as herbal medicine. Explants of V. thapsus (leaves and petioles) were cultured in vitro on Murashige and Skoog (MS) medium for shoot proliferation.Plantlet explants were cultured on MS medium supplemented with combination of Benzyl adenine (BA) and Naphthalene acetic acid (NAA) for callus induction. The best fresh and dry weight of callus formation was achieved using 0.5 mg/l BA. Quantitative analyses with High-performance liquid chromatography (HPLC) showed the content of phenols like Coumarin, Eugenol and Thymol were relatively low in leaves of mother plant, (10, 41, 310 ppm) respectively. The addition of different concentrations of amino acids as a precursor adding separately to the tissue culture medium led to raise the accumulation levels of phenolic compounds in callus tissue. Generally, the enhancement of accumulation depended on the type of amino acids and their concentration. The results showed 150 mg/l of Proline encouraged production of Comarin to 2752%, while 50 mg/l of Proline promoted accumulation of Eugenol to 290%. Whilst 150 mg/l of Tryptophan increased production of Thymol to 390%, in comparison with mother plant.