Genera of the Orobanchaceae family are holoparasites that parasitize various hosts. Several members of this family cause severe damage to diverse crop plants. While the biological and life cycles of these parasites have been studied, their metabolism has received little attention, most of which focused on Phelipanche aegyptiaca. This study aimed at obtaining more knowledge about the primary metabolic profiling of four parasite species belonging to the Orobanchaceae family – Orobanche cumana, Orobanche cernua, Phelipanche aegyptiaca and Phelipanche ramosa – that developed on tomato (Solanum lycopersicum L.) as a host. Using GC-MS, it was shown that significant differences in metabolites content occur between species belonging to Orobanche compared to those belonging to Phelipanche. This finding adds another layer to the separation of these two genera in addition to morphological separation. Moreover, each of these four species exhibits different metabolic profiles, indicating that the parasites can absorb the host’s metabolites but also have the ability to self-regulate their metabolites in order to grow and develop.

Seed banks are often crucial for the survival of plant species, especially short-lived ones. Nevertheless, empirical studies about the fate of seeds under natural conditions are scarce, particularly for parasitic plants. Therefore, fresh seeds of the holoparasitic Cuscuta epithymum were buried in the field under natural conditions in Belgium or kept at room temperature for up to 31 months, and germination was tested periodically by incubating seeds in light at 23°C. Buried C. epithymum seeds had cyclic changes in their germinability, while those stored dry at room temperature never germinated without scarification. Buried seeds exhibited a seasonal cycle of physiological dormancy, the first to be reported for a species with combinational (i.e. physical+physiological) dormancy. The physiological dormancy of the embryo was broken during winter ( ≤ 5°C) but induced during exposure to late spring temperatures (>10°C). Therefore, germination of C. epithymum seeds is fine tuned to seasonal temperature changes. Each year only a portion of the viable seeds could germinate. The portion of seeds buried in the soil that remained available for delayed germination, i.e. in the seed bank, decreased rather quickly, with only 8.5% of them being viable after 31 months of burial; all seeds stored in the laboratory remained viable. Nonetheless, we concluded that some C. epithymum seeds are capable of surviving for several years in the soil. These data indicate that the parasite is well adapted to survive in a dynamic heathland landscape where conditions for survival change constantly, but it is still sensitive to local extinction.