Furanocoumarins in Pastinaca sativa L. in vitro culture

Callus cultures of Pastinaca sativa L. (parsnip), Apiaceae, were cultivated on variants of Linsmaier-Skoog's medium, containing varying quantities (0.1-10.0 mg/l) of phytohormones: NAA-BAP and IBA-BAP which allowed to obtain 1.5-3-fold fresh biomass growth during 6-week subcultures. HPLC analyses showed that tissues cultured in vitro produced psoralen, bergapten, xanthotoxin, isopimpinellin and umbelliferone which are well known metabolites in plants growing under natural conditions. Total content of coumarins depended on the nature and quantity of phytohormones present in the medium, and ranged from 115.7 to 408.5 mg/100 g of the dry weight, isopimpinellin being the metabolite which dominated quantitatively (maximum content of 238.9 mg/100 g). Psoralen was also accumulated in callus tissues at considerable amounts (maximum content of 108.8 mg/100 g). This metabolite dominated in vegetative plant parts that have been analysed in our study (leaves, stems, roots) but its contents were lower than in the material from in vitro culture (48.9 mg/100 g 10.6 mg/100 g and 14.9 mg/100 g, respectively). Imperatorin was not detected in callus tissues although it dominated in the analysed fruits of the studied plant (200.0 mg/100 g). The best of the tested media in respect of promoting tissue biosynthetic capabilities was that which contained 3 mg/l NAA and 1 mg/l BAP. The studies showed that in vitro cultures of Pastinaca sativa L. can be a convenient model to study the biosynthesis of furanocoumarins and also a potential rich source of these compounds, particularly isopimpinellin.