Genetic control of seed chemistry and morphology in wild parsnip (Pastinaca sativa)

Wild parsnip seed contain furanocoumanns, secondary compounds that are toxic to a wide variety of organisms. Variation in the quantities of furanocoumarins in seed has been shown to be genetically based. Because thesecompounds are found exclusively within oil tubes in the fruit, we attempted to determine whether seed orphology, including the number and size of oil tubes, is genetically variable and serves as a constraint on chemical content. Quantitative genetic analyses revealed significant additive genetic variation for three of five chemicals, seed length, and the number and area of oil tubes. The content of all five furanocoumarins was most highly correlated with the combined area of the oil tubes; however, seed morphology overall accounted only for a small amount of the variation in chemical content. Nevertheless, a significant positive family mean correlation between oil tube area and one of the furanocoumarins (sphondin) suggested that the same genes control oil tube size and sphondin content.