Pollination, female gametophyte, and embryo and seed development in yellow cedar (Chamaecyparis nootkatensis)

1975 ◽  
Vol 53 (2) ◽  
pp. 186-199 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Seed Development ◽  
Female Gametophyte ◽  
Pollen Tubes ◽  
Variable Number ◽  
Male Gametes ◽  
Seed Cone ◽  
Complex Forms ◽  
The One ◽  
Mother Cells ◽  
Female Gametophyte Development

After dormancy, both pollen- and seed-cone buds resume development early in April at higher elevations on Vancouver Island. Pollen, formed the previous fall, is shed at the one-celled stage during the last half of April. Pollination occurs during a 2-week period. Pollen frequently germinates and elongates in the pollination drop within the micropyle before reaching the nucellus. Pollen tubes penetrate most of the nucellus during May and early June, then pollen-tube growth slows or stops until mid-July when the pollen tubes quickly extend to the surface of the neck cells and two large, equal-sized male gametes form. Meiosis of the megaspore mother cells occurs during April and early May. Female gametophyte development, similar to that in other members of the Cupressaceae, occurs from late May until late July. An archegonial complex forms with an average of nine archegonia. Fertilization occurs at the end of July and proembryo development begins immediately. A file of four free nuclei forms. Considerable variation exists in subsequent nuclear divisions and cell-wall formation. This may result from the long, narrow archegonia and highly variable number of archegonia. A four-tiered proembryo forms and cleavage polyembryony occurs. The embryos reach the multicellular or the massive stage with secondary suspensors by October when the cones, containing ovules which were pollinated in April, become dormant. Embryo and seed development resume the next April, 1 year after pollination, and development is usually complete in July or August. Embryo development occurs more rapidly near sea level but is complete by fall of the year after pollination at all elevations studied. Most seed is shed early in the fall, but some seed may not be shed until January. The distinction is made between immature 1-year-old and mature 2-year-old seeds and cones. Cones contained an average of 7.2 seeds, of which only 29% were filled.

scholarly journals Recent advances in understanding female gametophyte development

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 804 ◽  
Author(s):  
Debra J Skinner ◽  
Venkatesan Sundaresan
Keyword(s):  
Cell Fate ◽  
Female Gametophyte ◽  
Cell Communication ◽  
Embryo Sac ◽  
Cell Types ◽  
Egg Cell ◽  
Male Gametes ◽  
Reproductive Unit ◽  
Genetic Mechanisms ◽  
Female Gametophyte Development

The haploid female gametophyte (embryo sac) is an essential reproductive unit of flowering plants, usually comprising four specialized cell types, including the female gametes (egg cell and central cell). The differentiation of these cells relies on spatial signals which pattern the gametophyte along a proximal-distal axis, but the molecular and genetic mechanisms by which cell identities are determined in the embryo sac have long been a mystery. Recent identification of key genes for cell fate specification and their relationship to hormonal signaling pathways that act on positional cues has provided new insights into these processes. A model for differentiation can be devised with egg cell fate as a default state of the female gametophyte and with other cell types specified by the action of spatially regulated factors. Cell-to-cell communication within the gametophyte is also important for maintaining cell identity as well as facilitating fertilization of the female gametes by the male gametes (sperm cells).

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.

Sexual reproduction of mountain hemlock (Tsuga mertensiana)

1975 ◽  
Vol 53 (17) ◽  
pp. 1811-1826 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Cell Walls ◽  
Pollen Tubes ◽  
Linear Tetrad ◽  
Form Complex ◽  
Male Gametes ◽  
Canal Cell ◽  
Micropylar Canal ◽  
Tsuga Mertensiana ◽  
Mother Cells ◽  
Ventral Canal

Meiosis of pollen mother cells begins in October of the year in which cones are initiated. They reach pachytene then become dormant until the next March. Meiosis is complete and the winged pollen mature by mid-June. Meiosis of the megaspore mother cell occurs in May, forming a linear tetrad of megaspores. The female gametophyte undergoes free nuclear division at pollination in mid-June. No pollination drop is present; rather, the pollen adheres to the sticky, splayed edge of the micropyle, where it germinates and pollen tubes grow toward the nucellus. The nucellus elongates into the micropylar canal, forming a nucellar beak, which makes contact with the pollen tubes. Several pollen tubes penetrate the nucellus.At the time of fertilization early in August, each ovule contains two to four aichegonia each having two to four neck cells in one tier. Pollen tubes penetrate the neck cells and two male gametes are formed. The ventral canal cell breaks down and fusion occurs in the center of the archegonium. Four free nuclei form and migrate to the base of the archegonium. cell walls form, and a 16-celled proembryo develops. Both simple and cleavage polyembryony occur. Rosette cells divide but do not form complex embryos. The embryo and seed are mature in October and the cones dry and open during October and November. Mature cones averaged 70 seeds, of which 46% were filled.Reproduction in mountain hemlock (Tsuga mertensiana (Bong.) Carr.) is similar to that in other species of Tsuga except for the presence of winged pollen. Any attempt to place the species in the genus Picea or place it as a hybrid midway between Picea and Tsuga is unfounded based on all of the more-conservative reproductive and embryological characteristics.

Sexual reproduction of Abies amabilis

1977 ◽  
Vol 55 (21) ◽  
pp. 2653-2667 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Pollen Tubes ◽  
High Elevation ◽  
Early Embryo ◽  
Wind Pollination ◽  
Abies Amabilis ◽  
Seed Cone ◽  
Mother Cells ◽  
Pollen Cone ◽  
Functional Megaspore ◽  
Short Time

Pollen-cone and seed-cone buds which differentiated in the summer and fall of the year before pollination resumed development in early April after about 5 months of dormancy. The sporogenous cells present in the dormant pollen-cone bud divided and formed pollen mother cells which began meiosis by mid-April. Meiosis was completed by late April and mature five-celled pollen was formed by the 3rd week of May. Wind pollination occurred in late May.Each ovule developed a curved funnel-shaped integument tip with a shallowly notched flange-like lip to which pollen readily adhered. No pollination drop was observed. Pollen remained attached to the integument tip but did not germinate for about 1 month, during which time the nucellus grew out nearly to the micropyle and the lip of the integument folded slightly inward bringing the pollen close to the nucellar tip. Pollen tubes then developed rapidly and penetrated the nucellus during the 1st week of July.Each ovule contained a single large megaspore mother cell in the dormant seed-cone bud. Megaspore mother cells underwent meiosis in early May and the single functional megaspore began free nuclear division in mid-May. Female gametophyte development was similar to other members of the Pinaceae and was completed by the end of June. Archegonia varied from two to three and each had two tiers of neck cells.Fertilization occurred in mid-July and early embryo development was rapid. Both simple and cleavage polyembryony occurred and 16-celled proembryos formed. By late July, usually only one club-shaped embryo remained in each ovule. Distinct meristems and cotyledons developed in the embryos in early August and embryos were mature by late August. Ovuliferous scales, usually with two seeds attached, began to be shed in late September. All ovuliferous scales were shed by November.Poor seed production in Abies amabilis (Dougl.) Forbes results partly from the low cone-bearing capacity of the trees, the infrequent occurrence of abundant pollen and seed cones at the high elevation sites, and the high incidence of insect damage to seeds and cones. In addition, A. amabilis and other species of Abies have an unspecialized pollination mechanism, a long period of pollen dormancy after pollination, and a very short time after germination when pollen tubes must develop and penetrate the long nucellar tip. In A. amabilis the archegonia abort very quickly if they are not fertilized. This period when fertilization can effectively occur is very short and remarkably synchronized within a cone and a tree. These, plus the low number of archegonia, may be reasons for the low percentage of viable seed in A. amabilis.

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.

scholarly journals Pollination triggers female gametophyte development in immature Nicotiana tabacum flowers

2015 ◽  
Vol 6 ◽  
Author(s):  
Michael S. Brito ◽  
Lígia T. Bertolino ◽  
Viviane Cossalter ◽  
Andréa C. Quiapim ◽  
Henrique C. DePaoli ◽  
...  
Keyword(s):  
Nicotiana Tabacum ◽  
Female Gametophyte ◽  
Gametophyte Development ◽  
Female Gametophyte Development

scholarly journals Maternal Control of PIN1 Is Required for Female Gametophyte Development in Arabidopsis

PLoS ONE ◽  
2013 ◽  
Vol 8 (6) ◽  
pp. e66148 ◽  
Author(s):  
Luca Ceccato ◽  
Simona Masiero ◽  
Dola Sinha Roy ◽  
Stefano Bencivenga ◽  
Irma Roig-Villanova ◽  
...  
Keyword(s):  
Female Gametophyte ◽  
Maternal Control ◽  
Gametophyte Development ◽  
Female Gametophyte Development

scholarly journals Identification and evaluation of the novel genes for transcript normalization during female gametophyte development in sugarcane

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12298
Author(s):  
Maokai Yan ◽  
Xingyue Jin ◽  
Yanhui Liu ◽  
Huihuang Chen ◽  
Tao Ye ◽  
...  
Keyword(s):  
Gene Expression ◽  
Sexual Reproduction ◽  
Reference Genes ◽  
Female Gametophyte ◽  
Developmental Stages ◽  
Reproductive Organs ◽  
The Novel ◽  
Biofuel Feedstock ◽  
Gametophyte Development ◽  
Female Gametophyte Development

Background Sugarcane (Saccharum spontaneum L.), the major sugar and biofuel feedstock crop, is cultivated mainly by vegetative propagation worldwide due to the infertility of female reproductive organs resulting in the reduction of quality and output of sugar. Deciphering the gene expression profile during ovule development will improve our understanding of the complications underlying sexual reproduction in sugarcane. Optimal reference genes are essential for elucidating the expression pattern of a given gene by quantitative real-time PCR (qRT-PCR). Method In this study, based on transcriptome data obtained from sugarcane ovule, eighteen candidate reference genes were identified, cloned, and their expression levels were evaluated across five developmental stages ovule (AC, MMC, Meiosis, Mitosis, and Mature). Results Our results indicated that FAB2 and MOR1 were the most stably expressed genes during sugarcane female gametophyte development. Moreover, two genes, cell cycle-related genes REC8 and CDK, were selected, and their feasibility was validated. This study provides important insights into the female gametophyte development of sugarcane and reports novel reference genes for gene expression research on sugarcane sexual reproduction.

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