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Parasitic Plants Steal Host Genes and Use Them to Bypass Defenses

David Jennings
24th October, 2016

A team of researchers has found that a group of parasitic weeds regularly “steal” genes from their hosts. These genes are then incorporated into the plants’ DNA and are used to bypass the host’s defense mechanisms. The details are in a paper that was just published in the journal Proceedings of the National Academy of Sciences. Horizontal gene transfer (HGT) is the transfer of genes between two different organisms. Normally, genes are passed down from parents to offspring. In horizontal gene transfer, DNA is transferred in a different way and the swap often occurs between two separate species. Bacteria and other microbes are known for this ability. Although rare, there are some cases of HGT in eukaryotes, including certain plants. Researchers used information from the Parasitic Plant Genome Project, a database funded by the U.S. National Science Foundation. The team found evidence of HGT in three species of the Orobanchaceae family, a group of parasitic plants called broomrapes. Many broomrape weeds, such as witchweed, are highly destructive and often wipe out entire crops. The weeds are a source of economic hardship for hundreds of millions of farmers worldwide. The research team also discovered evidence of HGT in a nonparasitic plant species called Lindenbergia philippensis. In most cases, the stolen genes were from the parasites’ host plants. The authors speculate that these genes are incorporated into the parasite’s genome to help them invade and get past host defenses. Some of the genes may also help the parasitic plants avoid infections. Parasitic plants can achieve HGT easily because they’re already engaged in cellular contact with the host. The team’s findings provide new insights into eukaryotic HGT. This type of gene transfer was much more common in parasitic plants, which utilized the new genes to easily infect hosts. The team believes that their study will eventually lead to the development of parasite-resistant crops. REFERENCE Yang et al. Horizontal gene transfer is more frequent with increased heterotrophy and contributes to parasite adaptation. Proceedings of the National Academy of Sciences (2016).