The physiology of the established parasite-host association

Abstract

Parasitic plants rely on their hosts for part or all of their nutritional needs. The exact level of host dependence varies among parasitic species that are accordingly classified as either hemiparasites that perform at least some photosynthesis in part of their life cycle or holoparasites. This distinction has important implications for the physiological function of the haustorium, which has the capacity to absorb nutrients from the host. This chapter focuses on the key physiological aspects of parasite-host association: the types of materials that are translocated from host to parasite and back, the mechanisms of nutrient transfer, selectivity in extracting specific nutrients, induced changes in the host that increase the flow of nutrients and parasite utilization of acquired material. The physiological processes that are associated with the mature haustorium, the transfer of materials and the relevant metabolic capacity needed to integrate with overall parasite metabolism are discussed.