title: Long-distance trafficking of macromolecules in the phloem.
abstract: The fact that macromolecules such as proteins and mRNAs overcome the symplastic barriers between various tissue domains was first evidenced by the movement of plant viruses. We have recently demonstrated that viral infection disengages the symplastic restriction present between the sieve element-companion cell complex and neighboring cells in tobacco plants. As a result, green fluorescent protein, which was produced in mesophyll and bundle sheath cells, could traffic into the sieve tube and travel long distances within the vascular system. In this addendum we discuss the likely existence of a novel plant communication network in which macromolecules also act as long-distance trafficking signals. Plasmodesmata interconnecting sieve elements and companion cells as well as plasmodesmata connecting the sieve tube with neighboring cells may play a central role in establishing this communication network.
authors.affiliation: The Institute of Plant Sciences and Genetics in Agriculture and the Otto Warburg Minerva Center for Agricultural Biotechnology; The Hebrew University of Jerusalem; Faculty of Agricultural, Food and Environmental Quality Sciences; Rehovot, Israel.
authors.forename: Ayelet
authors.initials: A
authors.lastname: Omid
authors.forename: Dikla
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authors.lastname: Malter
authors.forename: Gadi
authors.initials: G
authors.lastname: Peleg
authors.forename: Shmuel
authors.initials: S
authors.lastname: Wolf
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