The role of hormones in parasitic plant infection

Plant parasitism is a widespread lifestyle found throughout the plant kingdom that plays important roles in ecology and agriculture. Parasitic plants rely on the formation of specialized parasitic organs called haustoria to invade their hosts and withdraw nutrients. Currently, our knowledge is growing regarding how parasitic plants use haustoria to infect their hosts, modify their physiology and regulate infection. Important factors in plant development are hormone signaling molecules that play essential roles in how plants grow and interact with their surroundings. In recent years, major progress has been made in understanding the relevance of various hormones in plant parasitism. Here, we review recent findings in the field, focusing on the role of hormones in several stages of parasitism, including haustoria induction, vascular development, and interaction with the host. We discuss and compare how hormones influence haustoria development in different parasitic plant lifestyles and species, and identify knowledge gaps in the field. Future work on understanding how hormones influence parasitism is crucial to develop novel ways to control the damage caused by parasitic plants to agriculture, and to discover how parasitic plants efficiently connect to their hosts.