Researchers at Penn State and Virginia Tech discovered dodder plants steal genetic material from their hosts including over a hundred functional genes. The genes the dodder steal not only contribute to its ability to lock onto the host, but also to its ability to send back genetic weapons.
Dodder plants are leafless, parasitic plants part of the morning glory family. They do not produce energy through photosynthesis, so they live by tapping into the host's nutrients and water supply through their haustoria, a root projection of the parasite. Dodder wrap around their host plants and extend into their vascular tissue. When these parasitic plants extract nutrients, they also grab genetic material which can be incorporated into their genome. The process described is called horizontal gene transfer, but it is usually not seen in plants but is common in bacteria. Researchers described the process as "the most dramatic case known of functional horizontal gene transfer ever found in complex organisms."
To measure if the genetic material is actually being used, researchers used genome-scale datasets since previous studies only investigated single transfer genes. The criteria to determine functionaility were as follows: "The gene had to be full length, they had to contain all the necessary parts of the gene, they had to be transcribed into an RNA sequence that later builds proteins, and they had to be expressed in relevant structures."
They were able to identify 108 genes that the dodder plant stole which happen to contribute to the dodder's haustoria structure, defense, and metabolism. Interestingly, one of the genes stolen were able to produce micro RNAs that could be sent back into the host to silence their defense genes. I believe the discovery by the research team is an amazing find because we usually learn horizontal gene transfer in the perspective of bacteria because of their way to become resistant to antibiotics. The discovery provides a fresh perspective into how parasitic plants become stronger and raises questions on to whether or not other parasites can perform horizontal gene transfer.
Links to Sources: