ACHIEVEMENTS IN HORIZONTAL GENE TRANSFER STUDIES IN PARASITIC PLANTS

Abstract

Horizontal gene transfer (HGT) is a process that allows genetic material to flow between even distantly related organisms. It is primarily observed in bacteria and protists but also in different lineages of eucaryotes. The first HGT cases in plants were discovered at the beginning of the 21st century and have been intensively studied ever since. Researchers have placed particular emphasis on the plant kingdom, especially parasitic plants. This review presents the current state of knowledge about this phenomenon in plants, with a special focus on parasitic plants. Among the described factors facilitating HGT, close physical contact between organisms is believed to be one of the most important. It is noted especially in the case of parasitism and similar relationships. For that reason, reported occurrences of this phenomenon in holoparasites, hemiparasites, and mycoheterotrophic plants are compared. The mechanisms responsible for HGT in plants still remain unclear, however, the studies described here suggest that both DNA and RNA may play a role as a carrier in that process. Also, the transfer between genomes of different organelles in the cell, intracellular gene transfer (IGT), and its relationships with HGT are described. The occurrence of the HGT and IGT phenomena concerning different genomes: nuclear, mitochondrial, and plastid is discussed in the review. Finally, some future areas of research in the field are proposed.