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The plant parasite Cuscuta spp. and its hosts
Fig 2. C. reflexa on the susceptible host plant Coleus blumei.
At present, we are mainly using Cuscuta spp. (Fig. 2) as a model plant parasite to addressing the questions raised above. Living as obligate holoparasites with a very broad host spectrum, plants of the genus Cuscuta possess neither roots nor expanded leaves. To survive, Cuscuta enwinds the stems of host plants and develops haustoria, establishing connections directly to the host’s vascular bundles. This haustorium penetration and accompanying wounding seems to go undetected by most host plants and the parasite succeeds in representing itself as an attractive sink by probably mimicking a part of “host-self”.
How can plants detect plants? We are interested in identifying signals and bioactive molecules on the parasite’s side that trigger visible or measurable responses in the host plant, for either plant development or for defense. On the host side, we study signaling and responses in the infested plant, focusing on perceptual systems that initiate downstream developmental signaling programs and control cellular responses.The chances and possibilities of hosts for defence may differ from those known for plant-microbe interactions. Given their significant evolutionary distance from microbes, over time all higher plants have established an innate immune system to defend against microbial pathogens. By means of pattern recognition receptors (PRRs), plants can sense so-called microbe-associated molecular patterns (MAMPs) and initiate defensive signaling programs that help the plant to restrict pathogen growth.
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