Wednesday, July 24, 2019

Parasitic Plants Are Able to Steal Genes From Their Hosts

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."

Image result for dodder plants

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.

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  1. Its really cool to think about horizontal gene transfer outside of the realm of bacteria, which is the only place where I had really ever heard of it. When you talked about how the dodder extracts nutrients and genetic information from the host plant, I wondered why the dodder plant hasn't yet taken the gene to produce more chloroplast to create more energy, or the gene to grow bigger leaves to have a larger surface area so they would not need to have a host plant.

  2. So the plant is able to distinguish between “junk” DNA and important DNA? I think that’s the most interesting part. Stealing a hosts instructions on hw to survive the environment it’s in, structure, defense, and metabolism, is extremely useful. It seems like it’d be a highly invasive plant species, that learns to adapt to most environments.