As large organisms, trees face some remarkable challenges, particularly regarding long-distance transport and communication. In addition to moving water and nutrients from their roots to their leaves, they must also integrate cell-to-cell communication over large areas. Furthermore, in order to function as a single, cohesive organism they must be able to effectively and efficiently send vital substancessuch as DNA regulating signalslong distances along a network of cells, sieve-tubes, and vessels.
But how effective is this cell-to-cell communication and how far can such solutes travel?
Xylem and phloem serve as the two main arterial systems within a plant, and substances travel along two main pathways. Apoplasmic transport, in the system of cell walls, is important for movement of water and mineral solutes. Symplasmic transport, in which openings in the cell walls allow the cytoplasm of cells to be connected, facilitates the transport of nutrients, small ions, hormones, and transcription factors along a series of cells. Although this intercellular transport system is crucial for regulating cell differentiation and subsequent tissue maturation, it is not known how extensive these symplasmic pathways are and whether they can effectively transport solutes long distances.
The fact that woody tissuesspecifically secondary xylemcontain long-living parenchyma cells, in addition to the dead cells primarily responsible for water transport, led Katarzyna Sokołowska and Beata Zagrska-Marek (University of Wroclaw, Poland) to investigate whether symplasmic pathways in these living cells might play an important role in transporting solutes from xylem to actively dividing tissues, such as the cambium. They've published their study in the most recent issue of the American Journal of Botany.
"Molecular transport of hormones and other signal
|Contact: Richard Hund|
American Journal of Botany