Salt effects on membranes of the hypodermis and mesophyll cells of Avicennia germinans (Avicenniaceae): a freeze-fracture study

Freeze-fracture electron microscopy was used to investigate intramembranous panicle (IMP) densities and particle distributions in the plasma membrane and tonoplast of the cells of secreting and nonsecreting leaves of Avicennia germinans (L.) Stearn. Intramembranous panicle densities of the protoplas...

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Bibliographic Details
Published in:American journal of botany 1995-04, Vol.82 (4), p.435-440
Main Authors: Balsamo, R.A. (University of California, Los Angeles, CA.), Thomson, W.W
Format: Article
Language:English
Subjects:
ADAPTACION
ADAPTATION
ANATOMIA DE LA PLANTA
ANATOMIE VEGETALE
AVICENNIA
Botany
Cell membranes
Cellular biology
CHLORURE DE SODIUM
CLORURO SODICO
ESTRUCTURA CELULAR
Flowers & plants
MEMBRANAS CELULARES
MEMBRANE CELLULAIRE
Membranes
MESOFILO
Mesophyll cells
MESOPHYLLE
P branes
Physiology, Biochemistry, and Cell Biology
Plant cells
Plant tissues
Plants
SALINIDAD
SALINITE
Salinity
SECRECIONES DE LAS PLANTAS
Secretion
SECRETION VEGETALE
STRUCTURE CELLULAIRE
Table salt
Tonoplast
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Summary:Freeze-fracture electron microscopy was used to investigate intramembranous panicle (IMP) densities and particle distributions in the plasma membrane and tonoplast of the cells of secreting and nonsecreting leaves of Avicennia germinans (L.) Stearn. Intramembranous panicle densities of the protoplasmic (P) and exoplasmic (E) face of the plasma membrane and tonoplast were significantly higher in hypodermal cells of secreting leaves than of nonsecreting leaves. In contrast, no significant differences in the frequency of intramembranous panicles were found in any membrane faces of secreting or nonsecreting mesophyll cells. However, panicle densities were higher in the plasma membrane and tonoplast of the mesophyll cells, compared to the hypodermal cells, with the exception of the P-face of hypodermal plasma membranes of secreting tissue, which had the highest panicle density measured. Particle distributions were dispersed and no discernible patterns such as paracrystalline arrays or other multi-IMP structures were observed. Results support the hypothesis that secretion is coupled to changes in membrane ultrastructure, and the possibility that salt secretion is an active process driven by integral membrane proteins such as the H+/ATPase. Additionally, the hypodermal cells of the leaf may function as storage reservoirs for salt as well as water, suggesting a regulatory role in salt secretion
ISSN:0002-9122
1537-2197
DOI:10.1002/j.1537-2197.1995.tb15661.x