Production of Phenolic Acids Improved in Callus Cultures of Lactuca undulata by Ultraviolet-B Irradiation

As a valuable industrial compound, cichoric acid has antiviral, antioxidant, and anti-inflammatory properties. It is effectively used in obesity prevention and for neuroprotective purposes. Here, we aimed to compare the effects of plant growth regulators and UV-B radiation on the induction of cichoric acid production under tissue culture conditions. For this purpose, Lactuca undulata, an herbaceous medicinal plant, was used as a new source of cichoric acid. Leaf explants were initially cultured on ½ MS (Murashige and Skoog) medium containing ۰.۱, ۱ mg/L Kinetin (Kin) and ۲,۴-Dichlorophenoxyacetic acid (۲,۴-D). The callus was then exposed to different UV-B exposure times (۰, ۲۰, ۴۰, and ۶۰ min) and was harvested after ۵, ۱۰, and ۱۵ days. The highest amounts of total phenol, cichoric acid, chlorogenic acid, and caffeic acid were achieved in callus samples that were treated with ۲۰ and ۴۰ minutes of UV-B radiation for ۱۰ days. Cichoric acid content reached an amount of ۶.۱۵±۰.۲۹۲ mg/g DW after ۲۰ min of radiation. Pearson’s correlation coefficient analysis (PCC) showed that Phenylalanine Ammonia Lyase (PAL) activity did not correlate with the production of caffeic acid derivatives. These results suggested that UV-B irradiation can be used as an elicitor to induce the production of cichoric acid in Lactuca undulata callus cultures.

Keywords:

Cichoric acid , chlorogenic acid , Exposure Time , Lactuca undulata , PAL