Together with pathogenic microbes and herbivorous insects, parasitic plants are emerging as aggressive threats on agriculture worldwide. Among them, Cuscuta (dodder), a stem holoparasite, extracts nutrients and water from host plants through phloem feeding. Dodder is parasitic on a very wide variety of plants, including a number of important agricultural and horticultural crops such as alfalfa, clover, tomatoes, and potatoes. Dodder infestations cause major economic concerns, including crop yield reduction and cost increase of crop harvesting. Understanding resistance mechanisms against dodder can provide potential solutions to effectively control dodder infestations.