Pollen grain wall structure ofCaytonanthus arberi (Caytoniales)

1986 ◽  
Vol 153 (3-4) ◽  
pp. 259-264 ◽  
Author(s):  
Michael S. Zavada ◽  
William L. Crepet
Keyword(s):  
Pollen Grain ◽  
Wall Structure ◽  
Pollen Grain Wall

Anatomy of the Unpollinated and Pollinated Watermelon Stigma

1982 ◽  
Vol 54 (1) ◽  
pp. 341-355
Author(s):  
M. SEDGLEY
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Light And Electron Microscopy ◽  
Freeze Fracture ◽  
Pollen Grain ◽  
Acidic Polysaccharides ◽  
Before And After ◽  
Em Autoradiography ◽  
Pollen Grain Wall ◽  
Stigma Secretion

The structure of the watermelon stigma before and after pollination was studied using light and electron microscopy, freeze-fracture and autoradiography. The wall thickenings of the papilla transfer cells contained callose and their presence prior to pollination was confirmed using EM-autoradiography, freeze-fracture and fixation. No further callose thickenings were produced following pollination. Pollination resulted in a rapid increase in aqueous stigma secretion and localized disruption of the cuticle, which appeared to remain on the surface of the secretion. Autolysis of the papilla cells, which had commenced prior to pollination, was accelerated and appeared to take place via cup-shaped vacuoles developed from distended endoplasmic reticulum. The reaction was localized to the papilla cells adjacent to the pollen tube only. Both pollen-grain wall and stigma secretion contained proteins, carbohydrates, acidic polysaccharides, lipids and phenolics.

Reproduction Multitasking: The Male Gametophyte

2021 ◽  
Vol 72 (1) ◽  
Author(s):  
Said Hafidh ◽  
David Honys
Keyword(s):  
Male Gametophyte ◽  
Cell Communication ◽  
Embryo Sac ◽  
Pollen Grain ◽  
Wall Structure ◽  
Annual Review ◽  
Publication Date ◽  
Developmental Phase ◽  
Double Fertilization ◽  
Male Gametes

The gametophyte represents the sexual phase in the alternation of generations in plants; the other, nonsexual phase is the sporophyte. Here, we review the evolutionary origins of the male gametophyte among land plants and, in particular, its ontogenesis in flowering plants. The highly reduced male gametophyte of angiosperm plants is a two- or three-celled pollen grain. Its task is the production of two male gametes and their transport to the female gametophyte, the embryo sac, where double fertilization takes place. We describe two phases of pollen ontogenesis—a developmental phase leading to the differentiation of the male germline and the formation of a mature pollen grain and a functional phase representing the pollen tube growth, beginning with the landing of the pollen grain on the stigma and ending with double fertilization. We highlight recent advances in the complex regulatory mechanisms involved, including posttranscriptional regulation and transcript storage, intracellular metabolic signaling, pollen cell wall structure and synthesis, protein secretion, and phased cell–cell communication within the reproductive tissues. Expected final online publication date for the Annual Review of Plant Biology, Volume 72 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Coenocytism, ameiosis, and chromosome diminution in intergeneric hybrids in the perennial Triticeae

Genome ◽  
1988 ◽  
Vol 30 (5) ◽  
pp. 766-775 ◽  
Author(s):  
Richard R.-C. Wang
Keyword(s):  
Intergeneric Hybrid ◽  
Chromosome Elimination ◽  
Intergeneric Hybrids ◽  
Pollen Grain ◽  
Unreduced Gamete ◽  
Pollen Mother Cells ◽  
Psathyrostachys Juncea ◽  
Hybrid Plants ◽  
Mother Cells ◽  
Pollen Grain Wall

Three different pathways of ameiotic microsporogenesis were observed in some intergeneric hybrids of the perennial Triticeae grasses. In one of the hybrids between Pseudoroegneria spicata ssp. inermis and Psathyrostachys juncea, pollen mother cells remained as premeiotic interphase cells when the pollen grain wall started to form. The microspores in such an ameiotic plant are presumably unreduced. Coenocyte formation coupled with ameiosis occurred in two hybrid plants of Psathyrostachys huashanica × Secale montanum. Less than 10% of the pollen mother cells had one nucleus. An average of 4.44 nuclei, ranging from 1 to 25 per pollen mother cell, was observed. The nuclei in coenocytes remained unfused when the pollen grain wall was formed. Nucleus splitting followed by cytoplasmic budding or cleavage, possibly a process of chromosome diminution or elimination, replaced meiotic divisions in most of the pollen mother cells in one plant of Leymus angustus × Hordeum bulbosum and two plants of Thinopyrum elongatum × Psathyrostachys juncea. It is evident that these meiotic abnormalities are under genetic control. Probable locations for these genes controlling these phenomena are suggested.Key words: coenocyte, ameiosis, chromosome diminution, chromosome elimination, microsporogenesis, unreduced gamete, polyploidy, intergeneric hybrid.

Localization of Antigens associated with the Pollen Grain Wall by Immunofluorescence

Nature ◽  
1970 ◽  
Vol 225 (5237) ◽  
pp. 1066-1068 ◽  
Author(s):  
R. B. KNOX ◽  
J. HESLOP-HARRISON ◽  
C. REED
Keyword(s):  
Pollen Grain ◽  
Pollen Grain Wall

scholarly journals A Route for the Transfer of Materials Through the Pollen Grain Wall

1959 ◽  
Vol 6 (3) ◽  
pp. 537-538 ◽  
Author(s):  
J. R. Rowley ◽  
K. Mühlethaler ◽  
A. Frey-Wyssling
Keyword(s):  
Pollen Grain ◽  
Pollen Grain Wall

scholarly journals Taxonomical Investigation on Some Species of Genus Allium Based on the Pollen Morphology

2019 ◽  
pp. 1-10
Author(s):  
Mehdi Heidarian ◽  
Seyed Mohammad Mehdi Hamdi ◽  
Mohammad Mehdi Dehshiri ◽  
Taher Nejadsattari ◽  
Seyed Mohammad Masoumi
Keyword(s):  
Electron Microscopy ◽  
Pollen Morphology ◽  
Numerical Taxonomy ◽  
Morphological Characteristics ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Wall Structure ◽  
Transmission Electron ◽  
Pollen Characters ◽  
Exine Ornamentation

Aims: The aim of this research was to investigate the morphological characteristics of the pollen grain of some species of genus Allium. Methodology: The pollen grains were examined by using Light Microscopy (LM), Scanning Electron Microscopy (SEM) and the pollen grains of one species under Transmission Electron Microscopy (TEM). Results: The pollen grains were oblate and medium in shape and size. The pollen ornamentation of exine surface, exine ornamentation on sulcus edge, lumina number in the exine surface and the state of pollen grain apex in the examined species were different. Semitectate and columellate ectexine with discontinuous endexine were seen in the pollen wall structure (sporoderm). The dendrogram obtained from the pollen characters in SEM observations by using the numerical taxonomy system (NTSYS) software placed the studied species in two types. Conclusion: Our palynological dendrogram can be used for segregation the sections and subgenera taxonomical levels in the studied species of genus Allium and confirmed the phylogram of the recent phylogenetic research.

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