Serbian Society for Microscopy
Academy of medical sciences, SMS
DEPARTMENT OF BIOLOGY AND ECOLOGY
Laboratory for plant anatomy and morphology
Faculty of natural sciences, University of Novi Sad
The application of scanning electron microscopy in plant anatomy
Ljiljana Merkulov, Lana Krstić, Jadranka Luković, Miloš Bokorov
1. INTRODUCTION
For investigations of the structure of vegetative and reproductive plant organs,
scanning electron microscopy (SEM) is of great importance in study of dermal tissue
anatomy and its special structures (stomata, glandular and nonglandular trichomes,
papillae, spacialized epidermal cells, pollen grain exinas, ornamentation of seed coats
and outer layers of pericarps). Dermal tissue as an outer leyer tissue towards the
environment, is specialized structure with several functional demands: effective
protection, transport of gasses, transpiration as well as secretion of different metabolic
products through specialized cells. As this tissue is in direct contact with the
environment, it clearly expresses adaptive structural characteristics induced by
numerous exogenous factors (stomata number and size, stomata distribution, amount of
epicuticular wax, etc.). On the other hand, some dermal tissue characteristics are
determined by genetic inheritance and therefore could not be changed, or change very
little, under the influence of environmental factors (types of stomata, trichomes,
cuticle, epicuticular wax shape, presence of specialized epidermal cells, etc.) and
represent taxonomically important diagnostic characters. SEM is of a great significance
in determination and analysis of those characters.
2. INVESTIGATIONS
During several years of investigations in Anatomical laboratory, SEM analysis
were used in examination of numerous plant taxa belonging to different ecological
groups, medicinal plants, as well as to autochtonous wild relatives of cultivated plant
species.
Saline plants (halophytes) are specialized group of plants addapted to increased salt
concentrations in the soil. Eco-physiological adaptations on different amounts and sorts
of soil salt are different for specific types of halophytes and for taxa that belong to
those types. A certain number of published papers deal with examination of epidermal
characterstics of different types of halophytes. SEM analyses of epidermal tissue of
halosuculent's aboveground vegetative organs showed differences between examined
taxa in the shape and the size of epidermal cells, the type, orientation and distribution
of stomata, their position in epidermis and the structure of cuticle surface layers.
Structural differences, caused by salt type, concentration and physical characteristics of
the saline soil, were also recorded for some taxa [1], [2] (Fig. 1). Besides the
characteristics of stomata and epidermal cells, in examination of halophytes that
43
Serbian Society for Microscopy
Academy of medical sciences, SMS
secrete salt attention had been paid to the analysis of specialized structures for
secretion of salt on plant surface – salt glands, as well as to determination of
differences in epidermal characteristics between different taxa and populations from
pedologicaly different types of soils [3] (Fig. 2).
Fig. 1. Suaeda maritima – leaf epidermis,
stomata
Fig. 2. Limonium gmelinii subsp. hungaricum –
leaf epidermis
The structure of glandular trichomes of aromatic medical plants, that secreted essential
oils, was also analysed. Types and distribution of those trichomes proved to be
valuable diagnostic characters. The results of those analyses pointed to differences in
thichome structure (different types and subtypes) and distribution between the taxa of
different genera as well as between different organs of the same taxa [4], [5], [6] (Fig.
3- 6).
Fig. 3. Salvia pratensis – leaf epidermis,
capitate glandular trichomes
Fig. 4. Origanum vulgare – leaf epidermis,
peltate glandular trichome
44
Serbian Society for Microscopy
Academy of medical sciences, SMS
Fig. 5. Origanum vulgare – calyx of the flower
Fig. 6. Salvia pratensis – calyx of the flower
SEM analyses proved to be important in determination of epidermal characteristics of
some autochtonous wild relatives of cultivated plants. The obtained results explained
the possibility of using these characteristics in breeding programs, directed towards
improvement of drought and disease tolerance and nutritive value of cultivated plants
[7], [8] (Fig. 7, 8).
Fig. 7. Trifolium medium – leaf epidermis,
papillae
Fig. 8. Trifolium incarnatum – calyx of the
flower
In some of the published papers, the results of the examinations of seed and fruit
micromorphological characteristics of taxa from different genera were presented [9],
[10] (Fig. 9-12).
Fig. 9. Trifolium trichopterum – seed
Fig. 10. Trifolium trichopterum – seed coat
45
Serbian Society for Microscopy
Academy of medical sciences, SMS
Structural characteristics of the outer seed coat layers and their ornamentations are one
of the very important taxonomic characters.
Fig. 11. Trifolium retusum – seed coat
Fig. 12. Iva xanthifolia – pericarp
The application of SEM in examination of plant organ's structure enabled
determination of specific dermal tissue characteristics and characteristics of its
specialized outgrowths. Such results are particularly significant from taxonomical
(identification of taxa, explanation of taxonomical problems) and ecological point of
view (determination of adaptive characteristics on specific environmental conditions)
and are especially important in selection of taxa or their traits that could be used in
plant breeding programs.
3. REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[11]
Janjatović, V., Anđelić, M., Merkulov, Lj. Zbornik Matice srpske za prirodne
nauke, 72, (1987), 63
Krstic L., Malencic Dj., Anackov G. Botanica Helvetica, 116, (2006), in press.
Krstic L., Anackov G., Lukovic J., Merkulov Lj. XI OPTIMA Meeting,
(2004), 79
Boža, P., Merkulov, Lj., Knežević, A., Kruščić, P. Zbornik radova PMF-a, ser.
biol. 23, (1993), 54
Janjatović, V., Merkulov, Lj., Adamović, D., Bokorov, M. Zbornik radova
PMF-a, ser. biol. 24, (1995), 33
Merkulov, Lj., Igić, R., Mimica-Dukić, N., Boža, P. Arhiv za farmaciju, 3-4,
(2000), 308
Vapa, Lj., Merkulov, Lj., Boža, P., Igić, R., Marin, P. Proc. of Int. Symposium
Drought and Plant Production 1, (1997), 549
Igić, R., Lazić, B., Merkulov, Lj., Butorac, B., Zlatković, B. Proc. of Int.
Symposium Drought and Plant Production, 1, (1997), 541
Marin, P., Boža, P., Merkulov, Lj., Krstić, B., Petković, B., Veljić, B., [10]
Pajević, S. Seed Sci. & Technol. 26, (1998), 17
Krstić, L, Anačkov, G., Boža, P., Igić, R., Luković, J., Vukov, D. Zbornik
Matice srpske za prirodne nauke (in press)
46