Abstract
Horizontal gene transfer (HGT) represents the incorporation of genetic material from one organism into another that is not its offspring. In plants, the majority of reported cases of HGT are limited to plant-microbe genetic exchanges, mitochondrial transfer, or the translocation of mobile elements among related species. Here we show clear evidence for recent HGT of a nuclear-encoded gene from a monocot host to a eudicot recipient, the parasitic "witchweed" Striga hermonthica.
S. hermonthica belongs to the eudicot Orobanchaceae, and infests to crop species, such as sorghum and rice, which belong to the monocot Poaceae. To identify the HGT events between hosts and the parasite, the S. hermonthica ESTs were searched for the genes conserved in monocot genomes but not in eudicot genomes. We found a strong candidate gene which encodes an unknown function protein. This candidate gene is most similar to homologues from sorghum, a common monocot host of the parasitic weed, with sequence similarity extending to the 5' and 3' untranslated regions of the open reading frame. Our results suggest that nuclear genes from crops can be captured by a parasitic weed in nature.
