The achenes’ micromorphological structure of six Artemisia species (A. absinthium, A. annua, A. argyi, A. dracunculus, A. marschalliana, and A. vulgaris) distributed in Ukraine was investigated with the aim to identify taxonomically significant carpological features for the studied species.Fruits were collected from wild plants growing in the recreation areas of Kyiv and from the plants hosted in the living collection of the M.M. Gryshko National Botanical Garden of the NAS of Ukraine. Macromorphological features were studied with a binocular microscope Stemi 2000 Carl Zeiss. The ultrastructure of the surface was studied using a scanning electron microscope JSM-6700F JEOL, in the mode of secondary electron emission. Carbon spraying was performed using vacuum thermal evaporation of the vacuum universal post VUP-5M SELMI; platinum spraying was performed with an ion-plasma etching device JFC-1600 JEOL.All investigated species have a well-expressed, true, multicellular, symmetrical, multi-row carpopodium but differ by its shape. The surface of A. annua achenes is reticulate-pitted due to the specific structure of the exocarp and the exotests located below it. Species with lobed and continuous apical rim and species without a rim around the place of attachment of the corolla were found. It was established that the primary ultrastructure of investigated fruits is caused by the shape and character of mucous cell arrangement; epidermal cells of the exocarp are mostly compressed, without clear boundaries. Mostly a thin and inconspicuous cuticle, sometimes wrinkled, with layers and small outgrowths, causes the secondary ultrastructure of these fruits. We believe that the mentioned carpological features may be used as additional criteria in combination with other features to identify studied species.
This study analyzed pollen morphology and characteristics of 20 Sambucus nigra L. genotypes from populations of various ecotypes and geographical localities from the territory of Slovakia. We used principal component analysis to explore variability in pollen grain size (polar and equatorial diameter), shape, aperture type, and exine ornamentation by scanning electron microscopy. The combination of these morphological characteristics and ultrastructure allows us to determine the differences or similarities between the same and various species and genotypes, which may be a useful tool for systematics with significant diagnostic value. The findings confirmed small differences among the genotypes in measured traits with polar and equatorial diameters in the range from 22.30 to 26.64 μm and from 12.81 to 14.45 μm, respectively. Shape index (P/E ratio) depending on elongation or roundness of pollen grains varied from 1.66 to 2.02. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) of morphological data helped to compare evaluated morphometric parameters and identified three closely related groups. It was noted that the diversity of surface sculpturing of pollen grains in combination with their shape and size enables us to use a complex of fine morphologic signs for S. nigra pollen identification. Pollen data combined with other morphological evidence (e.g., floral characters) have more recently become an important indicator of which genotypes may be the best representatives of species.
The studying of Castanea sativa Mill. pollen allows us to determine the details of morphological characteristics and described the most important parameters and pollen sculpture that can be used to identify representatives of species. The general characteristics and significant morphological traits of pollen grains of 16 genotypes Castanea sativa Mill. collected from M.M. Gryshko National Botanical Garden of Ukraine(Kyiv) were observed via a scanning electron microscope (SEM). The measurement of morphometric parameters was carried out on 50 pollen grains from each genotype using the AxioVision Rel. 4.8.2.0 program. The length of the polar axis (P) and the equatorial diameter (E) of grain, P/E ratio were measured and their variation was compared among studied genotypes. SEM investigations showed that the pollen grains of Castanea sativa are small-sized, the equatorial view is elliptic, the polar view is angular, with convex mesocolpia, more or less circular. This study showed the small differences between the genotypes in all measured factors. The average polar axis and equatorial diameter of pollen grains values varied in the interval 19.10 ±0.21-20.53 ±0.21 and 8.86 ±0.05-9.85 ±0.08, respectively. We determined the variation coefficient in the range of 3.37-8.93 %. It was noted that diversity of surface sculpturing of pollen grains in combination with shape and sizes enables to use of a complex of thin morphological signs for Castanea sativa pollen identifications.
in Nitra using an electron microscope Carl Zeiss LS 15. The measurement of morphometric parameters was carried out on 50 pollen grains from each phenotype using the AxioVision Rel. 4.8.2.0 program. The measurements were made in micrometer (μm). The length of polar axis (P) and the equatorial diameter (E) of grain, P/E ratio were measured and their variation was compared among studied genotypes. SEM investigations showed that the pollen grains are radial-symmetrical, isopolar, oblong-ellipsoid and 3-and 4-colporate. Texture is sinuous-tuberculate in equatorial zone and finely bumpy in polar zone. The polar axis and equatorial diameter of pollen grains values were varied from 34.16 to 50.14 μm and from 16.10 μm to 25.71 μm, respectively. This study showed that there were differences among the phenotypes in all measured factors. It is known that phenotypic variability is an evolutionarily fixed response of any group of organisms with a constant genotype to changes in environmental conditions and it is adaptive. Therefore, our research suggests that all individuals forming the introduction population of Aronia mitschurinii are sufficiently adapted to the conditions of M.M. Gryshko National Botanical Garden of NAS of Ukraine.
The aim of the work was to study the general characteristics and significant morphological traits of pollen grains, as the size, shape of pollen grains in Sambucus nigra L. The studies were performed on pollen obtained from genotypes cultivated in Ukraine (Kyiv). Morphology of pollen grain was described for thirteen Sambucus nigra genotypes (SN-1 -SN-13) at the laboratory of Department of Tropical and Subtropical plants of M.M. Gryshko National Botanical Garden. Pollen grains morphological traits were evaluated using the scanning and transmission electron microscopy. The measurement of morphometric parameters was carried out on 70 pollen grains from each genotype using the AxioVision Rel. 4.8.2.0 program. The measurements were made in micrometer (μm). The length of polar axis (P) and the equatorial diameter (E) of grain, P/E ratio were measured and their variation was compared among studied genotypes. SEM investigations showed that the pollen grains of Sambucus species are small to medium-sized, oblat-sphaeroidal-prolat shape, three-colporate and the exine adornments are of reticulate type without perpendicular thickness. This study showed that there were significant differences the genotypes in all measured factors. The polar axis and equatorial diameter of pollen grains values were varied from 22.11 to 29.07 μm and from 11.98 μm to 17.29 μm, respectively. This study confirmed small differences among the genotypes in all measured factors with variation coefficient in the range 2.87-6.02%. 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 Sambucus nigra pollen identifications.
Guarianthe bowringiana is one of the oldest samples cultivated at NBG’s orchid unit glasshouses since 1970s. An efficient protocol for asymbiotic in vitro seed germination of G. bowringiana has previously been established. Given that acclimatization is a crucial step in micropropagation, this study assesses the structural adaptation and antioxidant response of G. bowringiana seedlings during ex vitro acclimatization to ex vitro conditions. The leaf surface micromorphology of the G. bowringiana juvenile plants propagated in vitro from seeds as well as the leaves of adult plants cultivated in glasshouse were analyzed using scanning electron microscopy. The levels of lipid peroxidation (TBARS level), superoxide dismutase (SOD) activity, and the photosynthetic activity were monitored for seven days from the transfer of seedlings from the in vitro cultivation vessels as they are markers indicating the response of the leaves of in vitro propagated G. bowringiana plants to oxidative stress during the early stages of acclimatization to ex vitro conditions. During the initial 2 days of the monitored acclimatization period (0–7 days), the level of photosynthetic pigments (chlorophyll a , b , and carotenoid content) increased, followed by an insignificant increase during the successive period (by the seventh day) of acclimatization. At the same time, the level of the tested antioxidant enzyme (SOD) exhibited an increasing trend throughout the acclimatization period. The SOD activities in the leaves of G. bowringiana seedlings were significantly affected when they were transferred from in vitro to ex vitro conditions due to drought stress. Thus, it was revealed that in the early stages of acclimatizing to the altered environments, G. bowringiana seedlings exhibited a rapid increase in photosynthetic pigments, superoxide dismutase activity, and lipid peroxidation levels after being transferred to ex vitro conditions. Comparison of the leaf micromorphologies of G. bowringiana plants grown under in vitro and those grown under ex vitro conditions revealed that leaf development had undergone significant changes during acclimatization to the altered conditions. In vitro to ex vitro transfer leads to a transient decrease in photosynthetic parameters.
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