Researchers from Penn State, Virginia Tech, and Kennesaw University in the
US, discovered that parasitic plants steal genes from their host plants and
use it to efficiently absorb nutrients from their host. The study focused on
the parasitic plant dodder, which has stolen a huge quantity of genetic
material from its host plants, including over a hundred functional genes.
These genes contribute to the dodder's ability to attach better to its host
and siphon its nutrients.
Parasitic plants such as dodder cannot live independently through
photosynthesis. They access a host plant's water and nutrient supply through
structures called haustoria. The dodder envelops the host plant and grows
into its vascular tissue. Its usual hosts include wild plants as well
agricultural and horticultural crops.
The research team identified 108 genes that have been included to dodder's
genome through horizontal gene transfer. The genes appear to be functional
in the parasite, aiding haustoria structure, defense responses, and amino
acid metabolism. One of the stolen genes produce micro RNAs that are
returned to the host plant, working as a genetic weapon to put down host
defense genes. Eighteen of the 108 genes were also found in all dodder
species, which may imply that these genes were stolen by the ancestral form
of dodder and eventually retained by the modern species.
According to Claude dePamphilis, professor of biology at Penn State and
senior author of the study, the results "present the most dramatic case
known of functional horizontal gene transfer ever found in complex
organisms." The researchers are still studying how the genetic material is
being moved from host to parasite to determine if it is a one-way process or
if the host can also acquire genes from its parasite.