Symplasmic transport and phloem loading in gymnosperm leaves

J LiescheA Schulz


Despite more than 130 years of research, phloem loading is far from being understood in gymnosperms. In part this is due to the special architecture of their leaves. They differ from angiosperm leaves among others by having a transfusion tissue between bundle sheath and the axial vascular elements. This article reviews the somewhat inaccessible and/or neglected literature and identifies the key points for pre-phloem transport and loading of photoassimilates. The pre-phloem pathway of assimilates is structurally characterized by a high number of plasmodesmata between all cell types starting in the mesophyll and continuing via bundle sheath, transfusion parenchyma, Strasburger cells up to the sieve elements. Occurrence of median cavities and branching indicates that primary plasmodesmata get secondarily modified and multiplied during expansion growth. Only functional tests can elucidate whether this symplasmic pathway is indeed continuous for assimilates, and if phloem loading in gymnosperms is comparable with the symplasmic loading mode in many angiosperm trees. In contrast to angiosperms, the bundle sheath has properties of an endodermis and is equipped with Casparian strips or other wall modifications that form a domain border...Continue Reading


Sep 30, 1998·Proceedings of the National Academy of Sciences of the United States of America·R Turgeon, R Medville
Aug 6, 2000·Environmental and Experimental Botany·C SodaC Tani
Mar 26, 2003·Physiologia Plantarum·Xiaoqin WuLukas Schreiber
Oct 7, 2005·Current Opinion in Plant Biology·Insoon Kim, Patricia C Zambryski
May 4, 2006·Annual Review of Plant Biology·Lawren Sack, N Michele Holbrook
Jul 10, 2007·Plant, Cell & Environment·Maciej A ZwienieckiN Michele Holbrook
Mar 10, 2009·Plant Physiology·Nynne Meyn ChristensenKarl Oparka
Apr 29, 2009·Tree Physiology·Ana PinaHelle J Martens
Aug 12, 2009·Proceedings of the National Academy of Sciences of the United States of America·Emilie A Rennie, Robert Turgeon
Sep 15, 2009·Trends in Cell Biology·William J LucasJae-Yean Kim
Oct 23, 2009·Proceedings of the National Academy of Sciences of the United States of America·Cankui Zhang, Robert Turgeon
Mar 5, 2010·Plant Physiology·Robert Turgeon
Nov 17, 2010·Protoplasma·Robert Turgeon, Richard Medville
Dec 3, 2010·Protoplasma·Anna DavidsonRobert Turgeon
Jan 19, 2011·The Plant Journal : for Cell and Molecular Biology·Lidor GilShmuel Wolf
Aug 1, 2001·American Journal of Botany·R TurgeonK C Nixon
Feb 1, 1984·Planta·A C Wille, W J Lucas

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Methods Mentioned

confocal microscopy
electron microscopy

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