Some parasitic plants steal genetic material from their host plants and use the stolen genes to more effectively siphon off the host’s nutrients. A new study led by researchers at Penn State and Virginia Tech reveals that the parasitic plant dodder has stolen a large amount of genetic material from its hosts, including over 100 functional genes. These stolen genes contribute to dodder’s ability to latch onto and steal nutrients from the host and even to send genetic weapons back into the host. The new study appears July 22, 2019, in the journal Nature Plants.
“Horizontal gene transfer, the movement of genetic material from one organism into the genome of another species, is very common in microbes and is a major way that bacteria can acquire antibiotic resistance,” said Claude dePamphilis, professor of biology at Penn State and senior author of the study. “We don’t see many examples of horizontal gene transfer in complex organisms like plants, and when we do see it, the transferred genetic material isn’t generally used. In this study, we present the most dramatic case known of functional horizontal gene transfer ever found in complex organisms.”
Parasitic plants like dodder cannot live on their own by generating energy through photosynthesis. Instead, they use structures called haustoria to tap into a host plant’s supply of water and nutrients. Dodder wraps itself around its host plant, growing into its vascular tissue, and often feeds on multiple plants at one time. It can parasitize many different species, wild plants as well as those of agricultural and horticultural importance.
“Parasitic plants live very intimately in connection with their host, extracting nutrients,” said dePamphilis. “But they also get genetic material in the process, and sometimes they incorporate that material into their genome. Previous studies focused on single transferred genes. Here, we used genome-scale datasets about gene expression to determine whether the large amount of genetic material coming over through horizontal gene transfer is actually being used.” …
The researchers are currently investigating how exactly genetic material is being transferred from host to parasite. They would also like to explore whether this transfer is a one-way street, or if the host can obtain genetic material from its parasite.
“We’d love to know how extensive horizontal gene transfer really is,” said dePamphilis. “We looked at just one of species of dodder, which is just one of over 4000 species of parasitic plants. Does horizontal gene transfer of functional genes happen to the same extent in other species? Is it possible in non-parasitic plants? In other complex organisms? This may be the tip of the iceberg.” Paper. (paywall) – Zhenzhen Yang, Eric K. Wafula, Gunjune Kim, Saima Shahid, Joel R. McNeal, Paula E. Ralph, Prakash R. Timilsena, Wen-bin Yu, Elizabeth A. Kelly, Huiting Zhang, Thomas Nate Person, Naomi S. Altman, Michael J. Axtell, James H. Westwood, Claude W. dePamphilis. Convergent horizontal gene transfer and cross-talk of mobile nucleic acids in parasitic plants. Nature Plants, 2019; DOI: 10.1038/s41477-019-0458-0 More.
Indeed, HGT may well be “the tip of the iceberg,” as the researcher says. Consider: Darwinism is about ancestor-descendant relationships. Take that away and the whole elaborate catechism of altruism, kin selection, costly fitness, etc. is poof! And horizontal gene transfer does indeed take that away.
See also: Horizontal gene transfer: Sorry, Darwin, it’s not your evolution any more
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