Sexual reproduction of Pinus contorta. I. Pollen development, the pollination mechanism, and early ovule development

1981 ◽  
Vol 59 (10) ◽  
pp. 1828-1843 ◽  
Author(s):  
John N. Owens ◽  
Sheila J. Simpson ◽  
Marje Molder
Keyword(s):  
Pollen Development ◽  
Pinus Contorta ◽  
Distal Part ◽  
Nuclear Division ◽  
Reproductive Potential ◽  
Ovule Development ◽  
Open Pollination ◽  
Micropylar Canal ◽  
Germinating Pollen ◽  
Female Gametophyte Development

Details of development and the phenology of postdormancy cone-bud development, microsporogenesis, pollen development, and pollination were similar for Pinus contorta var. contorta and var. latifolia growing near Victoria, B.C., but comparable stages of development for var. latifolia occurred about 1 month later near Prince George, B.C. Several developmental aspects were found which affect the reproductive potential of the species. Only 25% of the ovuliferous scales, mostly in the distal part of the cone, bear fertile ovules. Secretions formed on the ovules and micropylar arms which caused pollen to adhere to these surfaces. Pollination is by means of pollination drops which began to be exuded from the ovules about 2 weeks after the conelets began to emerge from their bud scales. Pollination drops were present within each conelet for 2 to 4 days. At that time conelets were most widely open. Pollination drops were then withdrawn as ovuliferous scales enlarged and sealed the conelets. Pollination drop exudation and withdrawal were affected by humidity and water stress within the tree. Cells lining the micropylar canal enlarged and sealed the micropyle after the conelet closed. Pollen settled into a pollen chamber in the nucellus tip where it germinated about 2 months after pollination. Ovules lacking germinating pollen aborted after megasporogenesis and before free nuclear division began. If many ovules aborted within a conelet, the conelet aborted before winter dormancy. Ovules began free nuclear female gametophyte development and pollen tubes extended into the nucellus before conelets stopped developing in mid-August.

scholarly journals The mac1 Gene: Controlling the Commitment to the Meiotic Pathway in Maize

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 1009-1020 ◽  
Author(s):  
William F Sheridan ◽  
Nadezhda A Avalkina ◽  
Ivan I Shamrov ◽  
Tatyana B Batyea ◽  
Inna N Golubovskaya
Keyword(s):  
Female Gametophyte ◽  
Embryo Sac ◽  
Flowering Plants ◽  
Normal Female ◽  
Ovule Development ◽  
Partial Sterility ◽  
Embryo Sac Formation ◽  
Female Gametophyte Development ◽  
Normal Meiosis ◽  
Pleiotropic Mutation

Abstract The switch from the vegetative to the reproductive pathway of development in flowering plants requires the commitment of the subepidermal cells of the ovules and anthers to enter the meiotic pathway. These cells, the hypodermal cells, either directly or indirectly form the archesporial cells that, in turn, differentiate into the megasporocytes and microsporocytes. We have isolated a recessive pleiotropic mutation that we have termed multiple archesporial cells1 (macl) and located it to the short arm of chromosome 10. Its cytological phenotype suggests that this locus plays an important role in the switch of the hypodermal cells from the vegetative to the meiotic (sporogenous) pathway in maize ovules. During normal ovule development in maize, only a single hypodermal cell develops into an archesporial cell and this differentiates into the single megasporocyte. In macl mutant ovules several hypodermal cells develop into archesporial cells, and the resulting megasporocytes undergo a normal meiosis. More than one megaspore survives in the tetrad and more than one embryo sac is formed in each ovule. Ears on mutant plants show partial sterility resulting from abnormalities in megaspore differentiation and embryo sac formation. The sporophytic expression of this gene is therefore also important for normal female gametophyte development.

Sexual reproduction of Larix occidentalis

1979 ◽  
Vol 57 (23) ◽  
pp. 2673-2690 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Female Gametophyte ◽  
Pollen Grains ◽  
Larix Occidentalis ◽  
Embryo Abortion ◽  
Meristematic Tissue ◽  
Micropylar Canal ◽  
Empty Seed ◽  
Mother Cells ◽  
Pollen Cone ◽  
Female Gametophyte Development

Pollen-cone and seed-cone buds broke dormancy about 2 weeks before vegetative buds on the same tree. Pollen mother cells, which had over-wintered at pachytene or the diffuse stage of meiosis, resumed meiosis and tetrads of microspores were formed by mid-March. Wingless five-celled mature pollen developed by mid-to late April when pollination occurred.When development resumed after dormancy a ring of meristematic tissue formed the integument around the nucellus. The integument tip developed a short abaxial tip and a large adaxial lobe on which developed numerous long stigmatic hairs. A slit-like micropyle remained between the two lips. Several pollen grains usually adhered to the stigmatic hairs and then the two lips grew into the micropyle, engulfing the pollen. No pollination drop was observed. Within the micropylar canal, pollen greatly elongated then formed a pollen tube when the elongated pollen contacted the nucellus.Megaspore mother cells underwent meiosis at the time of pollination. Female gametophyte development, which was the same as in most other members of the Pinaceae, was completed in early June and two to five archegonia were formed. Fertilization occurred in early June, 6 to 8 weeks after pollination. A 16-celled proembryo developed. Simple polyembryony was common but cleavage polyembryony was not observed. Embryo development was similar to other members of the Pinaceae. Embryos and seeds were mature by mid-August.Normal appearing but inviable seed is common in L. occidentalis because the ovule is fully enlarged and the seed coat well developed at fertilization. Inviable seed commonly resulted from the absence of pollination, inviable pollen, lack of fertilization, later ovule abortion, or embryo abortion, primarily during early embryonic stages. Flat empty seed also occurred and resulted from abortion of the megaspore mother cell or early female gametophyte.

Anther and Ovule Development in Tasmannia (Winteraceae)

1992 ◽  
Vol 40 (6) ◽  
pp. 877 ◽  
Author(s):  
N Prakash ◽  
AL Lim ◽  
FB Sampson
Keyword(s):  
Mother Cell ◽  
Female Gametophyte ◽  
Cell Plate ◽  
Basic Type ◽  
Ovule Development ◽  
Linear Tetrad ◽  
Polygonum Type ◽  
Secretory Type ◽  
Mother Cells ◽  
Female Gametophyte Development

Three species of Tasmannia R.Br. ex DC., T. glaucifolia, T. insipida and T. stipitata are studied. The anther is tetrasporangiate and its waU development conforms to the Basic type. The tapetum follows the secretory type of development. Cytokinesis in the microspore mother cells is simultaneous but an evanescent cell plate is present at telophase I and anaphase I1 during meiosis. Pollen tetrads are permanent and tetrahedral. The mature pollen is anaulcerate, reticulate and 2-celled. The ovule. is anatropous, bitegmic and crassinucellate. The micropyle in T. stipitata and T. Glaucifolia is formed by the inner integument only whereas in T. insipida it is formed by both the integuments and is zigzag in outline. Meiosis in the single megaspore mother cell produces a linear or T-shaped megaspore tetrad in T. stipitata and T. glaucifolia but only a linear tetrad in T. insipida. Female gametophyte development is of the monosporic Polygonum type. Fertilisation is porogamous; triple fusion and syngamy occur simultaneously.

Seed development following reciprocal crossing among autotetraploid and diploid Acacia mangium and diploid A. auriculiformis

2016 ◽  
Vol 64 (1) ◽  
pp. 20 ◽  
Author(s):  
Q. C. Nghiem ◽  
A. R. Griffin ◽  
C. E. Harwood ◽  
J. L. Harbard ◽  
T. Ha Huy ◽  
...  
Keyword(s):  
Resource Competition ◽  
Acacia Mangium ◽  
Ovule Development ◽  
Viable Seed ◽  
Open Pollination ◽  
Crop Development ◽  
Respective Parent ◽  
Reciprocal Crossing ◽  
Environmental Causes

As part of a program to breed sterile triploid varieties of tropical Acacia, a series of inter-and intra-specific crosses were made among clones of neo-tetraploid A. mangium (AM-4x) and diploid A. mangium (AM-2x) and A. auriculiformis (AA-2x). The present paper reports variation in seed-crop development from anthesis to harvest, in comparison with that after open pollination of the respective parent trees. Abscission of spikes and pods within spikes commenced soon after anthesis and was more rapid in inter-cytotype crosses than in open-pollinated controls. Less than 12% of spikes were retained to maturity in either cytotype, emphasising the likely importance of resource competition during development. Inter-cytotype crosses showed higher levels of abnormal ovule development at 7 weeks after pollination and more undeveloped seeds in those pods which did develop to maturity. No inter-cytotype combination produced more than one viable seed per pod on average, and all needed to be germinated in vitro to survive. A directional effect was apparent in the inter-cytotype crosses within AM but this was not obvious when the cross was inter-specific. The study contributes new knowledge of the post-anthesis timeline for ovule, pod and spike abscission and discusses the likely genetic and environmental causes of observed differences between inter-and intra-cytotype crosses as well as the implications for breeding.

Embryo sac and early ovule development in Oryzopsis miliacea and Stipa tortilis

1970 ◽  
Vol 48 (1) ◽  
pp. 27-41 ◽  
Author(s):  
Jack Maze ◽  
Lesly R. Bohm ◽  
Lyle E. Mehlenbacher Jr.
Keyword(s):  
Cell Division ◽  
Pollen Tube ◽  
Nuclear Division ◽  
Outer Integument ◽  
Embryo Sac ◽  
Ovule Development ◽  
Polygonum Type ◽  
Embryo Sac Development

The ovules of Stipa tortilis and Oryzopsis miliacea are hemianatropous, bitegmetic, and pseudocrassinucellate (sensu Davis 1966). The hemianatropous shape of the ovule is the result of characteristic patterns of cell division and enlargement in the chalazal area and areas alongside the embryo sac. Embryo sac development in both is Polygonum-type and both have proliferating antipodals. Endosperm is nuclear, although in O. miliacea it is atypical in that nuclear division is synchronous within one portion of the embryo sac, e.g. micropylar, but not synchronous between different portions of the embryo sac, e.g., micropylar and chalazal. Differences in ovule initiation, persistence of the outer integument, fate of the inner integument, nature of the nucellus, shape of the embryo sac, nature of the synergids, cytoplasm of the egg, polar nuclei, and endosperm exist between these two taxa. Both synergids of O. miliacea undergo changes before fertilization and one degenerates before fertilization. The pollen tube enters the embryo sac at the base of the persistent synergid. There is presently insufficient embryological data to permit meaningful speculation on relationships between Stipa and Oryzopsis. Embryologically, Stipa and Oryzopsis are festucoid grasses, as much other evidence indicates. Embryo sac development in the Gramineae is more similar to that of the Restionaceae than to that of the Cyperaceae. This is in contradiction to recent speculations on the relationships of the Gramineae.

Floral Development in Acacia pycnantha Benth. In Hook

1981 ◽  
Vol 29 (4) ◽  
pp. 385 ◽  
Author(s):  
MS Buttrose ◽  
WJR Grant ◽  
M Sedgley
Keyword(s):  
Light Microscopy ◽  
Pollen Development ◽  
Shoot Growth ◽  
Floral Development ◽  
Developmental Stages ◽  
Early Stage ◽  
Embryo Sac ◽  
Late Winter ◽  
Ovule Development ◽  
Floral Buds

Floral buds of Acacia pycnantha were produced in every month of the year on new shoot growth. The buds produced between November and May developed through to flowering but those produced between June and October aborted at an early stage. Differences in the rate of floral development caused buds produced several months apart to flower in the same month in late winter. Developmental stages from newly produced flower heads to anthesis were studied by light microscopy. Pollen development preceded ovule development and the 16-celled polyads were formed 1 month prior to flowering and before development of the embryo sac.

Ovule and female gametophyte development in the Bromeliaceae: an embryological study of Pitcairnia encholirioides

Botany ◽  
2014 ◽  
Vol 92 (12) ◽  
pp. 883-894 ◽  
Author(s):  
Simone P. Mendes ◽  
Alexandra A. Mastroberti ◽  
Jorge E.A. Mariath ◽  
Ricardo C. Vieira ◽  
Karen L.G. De Toni
Keyword(s):  
Life Cycle ◽  
Female Gametophyte ◽  
Ovule Development ◽  
Filiform Apparatus ◽  
Cell Wall Component ◽  
Polygonum Type ◽  
Gametophyte Development ◽  
Structural Alterations ◽  
Female Gametophyte Development ◽  
Advance Knowledge

Pitcairnia encholirioides L.B.Sm. is an endangered species endemic to the Brazilian Atlantic Forest. This species exhibits limited flowering, late seed germination, and preference for clonal growth. Because little is known about its life cycle and female gametophyte development, the ovule development, gynosporogenesis, and gynogametogenesis were analysed to advance knowledge of the species’ life cycle and structural alterations during ovule and female gametophyte development. Also, identification of embryological characters contributing to systematics of Pitcairnioideae is relevant. The ovules are anatropous, bitegmic, and crassinucellate, the gynosporogenesis is monosporic, and the female gametophyte is a Polygonum type. Different patterns in development of the integuments, nucellus, chalazal appendage, and micropylar channel indicate the potential of these characters for subfamily systematics. In the filiform apparatus, a range of glycan-directed monoclonal antibodies was used; the filiform exhibited a biphasic structure. While only arabinogalactan proteins (AGPs) occurred in the translucent matrix, mannans were the most prevalent glycan in the denser matrix. These phases may have distinct mechanical or signalling properties, as they showed different cell wall component distributions. The distinct spatial distribution between AGPs and other glycans showed that the filiform apparatus is heterogeneous and has a common polymer assemblage for both synergids.

scholarly journals Dynamics of the cell fate specifications during female gametophyte development in Arabidopsis

PLoS Biology ◽  
2021 ◽  
Vol 19 (3) ◽  
pp. e3001123
Author(s):  
Daichi Susaki ◽  
Takamasa Suzuki ◽  
Daisuke Maruyama ◽  
Minako Ueda ◽  
Tetsuya Higashiyama ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Female Gametophyte ◽  
Nuclear Division ◽  
Cell Plate ◽  
Egg Cell ◽  
Specific Gene ◽  
Cell Plate Formation ◽  
Plate Formation ◽  
Female Gametophyte Development

The female gametophytes of angiosperms contain cells with distinct functions, such as those that enable reproduction via pollen tube attraction and fertilization. Although the female gametophyte undergoes unique developmental processes, such as several rounds of nuclear division without cell plate formation and final cellularization, it remains unknown when and how the cell fate is determined during development. Here, we visualized the living dynamics of female gametophyte development and performed transcriptome analysis of individual cell types to assess the cell fate specifications in Arabidopsis thaliana. We recorded time lapses of the nuclear dynamics and cell plate formation from the 1-nucleate stage to the 7-cell stage after cellularization using an in vitro ovule culture system. The movies showed that the nuclear division occurred along the micropylar–chalazal (distal–proximal) axis. During cellularization, the polar nuclei migrated while associating with the forming edge of the cell plate, and then, migrated toward each other to fuse linearly. We also tracked the gene expression dynamics and identified that the expression of MYB98pro::GFP–MYB98, a synergid-specific marker, was initiated just after cellularization in the synergid, egg, and central cells and was then restricted to the synergid cells. This indicated that cell fates are determined immediately after cellularization. Transcriptome analysis of the female gametophyte cells of the wild-type and myb98 mutant revealed that the myb98 synergid cells had egg cell–like gene expression profiles. Although in myb98, egg cell–specific gene expression was properly initiated in the egg cells only after cellularization, but subsequently expressed ectopically in one of the 2 synergid cells. These results, together with the various initiation timings of the egg cell–specific genes, suggest complex regulation of the individual gametophyte cells, such as cellularization-triggered fate initiation, MYB98-dependent fate maintenance, cell morphogenesis, and organelle positioning. Our system of live-cell imaging and cell type–specific gene expression analysis provides insights into the dynamics and mechanisms of cell fate specifications in the development of female gametophytes in plants.

scholarly journals Dynamics of the cell fate specifications during female gametophyte development in Arabidopsis

2020 ◽  
Author(s):  
Daichi Susaki ◽  
Takamasa Suzuki ◽  
Daisuke Maruyama ◽  
Minako Ueda ◽  
Tetsuya Higashiyama ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Female Gametophyte ◽  
Nuclear Division ◽  
Cell Plate ◽  
Egg Cell ◽  
Specific Gene ◽  
Cell Plate Formation ◽  
Plate Formation ◽  
Female Gametophyte Development

ABSTRACTThe female gametophytes of angiosperms contain cells with distinct functions, such as those that enable reproduction via pollen tube attraction and fertilization. Although the female gametophyte undergoes unique developmental processes, such as several rounds of nuclear division without cell plate formation, and the final cellularization, it remains unknown when and how the cell fate is determined during their development. Here, we visualized the living dynamics of female gametophyte development and performed transcriptome analysis of its individual cell types, to assess the cell fate specifications in Arabidopsis thaliana. We recorded time lapses of the nuclear dynamics and cell plate formation from the one-nucleate stage to the seven-cell stage after cellularization, using the in vitro ovule culture system. The movies showed that the nuclear division occurred along the micropylar–chalazal axis. During cellularization, the polar nuclei migrated while associating with forming edge of the cell plate. Then, each polar nucleus migrated to fuse linearly towards each other. We also tracked the gene expression dynamics and identified that the expression of the MYB98pro∷GFP, a synergid-specific marker, was initiated before cellularization, and then restricted to the synergid cells after cellularization. This indicated that cell fates are determined immediately after cellularization. Transcriptome analysis of the female gametophyte cells of the wild type and myb98 mutant, revealed that the myb98 synergid cells had the egg cell-like gene expression profile. Although in the myb98, the egg cell-specific gene expressions were properly initiated only in the egg cells after cellularization, but subsequently expressed ectopically in one of the two synergid cells. These results, together with the various initiation timings of the egg cell-specific genes suggest the complex regulation of the individual gametophyte cells, such as cellularization-triggered fate initiation, MYB98-dependent fate maintenance, cell morphogenesis, and organelle positioning. Our system of live-cell imaging and cell-type-specific gene expression analysis provides insights into the dynamics and mechanisms of cell fate specifications in the development of female gametophytes in plants.

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