Male cone morphogenesis, pollen development and pollen dispersal mechanism in Ginkgo biloba L.

Lu, Y., Wang, L., Wang, D., Wang, Y., Zhang, M., Jin, B. and Chen, P. 2011. Male cone morphogenesis, pollen development and pollen dispersal mechanism in Ginkgo biloba L. Can. J. Plant Sci. 91: 971–981. Ginkgo biloba L. is one of the oldest gymnosperms. Male cone morphogenesis, pollen development and dispersal are important for successful pollination and reproduction. In this study, we investigated the development of male cone, pollen and the sporangial wall in detail. The results indicate that: (1) The primordia of male cones and leaves begin to differentiate in early June and remain open until the following March. The male cones then mature and release pollen in mid-April. The male cones are drooped and approximately perpendicular to the leaves during pollination. (2) The microsporocytes develop from the sporogenous cell and form a tetrahedral tetrad after two simultaneous asymmetrically meioses, then produce a matured four-cell pollen after three polar mitotic divisions. The matured pollen is hemispheric in shape with a large aperture area and three pollen wall layers; once released from the microsporangia, the pollen becomes boat-like in shape. (3) The sporangial walls are eusporangiate and consist of epidermis, endothecium and tapetum. The differentiation of the tapetum occurs separately from that of the epidermis and endothecium, and originates from the outermost layer of sporogenous cells. The sporangial walls exhibit shrinkage of the epidermis, fibrous thickening of the endothecium, and enzymic dissolution of the tapetum during pollen dispersal, which contributes to microsporangia opening. Based on these results, we conclude that there many unique and primitive characteristics of the development of the male cones, pollen and sporangial wall of G. biloba. In addition, we also found that the male cones, pollen and sporangial walls have evolved efficient structural and morphological adaptations to anemophily.

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Asterobolus: a new parasitic hyphomycete with a novel dispersal mechanism

Canadian Journal of Botany ◽

10.1139/b72-059 ◽

1972 ◽

Vol 50 (3) ◽

pp. 409-412 ◽

Cited By ~ 11

Author(s):

Scott A. Redhead ◽

Peter W. Perrin

Keyword(s):

Leaf Spot ◽

Causal Agent ◽

Sporogenous Cell ◽

Gaultheria Shallon ◽

Dispersal Mechanism ◽

Conidial Stage

The genus Asterobolus is proposed for an undescribed hyphomycete characterized by multicelled, star-shaped conidia forcibly discharged by a downfolding of the radiating appendages and rupture of the sporogenous cell. Asterobolus gaultheriae sp. nov. is the causal agent of a leaf spot of Gaultheria shallon Pursh. The fungus also infects species of Vaccinium, Pteridium, Malus, and Menziesia. Sclerotia were observed only on Gaultheria and infections of other hosts were found only near infected Gaultheria. In addition to the star-shaped conidia, a Gliocladium-like conidial stage was also observed in cultures of the fungus.

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Cycas micronesica Stem Carbohydrates Decline Following Leaf and Male Cone Growth Events

Plants ◽

10.3390/plants9040517 ◽

2020 ◽

Vol 9 (4) ◽

pp. 517 ◽

Cited By ~ 1

Author(s):

Thomas E. Marler ◽

Gil N. Cruz

Keyword(s):

Carbon Source ◽

Rapid Growth ◽

Leaf Growth ◽

Indirect Evidence ◽

Alternative Methods ◽

Stem Tissue ◽

Leaf Removal ◽

Male Cone ◽

Male Cones ◽

Cone Growth

The growth of synchronized leaf flushes or male cones on Cycas trees is an ephemeral event, and non-structural carbohydrates (NSCs) are likely deployed from stem and root storage tissues to support their construction. The relationships among various stem NSCs and these rapid growth events have not been studied to date. Monosaccharides, disaccharides, and starch were quantified in Cycas micronesica stem tissue prior to and immediately after the growth of leaf flushes or male cones to determine the influences on the concentration of these carbohydrates. The pre-existing leaves were removed from half of the plants to determine if the elimination of this carbon source would influence the NSC behaviors. Starch and sucrose dominated the NSC profiles, and these two NSCs declined following cone or new leaf growth. Removal of pre-existing leaves generated a greater decline in starch and sucrose for cone growth, and a greater decline in sucrose, but not starch following new leaf growth than in control trees with no leaf removal. The initial differences in starch and sucrose among cortex, vascular, and pith tissues disappeared as the concentrations declined in all three tissue categories to reach similar post-growth concentrations among the stem tissue categories. The fructose, glucose, and maltose behaviors were not consistent, and their concentrations were low such that their influence on the total NSC behaviors was minimal. These results provided indirect evidence that stem NSCs were mobilized to support ephemeral male cone and new leaf growth for this arborescent cycad. Growth of female strobili is slow and lengthy, so we did not include female trees in this study. The contributions of stem NSCs to female strobili growth remain to be studied with alternative methods.

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MONOCOT POLLEN FLORA OF PASCHIM MEDINIPUR DISTRICT, WEST BENGAL WITH A NOTE ON POLLEN DISPERSAL MECHANISM

Current Botany ◽

10.19071/cb.2017.v8.3199 ◽

2017 ◽

Vol 8 ◽

Cited By ~ 1

Author(s):

Arundhati Ghosh ◽

Prakash Karmakar

Keyword(s):

Light Microscopy ◽

West Bengal ◽

Pollen Dispersal ◽

Pollen Grains ◽

Surface Features ◽

Dispersal Mechanism ◽

Morphological Studies

<p>During the present investigation pollen morphological studies of 66 species belonging to 19 families of monocots in Paschim Medinipur district have been worked out by light microscopy. The studied families are Agavaceae, Amaryllidaceae, Arecaceae, Asphodelaceae, Cannaceae, Colchicaceae, Commelinaceae, Costaceae, Cyperaceae, Hemerocallidaceae, Hydrocharitaceae, Iridaceae, Liliaceae, Limnocharitaceae, Musaceae, Poaceae, Pontederiaceae, Typhaceae and Zingiberaceae. The apertural patterns are mostly belong to two different categories viz. monosulcate form (Agavaceae, Amaryllidaceae, Arecaceae, Asphodelaceae, Colchicaceae, Commelinaceae, Costaceae, Hemerocallidaceae, Hydrocharitaceae, Iridaceae, Liliaceae, Limnocharitaceae, Musaceae, Poaceae, Pontederiaceae) and anaporate type (Cyperaceae, Poaceae and Typhaceae). The shape of the pollen grains with monosulcate apertures are mostly oblate to peroblate type whereas taxa showing anaporate apertures are more or less spheroidal. Regarding the mode of pollen dispersal plant taxa with monosulcate apertures and apiculate surface ornamentations (e.g., reticulate, rugulate, spinulate, verrucate) are entomophilous (mainly melittophilous) whilest anaporate with smooth or minutely apiculate surface features are anemophilous. Here, entomophilous taxa provide rewards as pollen grains and nectar to the honeybee speecies, therefore, contribute as resource mobilizer for sustainance of honeybee colonies. </p>

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Grain Dispersal Mechanism In Cereals Arose From a Genome Duplication Followed By Changes in Spatial Expression of Genes Involved In Pollen Development

10.21203/rs.3.rs-947707/v1 ◽

2021 ◽

Author(s):

Arthur Cross ◽

John Baijun ◽

Robbie Waugh ◽

Agnieszka Golicz ◽

Mohammad Pourkheirandish

Keyword(s):

Expression Profile ◽

Pollen Development ◽

Developmental Stages ◽

Biological Function ◽

Natural Mode ◽

Cell Wall Modification ◽

Spatial Expression ◽

Dispersal Mechanism ◽

A Genome ◽

Ancestral Function

Abstract One of the most critical events in the process of cereal domestication was the loss of the natural mode of grain dispersal. Grain dispersal in barley is controlled by two major genes, Btr1 and Btr2, which affect the thickness of cell walls around the disarticulation zone. The barley genome also encodes Btr1-like and Btr2-like genes, which have been shown to be the ancestral copies. While Btr and Btr-like genes are non-redundant, the biological function of Btr-like genes is unknown. We explored the potential biological role of the Btr-like genes by surveying their expression profile across 212 publicly available transcriptome datasets representing diverse organs, developmental stages and stress conditions. We found that Btr1-like and Btr2-like are expressed exclusively in immature anther samples throughout Prophase I of meiosis within the meiocyte. The similar and restricted expression profile of these two genes suggests they are involved in a common biological function. Further analysis revealed 141 genes co-expressed with Btr1-like and 122 genes co-expressed with Btr2-like, with 105 genes in common, supporting Btr-like genes involvement in a shared molecular pathway. We hypothesize that the Btr-like genes play a crucial role in pollen development by facilitating the formation of the callose wall around the meiocyte or in the secretion of callase by the tapetum. Our data suggest that Btr genes retained an ancestral function in cell wall modification and gained a new role in grain dispersal due to changes in their spatial expression becoming spike specific after gene-duplication.

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The Dermal Glands of Rhodnius Prolixus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100063202 ◽

1969 ◽

Vol 27 ◽

pp. 258-259

Author(s):

J. E. Lai-Fook

Keyword(s):

Fine Structure ◽

Secretory Activity ◽

Rhodnius Prolixus ◽

Outermost Layer ◽

Cement Layer ◽

Dermal Glands

Dermal glands are epidermal derivatives which are reported to secrete either the cement layer, which is the outermost layer of the epicuticle or some component of the moulting fluid which digests the endocuticle. The secretions do not show well-defined staining reactions and therefore they have not been positively identified. This has contributed to another difficulty, namely, that of determining the time of secretory activity. This description of the fine structure of the developing glands in Rhodnius was undertaken to determine the time of activity, with a view to investigating their function.

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Resolution of Channels in the Exine by Translocation of Colloidal Iron

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100065808 ◽

1971 ◽

Vol 29 ◽

pp. 352-353

Author(s):

John R. Rowley

Keyword(s):

Phosphate Buffer ◽

Pollen Development ◽

Osmium Tetroxide ◽

Pollen Grains ◽

Deionized Water ◽

Colloidal Iron ◽

Fixed Material ◽

Epilobium Angustifolium ◽

Untreated Material ◽

Microspore Mitosis

The morphology of the exine of many pollen grains, at the time of flowering, is such that one can suppose that transport of substances through the exine occurred during pollen development. Holes or channels, microscopic to submicroscopic, are described for a large number of grains. An inner part of the exine of Epilobium angustifolium L. and E. montanum L., which may be referred to as the endexine, has irregularly shaped channels early in pollen development although by microspore mitosis there is no indication of such channeling in chemically fixed material. The nucleus in microspores used in the experiment reported here was in prophase of microspore mitosis and the endexine, while lamellated in untreated grains, did not contain irregularly shaped channels. Untreated material from the same part of the inflorescence as iron treated stamens was examined following fixation with 0.1M glutaraldehyde in cacodylate-HCl buffer at pH 6.9 (315 milliosmoles) for 24 hrs, 4% formaldehyde in phosphate buffer at pH 7.2 (1,300 milliosmoles) for 12 hrs, 1% glutaraldehyde mixed with 0.1% osmium tetroxide for 20 min, osmium tetroxide in deionized water for 2 hrs and 1% glutaraldehyde mixed with 4% formaldehyde in 0.1M cacodylate-HCl buffer at pH 6.9 for two hrs.

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