External Morphological Characteristics for Periods during Pecan Microspore and Pollen Differentiation

Catkin external morphological characteristics of a protogynous (`Stuart') and a protandrous (`Desirable') cultivar of pecan [Carya illinoensis (Wangenh.) C. Koch] were related temporally to the differentiation of microspore and pollen grains. Reproductive cell development was divided into seven periods based on evaluations of number, location, and intensity of staining of the nucleus and/or nucleolus; and vacuolization and staining intensity of the cytoplasm. Catkins with anthers and bracteoles enclosed by bracts did not have reproductive cells that were matured to free microspore. Free microspore developed only after bracteoles became externally visible. The Period 1 nucleus was at the periphery of the cell and a large central vacuole was present; at Period 2, the nucleus was at the center and vacuolation had been reduced. As the angle between the bract and catkin rachis increased to 45°, vacnolation was reduced as the nucleus enlarged and moved to a central location in the microspore (Periods 3 and 4). The majority of the pollen grains were binucleate, and the generative nucleus became elliptical (Periods 5 and 6) by the time anthers became externally visible. Acetocarmine staining intensity of cellular components masked the presence of the generative nucleus (Period 7) just before anther dehiscence. Staining reaction for protein was positive from Period 1; starch from Period 3; lipids and polyphenols from Period 5. The mature pollen grain was abundant in stored reserves of starch and lipids and had a wall with a thicker exine than intine as demonstrated by acetolysis.

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Endogenous thyrotropin-releasing hormone in the anterior pituitary: sites of activity as identified by immunocytochemical staining.

Journal of Histochemistry & Cytochemistry ◽

10.1177/26.11.82570 ◽

1978 ◽

Vol 26 (11) ◽

pp. 901-908 ◽

Cited By ~ 27

Author(s):

G V Childs ◽

D E Cole ◽

M Kubek ◽

R B Tobin ◽

J F Wilber

Keyword(s):

Anterior Pituitary ◽

De Novo ◽

Secretory Granules ◽

Morphological Characteristics ◽

Staining Intensity ◽

Thyrotropin Releasing Hormone ◽

Immunocytochemical Staining ◽

Staining Reaction ◽

Releasing Hormone

Thyrotropin-releasing hormone (TRH) immunoreactivity was localized in the rat anterior pituitary with rabbit anti-TRH sera and the unlabeled antibody peroxidase-antiperoxidase complex (PAP) technique. Stain was present in secretory granules of cells possessing morphological characteristics of thyrotropes, gonadotropes and lactotropes. Antibody absorption studies with anti-TRH sera absorbed with TRH, 3 diastereoisomeric analogues of TRH, gonadotropin-releasing hormone (GnRH), bovine serum albumin, thyrotropin, prolactin, adrenocorticotropin, luteinizing hormone, follicle stimulating hormone were performed to determine the specificity of the staining reaction. Only absorption with TRH resulted in a significant reduction in staining intensity. In vitro experiments were then begun with hemipituitaries to ascertain if intrapituitary TRH might originate by sequestration of exogenous, plasma membrane bound TRH or by de novo synthesis. The results suggest that anterior pituitary TRH is of endogenous origin.

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ROS in tobacco stigma exudate affect pollen proteome and provoke membrane hyperpolarization

10.1101/2020.04.28.065706 ◽

2020 ◽

Author(s):

Breygina Maria ◽

Klimenko Ekaterina ◽

Shilov Eugeny ◽

Mamaeva Anna ◽

Zgoda Viktor ◽

...

Keyword(s):

Cell Metabolism ◽

Pollen Grains ◽

Plant Reproduction ◽

List Type ◽

Membrane Hyperpolarization ◽

Inhibitory Analysis ◽

The One ◽

Cellular Components ◽

Stigma Exudate

1.AbstractROS are known to be accumulated in stigmas of different species and can possibly perform different functions in plant reproduction. Here we confirm the assumption that they affect pollen by altering ion transport through the plasma membrane; as a more deferred effect, pollen proteome is modified. We detected ROS in stigma exudate, found hyperpolarization in exudate-treated growing pollen tubes and used flow cytometry of pollen protoplasts to compare the effects of fresh exudate and exogenous H2O2 on pollen tube plasmalemma. Exudate causes plasmalemma hyperpolarization similar to the one provoked by H2O2, which is abolished by catalase treatment and ROS quencher MnTMPP. Inhibitory analysis indicates the participation of Ca2+- and K+-conducting channels in the observed hyperpolarization, linking obtained data with previous patch-clamp studies in vitro. For a deeper understanding of pollen response to ROS we analyzed proteome alterations in H2O2-treated pollen grains. We found 50 unique proteins and 20 differently accumulated proteins that are mainly involved in cell metabolism, energetics, protein synthesis and folding. Thus, pollen is getting ready for effective resource usage, construction of cellular components and rapid growth.HighlightsThe active substance in stigma exudate is H2O2H2O2 causes hyperpolarization mediated by the activation of cation channels.H2O2 affects pollen proteome; we found 50 unique proteins.

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Tradescantia bracteata pollen in vitro: pollen tubes development and mitosis

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.1977.047 ◽

2015 ◽

Vol 46 (4) ◽

pp. 587-598 ◽

Cited By ~ 9

Author(s):

E. Lewandowska ◽

M. Charzyńska

Keyword(s):

Pollen Tube ◽

Generative Cell ◽

Metaphase Plate ◽

Pollen Grains ◽

Neutral Red ◽

Generative Nucleus ◽

Mitotic Spindles ◽

Germinating Pollen ◽

Vacuolar System

About 90 per cent of <i>Tradescantia bracteata</i> pollen germinates <i>in vitro</i> after 15 min. Mitosis starts in the pollen tube after about 3 h. The mitotic trans-formations of chromosomes within the generative nucleus are not synchronized. They involve succesively the linearly arranged chromosomes in the elongated generative nucleus. In metaphase the chromosomes are arranged tandem-like linearly along the pollen tube. The chromatides translocate in anaphase from various distances to the poles in a plane parallel to the metaphase plate. This suggests that chromosomes have individual mitotic spindles and that coordination of the chromosome transformations in the generative cell is much less strict than in a typical somatic mitosis. Starch is the storage material of pollen grains. In the vegetative cytoplasm of mature pollen grains minute reddish-orange vesicular structures are visible after staining with neutral red. They do not fuse with the vacuoles proper arising in germinating pollen grains to form the vacuolar system of the pollen tube.

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Modulation of Auxin Levels in Pollen Grains Affects Stamen Development and Anther Dehiscence in Arabidopsis

International Journal of Molecular Sciences ◽

10.3390/ijms19092480 ◽

2018 ◽

Vol 19 (9) ◽

pp. 2480 ◽

Cited By ~ 5

Author(s):

Hernán Salinas-Grenet ◽

Ariel Herrera-Vásquez ◽

Samuel Parra ◽

Allan Cortez ◽

Lilian Gutiérrez ◽

...

Keyword(s):

Acetic Acid ◽

Apical Meristem ◽

Seed Set ◽

Transgenic Arabidopsis ◽

Pollen Grains ◽

Anther Development ◽

Anther Dehiscence ◽

Transgenic Lines ◽

Indole 3 Acetic Acid ◽

Auxin Accumulation

Auxin regulates diverse aspects of flower development in plants, such as differentiation of the apical meristem, elongation of the stamen, and maturation of anthers and pollen. It is known that auxin accumulates in pollen, but little information regarding the biological relevance of auxin in this tissue at different times of development is available. In this work, we manipulated the amount of free auxin specifically in developing pollen, using transgenic Arabidopsis lines that express the bacterial indole-3-acetic acid-lysine synthetase (iaaL) gene driven by a collection of pollen-specific promoters. The iaaL gene codes for an indole-3-acetic acid-lysine synthetase that catalyzes the conversion of free auxin into inactive indole-3-acetyl-l-lysine. The transgenic lines showed several abnormalities, including the absence of short stamina, a diminished seed set, aberrant pollen tubes, and perturbations in the synchronization of anther dehiscence and stamina development. This article describes the importance of auxin accumulation in pollen and its role in stamina and anther development.

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Pollen morphology of chestnut cultivars in southern China by using scanning electron microscope

Bangladesh Journal of Botany ◽

10.3329/bjb.v49i1.49089 ◽

2020 ◽

Vol 49 (1) ◽

pp. 39-46

Author(s):

Huan Xiong ◽

De-Yi Yuan ◽

Ya Chen ◽

Genhua Niu ◽

Feng Zou

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Southern China ◽

Morphological Characteristics ◽

Pollen Grains ◽

Polar Axis ◽

Upgma Tree ◽

Equatorial Diameter ◽

Components Analysis ◽

Scanning Electron

The morphological characteristics of pollen grains of 16 cultivars belonging to two species of the genus Castanea (Castanea mollissima and C. henryi) collected from southern China were observed by using scanning electron microscope (SEM). The length of polar axis (PL), the equatorial diameter (ED), the length of colpus (CL) of grain, P/E ratio (polar axis to equatorial diameter), P/C ratio (polar axis to colpus length), and C/E ratio (colpus length to equatorial diameter) were measured and their variations were compared among studied taxa. The result of this study indicated that chestnut pollen grain was a tricolporate in aperture type, and aperprolate type in equatorial view. The morphological characteristics were mainly represented by PL, ED and CL as revealed by principal components analysis, which accounted for 99.56% of the total variations. The cluster analysis by the UPGMA tree divided the taxa into three groups and showed a great morphological affinity among the 16 cultivars.

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Microsporogenesis and microgametogenesis of Cardiospermum grandiflorum and Urvillea chacoensis (Sapindaceae, Paullinieae)

Australian Journal of Botany ◽

10.1071/bt10162 ◽

2010 ◽

Vol 58 (7) ◽

pp. 597 ◽

Cited By ~ 9

Author(s):

Stella M. Solís ◽

Beatriz Galati ◽

María S. Ferrucci

Keyword(s):

Electron Microscopy ◽

Pollen Grains ◽

Basic Type ◽

Anther Wall ◽

Anther Dehiscence ◽

Transmission Electron ◽

Pollen Ontogeny ◽

Tapetal Cells ◽

The Difference ◽

Mature Anther

Microsporogenesis and microgametogenesis of two species, Cardiospermum grandiflorum Sw. and Urvillea chacoensis Hunz. (Sapindaceae, Paullinieae), were studied using light and transmission electron microscopy. Both species are monoecious, with staminate and hermaphrodite, although functionally pistillate, flowers. A comparative pollen-development study of these two floral morphs is reported. For the present study, five stages of pollen ontogeny were identified. The development of the anther wall is of basic type. Its wall consists of epidermis, endothecium, two middle layers and a uninucleate secretory tapetum. The microspore tetrads are tetrahedral. The mature anther in staminate flowers presents the endothecium with well developed fibrillar thickenings, remains of tapetal cells, a single locule formed in the theca by dissolution of the septum before anther dehiscence and two-celled pollen grains when shed. In functionally pistillate flowers, the mature anthers present remnants of the middle layers, tapetal cells without signs of degradation, the theca with two locules and pollen grains uni- or bicellular, some of them with the cytoplasm collapsed. These anthers are not dehiscent. It can be concluded that male sterility is characterised by failure to produce functional pollen grains, an event that would be associated with the persistence of tapetal cells. Ultrastructural analysis clearly shows the difference in tapetal cells between the two flower morphs.

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Can Palynology be used for Reconstructing the Evolutionary History of Maize Agriculture?

NEXUS: The Canadian Student Journal of Anthropology ◽

10.15173/nexus.v14i1.166 ◽

2000 ◽

Vol 14 (1) ◽

Author(s):

Grant D. Zazula

Keyword(s):

Pollen Analysis ◽

Evolutionary History ◽

Morphological Characteristics ◽

Pollen Grains ◽

Fossil Pollen ◽

Evolutionary Transition ◽

Archaeological Evidence ◽

Maize Agriculture ◽

History Of ◽

Pollen Records

The lack of archaeological or macrobotanical evidence that directly links wild teosinte grass with early domesticated maize requires the exploration of alternative methodologies to document this evolutionary transition. The morphological characteristics and measurements for maize, teosinte and Tripsacum pollen are presented to determine if they display sufficient differentiation to be distinguished in fossil pollen records. Analysis of the data reveals a lack of distinguishing morphological characteristics between the pollen grains of these taxa and prevents palynology from be an effective method in documenting the evolutionary history of maize agriculture. Current methods of pollen analysis cannot be employed to document the evolution of teosinte to maize in the Tehuacan Valley of Mexico and pollen is not likely to provide an earlier record of this transition than what is found in the macrobotanical or archaeological evidence.

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Morphological Characteristics, Fruit Qualities and Evaluation of Reproductive Functions in Autotetraploid Satsuma Mandarin (Citrus unshiu Marcow)

Agronomy ◽

10.3390/agronomy11122441 ◽

2021 ◽

Vol 11 (12) ◽

pp. 2441

Author(s):

Miki Sudo ◽

Kiichi Yasuda ◽

Masaki Yahata ◽

Mai Sato ◽

Akiyoshi Tominaga ◽

...

Keyword(s):

Reproductive Potential ◽

Morphological Characteristics ◽

Pollen Grains ◽

Fruit Weight ◽

Citrus Unshiu ◽

Male And Female ◽

Reciprocal Crosses ◽

Satsuma Mandarin ◽

Seedless Fruits

The morphological characteristics and fruit quality of an autotetraploid plant selected from nucellar seedlings of Satsuma mandarin (Citrus unshiu Marcow.) were investigated. Additionally, in order to evaluate the reproductive potential of male and female gametes of the tetraploid Satsuma mandarin, reciprocal crosses with diploid cultivars were also carried out. The tetraploid had significantly thick and round leaves, as compared to those of the diploid Satsuma mandarin. The sizes of the flowers and pollen grains of the tetraploid were significantly larger than those of the diploid. Pollen fertility of tetraploid was high compared with that of the diploid. The tetraploid produced seedless fruits. The fruit weight of the tetraploid was equal to that of the diploid. Compared to the diploid fruits, the tetraploid fruit had less sugar contents and more organic acid contents. Although the tetraploid fruits showed similar traits to other Citrus tetraploids such as thick and hard peels, the tetraploid had a higher content of carotenoids in the flavedo than the diploid, and the rind color of the tetraploid was much better. In the reciprocal crosses between the tetraploid Satsuma mandarin and diploid cultivars, some seeds were obtained, and triploid progenies were obtained in all cross combinations.

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A Cytological Study of Anther and Pollen Development in Chinquapin (Castanea henryi)

HortScience ◽

10.21273/hortsci14934-20 ◽

2020 ◽

Vol 55 (6) ◽

pp. 945-950

Author(s):

Weiping Zhong ◽

Zhoujun Zhu ◽

Fen Ouyang ◽

Qi Qiu ◽

Xiaoming Fan ◽

...

Keyword(s):

Pollen Development ◽

Lipid Droplets ◽

Morphological Characteristics ◽

Pollen Grains ◽

Middle Layer ◽

Anther Development ◽

Mature Pollen ◽

Anther Wall ◽

Male Flowers ◽

Microspore Stage

The normal development of anthers and the formation of functional pollen are the prerequisites for successful pollination and fertilization. In this study, we observed dynamic changes in inflorescence and anther development in the chinquapin (Castanea henryi) using stereomicroscopy, light microscopy, and transmission electron microscopy. We found that cytokinesis during meiosis in microsporocytes was of the simultaneous type, and that the tetrads were mainly tetrahedral. Mature pollen grains contained two cells with three germ pores. The anther wall was of the basic type and composed of epidermis, endothecium, middle layers, and tapetum. Mature anthers had no middle layer and tapetum. The tapetum was of the glandular type. At the early microspore stage, a large number of starch granules appeared in the endothecium, which was deformed at the late microspore stage. Lipid droplets appeared in tapetum during the early microspore stage, and a few lipid droplets were still found during tapetum degeneration. The mature pollen accumulated a large amount of starch and lipids. These findings demonstrated that the anther wall provides nutrients and protection for pollen development. There is relatively stable correspondence between the external morphological characteristics of male flowers and internal structure of anther development.

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Intrafloral phenology of Trifolium polymorphum Poir. (Leguminosae) aerial flowers and reproductive implications

Acta Botanica Brasilica ◽

10.1590/s0102-33062009000300029 ◽

2009 ◽

Vol 23 (3) ◽

pp. 881-888 ◽

Cited By ~ 6

Author(s):

Gabriela Speroni ◽

Primavera Izaguirre ◽

Gabriel Bernardello ◽

Jorge Franco

Keyword(s):

Flower Development ◽

Pollen Viability ◽

Morphological Characteristics ◽

Structure And Function ◽

Anther Dehiscence ◽

Flower Longevity ◽

Floral Phenology ◽

Length Width ◽

And Function ◽

Reproductive Events

Trifolium polymorphum is an amphicarpic species that grows in Uruguay, Argentina, Brazil, Paraguay and Chile. Underground flowers are cleistogamous, obligately autogamous and morphologically highly modified in structure and function. Aerial flowers are chasmogamous, and as mentioned in earlier literature, either allogamous or autogamous. The aim of this study is to identify flower characteristics that facilitate or prevent autogamous or allogamous processes. Floral phenology stages are thus studied in correlation with estimated models of aerial flower development, pollen viability and stigmatic receptivity in three Uruguayan T. polymorphum populations. Flower longevity and development (length, width, and anther-stigma distance), anthesis and anther dehiscence initiation, pollen viability and stigmatic receptivity are the variables correlated with floral phenology. Morphological characteristics of aerial flowers favor autogamy processes - even in pre-anthesis - but phenological characteristics tend to prevent it. The most important reproductive events occurring during flower development, that facilitate autogamous or allogamous processes, are discussed here.

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