scholarly journals Reproductive studies in ipecac (Psychotria ipecacuanha (Brot.) stockes; Rubiaceae): pollen development and morphology

2008 ◽  
Vol 51 (5) ◽  
pp. 981-989 ◽  
Author(s):  
Margarete Magalhães Souza ◽  
Ernane Ronie Martins ◽  
Telma Nair Santana Pereira ◽  
Luiz Orlando de Oliveira
Keyword(s):  
Vegetative Propagation ◽  
Pollen Development ◽  
Pollen Morphology ◽  
Middle Layer ◽  
Anther Development ◽  
Sexual Process ◽  
Microspore Stage ◽  
Pollen Polymorphism ◽  
Outer Epidermis

The aim of this work was to carry out the reproductive studies on Brazilian accessions of ipecac, Psychotria ipecacuanha. It presented heterostyly, with brevistylous and longistylous flowers. The pollen development was observed from the sections of the anthers embedded in resin. Anther development was normal as usually observed in dicotyledones, displaying four layers: outer epidermis, endothecium, middle layer and inner tapetum. The pollen was bicellular and filled with starch at the microspore stage. Pollen morphology was studied using SEM, which showed pollen polymorphism within and between the two floral morphs. Five types of pollen with reticulate or perforate exine were identified. The characteristics showed that the sexual process was as important as the vegetative propagation for the reproduction of this species.

scholarly journals A Cytological Study of Anther and Pollen Development in Chinquapin (Castanea henryi)

HortScience ◽  
2020 ◽  
Vol 55 (6) ◽  
pp. 945-950
Author(s):  
Weiping Zhong ◽  
Zhoujun Zhu ◽  
Fen Ouyang ◽  
Qi Qiu ◽  
Xiaoming Fan ◽  
...  
Keyword(s):  
Pollen Development ◽  
Lipid Droplets ◽  
Morphological Characteristics ◽  
Pollen Grains ◽  
Middle Layer ◽  
Anther Development ◽  
Mature Pollen ◽  
Anther Wall ◽  
Male Flowers ◽  
Microspore Stage

The normal development of anthers and the formation of functional pollen are the prerequisites for successful pollination and fertilization. In this study, we observed dynamic changes in inflorescence and anther development in the chinquapin (Castanea henryi) using stereomicroscopy, light microscopy, and transmission electron microscopy. We found that cytokinesis during meiosis in microsporocytes was of the simultaneous type, and that the tetrads were mainly tetrahedral. Mature pollen grains contained two cells with three germ pores. The anther wall was of the basic type and composed of epidermis, endothecium, middle layers, and tapetum. Mature anthers had no middle layer and tapetum. The tapetum was of the glandular type. At the early microspore stage, a large number of starch granules appeared in the endothecium, which was deformed at the late microspore stage. Lipid droplets appeared in tapetum during the early microspore stage, and a few lipid droplets were still found during tapetum degeneration. The mature pollen accumulated a large amount of starch and lipids. These findings demonstrated that the anther wall provides nutrients and protection for pollen development. There is relatively stable correspondence between the external morphological characteristics of male flowers and internal structure of anther development.

Comparison of anther development in genic male-sterile (ms10) and in male-fertile corn (Zea mays) from light microscopy and scanning electron microscopy

1979 ◽  
Vol 57 (6) ◽  
pp. 578-596 ◽  
Author(s):  
P. C. Cheng ◽  
R. I. Greyson ◽  
D. B. Walden
Keyword(s):  
Light Microscopy ◽  
Middle Layer ◽  
Anther Development ◽  
Developmental Differences ◽  
Starch Accumulation ◽  
Male Sterile ◽  
Tapetal Cells ◽  
Anther Ontogeny ◽  
Microspore Stage ◽  
Pollen Stage

Anther ontogeny of a genic male-sterile mutant (ms 10/ms 10) and a related fertile cultivar of Zea was studied from the primordial stage through to tassel maturity. From material glutaraldehyde–formalin fixed, OsO4 postfixed, and plastic embedded, light microscopy of 0.7-μm sections revealed no developmental differences between the two until the young microspore stage. Vacuolation or cytoplasmic disintegration of tapetal cells was detected in male-sterile anthers at this stage. Disintegration of microspores was not detected until the intermediate microspore stage. By the young pollen stage, tapetal cells were highly disorganized and degeneration of the middle layer and endothecium was apparent. No endothecial wall thickenings developed in male-sterile anthers.In normal anther development in Zea, endothecial thickenings are found only at the anterior and posterior ends of the anther. A highly ridged anther cuticle, which is essentially absent in male-sterile anthers, is a common feature of fertile flowers. Anther dehiscence involves a separation of the epidermis from the underlying parenchyma of the connective to form a large pollen cavity from the two microsporangial locules. This process does not involve endothecial fibrous wall thickenings as they are not present over the bulk of the anther. Formation of the anterior pore is a separate process which involves changes in the endothecium wall thickenings.During normal anther development starch accumulates in the endothecium and epidermis at the precallose stage and disappears during the young microspore stage. No differences were noted in the male-sterile anthers. During the formation of normal pollen, considerable starch accumulation is evident. However, none is deposited at this late stage in the male-sterile anther.

scholarly journals OsMYB80 Regulates Anther Development and Pollen Fertility by Targeting Multiple Biological Pathways

2020 ◽  
Vol 61 (5) ◽  
pp. 988-1004 ◽  
Author(s):  
Xiaoying Pan ◽  
Wei Yan ◽  
Zhenyi Chang ◽  
Yingchao Xu ◽  
Ming Luo ◽  
...  
Keyword(s):  
Pollen Development ◽  
Male Fertility ◽  
Gene Networks ◽  
Affinity Purification ◽  
Anther Development ◽  
Rna Seq ◽  
Male Sterile ◽  
New Information ◽  
Gel Shift Assay

Abstract Pollen development is critical to the reproductive success of flowering plants, but how it is regulated is not well understood. Here, we isolated two allelic male-sterile mutants of OsMYB80 and investigated how OsMYB80 regulates male fertility in rice. OsMYB80 was barely expressed in tissues other than anthers, where it initiated the expression during meiosis, reached the peak at the tetrad-releasing stage and then quickly declined afterward. The osmyb80 mutants exhibited premature tapetum cell death, lack of Ubisch bodies, no exine and microspore degeneration. To understand how OsMYB80 regulates anther development, RNA-seq analysis was conducted to identify genes differentially regulated by OsMYB80 in rice anthers. In addition, DNA affinity purification sequencing (DAP-seq) analysis was performed to identify DNA fragments interacting with OsMYB80 in vitro. Overlap of the genes identified by RNA-seq and DAP-seq revealed 188 genes that were differentially regulated by OsMYB80 and also carried an OsMYB80-interacting DNA element in the promoter. Ten of these promoter elements were randomly selected for gel shift assay and yeast one-hybrid assay, and all showed OsMYB80 binding. The 10 promoters also showed OsMYB80-dependent induction when co-expressed in rice protoplast. Functional annotation of the 188 genes suggested that OsMYB80 regulates male fertility by directly targeting multiple biological processes. The identification of these genes significantly enriched the gene networks governing anther development and provided much new information for the understanding of pollen development and male fertility.

scholarly journals Dynamics of Polysaccharides and Neutral Lipids during Anther Development in Castor (Ricinus communis)

2015 ◽  
Vol 140 (4) ◽  
pp. 356-361 ◽  
Author(s):  
Dongmei Wei ◽  
Huimin Xu ◽  
Ruili Li
Keyword(s):  
Neutral Lipids ◽  
Ricinus Communis ◽  
Starch Content ◽  
Single Layer ◽  
Pollen Grains ◽  
Middle Layer ◽  
Anther Development ◽  
Anther Wall ◽  
Starch Grains ◽  
Tapetal Cells

Anthers contain starch and neutral lipids, which have key roles in microspore ontogeny and gametophyte development. In this study, we observed the dynamic changes in starch and neutral lipids in the anther developmental processes of castor (Ricinus communis) by cytochemical methods. Starch grains and neutral lipids presented a regular dynamic distribution during anther development. In young anthers, some neutral lipids accumulated in sporogenous cells, whereas neutral lipids disappeared with microspore growth. At the late microspore stage, starch grains began to accumulate in microspores, and the starch content of bicellular pollen significantly increased after microspore mitosis. At anthesis, starch grains and neutral lipids accumulated in the mature pollen grains. Visible changes occurred in anther wall cells. The epidermis, middle layer, and tapetum were degenerated, and only a single layer of endothecium remained at anthesis. The dynamic variation of starch grains and neutral lipids in tapetal cells was consistent with the changes in microspores and pollen during anther development. All these findings demonstrated that tapetal cells directly interacted with the developing gametophytes. The tapetal cells play an important role in supplying nutritional substances for microspore absorption. Moreover, the endothecium protects the pollen and contributes to anther dehiscence. The results of this study provide a foundation for the further research on sexual reproduction in angiosperms.

scholarly journals The Major Factors Causing the Microspore Abortion of Genic Male Sterile Mutant NWMS1 in Wheat (Triticum aestivum L.)

2019 ◽  
Vol 20 (24) ◽  
pp. 6252 ◽  
Author(s):  
Junchang Li ◽  
Jing Zhang ◽  
Huijuan Li ◽  
Hao Niu ◽  
Qiaoqiao Xu ◽  
...  
Keyword(s):  
Triticum Aestivum ◽  
Male Sterility ◽  
Genetic Research ◽  
Triticum Aestivum L ◽  
Anther Development ◽  
Sucrose Metabolism ◽  
Male Sterile ◽  
Pollen Abortion ◽  
Microspore Stage ◽  
Regulation Model

Male sterility is a valuable trait for genetic research and production application of wheat (Triticum aestivum L.). NWMS1, a novel typical genic male sterility mutant, was obtained from Shengnong 1, mutagenized with ethyl methane sulfonate (EMS). Microstructure and ultrastructure observations of the anthers and microspores indicated that the pollen abortion of NWMS1 started at the early uninucleate microspore stage. Pollen grain collapse, plasmolysis, and absent starch grains were the three typical characteristics of the abnormal microspores. The anther transcriptomes of NWMS1 and its wild type Shengnong 1 were compared at the early anther development stage, pollen mother cell meiotic stage, and binucleate microspore stage. Several biological pathways clearly involved in abnormal anther development were identified, including protein processing in endoplasmic reticulum, starch and sucrose metabolism, lipid metabolism, and plant hormone signal transduction. There were 20 key genes involved in the abnormal anther development, screened out by weighted gene co-expression network analysis (WGCNA), including SKP1B, BIP5, KCS11, ADH3, BGLU6, and TIFY10B. The results indicated that the defect in starch and sucrose metabolism was the most important factor causing male sterility in NWMS1. Based on the experimental data, a primary molecular regulation model of abnormal anther and pollen developments in mutant NWMS1 was established. These results laid a solid foundation for further research on the molecular mechanism of wheat male sterility.

scholarly journals βVPE is involved in tapetal degradation and pollen development by activating proprotease maturation in Arabidopsis thaliana

2019 ◽  
Vol 71 (6) ◽  
pp. 1943-1955 ◽  
Author(s):  
Ziyi Cheng ◽  
Xiaorui Guo ◽  
Jiaxue Zhang ◽  
Yadi Liu ◽  
Bing Wang ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Pollen Development ◽  
Tapetal Cell ◽  
Cysteine Proteases ◽  
Anther Development ◽  
Mature Protein ◽  
Processing Enzyme ◽  
Mature Enzyme ◽  
Mature Protease

Abstract Vacuolar processing enzyme (VPE) is responsible for the maturation and activation of vacuolar proteins in plants. We found that βVPE was involved in tapetal degradation and pollen development by transforming proproteases into mature protease in Arabidopsis thaliana. βVPE was expressed specifically in the tapetum from stages 5 to 8 of anther development. The βVPE protein first appeared as a proenzyme and was transformed into the mature enzyme before stages 7–8. The recombinant βVPE protein self-cleaved and transformed into a 27 kDa mature protein at pH 5.2. The mature βVPE protein could induce the maturation of CEP1 in vitro. βvpe mutants exhibited delayed vacuolar degradation and decreased pollen fertility. The maturation of CEP1, RD19A, and RD19C was seriously inhibited in βvpe mutants. Our results indicate that βVPE is a crucial processing enzyme that directly participates in the maturation of cysteine proteases before vacuolar degradation, and is indirectly involved in pollen development and tapetal cell degradation.

An ultrastructural study of pollen development in tomato (Lycopersicon esculentum). I. Tetrad to early binucleate microspore stage

1993 ◽  
Vol 71 (8) ◽  
pp. 1039-1047 ◽  
Author(s):  
P. L. Polowick ◽  
V. K. Sawhney
Keyword(s):  
Endoplasmic Reticulum ◽  
Lycopersicon Esculentum ◽  
Ultrastructural Study ◽  
Pollen Development ◽  
Pollen Wall ◽  
Ultrastructural Changes ◽  
Dense Matrix ◽  
Tetrad Stage ◽  
Microspore Stage ◽  
Electron Dense Matrix

Microspores undergo considerable ultrastructural changes between the tetrad and early binucleate microspore stages of microsporogenesis in tomato (Lycopersicon esculentum). Pollen wall deposition began late in the tetrad stage, and by the early microspore stage a lamellar foot layer and tectum were deposited. Sculpturing of the tectum was evident by the early binucleate microspore stage. Dictyosomes and vesicles were abundant during the period of pollen wall formation. Plastids were associated with the endoplasmic reticulum (ER) to form plastid–ER complexes, from the late tetrad to the vacuolate microspore stage. At the vacuolate microspore stage, endoplasmic reticulum independent of plastids was also observed, and at the early binucleate microspore stage ER was not associated with plastids. Free ribosomes were evenly distributed throughout the cytoplasm until the vacuolate microspore stage when they were organized into polysomes. Mitochondria were spherical to ellipsoid, with an electron-dense matrix and swollen cristae, until the early binucleate microspore stage when they were highly elongate and became convoluted. Key words: Lycopersicon esculentum, microsporogenesis, pollen development, tetrads, tomato, ultrastructure.

Aspterric Acid and 6-Hydroxymellein, Inhibitors of Pollen Development in Arabidopsis thaliana, Produced by Aspergillus terreus

2002 ◽  
Vol 57 (5-6) ◽  
pp. 459-464 ◽  
Author(s):  
Atsumi Shimada ◽  
Miyako Kusano ◽  
Sumiyo Takeuchi ◽  
Shozo Fujioka ◽  
Tomohisa Inokuchi ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Microscopic Examination ◽  
Pollen Development ◽  
Aspergillus Terreus ◽  
Higher Plants ◽  
Molecular Investigation ◽  
Microspore Stage ◽  
Stage 1

Aspterric acid (1) and 6-hydroxymellein (2), inhibitors of pollen development in Arabidopsis thaliana, have been isolated fromthe fungus Aspergillus terreus. 1 and 2 inhibited the pollen development at concentrations of 38 and 52 μᴍ, respectively. The microscopic examination of pollen development suggested that the inhibition by the treatment with 1 caused at meiosis and the inhibition by the treatment with 2 caused at microspore stage. 1 and 2 could be useful agents for the molecular investigation of anther and pollen development in higher plants.

scholarly journals Functional role of Polymerase IV during pollen development in Capsella

2019 ◽  
Author(s):  
Zhenxing Wang ◽  
Nicolas Butel ◽  
Juan Santos-González ◽  
Filipe Borges ◽  
Jun Yi ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Pollen Development ◽  
Functional Role ◽  
Small Interfering Rnas ◽  
Guide Rna ◽  
Pol Iv ◽  
Capsella Rubella ◽  
Rna Polymerase Iv ◽  
Microspore Stage

AbstractIn Arabidopsis thaliana, the DNA-dependent RNA polymerase IV (Pol IV) is required for the formation of transposable element (TE)-derived small RNA (sRNA) transcripts. These transcripts are processed by DICER-LIKE 3 into 24-nt small interfering RNAs (siRNAs) that guide RNA-dependent DNA methylation. In the pollen grain, Pol IV is also required for the accumulation of 21/22-nt epigenetically-activated siRNAs (easiRNAs) that likely silence TEs by post-transcriptional mechanisms. Despite this proposed functional role, loss of Pol IV function in Arabidopsis does not cause a discernable pollen defect. Here, we show that loss of NRPD1, encoding the largest subunit of Pol IV in the Brassicaceae Capsella rubella, causes post-meiotic arrest of pollen development at the microspore stage. As in Arabidopsis, all TE-derived siRNAs were depleted in Capsella nrpd1 microspores. In wild-type background, we found that the same TEs produced 21/22-nt and 24-nt siRNAs, leading us to propose that Pol IV is generating the direct precursors for 21-24-nt siRNAs, which are targeted by different DICERs. Arrest of Capsella nrpd1 microspores was accompanied by deregulation of genes targeted by Pol IV-dependent siRNAs. The distance of TEs to genes was much closer in Capsella rubella compared to Arabidopsis thaliana, providing a possible explanation for the essential role of Pol IV for pollen development in Capsella. Our study in Capsella uncovers a functional requirement of Pol IV in microspores, emphasizing the relevance of investigating different plant models.One-sentence summaryLoss of Polymerase IV function in Capsella rubella causes microspore arrest, revealing an important functional role of Polymerase IV during pollen development.The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantcell.org) is: Claudia Kohler ([email protected])

scholarly journals PRX9 and PRX40 are extensin peroxidases essential for maintaining tapetum and microspore cell wall integrity during Arabidopsis anther development

2018 ◽  
Author(s):  
Joseph R. Jacobowitz ◽  
Jing-Ke Weng
Keyword(s):  
Cell Wall ◽  
Pollen Development ◽  
Tapetal Cell ◽  
Pollen Grains ◽  
Anther Development ◽  
Cell Wall Integrity ◽  
Class Iii ◽  
Male Sterile ◽  
Male Gametes ◽  
Encoding Genes

AbstractPollen and microspore development is an essential step in the life cycle of all land plants that generate male gametes. Within flowering plants, pollen development occurs inside of the anther. Here, we report the identification of two class III peroxidase-encoding genes, PRX9 and PRX40, that are genetically redundant and essential for proper anther and pollen development in Arabidopsis thaliana. Arabidopsis double mutants devoid of functional PRX9 and PRX40 are male-sterile. The mutant anthers display swollen, hypertrophic tapetal cells and pollen grains, suggesting disrupted cell wall integrity. These phenotypes ultimately lead to nearly 100%-penetrant pollen degeneration upon anther maturation. Using immunochemical and biochemical approaches, we show that PRX9 and PRX40 are likely extensin peroxidases that contribute to the establishment of tapetal cell wall integrity during anther development. This work identifies PRX9 and PRX40 as the first extensin peroxidases to be described in Arabidopsis and highlights the importance of extensin cross-linking during plant development.

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