The researchers focused on transcriptomes -- expressed gene sequences -- of three parasitic plants:, Triphysaria versicolor, also called yellowbeak owl's-clover; Striga hermonthica, or giant witchweed; and Phelipanche aegyptiaca, called Egyptian broomrape, as well as the nonparasitic plant Lindenbergia philippensis, and genome sequences from 22 other nonparasitic plants. Because the researchers considered mRNA, which can move between hosts and their parasites, as a possible source of the transfers, they tested and re-tested the data to rule out the experimental host as the source of the genetic material. Instead, they found that the foreign sequences had been derived from entire genes of past host plants and incorporated into the parasitic plants genomes.
Future research may investigate the mechanism of horizontal gene transfer to help engineer improved plant defenses against parasitic attacks, dePamphilis said.