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Photo of Crenate broomrape in Morocco
Parasitic plants · Plant communication · Weed evolution
My research focuses on parasitic plants, which are interesting because of their remarkable adaptations to a parasitic lifestyle as well as their economic impact on agriculture.
Parasitic plants differ from typical autotrophic plants in that they obtain their water and nutrients from a "host" plant. To accomplish this, they have evolved a unique structure called a haustorium, which invades the host and connects to the host vascular system to enable the parasite to siphen off host resources. Some species of parasitic plants have evolved to completely lose their capacity for photosynthesis, and thus depend entirely on their hosts for survival.
Parasitic plants are masters of plant communication. The ability to locate and attach to a host plant is essential for survival of parasites, so it is no surprise that they have highly developed strategies for interacting with other plants. In fact, all plants have capacity to respond to their environment and communicate with other organisms, although this is widely overlooked by people outside of plant science. Plants are good at detecting shades of light, chemical signals, and physical contact, but parasitic plants provide some of the clearest illustrations of this. For example, seeds of some parasite species only germinate after they detect the presence of a root of an appropriate host. Additional communication takes place between cells of the two species after the parasite contacts the host, and parasite cells must interact with those of the host to coordinate nutrient transfer and suppress host defenses. We are especially interested in the roles played by the exchange of RNAs and other large molecules between parasites and their hosts.
Parasitic plants that attack crop plants are some of the world's most troublesome weeds. They can be especially destructive because they directly take resouces from the host crop, and are difficult to control due to their close connections to the host. All weeds evolve in response to selective pressures, adapting to survive control measures and expand their ranges. Parasitic weeds demonstrate exceptional ability to adapt, modifying their host preferences and moving to new parts of the world. Understanding how they do this is an important step in devising effective plans to manage parasitic weed problems.
To learn more, click the tabs for Research, Currently Funded Projects, and Parasitic Plant Information.
Research in the Westwood Lab
Our research has been funded by US agencies (National Science Foundation and US Deparpartment of Agriculture) for many years. One might ask: Why study parasitic plants? Why is this information important?
1. Global impact Although the most devastating species of parasitic plants are not found in the United States, they are major weeds in many parts of the world and impact the lives of millions of poeple. In Africa, witchweeds destroy staple crops of corn, sorghum and millet, contributing to starvation. Throughout the Mediterranean region, broomrapes attack pea and faba bean (as well as many other vegetables), causing farmers to abandon these crops. Finding ways to control parasitic weeds contributes directly to world food security.
2. Understanding plants Parasitic plants also contribute to fundamental understanding of how plants grow and interact with their environment. The ability of some parasites to link their seed germination to the detection of chemical signals exuded from host roots is an elegant example of plants reacting to other plants, and this contributed to the discovery of the strigolactone class of plant hormones. Also, the parasite haustorium interacts directly with cells of the host, transmitting chemicals between the two plants. Research on this topic has helped understand the ability of RNA molecules to move long distances within plants and funtion as signals between plants. This work may contribute to improving agriculture through improving plant growth and potentially providing new methods for weed control.
Recent journal articles
Adhikari, S., Mudalige, A., Phillips, L., Lee, H., Bernal-Galeano, V., Gruszewski, H., Westwood, J.H., and Park, S-Y. 2025. Agrobacterium-mediated Cuscuta campestris transformation as a tool for understanding plant–plant interactions. New Phytologist 245: 1774–1786. DOI: 10.1111/nph.20140
Sharma, G.; D. Haak, J. Westwood, S. Askew, and J. Barney. 2024. Transgenerational adaptation to herbicide stress is more rapid than to ecological stress in Arabidopsis. The Plant Journal 119:2375-2384. http://doi.org/10.1111/tpj.16923
PLANTCOM network: Claude Becker, Richard Berthomé, Philippe Delavault, Timothée Flutre, Hélène Fréville, Stéphanie Gibot-Leclerc, Valérie Le Corre, Jean-Benoit Morel, Nathalie Moutier, Stéphane Muños, Céline Richard-Molard, James Westwood, Pierre-Emmanuel Courty, Alexandre de Saint Germain, Gaëtan Louarn, Fabrice Roux. 2023. The ecologically relevant genetics of plant-plant interactions. Trends in Plant Science. https://doi.org/10.1016/j.tplants.2022.08.014
Bendaoud, F., G. Kim, H. Larose, J.H. Westwood, N. Zermane* and D.C. Haak*. 2022. GBS analysis of Orobanche crenata populations in Algeria reveals genetic differentiation. Ecology and Evolution 12:e8750 DOI: 10.1002/ece3.8750
Bernal-Galeano, V. K. Beard and J.H. Westwood. 2022. An artificial host system enables the obligate parasitic plant Cuscuta campestris to grow and complete its life cycle in vitro. Plant Physiology 189:687-702. DOI: 10.1093/plphys/kiac106
Park, S.-Y., K. Shimizu, J. Brown, K. Aoki and J.H. Westwood. 2022. Mobile host mRNAs are translated to protein in the associated parasitic plant Cuscuta campestris. Plants 11, 93. DOI: 10.3390/plants11010093
Sharma, G., J.N. Barney, J.H. Westwood and D.C. Haak. 2021. Into the weeds: new insights in plant stress. Trends in Plant Science 26:1050-106. https://doi.org/10.1016/j.tplants.2021.06.003
Gu, X., I.G. Chen, S.A. Harding, B. Nyamdari, M.A. Ortega, K. Clermont, J.H. Westwood and C.-J. Tsai. 2021. Plasma membrane phylloquinone biosynthesis in non-photosynthetic parasitic plants. Plant Physiology 185:1443-1456. DOI: 10.1093/plphys/kiab031
Clarke, C.R., S.-Y. Park, R. Tuosto, X. Jia, A. Yoder, J.H. Van Mullekom and J. Westwood. 2020. Multiple immune pathways control susceptibility of Arabidopsis thaliana to the parasitic weed Phelipanche aegyptiaca. PeerJ 8:e9268. DOI: 10.7717/peerj.9268
Dor, E., D. Plakhine, D.M. Joel, H. Larose, J.H. Westwood, E. Smirnov, H. Ziadna and J. Hershenhorn. 2020. A new race of sunflower broomrape (Orobanche cumana) with a wider host range due to changes in seed response to strigolactones. Weed Science 68:134-142. DOI: 10.1017/wsc.2019.73
Understanding and engineering host defense to a parasitic plant
This project is based on the idea that host plant defense systems can be improved to resist parasitism and this knowledge can be used to make crops that are not parasitized. We have evidence that host defense signaling networks influence the success of the parasitic plant Phelipanche aegyptiaca (Egyptian broomrape) attachment on host roots. We are using genetic and molecular tools to dissect the roles of host defense genes in the interactions with parasites using two hosts, the model plant Arabidopsis and tomato. We have also identified host gene promoters that are expressed with high specificity in response to parasite attack. We plan to generate transgenic plants expressing these promoters fused to the most effective defense genes. Ultimately, we aim to generate enhanced resistance to parasitism in both Arabidopsis and tomato hosts. This project will expand our understanding of host defense responses and host-parasitic plant communication.
Collaborator: Soyon Park, University of Missouri
Funded by: USDA NIFA award 2023-67013-39896
Collaborative Research: PlantTransform: Novel methods of plant genome editing enabled by theparasitic plant Cuscuta campestris
A major barrier to plant research and crop improvement is a scarcity of methods available for genetically manipulating plants. Techniques currently used include the culturing of plant tissues, the insertion or editing of DNA, and the regeneration of whole plants, but each of these steps represents a potential barrier because they don't work reliably in many species. To fill this gap, we propose that the parasitic plant dodder (Cuscuta species) can be used to deliver gene editing molecules to a wide range of plants. Dodder plants live by attaching themselves to the stems of host plants and forming connections to withdraw water and nutrients. The organs that form the connections are called haustoria, and function somewhat similar to the way a mosquito taps into a vein to feed, and dodder is able to transmit a variety of large molecules, including proteins and RNAs, to their hosts. Another key feature of dodder is its ability to connect to an unusually wide range of host species, including the most important broadleaf crops. We will evaluate the ability of dodder to mobilize genome editing molecules into its hosts, with the goal of producing gene-edited seeds. Success in this activity would establish a novel vehicle for genetic modification of plants that is relatively simple, rapid, and broadly applicable.
Collaborators: Soyon Park, University of Missouri; Michael Axtell, Penn State; Bastiaan Bargmann, Virginia Tech
Funded by: NSF (Plant Genome) IOS-2348321
- See the Cuscuta Introduction page for general information and fun.
- See the Cuscuta Research Resources page for sequences, protocols, etc.
A recent photo of people in the Westwood lab.
Current members:
Hope Gruszewski, Research Specialist Senior
Matilda Cashman, Laboratory Technician
Nyima Bojang, Undergraduate Student
Mae Hajjaj, Undergraduate Student
Cinaiya Huddleston, Undergraduate Student
Recent graduate:
Sukhmanpreet Kaur, Ph.D.
This page is under construction
Photo of Dr. Westwood
James H. Westwood
Professor
School of Plant and Environmental Science
Virginia Tech
401 Latham Hall (0390)
Blacksburg, VA 24061 USA
(540) 231-7519
westwood@vt.edu
Prospective students - Please read this:
Dr. Westwood is nearing retirement and is finishing up his research program. Therefore, he cannot take any new students. Best wishes in your search for continued training.
Recent news from the lab
Parasitic plants featured at the US Botanic Garden
The exhibit, “Fierce Flora: Tales of Survival and Demise” uses dodder videos made by Dr. Westwood. Check it out when you're in Washington D.C.
VT news feature on latest NSF grant award:
Organic collaboration propagates National Science Foundation grant
Latest publications
Cerda-Herrera, J., H. Zhang, E. Wafula, S. Adhikari, S.-Y. Park, S.B. Carey, A. Harkess, P. Ralph, J.H. Westwood, M.J. Axtell, and C.W. dePamphilis. 2025. Chromosome level assembly and annotation of Cuscuta campestris Yunck. ("dodder") a model parasitic plant. G3:Genes Genomes Genetics. https://doi.org/10.1093/g3journal/jkaf193
Westwood, J.H. and S. Kaur. Suppressing exudation hides the host from a parasitic plant. 2025. Trends in Parasitology 41: 269-270. https://doi.org/10.1016/j.pt.2025.03.006 (Invited Spotlight article)