sbornik_s_2011.pdf

XI. Workshop of Physical Chemists and Electrochemists´11 Brno
2. EXPERIMENT
Plant material (roots, stems, leaves) was collected in the botanical garden of
University of Veterinary and Pharmaceutical University Brno. For the anatomical study,
transversal, radial and tangential hand-made sections were used. For the visualization of
lignified plant tissues, ethanolic (50 %, v/v) mixture of acid fuchsine and malachite green
(both 1%, w/w; Sigma-Aldrich, USA) was used. Sections were stained for four minutes
and after it washed with acidic ethanol (60 %, v/v, with 37% hydrochloric acid 0.1 %, v/v,
Sigma-Aldrich, USA). At once, sections, which were not stained, were used for
microscopic analysis using fluorescence microscope (Carl Zeiss Axioscop 40, Zeiss,
Germany). In addition, sections were stained by aqueous solution of acridine orange (1 %,
w/w, Sigma-Aldrich, USA) for detection of non-lignified and lignified structures.
3. RESULTS AND DISCUSSION
The object of this study was focused on vegetative organs of Rhus hirta (L.) Sudw.
Roots were observed only in the secondary state because of very early formation of
vascular cambium, which produces elements of secondary xylem and secondary phloem.
Secondary xylem of roots is typical due to presence of high number of vessels of large
diameter. Amount of libriform is low; in addition, secondary cell walls if libriform are
very thin and almost without lignification. Secondary phloem consists of sieve tubemembers,
which are arranged in tangential groups, radial parenchyma forms well visible
rays. Axial parenchyma of secondary phloem are associated with sieve tube-members. In
the older parts of secondary phloem, there are large schizogenous intercellular cavities.
Secondary dermal tissue periderm consists of layers of phellem cells with suberinised cell
walls and 1-2-layered cork cambium (phellogene). Phelloderm is reduced to only several
cells, which undergo sclerification under formation of sclereids (see Fig. 3).
Stems as well as roots very early undergo process of secondary thickening due to
activity of vascular cambium and cork cambium. However, epidermis persists after
formation of vascular cambium. Some epidermal cells are modified into trichomes.
Glandular trichomes, which are associated with production of some secondary
metabolites, are typically multicellular. Cortex consists of collenchymatous hypodermis,
parenchymatous mesodermis and indistinct endodermis- starch sheath. Vascular bundles
are arranged in one ring (eustele) and are typically collateral. Elements of protophloem
undergo sclerification under formation of sclerenchyma on the periphery of vascular
bundles. Metaphloem is connected with formation of large schizogenous secretory
cavities, each vascular bundle contains one cavity. In comparison with roots, secondary
xylem of stem contains less vessels and higher amount of libriform with distinct secondary
cell walls. Axial parenchyma is associated with vessels, ray parenchyma forms
heterocellular rays. Pith is parenchymatous, some cells undergo sclerification and form
individual sclereids. In addition, pith contains schizogenous intercellular cavities with
distinct epithelial cells (see Fig. 4).
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