Carrot specific features of the phenylpropanoid pathway identified by feeding cultured cells with defined intermediates

Plants produce a vast array of secondary metabolites, many of which have important biological propertiesin animals when consumed as part of the diet. Interestingly, although the activities and benefits of plantsecondary metabolites in animals are well established, comparatively little is known about the endogenousfunctions of these compounds in plants. One way to investigate the role of secondary products inplants is to modify the secondary metabolome and investigate the impact of such modifications on thephenotype.We have designed a novel feeding approach using different hydroxycinnamic acids (HCAs) and thecyanidin precursor dihydroquercetin (DHQ) to modify the metabolome of carrot R3M suspension cells.This strategy increased the accumulation of specific metabolites in a predictable way, and providednovel insights into the carrot phenylpropanoid pathway, suggesting that (a) cells use HCA hexose estersas substrates in the biosynthetic pathway leading to the accumulation of the various HCA derivativesand (b) pcoumaricacid derivative levels play a key roles in the regulation the flux of HCAs along thepathway.Moreover, this rapid strategy for metabolome modification does not depend on the availability ofmolecular tools or knowledge and can therefore be applied to any plant species.