Cytologie et histologie de la reproduction chez le Nymphaea heudelotii

1992 ◽  
Vol 70 (10) ◽  
pp. 1991-1996 ◽  
Author(s):  
Françoise Van Miegroet ◽  
Michel Dujardin
Keyword(s):  
Key Words ◽  
Embryo Sac ◽  
Polar Nucleus ◽  
Pollen Grain ◽  
Storage Function ◽  
Embryo Sac Development ◽  
Nucellar Tissue ◽  
Functional Megaspore

The ontogenesis of reproductive cells has been cytologically analysed in Nymphaea heudelotii Planch., family Nymphaea-ceae, subclass Magnoliidae. Our observations of embryo sac development on sections differ from those made by Cook in 1906. Embryo sacs derive from a single functional megaspore and are four nucleate. After fertilization, the polar nucleus divides and successively generates two storage tissues that are located in two separate chambers. Nucellar tissue, which is filling up with starch inclusions, then insures a storage function. This species possesses 14 bivalents at meiosis and 14 somatic chromosomes at the first mitosis of the pollen grain. A reorganization of amyliferous organelle aggregates has also been observed in microsporocytes. Key words: reproduction, embryogenesis, microsporogenesis, megasporogenesis, Nymphaea.

Detection of the time of occurrence of nondisjunction induced by the r-X1 deficiency in Zea mays L.

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 782-785 ◽  
Author(s):  
Kevin D. Simcox ◽  
Jeffery D. Shadley ◽  
David F. Weber
Keyword(s):  
Zea Mays ◽  
Key Words ◽  
Zea Mays L ◽  
Embryo Sac ◽  
Mitotic Division ◽  
Polar Nucleus ◽  
Chromosome 6 ◽  
High Frequencies ◽  
The Third ◽  
Β Carotene

The r-X1 deficiency in maize produces high frequencies of aneuploid progeny by inducing nondisjunction during embryo sac development. The purpose of this investigation was to determine the embryo sac division at which the nondisjunctive event takes place. Monosomic-6 individuals were generated by crossing r-X1 containing plants by those carrying the y-pastel-8549 allele of the Y locus on chromosome 6. A strict dosage relationship exists between the number of dominant alleles of the Y locus and the level of β-carotene in the endosperm. We found that the level of β-carotene in the endosperm of kernels containing monosomic-6 embryos was comparable with that found in endosperms with one Y allele. This indicated that they contained only one maternally contributed chromosome 6. Only nondisjunction at the second postmeiotic division could have produced such an endosperm; thus, the nondisjunctive event occurs at this division. Another endosperm type expected from nondisjunction at this same division, with three dominant Y alleles, was not found. The absence of this endosperm type suggests that the egg nucleus and the polar nucleus originating at the micropylar pole are sister nuclei that arose from the same cell at the third embryo sac mitotic division. Key words: aneuploidy, embryo sac, nondisjunction, r-X1 deficiency, Zea.

scholarly journals Gibberellin-mediated RGA-LIKE1 degradation regulates embryo sac development in Arabidopsis

2020 ◽  
Vol 71 (22) ◽  
pp. 7059-7072 ◽  
Author(s):  
Maria Dolores Gomez ◽  
Daniela Barro-Trastoy ◽  
Clara Fuster-Almunia ◽  
Pablo Tornero ◽  
Jose M Alonso ◽  
...  
Keyword(s):  
Female Gametophyte ◽  
Central Area ◽  
Embryo Sac ◽  
Ovule Development ◽  
Embryo Sac Development ◽  
Della Proteins ◽  
Developmental Programme ◽  
Embryo Sac Formation ◽  
Functional Megaspore

Abstract Ovule development is essential for plant survival, as it allows correct embryo and seed development upon fertilization. The female gametophyte is formed in the central area of the nucellus during ovule development, in a complex developmental programme that involves key regulatory genes and the plant hormones auxins and brassinosteroids. Here we provide novel evidence of the role of gibberellins (GAs) in the control of megagametogenesis and embryo sac development, via the GA-dependent degradation of RGA-LIKE1 (RGL1) in the ovule primordia. YPet-rgl1Δ17 plants, which express a dominant version of RGL1, showed reduced fertility, mainly due to altered embryo sac formation that varied from partial to total ablation. YPet-rgl1Δ17 ovules followed normal development of the megaspore mother cell, meiosis, and formation of the functional megaspore, but YPet-rgl1Δ17 plants had impaired mitotic divisions of the functional megaspore. This phenotype is RGL1-specific, as it is not observed in any other dominant mutants of the DELLA proteins. Expression analysis of YPet-rgl1Δ17 coupled to in situ localization of bioactive GAs in ovule primordia led us to propose a mechanism of GA-mediated RGL1 degradation that allows proper embryo sac development. Taken together, our data unravel a novel specific role of GAs in the control of female gametophyte development.

Ultrastructural Observation on Embryo Sac Development inPhaius tankervilliae(Aiton)Bl.

2012 ◽  
Vol 30 (2) ◽  
pp. 188 ◽  
Author(s):  
Dong-Mei LI ◽  
Cheng-Hou WU ◽  
Xiu-Lin YE ◽  
Cheng-Ye LIANG
Keyword(s):  
Embryo Sac ◽  
Ultrastructural Observation ◽  
Embryo Sac Development

Embryo sac development and endogenous gibberellins in pollinated and unpollinated ovaries of walnut (Juglans regia)

1994 ◽  
Vol 91 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Francisco R. Tadeo ◽  
Manuel Talon ◽  
Eric Germain ◽  
Francoise Dosba
Keyword(s):  
Juglans Regia ◽  
Embryo Sac ◽  
Embryo Sac Development

Reproduction Multitasking: The Male Gametophyte

2021 ◽  
Vol 72 (1) ◽  
Author(s):  
Said Hafidh ◽  
David Honys
Keyword(s):  
Male Gametophyte ◽  
Cell Communication ◽  
Embryo Sac ◽  
Pollen Grain ◽  
Wall Structure ◽  
Annual Review ◽  
Publication Date ◽  
Developmental Phase ◽  
Double Fertilization ◽  
Male Gametes

The gametophyte represents the sexual phase in the alternation of generations in plants; the other, nonsexual phase is the sporophyte. Here, we review the evolutionary origins of the male gametophyte among land plants and, in particular, its ontogenesis in flowering plants. The highly reduced male gametophyte of angiosperm plants is a two- or three-celled pollen grain. Its task is the production of two male gametes and their transport to the female gametophyte, the embryo sac, where double fertilization takes place. We describe two phases of pollen ontogenesis—a developmental phase leading to the differentiation of the male germline and the formation of a mature pollen grain and a functional phase representing the pollen tube growth, beginning with the landing of the pollen grain on the stigma and ending with double fertilization. We highlight recent advances in the complex regulatory mechanisms involved, including posttranscriptional regulation and transcript storage, intracellular metabolic signaling, pollen cell wall structure and synthesis, protein secretion, and phased cell–cell communication within the reproductive tissues. Expected final online publication date for the Annual Review of Plant Biology, Volume 72 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Embryo sac development in some representatives of the tribe Cynodonteae (Poaceae)

Bothalia ◽  
1994 ◽  
Vol 24 (1) ◽  
pp. 101-105 ◽  
Author(s):  
A. Strydom ◽  
J. J. Spies
Keyword(s):  
Cynodon Dactylon ◽  
Embryo Sac ◽  
Polygonum Type ◽  
Embryo Sac Development ◽  
Obligate Apomixis ◽  
Chloris Virgata

Chloris virgata Sw., Cynodon dactylon (L.) Pers., Harpochloa falx (L. f.) Kuntze, and Tragus berteronianus Schult. have a Polygonum type of embryo sac development. Unreduced embryo sacs were found in Eustachys paspaloides (Vahl) Lanza Mattei,  Harpochloa falx, and  Rendlia altera (Rendle) Chiov. Both facultative and obligate apomixis were observed. The Hieracium type of embryo sac development was observed in the aposporic specimens.

The embryo sac development of Manfreda elongata (Asparagaceae)

Flora ◽  
2019 ◽  
Vol 260 ◽  
pp. 151480
Author(s):  
Ángel Martín Barranco-Guzmán ◽  
Alejandra G. González-Gutiérrez ◽  
Benjamín Rodríguez-Garay
Keyword(s):  
Embryo Sac ◽  
Embryo Sac Development
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