Arabidopsis adaptor protein 1G2 is required for female and male gametogenesis

Abstract Background: The gametophyte s are essential for the productive process in angiosperms. During sexual reproduction in flowering plants, haploid spores are formed from meioses of spore mother cells. The spores then undergo mitosis and develop into female and male gametes and give rise to seeds after fertilization. Results: We identified a female sterile mutant from EMS mutagenesis, and a BC1F2 population was generated for map based cloning of the causal gene. Genome re-sequencing of mutant and non-mutant pools revealed a candidate gene, AP1G2 . Analyses of two insertions mutants, ap1g2-1 +/- in exon 7 and ap1g2-3 -/- in 3’ UTR, revealed partial female sterility. Complementation test using native promoter of AP1G2 restored the function in ap1g2-1 +/- and ap1g2-3 -/- . AP1G2 is a paralog of AP1G1 , encoding the large subunit (γ) of adaptor protein-1 (AP-1). ap1g2 mutation led to defective female and male gametophyte development was determined. In the ap1g2 mutants, the mitotic cycles and synchronic development of female gametophytes were impaired, which led to the arrest of female gametophytes at one nucleus stage FG1. Pollen development in ap1g2 was also arrested at one nucleus stage before PMI (pollen mitosis I). AP1G2 was expressed at high levels in different stages of ovule and pollens and actively dividing tissues, including shoot apical meristems, leaf primordial and root tips. Conclusions: AP1G2 was identified to have a role in the processes of female and male gametogenesis by regulating the first mitosis at one nucleus stage, and the expression pattern suggested AP1G2 is crucial for plant growth and development. Keywords: Arabidopsis, AP1G2 , megagametogenesis, microgametogenesis, development.

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Characterization of the nuclear export adaptor protein Nmd3 in association with the 60S ribosomal subunit

The Journal of Cell Biology ◽

10.1083/jcb.201001124 ◽

2010 ◽

Vol 189 (7) ◽

pp. 1079-1086 ◽

Cited By ~ 49

Author(s):

Jayati Sengupta ◽

Cyril Bussiere ◽

Jesper Pallesen ◽

Matthew West ◽

Arlen W. Johnson ◽

...

Keyword(s):

Binding Site ◽

Nuclear Export ◽

Large Subunit ◽

Ribosomal Subunit ◽

Adaptor Protein ◽

Structural Data ◽

Release Mechanism ◽

Nuclear Pore ◽

Subunit Joining

The nucleocytoplasmic shuttling protein Nmd3 is an adaptor for export of the 60S ribosomal subunit from the nucleus. Nmd3 binds to nascent 60S subunits in the nucleus and recruits the export receptor Crm1 to facilitate passage through the nuclear pore complex. In this study, we present a cryoelectron microscopy (cryo-EM) reconstruction of the 60S subunit in complex with Nmd3 from Saccharomyces cerevisiae. The density corresponding to Nmd3 is directly visible in the cryo-EM map and is attached to the regions around helices 38, 69, and 95 of the 25S ribosomal RNA (rRNA), the helix 95 region being adjacent to the protein Rpl10. We identify the intersubunit side of the large subunit as the binding site for Nmd3. rRNA protection experiments corroborate the structural data. Furthermore, Nmd3 binding to 60S subunits is blocked in 80S ribosomes, which is consistent with the assigned binding site on the subunit joining face. This cryo-EM map is a first step toward a molecular understanding of the functional role and release mechanism of Nmd3.

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Reproduction Multitasking: The Male Gametophyte

Annual Review of Plant Biology ◽

10.1146/annurev-arplant-080620-021907 ◽

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.

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Epigenetic Regulation of Plant Gametophyte Development

International Journal of Molecular Sciences ◽

10.3390/ijms20123051 ◽

2019 ◽

Vol 20 (12) ◽

pp. 3051 ◽

Cited By ~ 5

Author(s):

Vasily V. Ashapkin ◽

Lyudmila I. Kutueva ◽

Nadezhda I. Aleksandrushkina ◽

Boris F. Vanyushin

Keyword(s):

Mother Cell ◽

Female Gametophyte ◽

Male Gametophyte ◽

Endosperm Development ◽

Epigenetic Changes ◽

Gametophyte Development ◽

Daughter Cells ◽

Second Stage ◽

Somatic Tissues ◽

Mother Cells

Unlike in animals, the reproductive lineage cells in plants differentiate from within somatic tissues late in development to produce a specific haploid generation of the life cycle—male and female gametophytes. In flowering plants, the male gametophyte develops within the anthers and the female gametophyte—within the ovule. Both gametophytes consist of only a few cells. There are two major stages of gametophyte development—meiotic and post-meiotic. In the first stage, sporocyte mother cells differentiate within the anther (pollen mother cell) and the ovule (megaspore mother cell). These sporocyte mother cells undergo two meiotic divisions to produce four haploid daughter cells—male spores (microspores) and female spores (megaspores). In the second stage, the haploid spore cells undergo few asymmetric haploid mitotic divisions to produce the 3-cell male or 7-cell female gametophyte. Both stages of gametophyte development involve extensive epigenetic reprogramming, including siRNA dependent changes in DNA methylation and chromatin restructuring. This intricate mosaic of epigenetic changes determines, to a great extent, embryo and endosperm development in the future sporophyte generation.

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Mitotic and meiotic irregularities in somatic hybrids of Lycopersicon esculentum and Solanum tuberosum

Genome ◽

10.1139/g94-103 ◽

1994 ◽

Vol 37 (5) ◽

pp. 726-735 ◽

Cited By ~ 30

Author(s):

A. M. A. Wolters ◽

H. C. H. Schoenmakers ◽

S. Kamstra ◽

J. van Eden ◽

M. Koornneef ◽

...

Keyword(s):

In Situ Hybridization ◽

High Frequency ◽

Somatic Hybrids ◽

Unreduced Gametes ◽

Root Tip ◽

Root Tips ◽

Tetrad Stage ◽

Chromosome Arm ◽

Mother Cells

Chromosome numbers were determined in metaphase complements of root-tip meristems of 107 tomato (+) potato somatic hybrids, obtained from five different combinations of parental genotypes. Of these hybrids 79% were aneuploid, lacking one or two chromosomes in most cases. All four hybrids that were studied at mitotic anaphase of root tips showed laggards and bridges, the three aneuploids in a higher frequency than the single euploid. Hybrid K2H2-1C, which showed the highest percentage of aberrant anaphases, possessed 46 chromosomes. Fluorescence in situ hybridization with total genomic DNA showed that this hybrid contained 23 tomato, 22 potato, and 1 recombinant chromosome consisting of a tomato chromosome arm and a potato chromosome arm. The potato parent of K2H2-1C was aneusomatic in its root tips with a high frequency of monosomic and trisomic cells and a relatively high frequency of cells with one fragment or telosome. Meiotic analyses of three tomato (+) potato somatic hybrids revealed laggards, which occurred most frequently in the triploid hybrids, and bridges, which were frequently present in pollen mother cells (PMCs) at anaphase I of hypotetraploid K2H2-1C. We observed putative trivalents in PMCs at diakinesis and metaphase I of eutriploid A7-82A and quadrivalents in part of the PMCs of hypotetraploid K2H2-1C, suggesting that homoeologous recombination between tomato and potato chromosomes occurred in these hybrids. All three hybrids showed a high percentage of first division restitution, giving rise to unreduced gametes. However, shortly after the tetrad stage all microspores completely degenerated, resulting in exclusively sterile pollen.Key words: tomato, potato, symmetric somatic hybrids, chromosomal irregularities, genomic in situ hybridization.

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NEMATODE (HETERODERA SCHACHTII) RESISTANCE AND MEIOSIS IN DIPLOID PLANTS FROM INTERSPECIFIC BETA VULGARIS × B. PROCUMBENS HYBRIDS

Canadian Journal of Genetics and Cytology ◽

10.1139/g78-019 ◽

1978 ◽

Vol 20 (2) ◽

pp. 177-186 ◽

Cited By ~ 31

Author(s):

Helen Savitsky

Keyword(s):

Beta Vulgaris ◽

Transmission Rate ◽

Nematode Resistance ◽

Heterodera Schachtii ◽

Next Generation ◽

Pollen Mother Cells ◽

Transmission Rates ◽

Male Gametes ◽

Mother Cells ◽

Lower Frequencies

Three diploid nematode-resistant plants derived from hybrids between Beta vulgaris L. and B. procumbens Chr. Sm. were crossed with diploid nematode-susceptible plants. The rates of resistance transmission from the F1 hybrids to the F2 varied from 7 to 27%. The transmission rate of F2 plants derived from F1 plants with transmission rates over 20% averaged 20.9%. The rate for F2 plants derived from F1 plants with transmission rates of 10% or lower averaged 11.3%. In diploid plants nematode resistance was transmitted through the pollen at lower frequencies than through egg cells. Transmission through female gametes varied from 11.0 to 31.4% and through male gametes of the same plants from 0 to 19.7%. In some pollen mother cells (PMCs) of diploid nematode-resistant plants meiosis was normal and gametes derived from these cells transmitted resistance to the next generation. Abnormalities were observed in other PMCs, including the detachment of the B. procumbens segment from the translocated chromosome, the formation of bridges, and the lagging of broken translocated chromosomes. The inadequate transmission of resistance was caused by a loss of the B. procumbens segment in some B. vulgaris bivalents.

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La morphogenèse florale chez le pétunia. III. Déviations dans le programme organogène chez un mutant femelle stérile

Canadian Journal of Botany ◽

10.1139/b91-112 ◽

1991 ◽

Vol 69 (4) ◽

pp. 866-872 ◽

Cited By ~ 1

Author(s):

Marie-France Turlier ◽

Josiane Alabouvette ◽

Diane Doulain-Douvier

Keyword(s):

Key Words ◽

Petunia Hybrida ◽

Male Gametophyte ◽

Female Sterility ◽

Pollen Sacs

A monogenic mutant of Petunia hybrida R-n57 exhibits flowers with abnormal gynoecium: various malformations, such as the opening of the style and the nonprotection of ovules, or the masculinization with development of pollen sacs, anthers, and male gametophyte growing with or within ovules. The same type of abnormalities happens over and over along one inflorescential axis so that an ontogenic analysis can be conducted. Some assumptions are supported by the histocytological study: a few punctual modifications of the normal organogenesis program, recently established, and one new stage ending at the masculine or abnormal gynoecium, with homeotic members, are involved. Relations between the deflected development and female sterility are argued. Key words: flower, teratology, morphogenesis, mutant, Petunia.

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Plasmodium falciparum Calcium-Dependent Protein Kinase 4 is Critical for Male Gametogenesis and Transmission to the Mosquito Vector

mBio ◽

10.1128/mbio.02575-21 ◽

2021 ◽

Author(s):

Sudhir Kumar ◽

Meseret T. Haile ◽

Michael R. Hoopmann ◽

Linh T. Tran ◽

Samantha A. Michaels ◽

...

Keyword(s):

Male Gamete ◽

Mosquito Vector ◽

Parasite Life Cycle ◽

Dependent Protein Kinase ◽

Calcium Dependent ◽

Male Gametogenesis ◽

Phosphorylation Of Proteins ◽

Male Gametes ◽

Dependent Protein ◽

Calcium Dependent Protein Kinase

Transmission of the malaria parasite to the mosquito vector is critical for the completion of the sexual stage of the parasite life cycle and is dependent on the release of male gametes from the gametocyte body inside the mosquito midgut. In the present study, we demonstrate that PfCDPK4 is critical for male gametogenesis and is involved in phosphorylation of proteins essential for male gamete emergence.

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The Study of Pollen Development in Nine Cultivars of Hazelnut (Corylusavellana)

HortScience ◽

10.21273/hortsci.40.4.1117a ◽

2005 ◽

Vol 40 (4) ◽

pp. 1117A-1117

Author(s):

Chantalak Tiyayon ◽

Anita Nina Azarenko

Keyword(s):

Pollen Development ◽

Developmental Stages ◽

Male Gametophyte ◽

Male Flower ◽

Pollen Grains ◽

Corylus Avellana ◽

Tissue Sections ◽

Development And Differentiation ◽

Mother Cells ◽

Pollen Shed

Pollen development is an important event in plant reproduction. Hazelnut (Corylus avellana) male flower differentiation starts in summer and pollen shed is in the winter. Hazelnut pollen shed can vary up to 3 months between early to late flowering genotypes. Microsporogenesis and microgametogenesis of hazelnut is not well understood. Pollen development and differentiation of nine genotypes, representing early to late blooming cultivars from the National Clonal Germplasm Repository in Corvallis, Ore., were studied. Catkins were collected weekly from Aug. to Nov. 2002. Tissue sections were examined under the light microscope. Microsporogenesis was divided into five stages: archesporial cells, sporogenous cells and parietal layers, pollen mother cells (PMC), tetrads, and microspores. Microgametogenesis was distinguished between young pollen grains (uninucleate) and mature pollen grains (binucleate). On 4 Aug., cultivars were at different developmental stages of microsporogenesis. Early blooming cultivars had PMCs present. Later-blooming cultivars only contained archesporial cells. PMCs were present in all cultivars by 22 Aug. Microspores were observed on 26 Sept. in all cultivars. This study contributes to a better understanding of male gametophyte development in hazelnut, which has increased our ability to correlate hazelnut pollen development with bloom phenology.

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Cytological Analysis of a Clethra alnifolia `Hokie Pink' × C. pringlei Hybrid

HortScience ◽

10.21273/hortsci.40.2.339 ◽

2005 ◽

Vol 40 (2) ◽

pp. 339-342

Author(s):

Sandra M. Reed

Keyword(s):

Chromosome Number ◽

Cold Hardiness ◽

Male Gamete ◽

Cytological Analysis ◽

Root Tips ◽

Chromosome Counts ◽

Pollen Mother Cells ◽

Size And Shape ◽

Mother Cells ◽

Deciduous Shrub

Clethra alnifolia L., a native deciduous shrub cultivated as an ornamental, was recently hybridized with C. pringlei S. Wats. The purpose of this hybridization was to combine the cold hardiness and adaptability of C. alnifolia with the ornamental foliage of C. pringlei. While most of the C. alnifolia × C. pringlei hybrids more closely resembled C. alnifolia than the paternal species, a `Hokie Pink' × C. pringlei hybrid (NA71586) with foliage that flushes red like C. pringlei was recovered. The objectives of this study were to analyze cytologically the F1 and produce a F2 population from NA71586. Chromosome counts from root tips cells indicated that NA71586 has 32 chromosomes. Since the chromosome number of C. alnifolia is 2n = 32 and that of C. pringlei was found to be 2n = 16, NA71586 appears to have developed following fertilization of a C. alnifolia egg with an unreduced male gamete from C. pringlei. Both `Hokie Pink' and C. pringlei exhibited primarily bivalent pairing in pollen mother cells (PMCs). Over half of the PMCs from NA71586 contained 16 bivalents, indicating substantial homology within the C. alnifolia genome. It was theorized that C. alnifolia is either an autotetraploid that exhibits bivalent pairing or a segmental allotetraploid produced from hybridization of species with similar genomes. More than 700 F2 progeny were obtained from self-pollination of NA71586. Although many of the F2 progeny resembled NA71586, variation in foliage color, size and shape was apparent in the population.

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Life after meiosis: patterning the angiosperm male gametophyte

Biochemical Society Transactions ◽

10.1042/bst0380577 ◽

2010 ◽

Vol 38 (2) ◽

pp. 577-582 ◽

Cited By ~ 22

Author(s):

Michael Borg ◽

David Twell

Keyword(s):

Cell Cycle ◽

Cell Fate ◽

Cell Cycle Progression ◽

Male Gametophyte ◽

Cell Fate Determination ◽

Double Fertilization ◽

Cycle Progression ◽

Fate Determination ◽

Male Gametogenesis ◽

The Impact

Pollen grains represent the highly reduced haploid male gametophyte generation in angiosperms. They play an essential role in plant fertility by generating and delivering twin sperm cells to the embryo sac to undergo double fertilization. The functional specialization of the male gametophyte and double fertilization are considered to be key innovations in the evolutionary success of angiosperms. The haploid nature of the male gametophyte and its highly tractable ontogeny makes it an attractive system to study many fundamental biological processes, such as cell fate determination, cell-cycle progression and gene regulation. The present mini-review encompasses key advances in our understanding of the molecular mechanisms controlling male gametophyte patterning in angiosperms. A brief overview of male gametophyte development is presented, followed by a discussion of the genes required at landmark events of male gametogenesis. The value of the male gametophyte as an experimental system to study the interplay between cell fate determination and cell-cycle progression is also discussed and exemplified with an emerging model outlining the regulatory networks that distinguish the fate of the male germline from its sister vegetative cell. We conclude with a perspective of the impact emerging data will have on future research strategies and how they will develop further our understanding of male gametogenesis and plant development.

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