Cuscuta spp. are widespread obligate holoparasitic plants with a broad host spectrum. Rootless Cuscuta penetrates host stems with so called haustoria to form a direct connection to the host vascular tissue (Dawson et al., 1994; Lanini and Kogan, 2005; Kaiser et al., 2015). This connection allows a steady uptake of water, assimilates and essential nutrients from the host plant and therefore enables Cuscuta growth and proliferation. To quantify the parasites’ ability to grow on potential host plants one can use the quantitative growth assay (Hegenauer et al., 2016) described herein, which exclusively utilizes fresh weight measurement as readout.
In research fields of plant-pathogen resistance, either in basic research or in economic plant breeding, it is unavoidable to have an assay to quantify resistance against pathogen infection. To quantify the resistance/susceptibility of different plants against Cuscuta infections the simplest way is to measure the gain of biomass of Cuscuta growing on a plant of interest. This is a reliable method since Cuscuta is a holoparasite and its gain of biomass is completely depending on its ability to successfully infect another plant. Thus, unsuccessful infection of a plant leads to a decrease in biomass and subsequently the death of the parasite Cuscuta.
Materials and Reagents
Gloves and lab suit (Cuscuta sap causes stains on skin and clothes)
Mature Cuscuta (e.g., Cuscuta reflexa; see Note 1 for cultivation)
Putative host plants
Equipment
Weighing machine/balance (mass range between 0.01-100 g)
Wooden planting rods (bamboo; diameter appropriate to the particular host plants stem diameter), available in gardening shops
Hegenauer, V., Welz, M., Körner, M. and Albert, M. (2017). Growth Assay for the Stem Parasitic Plants of the Genus Cuscuta. Bio-protocol 7(8): e2243. DOI: 10.21769/BioProtoc.2243.