Hawthorn (Crataegus aronia L.) callus growth dynamics and polyphenol production under different light intensities

Crataegus aronia is a wild medicinal plant belonging to the Rosaceae family and has been known for the medicinal activity of its extracts due to the high levels of flavonoids and phenolic compounds. Recently, in vitro culture of plant cells, callus and microshoots is widely used to maximize production of plant secondary metabolites. In this study, the effect of different light intensity levels (0, 20, 40, 60, 100, 150 and 200 µmole.m -2 .s -1 ) at different incubations periods (15, 20, 25, 30, 35 and 40 days) were used to evaluate in vitro callus growth and in vitro polyphenol production in Crataegus aronia. Callus growth was significantly increased after 20 days of culture. Maximum callus growth was reached at 30 days. Growing C. aronia callus for extended periods will not result in more growth especially under the high light levels, even more a reduced callus growth was seen in cultures grown at the high levels of radiation. Polyphenol production was affected by light level and duration of culture. Extended culture incubation resulted in low polyphenol production. Maximimum polyphenolic contents were obtained on C. aronia callus after 20 days of incubation at 40 µmole.m -2 .s -1 . The effect of storage of prepared extract on polyphenol content was compared to the freshly used samples and the results showed that storing polyphenol extracts for 1 day resulted in a drastic drop in polyphenol content. This may indicate fresh use of such material is preferred to processed or stored products.