scholarly journals Effect of Low Temperature on Changes in AGP Distribution during Development of Bellis perennis Ovules and Anthers

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1880
Author(s):  
Agata Leszczuk ◽  
Ewa Szczuka ◽  
Kinga Lewtak ◽  
Barbara Chudzik ◽  
Artur Zdunek
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Stress Conditions ◽  
Structural Element ◽  
Common Wall ◽  
Reproduction Process ◽  
The Common ◽  
Spatio Temporal ◽  
Lower Temperature ◽  
Developmental Phases

Arabinogalactan proteins (AGPs) are a class of heavily glycosylated proteins occurring as a structural element of the cell wall-plasma membrane continuum. The features of AGPs described earlier suggest that the proteins may be implicated in plant adaptation to stress conditions in important developmental phases during the plant reproduction process. In this paper, the microscopic and immunocytochemical studies conducted using specific antibodies (JIM13, JIM15, MAC207) recognizing the carbohydrate chains of AGPs showed significant changes in the AGP distribution in female and male reproductive structures during the first stages of Bellis perennis development. In typical conditions, AGPs are characterized by a specific persistent spatio-temporal pattern of distribution. AGP epitopes are visible in the cell walls of somatic cells and in the megasporocyte walls, megaspores, and embryo sac at every stage of formation. During development in stress conditions, the AGP localization is altered, and AGPs entirely disappear in the embryo sac wall. In the case of male development, AGPs are present in the tapetum, microsporocytes, and microspores in normal conditions. In response to development at lower temperature, AGPs are localized in the common wall of microspores and in mature pollen grains. Additionally, they are accumulated in remnants of tapetum cells.

Reproductive development in two species of Darwinia Rudge (Myrtaceae)

1969 ◽  
Vol 17 (2) ◽  
pp. 215 ◽  
Author(s):  
N Prakash
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Reproductive Development ◽  
Outer Zone ◽  
Mature Embryo ◽  
Globular Embryo ◽  
Primary Endosperm Nucleus ◽  
Oil Glands ◽  
Polygonum Type ◽  
History Of

In Darwinia the floral parts are differentiated in a "calyx-orolla-gynoeciumandroecium" sequence. In individual buds stages of microsporogenesis markedly precede corresponding stages of megasporogenesis. The anther is tetrasporangiate with all sporangia lying in one plane. The secretory tapetum is one- to three-layered within the same microsporangium and a large number of Ubisch bodies are formed. The anthers dehisce by minute lateral pores and an ingenious mechanism helps disperse the twocelled pollen grains. A basal placenta in the single loculus of the ovary bears four ovules in D. micropetala and two in D. fascicularis. In both species, however, only one ovule is functional after fertilization. The fully grown ovules are anatropous, crassinucellar, and bitegmic; the inner integument forms the micropyle. The parietal tissue is most massive at the completion of megasporogenesis but is progressively destroyed later. The embryo sac follows the Polygonum type of developnlent and when mature is five-nucleate, the three antipodals being ephemeral. Following fertilization, the primary endosperm nucleus divides before the zygote. Subsequent nuclear divisions in the endosperm mother cell are synchronous and lead to a free-nuclear endosperm which becomes secondarily cellular, starting from the micropylar end at the time the globular embryo assumes an elongated shape. Embryogeny is irregular and the mature embryo is straight with a massive radicle and a hypocotyl which terminates in two barely recognizable cotyledons. Sometimes the minute cotyledons are borne on a narrow neck-like extension of the hypocotyl. A suspensor is absent. Both integuments are represented in the seed coat and only the outer layer of the outer and the inner layer of the inner integuments, with their thick-walled tanniniferous cells, remain in the fully grown seed. The ovary wall is demarcated into an outer zone containing oil glands surrounded by cells containing a tannin-like substance and an inner zone of spongy parenchyma. In the fruit this spongy zone breaks down completely but the outer zone is retained. The two species of Darwinia, while closely resembling each other in their embryology, differ significantly from other Myrtaceae. However, no taxonomic conclusions are drawn at this stage, pending enquiry into the life history of other members of the tribe Chamaelaucieae.

Embryological studies in the compositae, I. Sporogenesis, Gametogenesis, and Embryogeny in Cotula australis (Less.) Hook. F

1962 ◽  
Vol 10 (1) ◽  
pp. 1 ◽  
Author(s):  
GL Davis
Keyword(s):  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Embryo Sac ◽  
Subsequent Development ◽  
Pollen Grains ◽  
Archesporial Cell ◽  
Polygonum Type ◽  
Wall Formation ◽  
Chalazal Megaspore

Cotula australis has a discoid heterogamous capitulum in which the outermost three whorls of florets are female and naked. The bisexual disk florets are fully fertile and have a four-lobed corolla with four shortly epipetalous stamens. The anthers contain only two microsporangia. Wall formation and microsporogenesis are described and the pollen grains are shed at the three-celled condition. The ovule is teguinucellate and the hypodermal archesporial cell develops directly as the megaspore mother cell. Megasporogenesis is normal and the monosporio embryo sac develops from the chalazal megaspore. Breakdown of the nucellar epidermis takes place when the embryo sac is binucleate and its subsequent development follows the Polygonum type. The synergids extend deeply into the micropyle and one persists until late in embryogeny as a haustorium. The development of the embryo is of the Asterad type, and the endosperm is cellular. C. coronopifolia agrees with C. australis in the presence of only two microsporangia in each anther and the development of a synergid haustorium.

The State and Democratization: The United States in Comparative Perspective

2004 ◽  
Vol 34 (2) ◽  
pp. 193-210 ◽  
Author(s):  
FRANCISCO E. GONZÁLEZ ◽  
DESMOND KING
Keyword(s):  
American Exceptionalism ◽  
The United States ◽  
The State ◽  
Comparative Perspective ◽  
Third Wave ◽  
Liberal Democracies ◽  
Historical Process ◽  
American Experience ◽  
The Common ◽  
Spatio Temporal

In this article we defend the importance of the concept of ‘stateness’ in scholarly understanding of political democratization. We argue that because processes of political democratization in different spatio-temporal settings often share important similarities they are therefore comparable. We investigate this proposition by comparing the process of American political democratization with those of other liberal democracies, old and new. We review extant accounts of the historical process of American democratization – including those addressing American exceptionalism, class structures, multiple traditions, social movements, and international pressures – before presenting an alternative comparative account based on the idea of stateness. Attention to stateness problems defined along legal, bureaucratic and ideological dimensions and derived from both the classic Weberian perspective on the state and the more recent ‘third wave’ of democratization theory help to place the long American experience of democratization in comparative perspective. This finding illuminates some of the common political challenges in the construction of liberal democracies, old and new.

scholarly journals Interspecific Hybridization Processes between Michelia yunnanensis and M. crassipes and Embryogenesis of the Heterozygote

HortScience ◽  
2017 ◽  
Vol 52 (8) ◽  
pp. 1043-1047
Author(s):  
Haiyan Xu ◽  
Folian Li ◽  
Yuezhi Pan ◽  
Xun Gong
Keyword(s):  
Reciprocal Cross ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Blue Staining ◽  
Formation Processes ◽  
Callose Deposition ◽  
Cross Compatibility ◽  
Direct Cross ◽  
Hybrid Seeds ◽  
Aniline Blue Staining

The investigation of hybridization processes and embryogenesis of heterozygote is an effective approach for early hybrids’ identification, which could provide reliable information for successful crossbreeding. In this study, we reported the whole hybridization processes of the direct cross and reciprocal cross between Michelia yunnanensis Franch. ex Finet et Gagnep. and Michelia crassipes Law using fluorescence microscopy after aniline blue staining, with the pollen germination on stigmas, pollen tube growth in styles, and subsequent extension into the embryo sac as well as the double fertilization processes are documented in detail. The M. yunnanensis × M. crassipes combination displayed considerable cross-compatibility, and the heterozygote embryogenesis was further observed with an approach of modified cryosectioning technique. Besides, the whole formation processes of hybrid seeds from artificial pollination to maturation were successfully observed. However, in the reciprocal cross, we found incompatibility between pollen grains of M. yunnanensis and stigmas of M. crassipes for the reason of hysteretic identification, as well as the abnormal callose deposition which belongs to the prefertilization barriers. This is the first study in which the complete and clear hybridization processes in Michelia were reported. We inferred that unilateral incompatibility of M. crassipes detected in this study may also exist in some other Michelia species. In artificial hybridization practices, we suggest some special treatments for overcoming prefertilization barrier should be taken when treating M. crassipes as the maternal parent.

scholarly journals The possible origin of the common wall lizard, Podarcis muralis (Laurenti, 1768) in Ukraine

Herpetozoa ◽  
2020 ◽  
Vol 33 ◽  
pp. 87-93
Author(s):  
Oleksandra Oskyrko ◽  
Hanna Laakkonen ◽  
Iolanda Silva-Rocha ◽  
Daniel Jablonski ◽  
Oleksiy Marushchak ◽  
...  
Keyword(s):  
Mitochondrial Gene ◽  
Geographic Region ◽  
Danube River ◽  
Eastern European ◽  
Native Population ◽  
Podarcis Muralis ◽  
Common Wall ◽  
The Common ◽  
Genetic Signal ◽  
Human Transport

The phylogenetic relationships and possible origin of a putative non-native population of Podarcis muralis in Ukraine were assessed based on sequences of the mitochondrial gene cytochrome b. Phylogenetic analysis showed that the Ukrainian lizards belong to two distinct mitochondrial lineages (haplogroups), both occurring within the Central Balkan clade, which includes most of central and south-eastern European populations. From overall three detected Ukrainian haplotypes, one haplotype share same genetic signal with the hyplotype from the locality Bjala (Bulgaria), the other two are unique for Ukrainian population. Two of haplotypes correspond with haplogroup covering large geographic region of Bulgaria, Serbia, and Romania. These results reinforce previous findings that the species has the ability to establish new populations out of its native range. While most introductions to Germany and Britain have been deliberate, it appears likely that human transport of goods via the Danube river of goods is responsible for the range expansion into Ukraine.

Lateralization in the escape behaviour of the common wall lizard (Podarcis muralis)

2010 ◽  
Vol 207 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Beatrice Bonati ◽  
Davide Csermely ◽  
Pilar López ◽  
José Martín
Keyword(s):  
Escape Behaviour ◽  
Podarcis Muralis ◽  
Common Wall ◽  
The Common

scholarly journals Flowering dynamics and pollen production of Laburnum anagyroides Med. under the conditions of south-eastern Poland

2013 ◽  
Vol 57 (2) ◽  
pp. 103-115 ◽  
Author(s):  
Ernest Stawiarz ◽  
Anna Wróblewska
Keyword(s):  
Pollen Grains ◽  
Average Weight ◽  
Pollen Production ◽  
Full Bloom ◽  
Flowering Duration ◽  
The Third ◽  
Laburnum Anagyroides ◽  
Golden Yellow ◽  
Single Flower ◽  
The Common

Abstract A study on the flowering biology and pollen production of the common laburnum (Laburnum anagyroides Med.) was conducted under the conditions of Lublin during the period 2004 - 2006. The flowering of this species began in the second 10-day period of May and lasted for 2.5 - 4 weeks. The flowers of common laburnum are borne in showy golden-yellow pendulous racemes. They develop successively, starting from the base and moving to the tip of an inflorescence. During the growing season, one shrub produces 800 to 3200 racemes, with 14 to 35 flowers in a single raceme. On average, the flowering duration for a raceme was 12.8 days and 8.7 days for a single flower. Throughout the study years, the shrubs proved to be most attractive in the third 10-day period of May when they reached full bloom. The average weight of pollen produced was 6.08 mg per 10 flowers of Laburnum anagyroides, 14.02 mg per raceme, and 26.0 g per shrub. Pollen grains reached average dimensions of 24.01 μm × 24.26 μm.

The floral morphology and embryology of Themeda australis (R. Br.) Stapf

1964 ◽  
Vol 12 (2) ◽  
pp. 157 ◽  
Author(s):  
PS Woodland
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Low Fertility ◽  
Linear Tetrad ◽  
Polygonum Type ◽  
Morphological Variations ◽  
Endosperm Formation ◽  
Secretory Type ◽  
Successive Cytokinesis ◽  
Mother Cells

A comparative study was carried out between diploid and tetraploid races of Themeda australis from Armidale and Cobar, respectively. Some morphological variations occur in both populations, but sporogenesis and gametogenesis are identical. The anther is tetrasporangiate and the development of its four-layered wall is described. The tapetum is of the secretory type and its cells become binucleate at the initiation of meiosis in the adjacent microspore mother cells which undergo successive cytokinesis. Microspore tetrads are usually isobilateral and the pollen grains are three-celled at dehiscence, which takes place by lateral longitudinal slits. The ovule is of a modified anatropous form and bitegmic, the broad micropyle being formed of both integuments. The single hypodermal archesporial cell develops directly into the megaspore mother cell and the nucellar epidermis undergoes periclinal and anticlinal divisions to form a conspicuous epistase. The chalaza1 megaspore of the linear tetrad gives rise to a Polygonum-type embryo sac. Material from the Armidale population showed one embryo sac per ovule, but two to five embryo sacs were present in that from Cobar. Embryogeny is typically graminaceous and endosperm formation is at first free-nuclear, later becoming cellular. Polyembryony follows fertilization of several embryo sacs within the same ovule. The reasons for low fertility of T. australis and poor germination of seeds are discussed.

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