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X‐Ray Microprobe Analyses of Vacuoles of Spruce Needle Mesophyll, Endodermis and Transfusion Parenchyma Cells at Different Seasons of the Year *
Author(s) -
Stelzer R.,
Lehmann H.,
Kramer D.,
Lüttge U.
Publication year - 1990
Publication title -
botanica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0932-8629
DOI - 10.1111/j.1438-8677.1990.tb00183.x
Subject(s) - endodermis , parenchyma , vacuole , biology , botany , chloroplast , cytoplasm , biophysics , electron microprobe , anatomy , chemistry , mineralogy , microbiology and biotechnology , biochemistry , gene
The needles of an outdoor‐grown healthy Picea abies (L.) Karst. tree were routinely investigated from bud break up to 16 months thereafter. Transmission electron microscopical (TEM) and cryoscanning electron microscopical (CSEM) techniques were used for structural observations. Energy dispersive microanalyses (EDX) on bulk‐frozen hydrated specimens served for direct determination of element levels in the vacuoles of the mesophyll, endodermis and transfusion parenchyma cells. Both, CSEM and TEM micrographs show comparable seasonal variations e.g. in chloroplast structure and in vacuolar inclusions. EDX‐analyses clearly point out that high Mg concentrations are characteristic of mature endodermis cells. Conversely, K concentrations incline to become lower in the maturing endodermis than in the surrounding tissues. The elements P and S represent the major part of the potentially inorganic counterions for Mg and K. It is concluded that the endodermis cells serve as a storage buffer for maintaining homeostasis of Mg and S levels in the adjacent cells throughout the year.