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Chen G, Hu H, Chen X, Chen J, Wang S, Ning H, Zhu C, Yang S. TFIIB-Related Protein BRP5/PTF2 Is Required for Both Male and Female Gametogenesis and for Grain Formation in Rice. Int J Mol Sci 2023; 24:16473. [PMID: 38003663 PMCID: PMC10671200 DOI: 10.3390/ijms242216473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
Transcription factor IIB (TFIIB) is a general transcription factor for RNA polymerase II, exerting its influence across various biological contexts. In the majority of eukaryotes, TFIIB typically has two homologs, serving as general transcription factors for RNA polymerase I and III. In plants, however, the TFIIB-related protein family has expanded greatly, with 14 and 9 members in Arabidopsis and rice, respectively. BRP5/pollen-expressed transcription factor 2 (PTF2) proteins belong to a subfamily of TFIIB-related proteins found only in plants and algae. The prior analysis of an Arabidopsis atbrp5 mutant, characterized by a T-DNA insertion at the 5' untranslated region, demonstrated the essential role of BRP5/PTF2 during the process of pollen germination and embryogenesis in Arabidopsis. Using a rice transformation system based on CRISPR/Cas9 technology, we have generated transgenic rice plants containing loss-of-function frameshift mutations in the BRP5/PTF2 gene. Unlike in the Arabidopsis atbrp5 mutant, the brp5/ptf2 frameshift mutations were not transmitted to progeny in rice, indicating an essential role of BRP5/PTF2 in both male and female gamete development or viability. The silencing of rice BRP5/PTF2 expression through RNA interference (RNAi) had little effect on vegetative growth and panicle formation but strongly affected pollen development and grain formation. Genetic analysis revealed that strong RNAi silencing of rice BRP5/PTF2 was still transmissible to progeny almost exclusively through female gametes, as found in the Arabidopsis atbrp5 knockdown mutant. Thus, reduced rice BRP5/PTF2 expression impacted pollen preferentially by interfering with male gamete development or viability. Drawing upon these findings, we posit that BRP5/PTF2 assumes a distinct and imperative function in the realm of plant sexual reproduction.
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Affiliation(s)
- Guangna Chen
- College of Life Sciences, China Jiliang University, 258 Xueyuan Street, Hangzhou 310018, China; (G.C.); (H.H.); (X.C.); (J.C.); (S.W.); (C.Z.)
| | - Hongliang Hu
- College of Life Sciences, China Jiliang University, 258 Xueyuan Street, Hangzhou 310018, China; (G.C.); (H.H.); (X.C.); (J.C.); (S.W.); (C.Z.)
| | - Xinhui Chen
- College of Life Sciences, China Jiliang University, 258 Xueyuan Street, Hangzhou 310018, China; (G.C.); (H.H.); (X.C.); (J.C.); (S.W.); (C.Z.)
| | - Jialuo Chen
- College of Life Sciences, China Jiliang University, 258 Xueyuan Street, Hangzhou 310018, China; (G.C.); (H.H.); (X.C.); (J.C.); (S.W.); (C.Z.)
| | - Siyi Wang
- College of Life Sciences, China Jiliang University, 258 Xueyuan Street, Hangzhou 310018, China; (G.C.); (H.H.); (X.C.); (J.C.); (S.W.); (C.Z.)
| | - He Ning
- College of Life Sciences, China Jiliang University, 258 Xueyuan Street, Hangzhou 310018, China; (G.C.); (H.H.); (X.C.); (J.C.); (S.W.); (C.Z.)
| | - Cheng Zhu
- College of Life Sciences, China Jiliang University, 258 Xueyuan Street, Hangzhou 310018, China; (G.C.); (H.H.); (X.C.); (J.C.); (S.W.); (C.Z.)
| | - Su Yang
- College of Life Sciences, China Jiliang University, 258 Xueyuan Street, Hangzhou 310018, China; (G.C.); (H.H.); (X.C.); (J.C.); (S.W.); (C.Z.)
- Institute of Crop Science and Zhejiang Key Laboratory of Crop Germplasm, Zhejiang University, Hangzhou 310058, China
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Lohani N, Golicz AA, Allu AD, Bhalla PL, Singh MB. Genome-wide analysis reveals the crucial role of lncRNAs in regulating the expression of genes controlling pollen development. PLANT CELL REPORTS 2023; 42:337-354. [PMID: 36653661 DOI: 10.1007/s00299-022-02960-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 11/25/2022] [Indexed: 06/17/2023]
Abstract
The genomic location and stage-specific expression pattern of many long non-coding RNAs reveal their critical role in regulating protein-coding genes crucial in pollen developmental progression and male germ line specification. Long non-coding RNAs (lncRNAs) are transcripts longer than 200 bp with no apparent protein-coding potential. Multiple investigations have revealed high expression of lncRNAs in plant reproductive organs in a cell and tissue-specific manner. However, their potential role as essential regulators of molecular processes involved in sexual reproduction remains largely unexplored. We have used developing field mustard (Brassica rapa) pollen as a model system for investigating the potential role of lncRNAs in reproductive development. Reference-based transcriptome assembly performed to update the existing genome annotation identified novel expressed protein-coding genes and long non-coding RNAs (lncRNAs), including 4347 long intergenic non-coding RNAs (lincRNAs, 1058 expressed) and 2,045 lncRNAs overlapping protein-coding genes on the opposite strand (lncNATs, 780 expressed). The analysis of expression profiles reveals that lncRNAs are significant and stage-specific contributors to the gene expression profile of developing pollen. Gene co-expression networks accompanied by genome location analysis identified 38 cis-acting lincRNA, 31 cis-acting lncNAT, 7 trans-acting lincRNA and 14 trans-acting lncNAT to be substantially co-expressed with target protein-coding genes involved in biological processes regulating pollen development and male lineage specification. These findings provide a foundation for future research aiming at developing strategies to employ lncRNAs as regulatory tools for gene expression control during reproductive development.
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Affiliation(s)
- Neeta Lohani
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Melbourne, VIC, Australia
- School of Science, Western Sydney University, Richmond, Australia
| | - Agnieszka A Golicz
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Melbourne, VIC, Australia
- Department of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University Gießen, Gießen, Germany
| | - Annapurna D Allu
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Melbourne, VIC, Australia
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Prem L Bhalla
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Melbourne, VIC, Australia
| | - Mohan B Singh
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Melbourne, VIC, Australia.
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Babaei S, Singh MB, Bhalla PL. Role of long non-coding RNAs in rice reproductive development. FRONTIERS IN PLANT SCIENCE 2022; 13:1040366. [PMID: 36457537 PMCID: PMC9705774 DOI: 10.3389/fpls.2022.1040366] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 10/28/2022] [Indexed: 05/13/2023]
Abstract
Rice is a staple crop, feeding over half of the global population. The future demand of population growth and climate change requires substantial rice improvement. Recent advances in rice genomics have highlighted the vital role of the non-coding part of the genome. The protein-coding regions account for only a tiny portion of the eukaryotic genome, and most of the genomic regions transcribe copious amounts of non-coding RNAs. Of these, the long non-coding RNAs, including linear non-coding RNAs (lncRNAs) and circular non-coding RNAs (circRNAs), have been shown to play critical roles in various developmental processes by regulating the expression of genes and functions of proteins at transcriptional, post-transcriptional and post-translational levels. With the advances in next-generation sequencing technologies, a substantial number of long non-coding RNAs have been found to be expressed in plant reproductive organs in a cell- and tissue-specific manner suggesting their reproductive development-related functions. Accumulating evidence points towards the critical role of these non-coding RNAs in flowering, anther, and pollen development, ovule and seed development and photoperiod and temperature regulation of male fertility. In this mini review, we provide a brief overview of the role of the linear and circular long non-coding RNAs in rice reproductive development and control of fertility and crop yield.
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Affiliation(s)
| | | | - Prem L. Bhalla
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, VIC, Australia
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4
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Golicz AA, Allu AD, Li W, Lohani N, Singh MB, Bhalla PL. A dynamic intron retention program regulates the expression of several hundred genes during pollen meiosis. PLANT REPRODUCTION 2021; 34:225-242. [PMID: 34019149 DOI: 10.1007/s00497-021-00411-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 04/19/2021] [Indexed: 05/12/2023]
Abstract
Intron retention is a stage-specific mechanism of functional attenuation of a subset of co-regulated, functionally related genes during early stages of pollen development. To improve our understanding of the gene regulatory mechanisms that drive developmental processes, we performed a genome-wide study of alternative splicing and isoform switching during five key stages of pollen development in field mustard, Brassica rapa. Surprisingly, for several hundred genes (12.3% of the genes analysed), isoform switching results in stage-specific expression of intron-retaining transcripts at the meiotic stage of pollen development. In such cases, we report temporally regulated switching between expression of a canonical, translatable isoform and an intron-retaining transcript that is predicted to produce a truncated and presumably inactive protein. The results suggest a new pervasive mechanism underlying modulation of protein levels in a plant developmental program. The effect is not based on gene expression induction but on the type of transcript produced. We conclude that intron retention is a stage-specific mechanism of functional attenuation of a subset of co-regulated, functionally related genes during meiosis, especially genes related to ribosome biogenesis, mRNA transport and nuclear envelope architecture. We also propose that stage-specific expression of a non-functional isoform of Brassica rapa BrSDG8, a non-redundant member of histone methyltransferase gene family, linked to alternative splicing regulation, may contribute to the intron retention observed.
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Affiliation(s)
- Agnieszka A Golicz
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Melbourne, VIC, Australia
- Department of Plant Breeding, Justus Liebig University, Giessen, Germany
| | - Annapurna D Allu
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Melbourne, VIC, Australia
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Wei Li
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Melbourne, VIC, Australia
| | - Neeta Lohani
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Melbourne, VIC, Australia
| | - Mohan B Singh
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Melbourne, VIC, Australia
| | - Prem L Bhalla
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Melbourne, VIC, Australia.
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5
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Singh MB, Lohani N, Bhalla PL. The Role of Endoplasmic Reticulum Stress Response in Pollen Development and Heat Stress Tolerance. FRONTIERS IN PLANT SCIENCE 2021; 12:661062. [PMID: 33936150 PMCID: PMC8079734 DOI: 10.3389/fpls.2021.661062] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 03/15/2021] [Indexed: 05/15/2023]
Abstract
Endoplasmic reticulum (ER) stress is defined by a protracted disruption in protein folding and accumulation of unfolded or misfolded proteins in the ER. This accumulation of unfolded proteins can result from excessive demands on the protein folding machinery triggered by environmental and cellular stresses such as nutrient deficiencies, oxidative stress, pathogens, and heat. The cell responds to ER stress by activating a protective pathway termed unfolded protein response (UPR), which comprises cellular mechanisms targeted to maintain cellular homeostasis by increasing the ER's protein folding capacity. The UPR is especially significant for plants as being sessile requires them to adapt to multiple environmental stresses. While multiple stresses trigger the UPR at the vegetative stage, it appears to be active constitutively in the anthers of unstressed plants. Transcriptome analysis reveals significant upregulation of ER stress-related transcripts in diploid meiocytes and haploid microspores. Interestingly, several ER stress-related genes are specifically upregulated in the sperm cells. The analysis of gene knockout mutants in Arabidopsis has revealed that defects in ER stress response lead to the failure of normal pollen development and enhanced susceptibility of male gametophyte to heat stress conditions. In this mini-review, we provide an overview of the role of ER stress and UPR in pollen development and its protective roles in maintaining male fertility under heat stress conditions.
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Affiliation(s)
| | | | - Prem L. Bhalla
- Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
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Russell SD, Jones DS, Anderson S, Wang X, Sundaresan V, Gou X. Isolation of Rice Sperm Cells for Transcriptional Profiling. Methods Mol Biol 2017; 1669:211-219. [PMID: 28936661 DOI: 10.1007/978-1-4939-7286-9_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The male germline of flowering plants displays unexpectedly divergent transcriptional profiles compared to other cell types and tissues of plants. As these are among the smallest cells, and are harbored within pollen, isolating a pure collection of germline RNA presents unusual challenges. The sperm cells of rice represent a particularly challenging subject for study as the pollen are unusually short lived upon release from the anther, and the marker gene sequences that make FACS possible in Arabidopsis have not yet been introduced into rice. The purity of the germline samples requires careful collection because of the limited amount of material available and potential contamination by other nearby tissues, pollen, and RNases. A discontinuous Percoll density gradient centrifuge was developed to isolate and obtain enough rice sperm cells for RNA-seq or microarray analysis.
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Affiliation(s)
- Scott D Russell
- Department of Microbiology and Plant Biology, University of Oklahoma, 770 Van Vleet Oval, Norman, OK, 73019, USA.
| | - Daniel S Jones
- Department of Microbiology and Plant Biology, University of Oklahoma, 770 Van Vleet Oval, Norman, OK, 73019, USA
| | - Sarah Anderson
- Department of Plant Biology, University of California, Davis, CA, 95616, USA
| | - Xinkun Wang
- NUSeq Core Research Facility, Northwestern University, Evanston, IL, 60208, USA
| | | | - Xiaoping Gou
- School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
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7
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Yang H, Yang N, Wang T. Proteomic analysis reveals the differential histone programs between male germline cells and vegetative cells in Lilium davidii. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 85:660-674. [PMID: 26846354 DOI: 10.1111/tpj.13133] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 01/12/2016] [Accepted: 01/25/2016] [Indexed: 06/05/2023]
Abstract
In flowering plants, male germline fate is determined after asymmetric division of the haploid microspore. Daughter cells have distinct fates: the generative cell (GC) undergoes further mitosis to generate sperm cells (SCs), and the vegetative cell (VC) terminally differentiates. However, our understanding of the mechanisms underlying germline development remains limited. Histone variants and modifications define chromatin states, and contribute to establishing and maintaining cell identities by affecting gene expression. Here, we constructed a lily protein database, then extracted and detailed histone entries into a comprehensive lily histone database. We isolated large amounts of nuclei from VCs, GCs and SCs from lily, and profiled histone variants of all five histone families in all three cell types using proteomics approaches. We revealed 92 identities representing 32 histone variants: six for H1, 11 for H2A, eight for H2B, five for H3 and two for H4. Nine variants, including five H1, two H2B, one H3 and one H4 variant, specifically accumulated in GCs and SCs. We also detected H3 modification patterns in the three cell types. GCs and SCs had almost identical histone profiles and similar H3 modification patterns, which were significantly different from those of VCs. Our study also revealed the presence of multiple isoforms, and differential expression patterns between isoforms of a variant. The results suggest that differential histone programs between the germline and companion VCs may be established following the asymmetric division, and are important for identity establishment and differentiation of the male germline as well as the VC.
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Affiliation(s)
- Hao Yang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ning Yang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Tai Wang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
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8
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Gómez JF, Talle B, Wilson ZA. Anther and pollen development: A conserved developmental pathway. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2015; 57:876-91. [PMID: 26310290 PMCID: PMC4794635 DOI: 10.1111/jipb.12425] [Citation(s) in RCA: 182] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 08/23/2015] [Indexed: 05/19/2023]
Abstract
Pollen development is a critical step in plant development that is needed for successful breeding and seed formation. Manipulation of male fertility has proved a useful trait for hybrid breeding and increased crop yield. However, although there is a good understanding developing of the molecular mechanisms of anther and pollen anther development in model species, such as Arabidopsis and rice, little is known about the equivalent processes in important crops. Nevertheless the onset of increased genomic information and genetic tools is facilitating translation of information from the models to crops, such as barley and wheat; this will enable increased understanding and manipulation of these pathways for agricultural improvement.
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Affiliation(s)
- José Fernández Gómez
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, LE12 5RD, UK
| | - Behzad Talle
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, LE12 5RD, UK
| | - Zoe A Wilson
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, LE12 5RD, UK
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9
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Sehgal A, Mann N, Mohan Ram HY. Structural and developmental variability in the female gametophyte of Griffithella hookeriana, Polypleurum stylosum, and Zeylanidium lichenoides and its bearing on the occurrence of single fertilization in Podostemaceae. PLANT REPRODUCTION 2014; 27:205-23. [PMID: 25394544 DOI: 10.1007/s00497-014-0252-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 10/30/2014] [Indexed: 05/20/2023]
Abstract
Angiosperms are characterized by the phenomenon of double fertilization with Podostemaceae as an exception that appears to extend to the entire family. Our earlier work demonstrated the cause of failure of double fertilization and ascertained the occurrence of single fertilization in Dalzellia zeylanica (Tristichoideae, Podostemaceae). In continuation with this work, three more members, i.e., Griffithella hookeriana (Tul.) Warming, Polypleurum stylosum (Wight) Hall, and Zeylanidium lichenoides (Kurz) Engl. (Podostemoideae), have been investigated in the present work. We studied the ontogenetic development of female gametophyte and tracked the path of the two sperm cells from the time of their formation in the pollen tube through their entry into the synergid and gamete fusion. We report the occurrence of a remarkably reduced 3-nucleate, 3-celled mature female gametophyte consisting of an egg cell and two synergids in all the three genera. Interestingly, the central cell is formed during female gametophyte development, but exhibits a species-specific, limited life span, and eventually degenerates prior to the entry of the pollen tube into the synergid, resulting in a failure of double fertilization. Sperm dimorphism on the basis of fluorochrome stainability has been recorded in Z. lichenoides. Further, morphogenetic constraints on the part of male (sperm selection, functional reductionism) and female gametophyte (structural reductionism, inaccessibility of central cell) presumably ensure the failure of double fertilization in these species. Thus, loss of double fertilization in this family is likely a derived condition.
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Affiliation(s)
- Anita Sehgal
- Department of Botany, Miranda House, University of Delhi, Delhi, 110007, India,
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10
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Dukowic-Schulze S, Chen C. The meiotic transcriptome architecture of plants. FRONTIERS IN PLANT SCIENCE 2014; 5:220. [PMID: 24926296 PMCID: PMC4046320 DOI: 10.3389/fpls.2014.00220] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 05/02/2014] [Indexed: 05/21/2023]
Abstract
Although a number of genes that play key roles during the meiotic process have been characterized in great detail, the whole process of meiosis is still not completely unraveled. To gain insight into the bigger picture, large-scale approaches like RNA-seq and microarray can help to elucidate the transcriptome landscape during plant meiosis, discover co-regulated genes, enriched processes, and highly expressed known and unknown genes which might be important for meiosis. These high-throughput studies are gaining more and more popularity, but their beginnings in plant systems reach back as far as the 1960's. Frequently, whole anthers or post-meiotic pollen were investigated, while less data is available on isolated cells during meiosis, and only few studies addressed the transcriptome of female meiosis. For this review, we compiled meiotic transcriptome studies covering different plant species, and summarized and compared their key findings. Besides pointing to consistent as well as unique discoveries, we finally draw conclusions what can be learned from these studies so far and what should be addressed next.
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Affiliation(s)
| | - Changbin Chen
- Department of Horticultural Science, University of MinnesotaSt. Paul, MN, USA
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Zhao X, Yang N, Wang T. Comparative proteomic analysis of generative and sperm cells reveals molecular characteristics associated with sperm development and function specialization. J Proteome Res 2013; 12:5058-71. [PMID: 23879389 DOI: 10.1021/pr400291p] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In flowering plants, two sperm cells (SCs) are generated from a generative cell (GC) in the developing pollen grain or growing pollen tube and are then delivered to the embryo sac to initiate double fertilization. SC development and function specialization involve the strict control of the protein (gene) expression program and coordination of diverse cellular processes. However, because methods for collecting a large amount of highly purified GCs and SCs for proteomic and transcriptomic studies from a plant are not available, molecular information about the program and the interconnections is lacking. Here, we describe a method for obtaining a large quantity of highly purified GCs and SCs from just-germinated lily pollen grains and growing pollen tubes for proteomic analysis. Our observation showed that SCs had less condensed chromatin and more vacuole-like structures than GCs and that mature SCs were arrested at the G2 phase. Comparison of SC and GC proteomes revealed 101 proteins differentially expressed in the two proteomes. These proteins are involved in diverse cellular and metabolic processes, with preferential involvement in metabolism, the cell cycle, signaling, the ubiquitin/proteasome pathway, and chromatin remodeling. Impressively, almost all proteins in SCF complex-mediated proteolysis and the cell cycle were up-regulated in SCs, whereas those in chromatin remodeling and stress response were down-regulated. Our data also reveal the coordination of SCF complex-mediated proteolysis, cell cycle progression, and DNA repair in SC development and function specialization. This study revealed for the first time a difference in protein profiles between GCs and SCs.
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Affiliation(s)
- Xin Zhao
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences and National Center for Plant Gene Research , Beijing 100093, China
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Ueda K, Ono M, Iwashita J, Wabiko H, Inoue M. Generative cell-specific activation of the histone gH2A gene promoter of Lilium longiflorum in tobacco. SEXUAL PLANT REPRODUCTION 2012; 25:247-55. [PMID: 22820801 DOI: 10.1007/s00497-012-0194-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 06/25/2012] [Indexed: 01/02/2023]
Abstract
The Lilium longiflorum gH2A promoter is active exclusively in the generative cells of mature pollen in transgenic tobacco expressing the gH2A promoter::GUS (β-glucuronidase) construct as a reporter gene. Temporal and spatial aspects of gH2A promoter activity examined during pollen development in transgenic tobacco reveal that GUS reporter activity was not detected until developing pollen entered the early bicellular developmental stage. Activity was first detected in generative cells at early-mid stages and gradually increased to maximum levels at mid-bicellular stages. The patterns of appearance and longevity of GUS activity in tobacco were very similar to those of gH2A mRNA during pollen development in Lilium. Exogenous treatment with colchicine, a well-known microtubule depolymerize, blocked microspore mitosis and inhibited generative cell differentiation. No GUS signal was detected in the resulting anomalous pollen, which lacked generative cell differentiation. These data strongly suggest that normal generative cell development is essential for activation of the gH2A promoter. Furthermore, these results indicate that common transcriptional activator(s) of the gH2A promoter may be present in both Lilium and Nicotiana, and that such putative factor(s) activates the gH2A promoter only when generative cells undergo normal development.
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Affiliation(s)
- Kenji Ueda
- Akita Prefectural University, Akita, 010-0195, Japan.
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Russell SD, Gou X, Wong CE, Wang X, Yuan T, Wei X, Bhalla PL, Singh MB. Genomic profiling of rice sperm cell transcripts reveals conserved and distinct elements in the flowering plant male germ lineage. THE NEW PHYTOLOGIST 2012; 195:560-573. [PMID: 22716952 DOI: 10.1111/j.1469-8137.2012.04199.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Genomic assay of sperm cell RNA provides insight into functional control, modes of regulation, and contributions of male gametes to double fertilization. Sperm cells of rice (Oryza sativa) were isolated from field-grown, disease-free plants and RNA was processed for use with the full-genome Affymetrix microarray. Comparison with Gene Expression Omnibus (GEO) reference arrays confirmed expressionally distinct gene profiles. A total of 10,732 distinct gene sequences were detected in sperm cells, of which 1668 were not expressed in pollen or seedlings. Pathways enriched in male germ cells included ubiquitin-mediated pathways, pathways involved in chromatin modeling including histones, histone modification and nonhistone epigenetic modification, and pathways related to RNAi and gene silencing. Genome-wide expression patterns in angiosperm sperm cells indicate common and divergent themes in the male germline that appear to be largely self-regulating through highly up-regulated chromatin modification pathways. A core of highly conserved genes appear common to all sperm cells, but evidence is still emerging that another class of genes have diverged in expression between monocots and dicots since their divergence. Sperm cell transcripts present at fusion may be transmitted through plasmogamy during double fertilization to effect immediate post-fertilization expression of early embryo and (or) endosperm development.
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Affiliation(s)
- Scott D Russell
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA
| | - Xiaoping Gou
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA
| | - Chui E Wong
- Plant Molecular Biology and Biotechnology Laboratory, Australian Research Council Centre of Excellence for Integrative Legume Research, Melbourne School of Land and Environment, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Xinkun Wang
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS 66047, USA
| | - Tong Yuan
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA
| | - Xiaoping Wei
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA
| | - Prem L Bhalla
- Plant Molecular Biology and Biotechnology Laboratory, Australian Research Council Centre of Excellence for Integrative Legume Research, Melbourne School of Land and Environment, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Mohan B Singh
- Plant Molecular Biology and Biotechnology Laboratory, Australian Research Council Centre of Excellence for Integrative Legume Research, Melbourne School of Land and Environment, University of Melbourne, Parkville, Victoria 3010, Australia
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Xin HP, Peng XB, Ning J, Yan TT, Ma LG, Sun MX. Expressed sequence-tag analysis of tobacco sperm cells reveals a unique transcriptional profile and selective persistence of paternal transcripts after fertilization. SEXUAL PLANT REPRODUCTION 2011; 24:37-46. [PMID: 20981558 DOI: 10.1007/s00497-010-0151-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 10/11/2010] [Indexed: 11/26/2022]
Abstract
Transcript analysis of male gametes of Nicotiana tabacum was conducted to gather gene expression data regarding the specialization of male germ cells and transmission of paternal transcripts during fertilization. We constructed a tobacco sperm cell cDNA library yielding 1,864 expressed sequence tags representing 1,050 clusters; 37.2% of these clusters have no homologs in GenBank, and 42% did not match any functionally classified protein. A comparative analysis of tobacco sperm transcripts with those of Arabidopsis and maize confirms that some genes are conserved in sperm specialization, while some are distinct to tobacco germline cells. Using reverse transcription-PCR (RT-PCR) of selected transcripts, we evaluated expression of sperm-obtained sequences in vegetative tissue, isolated egg cells, zygotes, and two-celled proembryos, identifying sperm cell-specific transcripts as potential markers for fertilization analysis. We further confirmed that two clusters of sperm transcripts were detected in zygotes about 10 h after fertilization, offering new examples of apparently paternally transmitted transcripts that may be involved in egg cell activation and/or early embryogenesis.
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Affiliation(s)
- Hai-Ping Xin
- Key Laboratory of the Ministry of Education for Plant Developmental Biology, College of Life Science, Wuhan University, Wuhan, China
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15
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Drews GN, Wang D, Steffen JG, Schumaker KS, Yadegari R. Identification of genes expressed in the angiosperm female gametophyte. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:1593-9. [PMID: 21118822 DOI: 10.1093/jxb/erq385] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Until recently, identification of gene regulatory networks controlling the development of the angiosperm female gametophyte has presented a significant challenge to the plant biology community. The angiosperm female gametophyte is fairly inaccessible because it is a highly reduced structure relative to the sporophyte and is embedded within multiple layers of the sporophytic tissue of the ovule. Moreover, although mutations affecting the female gametophyte can be readily isolated, their analysis can be difficult because most affect genes involved in basic cellular processes that are also required in the diploid sporophyte. In recent years, expression-based approaches in multiple species have begun to uncover gene sets expressed in specific female gametophyte cells as a means of identifying regulatory networks controlling cell differentiation in the female gametophyte. Here, recent efforts to identify and analyse gene expression programmes in the Arabidopsis female gametophyte are reviewed.
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Affiliation(s)
- Gary N Drews
- Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA
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Ge L, Gou X, Yuan T, Strout GW, Nakashima J, Blancaflor EB, Tian HQ, Russell SD. Migration of sperm cells during pollen tube elongation in Arabidopsis thaliana: behavior during transport, maturation and upon dissociation of male germ unit associations. PLANTA 2011; 233:325-332. [PMID: 21046146 DOI: 10.1007/s00425-010-1305-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2010] [Accepted: 10/13/2010] [Indexed: 05/28/2023]
Abstract
The promoter sequence of sperm-expressed gene, PzIPT isolated from the S(vn) (sperm associated with the vegetative nucleus) of Plumbago zeylanica, was fused to a green fluorescent protein (GFP) reporter sequence and transformed into Arabidopsis thaliana to better visualize the live behavior of angiosperm sperm cells. Angiosperm sperm cells are not independently motile, migrating in a unique cell-within-a-cell configuration within the pollen tube. Sperm cells occur in association with the vegetative nucleus forming a male germ unit (MGU). In Arabidopsis, GFP was expressed equally in both sperm cells and was observed using a spinning disk confocal microscope, which allowed long duration observation of cells without bleaching or visible laser radiation damage. Pollen activation is reflected by conspicuous movement of sperm and pollen cytoplasm. Upon pollen germination, sperm cells enter the forming tube and become oriented, typically with a sperm cytoplasmic projection leading the sperm cells in the MGU, which remains intact throughout normal pollen tube elongation. Maturational changes, including vacuolization, general rounding and entry into G2, were observed during in vitro culture. When MGUs were experimentally disrupted by mild temperature elevation, sperm cells no longer tracked the growth of the tube and separated from the MGU, providing critical direct evidence that the MGU is a functional unit required for sperm transmission.
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Affiliation(s)
- Lili Ge
- Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA
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17
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Zienkiewicz K, Suwinska A, Niedojadło K, Zienkiewicz A, Bednarska E. Nuclear activity of sperm cells during Hyacinthus orientalis L. in vitro pollen tube growth. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:1255-1269. [PMID: 21081664 PMCID: PMC3022407 DOI: 10.1093/jxb/erq354] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 10/14/2010] [Accepted: 10/15/2010] [Indexed: 05/29/2023]
Abstract
In this study, the transcriptional state and distribution of RNA polymerase II, pre-mRNA splicing machinery elements, and rRNA transcripts were investigated in the sperm cells of Hyacinthus orientalis L. during in vitro pollen tube growth. During the second pollen mitosis, no nascent transcripts were observed in the area of the dividing generative cell, whereas the splicing factors were present and their pools were divided between newly formed sperm cells. Just after their origin, the sperm cells were shown to synthesize new RNA, although at a markedly lower level than the vegetative nucleus. The occurrence of RNA synthesis was accompanied by the presence of RNA polymerase II and a rich pool of splicing machinery elements. Differences in the spatial pattern of pre-mRNA splicing factors localization reflect different levels of RNA synthesis in the vegetative nucleus and sperm nuclei. In the vegetative nucleus, they were localized homogenously, whereas in the sperm nuclei a mainly speckled pattern of small nuclear RNA with a trimethylguanosine cap (TMG snRNA) and SC35 protein distribution was observed. As pollen tube growth proceeded, inhibition of RNA synthesis in the sperm nuclei was observed, which was accompanied by a gradual elimination of the splicing factors. In addition, analysis of rRNA localization indicated that the sperm nuclei are likely to synthesize some pool of rRNA at the later steps of pollen tube. It is proposed that the described changes in the nuclear activity of H. orientalis sperm cells reflect their maturation process during pollen tube growth, and that mature sperm cells do not carry into the zygote the nascent transcripts or the splicing machinery elements.
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Affiliation(s)
- Krzysztof Zienkiewicz
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín CSIC, Profesor Albareda 1, 18008 Granada, Spain.
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18
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Xin H, Sun M. What we have learned from transcript profile analyses of male and female gametes in flowering plants. SCIENCE CHINA-LIFE SCIENCES 2010; 53:927-33. [PMID: 20821291 DOI: 10.1007/s11427-010-4033-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Accepted: 06/21/2010] [Indexed: 11/30/2022]
Abstract
Double fertilization is one of the predominant features of sexual reproduction in flowering plants but, because of the physical inaccessibility of gametes, the essential molecular mechanisms in these processes are largely unknown. Based on the techniques for isolating highly purified gametes from several species and well-developed methods for manipulating RNA from limited quantities of gametes, genome-wide investigations of gamete transcription profiles were recently conducted in flowering plants. In this review, we survey the accumulated knowledge on gamete collection and purification, cDNA library construction, and transcript profile analysis to assess our understanding of the molecular mechanisms of gamete specialization and fertilization.
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Affiliation(s)
- HaiPing Xin
- Key Laboratory of the Ministry of Education for Plant Developmental Biology, College of Life Science, Wuhan University, Wuhan, China
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19
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Abstract
Flowering plant reproduction is characterized by double fertilization, in which two diminutive brother sperm cells initiate embryo and endosperm. The role of the male gamete, although studied structurally for over a century at various levels, is still being explored on a molecular and cellular level. The potential of the male to influence development has been historically underestimated and the reasons for this are obvious: limitations provided by maternal imprinting, the much greater cellular volume of female gametes and the general paucity of paternal effects. However, as more is known about molecular expression of chromatin-modifying proteins, ubiquitin pathway proteins and transcription factors in sperm cells, as well as their ability to achieve effect by intaglio expression, passing transcripts directly into translation, the role of the male is likely to expand. Much of the expression in the male germline that appears to be distinct from patterns of pollen vegetative cell expression may be the result of chromosomal level regulation of transcription.
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Wei LQ, Xu WY, Deng ZY, Su Z, Xue Y, Wang T. Genome-scale analysis and comparison of gene expression profiles in developing and germinated pollen in Oryza sativa. BMC Genomics 2010; 11:338. [PMID: 20507633 PMCID: PMC2895629 DOI: 10.1186/1471-2164-11-338] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Accepted: 05/28/2010] [Indexed: 11/24/2022] Open
Abstract
Background Pollen development from the microspore involves a series of coordinated cellular events, and the resulting mature pollen has a specialized function to quickly germinate, produce a polar-growth pollen tube derived from the vegetative cell, and deliver two sperm cells into the embryo sac for double fertilization. The gene expression profiles of developing and germinated pollen have been characterised by use of the eudicot model plant Arabidopsis. Rice, one of the most important cereal crops, has been used as an excellent monocot model. A comprehensive analysis of transcriptome profiles of developing and germinated pollen in rice is important to understand the conserved and diverse mechanism underlying pollen development and germination in eudicots and monocots. Results We used Affymetrix GeneChip® Rice Genome Array to comprehensively analyzed the dynamic changes in the transcriptomes of rice pollen at five sequential developmental stages from microspores to germinated pollen. Among the 51,279 transcripts on the array, we found 25,062 pollen-preferential transcripts, among which 2,203 were development stage-enriched. The diversity of transcripts decreased greatly from microspores to mature and germinated pollen, whereas the number of stage-enriched transcripts displayed a "U-type" change, with the lowest at the bicellular pollen stage; and a transition of overrepresented stage-enriched transcript groups associated with different functional categories, which indicates a shift in gene expression program at the bicellular pollen stage. About 54% of the now-annotated rice F-box protein genes were expressed preferentially in pollen. The transcriptome profile of germinated pollen was significantly and positively correlated with that of mature pollen. Analysis of expression profiles and coexpressed features of the pollen-preferential transcripts related to cell cycle, transcription, the ubiquitin/26S proteasome system, phytohormone signalling, the kinase system and defense/stress response revealed five expression patterns, which are compatible with changes in major cellular events during pollen development and germination. A comparison of pollen transcriptomes between rice and Arabidopsis revealed that 56.6% of the rice pollen preferential genes had homologs in Arabidopsis genome, but 63.4% of these homologs were expressed, with a small proportion being expressed preferentially, in Arabidopsis pollen. Rice and Arabidopsis pollen had non-conservative transcription factors each. Conclusions Our results demonstrated that rice pollen expressed a set of reduced but specific transcripts in comparison with vegetative tissues, and the number of stage-enriched transcripts displayed a "U-type" change during pollen development, with the lowest at the bicellular pollen stage. These features are conserved in rice and Arabidopsis. The shift in gene expression program at the bicellular pollen stage may be important to the transition from earlier cell division to later pollen maturity. Pollen at maturity pre-synthesized transcripts needed for germination and early pollen tube growth. The transcription regulation associated with pollen development would have divergence between the two species. Our results also provide novel insights into the molecular program and key components of the regulatory network regulating pollen development and germination.
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Affiliation(s)
- Li Q Wei
- Research Center of Molecular and Developmental Biology, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
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Gou X, Yuan T, Wei X, Russell SD. Gene expression in the dimorphic sperm cells of Plumbago zeylanica: transcript profiling, diversity, and relationship to cell type. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 60:33-47. [PMID: 19500307 DOI: 10.1111/j.1365-313x.2009.03934.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Plumbago zeylanica produces cytoplasmically dimorphic sperm cells that target the egg and central cell during fertilization. In mature pollen, the larger sperm cell contains numerous mitochondria, is associated with the vegetative nucleus (S(vn)), and fuses preferentially with the central cell, forming endosperm. The other, plastid-enriched sperm cell (S(ua)) fuses with the egg cell, forming the zygote and embryo. Sperm expressed genes were investigated using ESTs produced from each sperm type; differential expression was validated through suppression subtractive hybridization, custom microarrays, real-time RT-PCR and in situ hybridization. The expression profiles of dimorphic sperm cells reflect a diverse and broad complement of genes, including high proportions of conserved and unknown genes, as well as distinct patterns of expression. A number of genes were highly up-regulated in the male germ line, including some genes that were differentially expressed in either the S(ua) or the S(vn). Differentially up-regulated genes in the egg-targeted S(ua) showed increased expression in transcription and translation categories, whereas the central cell-targeted S(vn) displayed expanded expression in the hormone biosynthesis category. Interestingly, the up-regulated genes expressed in the sperm cells appeared to reflect the expected post-fusion profiles of the future embryo and endosperm. As sperm cytoplasm is known to be transmitted during fertilization in this plant, sperm-contributed mRNAs are probably transported during fertilization, which could influence early embryo and endosperm development.
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Affiliation(s)
- Xiaoping Gou
- Department of Botany, University of Oklahoma, Norman, OK 73019, USA
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22
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Borg M, Brownfield L, Twell D. Male gametophyte development: a molecular perspective. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:1465-78. [PMID: 19213812 DOI: 10.1093/jxb/ern355] [Citation(s) in RCA: 215] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Pollen grains represent the highly reduced haploid male gametophyte generation in flowering plants, consisting of just two or three cells when released from the anthers. Their role is to deliver twin sperm cells to the embryo sac to undergo fusion with the egg and central cell. This double fertilization event along with the functional specialization of the male gametophyte, are considered to be key innovations in the evolutionary success of flowering plants. This review encompasses important recent advances in our understanding of the molecular mechanisms controlling male gametophyte development. A brief overview of pollen development is presented, followed by a discussion of genome-wide transcriptomic studies of haploid gene expression. The progress achieved through genetic analysis of landmark events of male gametogenesis is discussed, with a focus on sperm cell production, and an emerging model of the regulatory network governing male germline development is presented. The review concludes with a perspective of the impact these data will have on future research strategies to further develop our understanding of the gametophytic control of pollen development.
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Affiliation(s)
- Michael Borg
- Department of Biology, University of Leicester, UK
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Peng XB, Sun MX. Gamete recognition in higher plants: an abstruse but charming mystery. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2008; 50:868-874. [PMID: 18713397 DOI: 10.1111/j.1744-7909.2008.00706.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Although much effort has been made to uncover the mechanism underlying double fertilization, little knowledge has been acquired for understanding the molecular base of gamete recognition, mainly because of technical limitations. Still, progress has been made in terms of the mechanism, including the identification of candidate molecules that are involved in gamete recognition in angiosperms. New cues for gamete recognition have been found by the successful separation of the gametes and construction of gamete-specific cDNA libraries in several species, and the application of molecular approaches for studying this process by mutations. Thus, the topic is considered an abstruse but charming mystery.
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Affiliation(s)
- Xiong-Bo Peng
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China
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Márton ML, Dresselhaus T. A comparison of early molecular fertilization mechanisms in animals and flowering plants. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s00497-007-0062-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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25
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