Protein-accumulating cells and dilated cisternae of the endoplasmic reticulum in three glucosinolate-containing genera: Armoracia,Capparis, Drypetes

Three glucosinolate-containing species, Armoracia rusticana Gaertner, Meyer et Scherbius (Brassicaceae), Capparis cynophallophora L. (Capparaceae) and Drypetes roxburghii (Wall.) Hurusawa (Euphorbiaceae), are shown by both light and electron microscopy to contain protein-accumulating cells (PAC). The PAC of Armoracia and Copparis (former myrosin cells) occur as idioblasts. The PAC of Drypetes are usual members among axial phloem parenchyma cells rather than idioblasts. In Drypetes the vacuoles of the PAC are shown ultrastructurally to contain finely fibrillar material and to originate from local dilatations of the endoplasmic reticulum. The vacuoles in PAC of Armoracia and Capparis seem to originate in the same way; but ultrastructurally, their content is finely granular. In addition, Armoracia and Capparis are shown by both light and electron microscopy to contain dilated cisternae (DC) of the endoplasmic reticulum in normal parenchyma cells, in accord with previous findings for several species within Brassicaceae. The relationship of PAC and DC to glucosinolates and the enzyme myrosinase is discussed.Abbreviations ABB aniline blue black - DC dilated cisternae - EM electron microscopy - ER endoplasmic reticulum - GMA glycolmethacrylate - LM light microscopy - MBB mercuric bromphenol blue - PAC protein-accumulating cells - PAS periodic acid-Schiff Recipient of an Alexander von Humboldt Award and in residence at the University of Heidelberg during the period when this research was carried out. Permanent address: Department of Botany and Cell Research Institute, University of Texas, Austin, Texas 78712, USA