You are What You Eat: Interactions Between Root Parasitic Plants and Their Hosts

In this review we will discuss three main areas of research in plant–parasitic plant interactions. In the first section, we will deal with the physiology and biochemistry of the plant parasitic interaction, primarily focusing on the effects of resource abstraction. A functional split shall be introduced between parasites that are either predominantly xylem- or predominantly phloem feeding, and the implications of these two parasitic strategies discussed. In the second section we shall discuss the events leading up to the mature system, and the defenses employed by host plants against parasites. This section will focus on parasites’ life cycles, and on the hosts’ defense mechanisms against parasitism. Host plants and parasites are locked in a perpetual evolutionary arms race, with host plants evolving defenses, and parasites evolving counter-defense mechanisms. Significant events, such as parasite germination, and its subsequent attachment (or not) are discussed in reference to the functional groups introduced earlier. Finally, we discuss the evolution of parasitic plants and their ecological effects, from the negative effects of parasitic plants on agro-ecosystems, to their positive effects on plant biodiversity, via the suppression of dominant species, in natural and seminatural ecosystems.