Parasitic Dodders Stole a Gene and Rebuilt It Without Losing Its Function

Parasitic dodder plants appear to have done more than borrow a useful gene from another species: they reshaped it over millions of years while preserving its original biological function, according to research reported by Phys.org. The study focused on CYP81Q, a gene involved in producing sesamin, a lignan compound with antioxidant properties. Researchers led by Koh Aoki of Osaka Metropolitan University traced the gene’s evolutionary history and found evidence that it originally came from another flowering plant in the order Lamiales, a group that includes medicinal and culinary herbs. The gene later entered the dodder lineage through horizontal gene transfer. Unlike ordinary inheritance between parents and offspring, horizontal gene transfer moves genetic material between unrelated organisms. Parasitic plants may have unusual opportunities for this kind of exchange because they form direct physical connections with their hosts. After CYP81Q arrived in dodder, it did not remain an untouched copy. The researchers found that pieces of transposable elements—sometimes called “jumping DNA”—inserted dodder DNA into the borrowed sequence. One insertion eventually became part of a new intron, a section removed from the gene’s RNA before the instructions are used to make a protein. Despite these structural changes, the remodeled gene still produced a functional enzyme capable of synthesizing sesamin. The finding indicates that horizontal gene transfer can be followed by further evolutionary changes as a gene becomes integrated into its new genomic environment. The researchers described the result as evidence that horizontal gene transfer occurs in plants as well as in organisms where the process is more commonly discussed, such as bacteria. In parasitic plants, transferred genes may provide useful biological capabilities while also becoming material for additional evolutionary change. The study, titled “Transposon-colonized intron gain follows parasitism-mediated horizontal transfer of a cytochrome P450 gene,” was published in Plant Physiology.