Source of nitrogen as a factor limiting saponin production by hairy root and suspension cultures of Calendula officinalis L.

Triterpenic saponins represented in Calendula officinalis L. by oleanolic acid (OA) glycosides are pentacyclic triterpene compounds with a wide range of biological and medicinal properties. This report demonstrates nitrogen source impact on growth, saponin accumulation, and secretion in hairy root and suspension cultures of marigold. Hairy roots preferred nitrate as a mineral source of nitrogen, but its impact on growth, OA glycosides accumulation, and secretion were line-dependent. The best productivity of OA glycosides was found in CC16 line (74.86 mg flask(-1)) in 1/2 MS medium modified by 2.5x KNO3 and ammonium elimination with 2.5 g l(-1) peptone. Organic nitrogen source at 27.5-g l(-1) impairs the growth rate of hairy roots. Its effect on saponin accumulation and secretion to the surrounding medium depended on line and media composition. Nitrate: ammonium ratio of 4: 2 for CC16 resulted in 5.7-fold increment of saponin secretion comparing to the standard medium. Embryo roots, apical bud, and hypocotyls explants were crucial for induction of suspension culture synthesizing saponins; however, effect of mineral form of nitrogen in cultivating medium had to be considered. The highest OA glycosides level (171.97 mu g g(-1) of dry weight) was recorded in the root derived culture with nitrate as a sole mineral form of nitrogen. Peptone from lactalbumin decidedly inhibited the saponin formation; however, it was essential for culture initiation, proliferation, and organ differentiation.