Induction of carotenoid pigments in callus cultures of Calendula officinalis L. in response to nitrogen and sucrose levels

In vitro carotenoid pigment production in callus cultures of Calendula officinalis L. was investigated using two basal media, semi-solid versus liquid media and varied concentrations of sucrose, ammonium, and nitrate nitrogen. Of the two explants that were evaluated, floret explants were best for callus induction using Murashige and Skoog (MS) medium supplemented with 2.0 mg l(-1) 2,4-dichlorophenoxyacetic acid under complete darkness. Carotenoid pigment induction was significantly augmented when the sucrose concentration was increased. Low sucrose concentrations in the culture medium deferred the onset of pigment induction and reduced the overall levels of carotenoid pigments produced. The highest amount of carotenoid pigments was observed when the callus was grown on the MS medium without ammonium nitrogen. The quantity of carotenoids was slightly elevated in cultures grown on semi-solid medium than those grown in liquid medium. In vitro carotenoid production was optimized by modifying the concentration of ammonium nitrogen to nitrate nitrogen in the culture medium and enhancing the sucrose concentration.