Nucleic acid transport in plant-microbe interactions: The molecules that walk through the walls

Many microbes "genetically invade" plants by introducing DNA or RNA molecul es into the host cells. For example, plant viruses transport their genomes between host cells, whereas Agrobacterium spp. transfer T-DNA to the cell n ucleus and integrate it into the plant DNA. During these events, the transp orted nucleic acids must negotiate several barriers, such as pi ant cell wa lls, plasma membranes, and nuclear envelopes. This review describes the mic robial and host proteins that participate in cell-to-cell transport and nuc lear import of nucleic acids during infection by plant viruses and Agrobact erium spp. Possible molecular mechanisms by which these transport processes occur are discussed.