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5 International Scientific Online Conference DOI: https://doi.org/10.15414/2021.9788055224015

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SCANNING ELECTRON MICROSCOPY STUDY OF POLLEN MORPHOLOGICAL CHARACTERS
OF MALUS DOMESTICA BORKH.
1
Vladimíra Horčinová Sedláčková , Erika Mňahončáková , Inna Goncharovska ,
2
1
Ján Brindza
1
1 Institute of Plant and Environmental Sciences, Slovak University of Agriculture in Nitra, Slovak
Republic; E-mail.: vladimira.sedlackova@uniag.sk
2 M.M. Gryshko National Botanical Garden of the National Academy of Sciences of Ukraine, Kyiv,
Ukraine
The complex of morphological characteristics and ultrastructure of pollen grains allows
determining the differences or similarities between the same species. External variables such
as extreme climatic changes, but also mineral nutrition and many internal factors (e. i. number
of chromosomes) may contribute to the variability of pollen morphological features, especially
pollen grain size.
The aim of the study was general characteristics and significant morphological traits of
pollen grains of domesticated apple (Malus domestica Borkh.) obtained from seven genotypes
cultivated in Slovakia. Analyses were studied at the Institute of Biodiversity Conservation and
Biosafety using the scanning and transmission electron microscopy. The morphometric
parameters were carried out on 50 pollen grains from each genotype using the AxioVision Rel.
4.8.2.0. The length of the polar axis (P) and the equatorial diameter (E) of grains, P/E ratio were
measured and compared among studied samples, structure of pollen grain surface was
described.
The pollen grains are medium-sized, as we can classify them in the 25–50 μm category.
The smallest pollen grains from the tested genotypes were recorded at the Md-1/4 genotype
(31.85 μm) and the largest at the Md-11/2 genotype (42.85 μm). The coefficient of variation
indicates a certain degree of variability of the mentioned traits – the average length of the polar
axis (6.05–10.68 %) and the equatorial axis (4.05–10.18 %). The genotype with the smallest
pollen grains was characterized by the greatest variability in the mentioned traits. Shape index
varied from 1.44 to 1.87.
Based on the type and number of apertures pollen grains of Malus domestica are
tricolporate, and according to the location of the apertures zonocolpate. This means that the
elongated apertures – colps are distributed equidistantly – at the same distance on the surface
of pollen grains with the center in the equatorial plane. They are traditionally tapered towards
poles. The place of narrowing of the ridges at the pole (apocolpium) has an average of 7.2–8.0
μm. The mesocolpium or intercolpium is widest at the equator, i. e. at the same distance from
both poles. The average width of the mesocolpium at the equator ranged from 15.0 to 25.2 μm.
In the middle of the mesocolpium, we can observe the ridge of exina above the surface of the
pollen grain.
The colour of pollen grains is also a taxonomic feature and tends to be different, mostly
yellow in different shades. The colour of the pollen depends on the content of the type of plant
dyes. The selected pollen grains were yellow with a shade of brown.
It was noted that diversity of surface sculpturing of pollen grains in combination with
shape and sizes of them enables to use complex of thin morphologic signs for Malus domestica
pollen identifications.

Keywords: Malus domestica, pollen, SEM, morphology.
Acknowledgments
Co-authors is grateful to SAIA and Visegrad Fund for the scholarship for the research during which the
presented knowledge were obtained.

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Spiritual Human Development
November 3 2021
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