Broomrape

Broomrape is a genus of plant that contains over 200 species. They are small parasitic flowering plants and native to the Northern Hemisphere. They usually have yellow or tan-colored stems and lack any chlorophyll. When they aren’t flowering, they are not visible above the soil. It is a major weed on broadleaf crop plants in Australia, such as lentils and canola. Broomrape plants are parasitic, using other plants to gain the energy they need as they lack chlorophyll and cannot be autotrophs like other plants. It sends out a root that attaches to the roots of the host plant and steals water and nutrients for itself. Similar to bacteriophages, some only parasitise a single species of plant. All of these traits make it one of the worst parasites for a gardener to see. These pests are dealt with in several key ways, CRISPR, RNA interference, and suicidal germination.

CRISPR can be used to alter the DNA of host plants so that they are unable to help and give nutrients to the parasitic broomrapes. Broomrape seeds only germinate when they detect chemical signals exuded by host roots called strigolactones. Altering these signals has already been accomplished by multiple different companies, most notably Lark Seeds International which has accomplished this in tomato plants. Altering these signals makes the parasites never germinate, meaning they never grow up to be a parasite, alternatively some CRISPR mutations block the signal entirely instead of altering it, producing the same effect. Additionally, certain genes in plants, if modified, can increase the resistance of plants to the parasite. This makes the parasite unable to connect and form an attachment to the host plant.

RNA interference uses Host-Induced Gene Silencing, turning the parasite's feeding mechanism against itself. Due to how the feeding mechanism works in broomrapes, they absorb small bits of RNA along with nutrients, if these RNA are modified to disable the parasite’s essential functions, the feeding will kill the parasite from the inside, protecting the host plant.

Another strategy is creating a synthetic strigolactone to spread across a field without any plants. Once this is done, all the dormant seeds for the broomrapes start to germinate due to the presence of the strigolactone. Then without any host to attach to, they all die immediately, making the field completely free of broomrapes and safe for incoming plants.

Quiz:

References:

Jhu, Min-Yao, et al. “CRISPR Gene Editing to Improve Crop Resistance to Parasitic Plants.” Frontiers in Genome Editing, U.S. National Library of Medicine, 25 Oct. 2023, pmc.ncbi.nlm.nih.gov/articles/PMC10642197/.

P;, Zainali N;Alizadeh H;Delavault. “Gene Silencing in Broomrapes and Other Parasitic Plants of the Orobanchaceae Family: Mechanisms, Considerations, and Future Directions.” Journal of Experimental Botany, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/39289888/. Accessed 9 Aug. 2026.

Fernández-Aparicio, Mónica, et al. “Broomrape Weeds. Underground Mechanisms of Parasitism and Associated Strategies for Their Control: A Review.” Frontiers in Plant Science, U.S. National Library of Medicine, 19 Feb. 2016, pmc.ncbi.nlm.nih.gov/articles/PMC4759268/.

"Broomrape, Branched Broomrape, Hemp Broomrape, Clover Broomrape, Common Broomrape.” Weeds Australia, 13 Oct. 2024, weeds.org.au/profiles/broomrape-branched-hemp/.