Palynomorphological and anatomical characters of the section Mesocentron from the genus Centaurea (Asteraceae)

Morphology of pollen grains collected from healthy and virus infected plants ofChenopodium quinoa L.,Chenopodium album L. andNicotiana tabacum L. cv. Samsun was investigated using scanning electron microscopy (SEM). Pollen grains from tobacco plans infected with tobacco mosaic virus (TMV) were smaller, with rounded shape and conspicuous deformation of aperture unlike oval and smooth pollen grains from healthy plants. No morphological alterations were observed inC. quinoa andC. album plants infected with TMV and cucumber mosaic virus (CMV). Polyacrylamide gel electrophoresis of pollen proteins revealed substantial quantitative and qualitative differences in protein components of pollen grains collected from healthy and virus infected plants

A new method which utilises confocal optical imaging has been developed which can be expected to improve grass pollen analysis. Confocal microscopy, in reflection mode, was used to examine the exine morphology of unacetolysed pollen grains from the following species of common wild grasses: Paspalum dilatatum, Setaria gracilis, Bromus catharticus, Daclylis glomerata, Lolium perenne, Poa pratensis, and Phalaris aquatica. Variations in the surface texture patterns, similar to those hitherto only seen by scanning electron microscopy, were visualised. In contrast to the latter method, specimen preparation for this confocal microscopy based technique was characterised by its simplicity, permitting the use of fresh and chemically untreated pollen grains. This confocal imaging technique, with its capacity for optical sectioning of specimens, offered the additional advantage of allowing the examination of the sub‐surface exine layers as well as the surface morphology of the pollen grains. Furthermore, three‐dimensional reconstruction of these optical sections enabled visualisation of the identified sculptural and structural exine elements and layers. A number of differences in these patterns were found, which indicate that confocal microscopy, in combination with image analysis, may enable finer taxonomic distinctions to be made than those currently provided by other light microscope based methods.

Pollen grains of Cycadopites-type were found in the pollen chamber of a supposed ginkgoalean seed Allicospermum sp. from the Middle Jurassic deposits of Uzbekistan (Angren locality). The pollen grains were studied with help of LM, CLSM, SEM, and TEM. All pollen grains show the identical morphology and exine ultrastructure allowing us to suppose the same botanical affinity. The pollen morphological data do not contradict the ginkgoalean interpretation of the seed; therefore, the pollen grains and the seed most probably did belong to the same parent plant. The pollen grains are monosulcate, the non-apertural surface is nearly psilate, with low short elements, which are occasionally scattered over the surface or more densely distributed. The aperture and adjacent areas appear to bear more distinct sculpturing. The ectexine is composed of a prominent solid tectum, a thin infratectum, and a thin foot layer. The infratectum is formed of one row of alveolae, which are more voluminous laterally, where the ultrastructure is more easily understandable. The endexine is multilamellate, although it is evident only in some regions of stained sections. Towards the aperture the ectexine becomes gradually thinner; over the aperture no sublayers can be discerned within the ectexine. The ectexine of the apertural region repeatedly varies in thickness, reflecting a sculpturing surface of this region. The obtained data contribute to the knowledge about the exine ultrastructure of ginkgoaleans; nonetheless, a TEM study of ginkgoalean pollen grains extracted from pollen organs is still highly desirable. We also considered pluses and minuses of CLSM: it failed to substitute SEM, since the surface pattern under study was too fine, but demonstrated the general morphology of the pollen grains under study better than conventional LM. The possibility of viewing virtual sections of any area of the pollen grain was profitable for later interpretation of TEM sections. CLSM would give better results in interpreting relatively large palynological objects with distinct sculptural elements, a complicated architecture, variously arranged appendages, or possessing cameras.

In this paper the morphology of pollen grains yielded by male Gymnosperm fructifications from the Jurassic flora of Yorkshire is studied and discussed. Several new male fructifications were found and described: Hastystrobus gen. nov. was erected for male cones yielding the Eucommiidites type of pollen grains. This genus is monotypic and the type species Hastystrobus muirii yielded pollen grains that agree with Eucommiidites troedssonii. Hastystrobus muirii very probably has Cycadalean affinities, because the whole abaxial surface of the microsporophylls is covered with sporangia. For the first time the male fructification of Ginkgo huttoni (Heer) Sternberg is described. It resembles in general the male fructification of the recent Ginkgo biloba L., and the pollen grains agree with those of Ginkgo biloba. Male cones associated with Brachyphyllum crucis Kendall have been found and described. They yielded pollen grains that after short maceration were identifiable as Circulina, while after prolonged maceration they could be assigned to Classopollis multistriatus Burger. Brachyphyllum crucis is provisionally assigned to the Hirmerella-group on the basis of its male cone and pollen grains. The cones were compared with other male cones containing Classopollis pollen, which were also attributed to the Hirmerella-group. It is suggested that all members of the Hirmerella-group have an epidermis with a special type of stoma. Masculostrobus harrisii sp. nov. is described. This male cone resembles closely the male cone of Elatides williamsoni (Brgt) Sew., but its pollen grains are of the Inaperturopollenites-type, instead of the Perinopollenites-type. The new species Pityanthus scalbiensis yielding bisaccate pollen grains of a rather primitive type is described; there is almost no saccus infrastructure present. The Czekanowskia-group (including Leptostrobus and Solenites) in all probability does not belong to the Ginkgoales but to the Conifers. An interesting find was that the pollen grains of the Araucariaceous Brachyphyllum mamillare Brgt are of two types: In type 1 the nexine and sexine are attached to each other, while in type 2 the nexine is loose from the sexine and is somewhat shrunk. In the latter type also pollen grains were found that are somewhat trilobate. A similar dimorphism of pollen grains was also found in the recent Araucaria araucana (Molina) K. Koch. The pollen grains from the various male fructifications were compared with those from other male fructifications related to them. If the cones were assigned to recent taxa, the pollen grains were compared with recent pollen grains from those taxa (Cycadales, Ginkgoales and Coniferospermae). The pollen grains were also compared with dispersed pollen grains, mainly from the Jurassic.

Pollen grain morphology and the characterization of additional structures related to pollen dispersion can help to understand the strategies presented by species as well as their taxonomic circumscription. This work investigates the morphology of pollen grains and orbicules of Cedrela fissilis Vell. and Cedrela odorata L., two threatened species of the genus Cedrela P. Browne (Meliaceae A. Juss.) in Brazil. Observations of pollen grains and orbicules of the species were carried out pre- and post-chemical treatment of the samples, under light and scanning electron microscopy, aiming at recognizing structures, detailing morphological characterizations and taking measurements, the last of which were submitted to statistical treatment. The results demonstrate that the pollen grains of the two species are medium in size (measuring between 25 and 50µm), radially symmetrical, isopolar, prolate-spheroidal and 4,5-colporate with subcircular to subquadrangular amb and psilate ornamentation; the orbicules also have a smooth surface and measure about 7 to 10µm. Variation was observed in the size of pollen grains, which presented high coefficient of variation and in the orbicules, as well as in the number of apertures.

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.

Palynology, the study of pollen, had a big role in paleontology, archeology, and forensics. Pollens from different plants had different morphology, such as in Liliaceae. Scanning electron microscopy (SEM) was applied to observe the morphology of Liliaceae pollens. This study aimed to determine the pollen grains morphology and morphometry in Liliaceae. The descriptive qualitative research was used five different species from three genera as the sample, namely Hemerocallis fulva, Hemerocallis lilioasphodelus, Aloe vera, Lilium longiflorum, and Lilium candidum. Parameters measured in this study were the types of pollen sizes, pollen shape, aperture characteristic, and ornamentation type of exine. The results showed that in Liliaceae had various shapes of pollen grains, i.e., prolate (1.33-2 μm) and per-prolate (≥ 2 μm), as well as the pollen grains size, from minuta (10-25 μm in diameter) to medium (25-50 μm in diameter). Aperture characteristic of the pollen grains was monocolpate which has one colpus, and the ornamentation type of exine was reticulate patterns.

Exine ultrastructure of in situ pollen from the cycadalean cone Androstrobus prisma Thomas et Harris 1960 from the Jurassic of England

Morphology of pollen grain was described for nine American persimmons (Diospyros virginiana L.) genotypes (DV-01 – DV-09) at the Institute of Biodiversity and Biological Safety of Slovak Agricultural University in Nitra using an electron microscope Carl Zeiss LS 15, and the microphotographs were taken. 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 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. The polar axis and equatorial diameter of pollen grains values were varied from 51.94 to 78.60 μm and from 23.00 μm to 42.71 μm, respectively. This study showed that there were significant differences among the genotypes in all measured factors. Pollen grains are radial-symmetrical, isopolar, tricolpate (with three sulcus). Exine surface is a bicomponent sculptural type with small perforate-undulate or wrinkled weakly perforate. Percentages of abnormal pollen grains ranged from 2.0 to 19.3% among the genotypes. 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 Diospyros virginiana pollen identification.

This study is the first comparison of the morphology of pollen grains in ten cultivars of three species of the Taxus, Torreya nucifera and Cephalotaxus harringtonia var. drupacea genera. The material came from the Botanical Garden of Adam Mickiewicz University in Poznań, Poland. Each measurement sample consisted of 50 pollen grains. In total, 750 pollen grains were analyzed. Light and electron scanning microscopy was used for the morphometric observation and analysis of pollen grains. The pollen grains were inaperturate and classified as small and medium-sized. They were prolate-spheroidal, subprolate to prolate in shape. The surface of the exine was microverrucate-orbiculate, perforate in Cephalotaxus harringtonia var. drupacea, granulate-orbiculate, perforate in all Taxus taxa and granulate-microverrucate-orbiculate, perforate in Torreya. The orbicules were rounded to oval in surface view, and the size was considerably diversified. The pollen features were insufficient to distinguish between individual Taxus members – only groups were identified. The values of the coefficient of variability of three features (LA, SA and LA/SA) were significantly lower than the orbicule diameter. The pollen surface of all Taxus specimens was similar, so it was not a good identification criterion. The pollen grains of the Taxus taxa were smaller and had more orbicules than Cephalotaxus and Torreya. Palynological studies provided taxonomic support for recognition of two different genera of the Cephalotaxaceae and Taxaceae families, which are closely related.

Pollen abortion occurs in virtually all species and often does not prejudice reproductive success. However, large numbers of abnormal pollen grains are characteristic of some groups. Among them is Miconia, in which partial and complete male sterility is often related to apomixis. In this study, we compared the morphology of pollen grains over several developmental stages in Miconia species with different rates of male sterility. Our aim was to improve the knowledge of mechanisms that lead to male sterility in this ecologically important tropical group. Routine techniques for microscopy were used to examine anthers in several developmental stages collected from the apomictic species Miconia albicans and M. stenostachya. Both species are completely male sterile since even the pollen grains with apparently normal cytoplasm were not able to develop a pollen tube. Meiosis is a rare event in M. albicans anthers and happens in an irregular way in M. stenostachya, leading to the pollen abortion. M. albicans has more severe abnormalities than M. stenostachya since even the microspores and pollen grain walls were affected. Moreover, in M. stenostachya, most mitosis occurring during microgametogenesis was also abnormal, leading to the formation of bicellular pollen grains with two similar cells, in addition to the formation of pollen grains of different sizes. Notably, abnormalities in both species did not reach the production of Übisch bodies, suggesting little or no tapetum involvement in male sterility in these two species.

On the therapy of hay fever: Ertl, E.: Wien. klin. Wchnschr. 52: 643, 1939

The objective of this work was to characterize the viability, production and morphology of pollen for different species in the genus Manihot. Floral buds from Manihot accessions were collected from two germplasm banks at Embrapa Cassava & Fruits. The viability of the pollen was assessed via colorimetric, in vitro and in vivo assays. The diameter of the pollen grains was determined by measuring the transversal length of the grain. The experimental design was entirely randomized. Studies on pollen ultrastructure were performed via scanning electron microscopy. Pollen viability was high in the colorimetric tests and intermediate in vivo tests; there was no germination in the in vitro tests. The average production for all accessions was 1,253 pollen grains per floral bud. The size of the pollen grains varied from 132 to 163 µm in the wild accessions, and 129 to 146 µm in the cultivated accessions. The pollen grains for all accessions were very large, apolar, spherical as well as inaperturate, with an exine ornamented with pila organized in a Croton pattern. The wild accessions, in general, produced more and larger pollen grains compared with the cultivated accessions.

The morphology of pollen grains of the 06 species of tribe Acacieae (Mimosaceae) belonging to one genus were investigated using scanning electron microscopic (SEM) and light microscopic (LM) approach. Lactic acid acetolysis method was used for (LM) while non-acetolysis for (SEM). The species were examined for the both qualitative and quantitative palynological features. Qualitatively the pollen was studied for the shape, exine sculpturing, pollen shape, and pollen type. Oblate spheroidal shape of pollen was observed in Accacia modesta. Subprolate shape in Accaca nilotica. In Accacia farnesiana, prolate pollen was examined while prolate spheroidal in Acacia tortilis and spheroidal pollen grains were studied in Acacia catechu, respectively. Pollen exine sculpturing of the studied tribe possesses novel variation. Foveolate, reticulate, foveolate-psilate, faint reticulate, fossulate, perforate, and scrabate exine sculpturing were noticed. Colpi were absent in all species. Excessive variation was observed in both qualitative and quantitative character of pollen. SPSS software was use for the quantitative measurement of the pollen grains. The current study will be helpful for the identification of the problematic species and phylogenetic studies of family Mimosaceae.

Analysis of pollen viability and morphological characterisation of 20 coconut varieties (eleven tall, four dwarf, and five hybrids) was carried out to identify distinctive characteristics at the genotype level. Light microscopy (LM) and scanning electron microscopy (SEM) were used to study the morphology of pollen grains. Significant variations were observed in the morphology of pollen grains of different coconut varieties. Pollen from coconut varieties exhibited a monosulcate-elongated structure, ranging in shape from prolate to perprolate. The exine ornamentation was predominantly faveolate across these varieties. Significant differences were noted in polar axis length (P), equatorial axis length (E), P/E ratio, size index, and the number of pores per square micrometres. Hierarchical cluster analysis based on pollen characteristics delineated two major groups among the 20 varieties. The pollen morphology and viability can be considered as supplementary traits to enable fine differentiation of coconut accessions, in addition to other reproductive characteristics specific to palms used in coconut breeding.