Discovery of an extended bundle sheath in Ricinus communis L. and its role as a temporal storage compartment for the iron chelator nicotianamine.
The extended bundle sheath (EBS) is a specialized layer of cells that enhances the lateral transport of photoassimilates within the leaf. This little-known tissue is often considered to be legume-specific. We identified an EBS in cotyledons and leaves of the non-legume Ricinus communis L. By means of cytological and immunological studies and using the localization of the iron-chelator nicotianamine as an established indicator for mass transport, we confirmed its role as a transport tissue and a temporal sink. Observations on cotyledons of Ricinus seedlings further proved that the EBS carries out these tasks from a very early stage of development onwards. This is the first time that information has been obtained on the physiological role of an EBS in a non-legume. Our results support the idea of its widespread occurrence among higher plants.
Rutten
T
T
Institute of Plant Genetics and Crop Plant Research, Corrensstrasse 3, 06466 Gatersleben, Germany. rutten@ipk-gatersleben.de
Krüger
C
C
Melzer
M
M
Stephan
U W
UW
Hell
R
R
D001383:Azetidinecarboxylic Acid / Q000031:analogs & derivatives* / Q000378:metabolism*; D035264:Flowers / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D007502:Iron Chelating Agents / Q000378:metabolism*; D008854:Microscopy, Electron; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D012278:Ricinus / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure
D007502:Iron Chelating Agents; C082893:nicotianamine; D001383:Azetidinecarboxylic Acid