Phenological changes in primary and secondary chemistry of reproductive parts in wild parsnip

Abstract

Few studies have documented the developmental profile of both primary and secondary metabolites of plants; we set out to construct such a profile, in order to determine the extent to which primary and secondary metabolites covary. Primary and secondary chemistry have been documented for buds, female flowers and green fruits of wild parsnip Pastinaca sativa. A distinct qualitative shift in secondary chemistry occurs over the course of development. Mono- and sesquiterpenes were abundant in buds but absent from female flowers and green fruits. Furanocoumarins, which were found in all organs, were present at low concentration in buds, at intermediate concentrations in female flowers, and at highest concentrations in fruits. Among the primary metabolites, developmental shifts were, for the most part, quantitative. Soluble protein and fatty acid content declined with development. A qualitative change in fatty acid composition was observed in that linolenic acid inbuds was replaced by petroselinic acid in fruits. Overall variation in primary metabolites was rarely correlated with variation in secondary metabolites: of the 233 possible correlations, only 25 were significant.