scholarly journals Unequal plastid distribution during the development of the male gametophyte of angiosperms

2014 ◽  
Vol 50 (1-2) ◽  
pp. 321-327 ◽  
Author(s):  
R. Hagemann
Keyword(s):  
Pollen Development ◽  
Male Gametophyte ◽  
Pollen Mitosis ◽  
Plastid Inheritance ◽  
Simple Mechanism ◽  
Plastid Distribution ◽  
The Difference

The difference between the uniparental maternal and biparental type of plastid inheritance is based upon a relatively simple mechanism. In the uniparental type plastids are excluded from the generative or siperm cells during the firts pollen mitosis or during pollen development. In some angiosperms this exclusion is completely lacking or carried out partially.

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

HortScience ◽  
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.

Pollen development in orchids

1991 ◽  
Vol 99 (2) ◽  
pp. 273-281 ◽  
Author(s):  
R. C. BROWN ◽  
B. E. LEMMON
Keyword(s):  
Plasma Membrane ◽  
Nuclear Envelope ◽  
Pollen Development ◽  
Nuclear Migration ◽  
Pollen Mitosis ◽  
Polar Structure ◽  
Microtubular Cytoskeleton ◽  
Distal Surface

Cytoplasmic preparation for the unequal first mitosis in non-vacuolate pollen of moth orchids (Phalaenopsis) includes reorganization of the microtubular cytoskeleton and nuclear migration. Following meiotic cytokinesis, both microtubules and F-actin are unpolarized in microspores of persistent tetrads. Microtubules radiate from the centrally located nucleus and F-actin forms a reticulate pattern in the cytoplasm. Polarization of the microspores is marked by a dramatic reorganization of microtubules while the pattern of F-actin remains unchanged. We describe a novel system of microtubules at the generative pole (GPMS), which forms a polar structure structure at the distal surface and marks the path of nuclear migration prior to pollen mitosis. The GPMS consists of numerous microtubules that extend between the plasma membrane and nuclear envelope. The nucleus becomes displaced toward the generative pole and flattened in association with microtubules of the GPMS. Initiation of the GPMS is marked by a localized proliferation of ER and clearing of large organelles from the generative pole.

scholarly journals Five Gametophytic Mutations Affecting Pollen Development and Pollen Tube Growth in Arabidopsis thaliana

Genetics ◽  
2001 ◽  
Vol 158 (4) ◽  
pp. 1773-1783 ◽  
Author(s):  
Antonia Procissi ◽  
Solveig de Laissardière ◽  
Madina Férault ◽  
Daniel Vezon ◽  
Georges Pelletier ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Pollen Development ◽  
Male Gametophyte ◽  
Pollen Grains ◽  
Segregation Ratio ◽  
Variable Number ◽  
Tube Growth ◽  
Mutant Lines

Abstract Mutant analysis represents one of the most reliable approaches to identifying genes involved in plant development. The screening of the Versailles collection of Arabidopsis thaliana T-DNA insertion transformants has allowed us to isolate different mutations affecting male gametophytic functions and viability. Among several mutated lines, five have been extensively studied at the genetic, molecular, and cytological levels. For each mutant, several generations of selfing and outcrossing have been carried out, leading to the conclusion that all these mutations are tagged and affect only the male gametophyte. However, only one out of the five mutations is completely penetrant. A variable number of T-DNA copies has integrated in the mutant lines, although all segregate at one mutated locus. Two mutants could be defined as “early mutants”: the mutated genes are presumably expressed during pollen grain maturation and their alteration leads to the production of nonfunctional pollen grains. Two other mutants could be defined as “late mutant” since their pollen is able to germinate but pollen tube growth is highly disturbed. Screening for segregation ratio distortions followed by thorough genetic analysis proved to be a powerful tool for identifying gametophytic mutations of all phases of pollen development.

Runaway Dispersal in Social Species

2020 ◽  
pp. 68-99
Author(s):  
Daniel Oro
Keyword(s):  
Point Of View ◽  
Patch Quality ◽  
Social Species ◽  
Simple Mechanism ◽  
Social Animals ◽  
Dynamic Landscape ◽  
Neoclassical Economic Theory ◽  
The Difference ◽  
Decision To Stay ◽  
Landscape Information

Local populations are in most cases open and connected with other populations through dispersal. Dispersal, aside from its multiplicative nature, has a demographic additive effect for the spatiotemporal dynamics and extinction–colonization turnover of the donor and the receiver populations. Population dynamics are more sensitive to dispersal under perturbations, because dispersing is a resilience mechanism to avoid or reduce novel mortality risk. Furthermore, dispersing individuals carry information, a process that may create dynamic landscape information networks. In social species, the decision to stay or to disperse is made based on decisions made by others. When perturbations accumulate and jeopardize survival or fecundity, leading individuals may decide to disperse, and this decision is copied by others, generating a runaway dispersal to other patches. The decision trade-off between staying and dispersing depends on the dynamic spatiotemporal heterogeneity in patch quality. What matters for making a decision is not the difference in patch quality, but the ratio between the patch currently occupied and the rest of the patches. Decision-making in social animals for dispersing is explored under the frameworks of the prospect theory, the neoclassical economic theory, and the hypercycle theory. It is also shown how runaway dispersal may occur from a theoretical point of view due to a very simple mechanism of copying others in a density-dependent manner. This simple mechanism overruns a rational scenario when making decisions in social animals. This chapter ends by assessing the potential consequences of runaway dispersal for nonlinear responses in communities and entire ecosystems.

AtNOT1 Is a Novel Regulator of Gene Expression during Pollen Development

2019 ◽  
Vol 61 (4) ◽  
pp. 712-721 ◽  
Author(s):  
Kazuki Motomura ◽  
Toshihiro Arae ◽  
Haruka Araki-Uramoto ◽  
Yuya Suzuki ◽  
Hidenori Takeuchi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pollen Development ◽  
Male Gametophyte ◽  
Regulation Of Gene Expression ◽  
Specific Protein ◽  
Negative Regulation ◽  
Limited Information ◽  
Phenotypic Analysis ◽  
Pollen Stage ◽  
Mutant Pollen

Abstract Development of pollen, the male gametophyte of flowering plants, is tightly controlled by dynamic changes in gene expression. Recent research to clarify the molecular aspects of pollen development has revealed the involvement of several transcription factors in the induction of gene expression. However, limited information is available about the factors involved in the negative regulation of gene expression to eliminate unnecessary transcripts during pollen development. In this study, we revealed that AtNOT1 is an essential protein for proper pollen development and germination capacity. AtNOT1 is a scaffold protein of the AtCCR4–NOT complex, which includes multiple components related to mRNA turnover control in Arabidopsis. Phenotypic analysis using atnot1 heterozygote mutant pollen showed that the mature mutant pollen failed to germinate and also revealed abnormal localization of nuclei and a specific protein at the tricellular pollen stage. Furthermore, transcriptome analysis of atnot1 heterozygote mutant pollen showed that the downregulation of a large number of transcripts, along with the upregulation of specific transcripts required for pollen tube germination by AtNOT1 during late microgametogenesis, is important for proper pollen development and germination. Overall, our findings provide new insights into the negative regulation of gene expression during pollen development, by showing the severely defective phonotype of atnot1 heterozygote mutant pollen.

scholarly journals Elimination of Viroids from Tobacco Pollen Involves a Decrease in Propagation Rate and an Increase of the Degradation Processes

2020 ◽  
Vol 21 (8) ◽  
pp. 3029
Author(s):  
Jaroslav Matoušek ◽  
Lenka Steinbachová ◽  
Lenka Záveská Drábková ◽  
Tomáš Kocábek ◽  
David Potěšil ◽  
...  
Keyword(s):  
Pollen Development ◽  
Developmental Stages ◽  
Degradation Products ◽  
Male Gametophyte ◽  
Propagation Rate ◽  
Circular Rna ◽  
Apple Fruit ◽  
Mrna Accumulation ◽  
Tobacco Pollen ◽  
Replication Intermediates

Some viroids—single-stranded, non-coding, circular RNA parasites of plants—are not transmissible through pollen to seeds and to next generation. We analyzed the cause for the elimination of apple fruit crinkle viroid (AFCVd) and citrus bark cracking viroid (CBCVd) from male gametophyte cells of Nicotiana tabacum by RNA deep sequencing and molecular methods using infected and transformed tobacco pollen tissues at different developmental stages. AFCVd was not transferable from pollen to seeds in reciprocal pollinations, due to a complete viroid eradication during the last steps of pollen development and fertilization. In pollen, the viroid replication pathway proceeds with detectable replication intermediates, but is dramatically depressed in comparison to leaves. Specific and unspecific viroid degradation with some preference for (−) chains occurred in pollen, as detected by analysis of viroid-derived small RNAs, by quantification of viroid levels and by detection of viroid degradation products forming “comets” on Northern blots. The decrease of viroid levels during pollen development correlated with mRNA accumulation of several RNA-degrading factors, such as AGO5 nuclease, DICER-like and TUDOR S-like nuclease. In addition, the functional status of pollen, as a tissue with high ribosome content, could play a role during suppression of AFCVd replication involving transcription factors IIIA and ribosomal protein L5.

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