Breaching the Callose Wall

1992 ◽  
Vol 4 (7) ◽  
pp. 745
Author(s):  
Rebecca Chasan
Keyword(s):  
Callose Wall

Autoradiography of Soluble [2-14C]Thymidine Derivatives During Meiosis And Microsporogenesis in Lilium Anthers

1967 ◽  
Vol 2 (3) ◽  
pp. 387-400 ◽  
Author(s):  
J. HESLOP-HARRISON ◽  
A. MACKENZIE
Keyword(s):  
Meiotic Prophase ◽  
Trichloroacetic Acid ◽  
Thymidine Incorporation ◽  
Callose Wall ◽  
Autoradiographic Method ◽  
Tapetal Cells ◽  
Mother Cells

A dry autoradiographic method suitable for locating soluble tracers has been used to follow the fate of [2-14C]thymidine supplied to detached buds and inflorescences of Lilium henryi and a related cultivar. During the interval from the archesporial phase until pachytene, the derivative (or derivatives) reaching the anther loculi moved freely into the meiocytes. Subsequently, the tracer was excluded from the mother cells until the dissolution of the tetrads. The young spores readily took up tracer in the thecal fluid upon their release, and yielded strongly localized autoradiographs. These observations are interpreted as indicating that access of materials to the meiocytes is related to the formation of cytoplasmic links between mother cells in the early meiotic prophase, and the later severance of these links through the growth of the isolating callose wall which comes to invest the tetrads. Judged from the tracer retained in preparations extracted with trichloroacetic acid, thymidine incorporation occurs mostly in the premeiotic and early leptotene period, although there is some slight evidence of incorporation later in prophase. In the tapetal cells, incorporation occurred in most of the stages tested, but there was no indication of a transfer of labelled materials from tapetum to spores in the post-meiotic period.

scholarly journals Breaching the Callose Wall

1992 ◽  
Vol 4 (7) ◽  
pp. 745-746 ◽  
Author(s):  
R. Chasan
Keyword(s):  
Callose Wall

scholarly journals The influence of tetrad shape and intersporal callose wall formation on pollen aperture pattern ontogeny in two eudicot species

2010 ◽  
Vol 106 (4) ◽  
pp. 557-564 ◽  
Author(s):  
Béatrice Albert ◽  
Sophie Nadot ◽  
Leanne Dreyer ◽  
Adrienne Ressayre
Keyword(s):  
Callose Wall ◽  
Wall Formation

Scanning electron microscopy of the callose wall and intermeiocyte connections in angiosperms

1974 ◽  
Vol 52 (6) ◽  
pp. 1215-1218 ◽  
Author(s):  
Ernest D. P. Whelan ◽  
G. H. Haggis ◽  
E. J. Ford
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Solanum Tuberosum ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Plasma Membranes ◽  
Nuclear Region ◽  
Lupinus Polyphyllus ◽  
Callose Wall ◽  
Scanning Electron

Scanning electron microscope studies of anthers of the dicotyledons Helianthus annuus, Solanum tuberosum, and Lupinus polyphyllus, and the monocotyledons Iris pseudo-acoris and a Lilium hybrid revealed discontinuities or holes in the meiocyte callose wall and continuity of the plasma membranes of adjacent meiocytes. The holes in the callose wall generally were confined to areas where neighboring meiocytes were in contact. The holes varied in size within locations and between taxa. The largest holes, about 2.4 μm diameter, were found in Lupinus. Fixation in standard acid–alcohol fixatives resulted in marked plasmolysis and loss of cytoplasmic detail, but the nucleolus and bivalents were readily apparent. Fixation in buffered glutaraldehyde, with or without postfixation in OSU4, preserved the cytoplasmic organelles and plasmolysis was minimal, but bivalents could not be distinguished. All fixatives preserved the nuclear membrane so that the nuclear region was clearly delimited from the cytoplasm.

scholarly journals Development of the pollen in the antarctic flowering plant Colobanthus quitensis (Kunth) Bartl.

2012 ◽  
Vol 60 (2) ◽  
pp. 3-8 ◽  
Author(s):  
Irena Giełwanowska ◽  
Anna Bochenek ◽  
Ewa Szczuka
Keyword(s):  
Osmotic Stress ◽  
Flowering Plant ◽  
Natural Conditions ◽  
Callose Wall ◽  
Colobanthus Quitensis ◽  
Mother Cells ◽  
The Antarctic

<i>Colobanthus quitensis</i> (Kunth) Bartl. produced two types very small bisexual fl owers. In the Antarctic natural conditions chasmogamic and cleistogamic fl owers most often form fi ve stamina with short fi laments. Two microsporangia with a three-layer wall form in the anther. Microspore mother cells, which develop into microspores after meiosis, form inside the microsporangium. Microsporocytes of <i>Colobanthus quitensis</i> are surrounded with a thick callose layer, the special wall. After meiosis, the callose wall is dissolved and microspores are released from the tetrad. The production of proorbicules, orbicules and peritapetal membrane, and the construction of a complex sporoderm with numerous apertural sites were observed. When microspore and pollen protoplasts underwent necrosis, probably as a result of temperature and osmotic stress, sporoderm layers formed around microspores, and the cell tapetum did not disintegrate. However, woody wall layers did not accumulate in endothecium cells.

scholarly journals DCET1 Controls Male Sterility Through Callose Regulation, Exine Formation, and Tapetal Programmed Cell Death in Rice

2021 ◽  
Vol 12 ◽  
Author(s):  
Riaz Muhammad Khan ◽  
Ping Yu ◽  
Lianping Sun ◽  
Adil Abbas ◽  
Liaqat Shah ◽  
...  
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Male Sterility ◽  
Tapetal Cell ◽  
Pollen Wall ◽  
Rna Recognition Motif ◽  
Male Sterile ◽  
Cell Degeneration ◽  
Regulatory Pathways ◽  
Callose Wall

In angiosperms, anther development comprises of various complex and interrelated biological processes, critically needed for pollen viability. The transitory callose layer serves to separate the meiocytes. It helps in primexine formation, while the timely degradation of tapetal cells is essential for the timely callose wall dissolution and pollen wall formation by providing nutrients for pollen growth. In rice, many genes have been reported and functionally characterized that are involved in callose regulation and pollen wall patterning, including timely programmed cell death (PCD) of the tapetum, but the mechanism of pollen development largely remains ambiguous. We identified and functionally characterized a rice mutant dcet1, having a complete male-sterile phenotype caused by defects in anther callose wall, exine patterning, and tapetal PCD. DCET1 belongs to the RNA recognition motif (RRM)-containing family also called as the ribonucleoprotein (RNP) domain or RNA-binding domain (RBD) protein, having single-nucleotide polymorphism (SNP) substitution from G (threonine-192) to A (isoleucine-192) located at the fifth exon of LOC_Os08g02330, was responsible for the male sterile phenotype in mutant dcet1. Our cytological analysis suggested that DCET1 regulates callose biosynthesis and degradation, pollen exine formation by affecting exine wall patterning, including abnormal nexine, collapsed bacula, and irregular tectum, and timely PCD by delaying the tapetal cell degeneration. As a result, the microspore of dcet1 was swollen and abnormally bursted and even collapsed within the anther locule characterizing complete male sterility. GUS and qRT-PCR analysis indicated that DCET1 is specifically expressed in the anther till the developmental stage 9, consistent with the observed phenotype. The characterization of DCET1 in callose regulation, pollen wall patterning, and tapetal cell PCD strengthens our knowledge for knowing the regulatory pathways involved in rice male reproductive development and has future prospects in hybrid rice breeding.

scholarly journals Ultrastructural transformations in the cytoplasm of differentiating Hyacinthus orientalis L. pollen cells

2014 ◽  
Vol 57 (2) ◽  
pp. 235-245 ◽  
Author(s):  
Elżbieta Bednarska
Keyword(s):  
Vegetative Cell ◽  
Generative Cell ◽  
Pollen Grain ◽  
Border Region ◽  
Ultrastructural Changes ◽  
Grain Development ◽  
Callose Wall ◽  
Highly Active ◽  
Hyacinthus Orientalis

The sequence of ultrastructural changes in the cytoplasm during the successive stages of pollen grain development in <em>Hyacinthus orientulis</em> pollen cells was studied. The cytoplasmic transformations of the generative cell included the elimination of plastids, increase in the number of mitochondria, assumption of a spindle shape with the aid of microtubules and the characteristic development of the vacuole system with the formation of so-called colored bodies. The cytoplasmic transformations of the generative cell encompassed changes in the plastids, which began to accumulate starch soon after the cell was formed, then released it shortly before anthesis, an increase in the number of mitochondria and an increase in the number of highly active dictyosomes just before anthesis. Changes in the structure of the border region between the differentiating pollen cells were associated mainly with the periodical appearance of a callose wall and the presence of lysosome-like bodies in the cytoplasm of the vegetative cell surrounding the generative cell. They arose soon after the disappearance of the callose wall and disappeared shortly before anthesis.

Post-pollination callose development in ovules of Rhododendron and Ledum (Ericaceae): zygote special wall

1984 ◽  
Vol 69 (1) ◽  
pp. 127-135
Author(s):  
E.G. Williams ◽  
R.B. Knox ◽  
V. Kaul ◽  
J.L. Rouse
Keyword(s):  
Periodic Acid ◽  
Embryo Sac ◽  
Aniline Blue ◽  
Blue Fluorescence ◽  
Callose Deposition ◽  
Periodic Acid Schiff ◽  
Callose Wall ◽  
Unfertilized Ovules ◽  
Ledum Groenlandicum

In Rhododendron spp. and Ledum groenlandicum a callose wall is laid down around the zygote in the first 2 days after fertilization. The periodic acid/Schiff-positive, aniline blue-fluorescence-positive callosic wall is initiated adjacent to the degenerating synergid, extends to cover the entire zygote surface, and remains visible during the initiation of embryogeny as the zygote elongates before the first proembryonal division. Unfertilized ovules show eventual callose deposition in the ovule wall cells during senescence in undeveloped abscising pistils, but show no development of callose within the embryo sac. Possible roles of a zygote special callose wall are discussed.

Discontinuities in the callose wall, intermeiocyte connections, and cytomixis in angiosperm meiocytes

1974 ◽  
Vol 52 (6) ◽  
pp. 1219-1224 ◽  
Author(s):  
Ernest D. P. Whelan
Keyword(s):  
Phase Contrast ◽  
Hole Size ◽  
Lupinus Polyphyllus ◽  
Callose Wall ◽  
Regular Distribution

Discontinuities, considered to be holes, were observed in the meiocyte callose wall of 25 dicotyledon and 5 monocotyledon taxa investigated by phase-contrast and Nomarski interference-contrast optics. With the exception of the Helianthus spp., where regular distribution was observed, the holes were confined to two to four discrete areas of the callose wall. Hole size was highly variable; the largest, of about 2 μm diameter, occurred in lupin (Lupinus polyphyllus Ldl.). Cytoplasmic connections between neighboring meiocytes and (or) cytomictic phenomena were observed in 13 of the 30 taxa investigated.

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