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Liu X, Yu F. New insights into the functions and regulations of MAP215/MOR1 and katanin, two conserved microtubule-associated proteins in Arabidopsis. PLANT SIGNALING & BEHAVIOR 2023; 18:2171360. [PMID: 36720201 PMCID: PMC9891169 DOI: 10.1080/15592324.2023.2171360] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 01/07/2023] [Accepted: 01/18/2023] [Indexed: 06/18/2023]
Abstract
Plant microtubules (MTs) form highly dynamic and distinct arrays throughout the cell cycle and are essential for cell and organ morphogenesis. A plethora of microtubule associated-proteins (MAPs), both conserved and plant-specific, ensure the dynamic response of MTs to internal and external cues. The MAP215 family MT polymerase/nucleation factor and the MT severing enzyme katanin are among the most conserved MAPs in eukaryotes. Recent studies have revealed unexpected functional and physical interactions between MICROTUBULE ORGANIZATION 1 (MOR1), the Arabidopsis homolog of MAP215, and KATANIN 1 (KTN1), the catalytic subunit of katanin. In this minireview, we provide a short overview on current understanding of the functions and regulations of MOR1 and katanin in cell morphogenesis and plant growth and development.
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Affiliation(s)
- Xiayan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Fei Yu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
- Institute of Future Agriculture, Northwest A&F University, Yangling, Shaanxi, China
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2
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Renzaglia KS, Ashton NW, Suh DY. Sporogenesis in Physcomitrium patens: Intergenerational collaboration and the development of the spore wall and aperture. Front Cell Dev Biol 2023; 11:1165293. [PMID: 37123413 PMCID: PMC10133578 DOI: 10.3389/fcell.2023.1165293] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 03/22/2023] [Indexed: 05/02/2023] Open
Abstract
Although the evolution of spores was critical to the diversification of plants on land, sporogenesis is incompletely characterized for model plants such as Physcomitrium patens. In this study, the complete process of P. patens sporogenesis is detailed from capsule expansion to mature spore formation, with emphasis on the construction of the complex spore wall and proximal aperture. Both diploid (sporophytic) and haploid (spores) cells contribute to the development and maturation of spores. During capsule expansion, the diploid cells of the capsule, including spore mother cells (SMCs), inner capsule wall layer (spore sac), and columella, contribute a locular fibrillar matrix that contains the machinery and nutrients for spore ontogeny. Nascent spores are enclosed in a second matrix that is surrounded by a thin SMC wall and suspended in the locular material. As they expand and separate, a band of exine is produced external to a thin foundation layer of tripartite lamellae. Dense globules assemble evenly throughout the locule, and these are incorporated progressively onto the spore surface to form the perine external to the exine. On the distal spore surface, the intine forms internally, while the spiny perine ornamentation is assembled. The exine is at least partially extrasporal in origin, while the perine is derived exclusively from outside the spore. Across the proximal surface of the polar spores, an aperture begins formation at the onset of spore development and consists of an expanded intine, an annulus, and a central pad with radiating fibers. This complex aperture is elastic and enables the proximal spore surface to cycle between being compressed (concave) and expanded (rounded). In addition to providing a site for water intake and germination, the elastic aperture is likely involved in desiccation tolerance. Based on the current phylogenies, the ancestral plant spore contained an aperture, exine, intine, and perine. The reductive evolution of liverwort and hornwort spores entailed the loss of perine in both groups and the aperture in liverworts. This research serves as the foundation for comparisons with other plant groups and for future studies of the developmental genetics and evolution of spores across plants.
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Affiliation(s)
- Karen S. Renzaglia
- Department of Plant Biology, Southern Illinois University, Carbondale, IL, United States
- *Correspondence: Karen S. Renzaglia,
| | - Neil W. Ashton
- Department of Chemistry and Biochemistry, University of Regina, Regina, SK, Canada
| | - Dae-Yeon Suh
- Department of Chemistry and Biochemistry, University of Regina, Regina, SK, Canada
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3
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Liu J, Ghelli R, Cardarelli M, Geisler M. Arabidopsis TWISTED DWARF1 regulates stamen elongation by differential activation of ABCB1,19-mediated auxin transport. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:4818-4831. [PMID: 35512423 DOI: 10.1093/jxb/erac185] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 05/04/2022] [Indexed: 06/14/2023]
Abstract
Despite clear evidence that a local accumulation of auxin is likewise critical for male fertility, much less is known about the components that regulate auxin-controlled stamen development. In this study, we analyzed physiological and morphological parameters in mutants of key players of ABCB-mediated auxin transport, and spatially and temporally dissected their expression on the protein level as well as auxin fluxes in the Arabidopsis stamens. Our analyses revealed that the FKBP42, TWISTED DWARF1 (TWD1), promotes stamen elongation and, to a lesser extent, anther dehiscence, as well as pollen maturation, and thus is required for seed development. Most of the described developmental defects in twd1 are shared with the abcb1 abcb19 mutant, which can be attributed to the fact that TWD1-as a described ABCB chaperone-is a positive regulator of ABCB1- and ABCB19-mediated auxin transport. However, reduced stamen number was dependent on TWD1 but not on investigated ABCBs, suggesting additional players downstream of TWD1. We predict an overall housekeeping function for ABCB1 during earlier stages, while ABCB19 seems to be responsible for the key event of rapid elongation at later stages of stamen development. Our data indicate that TWD1 controls stamen development by differential activation of ABCB1,19-mediated auxin transport in the stamen.
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Affiliation(s)
- Jie Liu
- University of Fribourg, Department of Biology, CH-1700 Fribourg, Switzerland
| | - Roberta Ghelli
- IBPM-CNR, Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, P. le A. Moro 5, 00185 Roma, Italy
| | - Maura Cardarelli
- IBPM-CNR, Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, P. le A. Moro 5, 00185 Roma, Italy
| | - Markus Geisler
- University of Fribourg, Department of Biology, CH-1700 Fribourg, Switzerland
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4
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Huang X, Sun MX. H3K27 methylation regulates the fate of two cell lineages in male gametophytes. THE PLANT CELL 2022; 34:2989-3005. [PMID: 35543471 PMCID: PMC9338816 DOI: 10.1093/plcell/koac136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 05/03/2022] [Indexed: 05/14/2023]
Abstract
During angiosperm male gametogenesis, microspores divide to produce a vegetative cell (VC) and a male germline (MG), each with distinct cell fates. The mechanism underlying determination of the MG cell/VC fate remains an important area of research, with many unanswered questions. Here, we report that H3K27me3 is essential for VC fate commitment in male Arabidopsis thaliana gametophytes; H3K27me3 erasure contributes to MG cell fate initiation. VC-targeted H3K27me3 erasure disturbed VC development and shifted the VC fate toward a gamete destination, which suggests that MG cells require H3K27me3 erasure to trigger gamete cell fate. Multi-omics and cytological analyses confirmed the occurrence of extensive cell identity transition due to H3K27me3 erasure. Therefore, we experimentally confirmed that MG cell/VC fate is epigenetically regulated. H3K27 methylation plays a critical role in guiding MG cell/VC fate determination for pollen fertility in Arabidopsis. Our work also provides evidence for two previous hypotheses: the germline cell fate is specified by the differential distribution of unknown determinants and VC maintains the default microspore program (i.e. the H3K27me3 setting) while MG requires reprogramming.
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Affiliation(s)
- Xiaorong Huang
- State Key Laboratory of Hybrid Rice, College of Life Science, Wuhan University, Wuhan 430072, China
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5
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Chen Y, Liu X, Zhang W, Li J, Liu H, Yang L, Lei P, Zhang H, Yu F. MOR1/MAP215 acts synergistically with katanin to control cell division and anisotropic cell elongation in Arabidopsis. THE PLANT CELL 2022; 34:3006-3027. [PMID: 35579372 PMCID: PMC9373954 DOI: 10.1093/plcell/koac147] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 05/07/2022] [Indexed: 05/20/2023]
Abstract
The MAP215 family of microtubule (MT) polymerase/nucleation factors and the MT severing enzyme katanin are widely conserved MT-associated proteins (MAPs) across the plant and animal kingdoms. However, how these two essential MAPs coordinate to regulate plant MT dynamics and development remains unknown. Here, we identified novel hypomorphic alleles of MICROTUBULE ORGANIZATION 1 (MOR1), encoding the Arabidopsis thaliana homolog of MAP215, in genetic screens for mutants oversensitive to the MT-destabilizing drug propyzamide. Live imaging in planta revealed that MOR1-green fluorescent protein predominantly tracks the plus-ends of cortical MTs (cMTs) in interphase cells and labels preprophase band, spindle and phragmoplast MT arrays in dividing cells. Remarkably, MOR1 and KATANIN 1 (KTN1), the p60 subunit of Arabidopsis katanin, act synergistically to control the proper formation of plant-specific MT arrays, and consequently, cell division and anisotropic cell expansion. Moreover, MOR1 physically interacts with KTN1 and promotes KTN1-mediated severing of cMTs. Our work establishes the Arabidopsis MOR1-KTN1 interaction as a central functional node dictating MT dynamics and plant growth and development.
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Affiliation(s)
| | | | - Wenjing Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Jie Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Haofeng Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Lan Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Pei Lei
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Hongchang Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Fei Yu
- Author for correspondence:
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6
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Gu Y, Rasmussen CG. Cell biology of primary cell wall synthesis in plants. THE PLANT CELL 2022; 34:103-128. [PMID: 34613413 PMCID: PMC8774047 DOI: 10.1093/plcell/koab249] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 10/01/2021] [Indexed: 05/07/2023]
Abstract
Building a complex structure such as the cell wall, with many individual parts that need to be assembled correctly from distinct sources within the cell, is a well-orchestrated process. Additional complexity is required to mediate dynamic responses to environmental and developmental cues. Enzymes, sugars, and other cell wall components are constantly and actively transported to and from the plasma membrane during diffuse growth. Cell wall components are transported in vesicles on cytoskeletal tracks composed of microtubules and actin filaments. Many of these components, and additional proteins, vesicles, and lipids are trafficked to and from the cell plate during cytokinesis. In this review, we first discuss how the cytoskeleton is initially organized to add new cell wall material or to build a new cell wall, focusing on similarities during these processes. Next, we discuss how polysaccharides and enzymes that build the cell wall are trafficked to the correct location by motor proteins and through other interactions with the cytoskeleton. Finally, we discuss some of the special features of newly formed cell walls generated during cytokinesis.
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Affiliation(s)
- Ying Gu
- Author for correspondence: (Y.G.), (C.G.R.)
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Rui Q, Tan X, Liu F, Li Y, Liu X, Li B, Wang J, Yang H, Qiao L, Li T, Fang S, Gao R, Wang W, Bednarek SY, Bao Y. Syntaxin of plants31 (SYP31) and SYP32 is essential for Golgi morphology maintenance and pollen development. PLANT PHYSIOLOGY 2021; 186:330-343. [PMID: 33576796 PMCID: PMC8154079 DOI: 10.1093/plphys/kiab049] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 01/19/2021] [Indexed: 05/27/2023]
Abstract
Pollen development is a key process for the sexual reproduction of angiosperms. The Golgi plays a critical role in pollen development via the synthesis and transport of cell wall materials. However, little is known about the molecular mechanisms underlying the maintenance of Golgi integrity in plants. In Arabidopsis thaliana, syntaxin of plants (SYP) 3 family proteins SYP31 and SYP32 are the only two Golgi-localized Qa-soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs) with unknown endogenous functions. Here, we demonstrate the roles of SYP31 and SYP32 in modulating Golgi morphology and pollen development. Two independent lines of syp31/+ syp32/+ double mutants were male gametophytic lethal; the zero transmission rate of syp31 syp32 mutations was restored to largely normal levels by pSYP32:SYP32 but not pSYP32:SYP31 transgenes, indicating their functional differences in pollen development. The initial arrest of syp31 syp32 pollen occurred during the transition from the microspore to the bicellular stage, where cell plate formation in pollen mitosis I (PMI) and deposition of intine were abnormal. In syp31 syp32 pollen, the number and length of Golgi cisterna were significantly reduced, accompanied by many surrounding vesicles, which could be largely attributed to defects in anterograde and retrograde trafficking routes. SYP31 and SYP32 directly interacted with COG3, a subunit of the conserved oligomeric Golgi (COG) complex and were responsible for its Golgi localization, providing an underlying mechanism for SYP31/32 function in intra-Golgi trafficking. We propose that SYP31 and SYP32 play partially redundant roles in pollen development by modulating protein trafficking and Golgi structure.
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Affiliation(s)
- Qingchen Rui
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Xiaoyun Tan
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Feng Liu
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Yanbin Li
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Xin Liu
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Bingxuan Li
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Junxia Wang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Huiting Yang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Lixin Qiao
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Tingting Li
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Shuo Fang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Rongrong Gao
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Wang Wang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Sebastian Y Bednarek
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Yiqun Bao
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P. R. China
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8
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Oh SA, Park HJ, Kim MH, Park SK. Analysis of sticky generative cell mutants reveals that suppression of callose deposition in the generative cell is necessary for generative cell internalization and differentiation in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 106:228-244. [PMID: 33458909 DOI: 10.1111/tpj.15162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 01/11/2021] [Indexed: 06/12/2023]
Abstract
In flowering plants, double fertilization between male and female gametophytes, which are separated by distance, largely depends on the unique pattern of the male gametophyte (pollen): two non-motile sperm cells suspended within a tube-producing vegetative cell. A morphological screen to elucidate the genetic control governing the strategic patterning of pollen has led to the isolation of a sticky generative cell (sgc) mutant that dehisces abnormal pollen with the generative cell immobilized at the pollen wall. Analyses revealed that the sgc mutation is specifically detrimental to pollen development, causing ectopic callose deposition that impedes the timely internalization and differentiation of the generative cell. We found that the SGC gene encodes the highly conserved domain of unknown function 707 (DUF707) gene that is broadly expressed but is germline specific during pollen development. Additionally, transgenic plants co-expressing fluorescently fused SGC protein and known organelle markers showed that SGC localizes in the endoplasmic reticulum, Golgi apparatus and vacuoles in pollen. A yeast two-hybrid screen with an SGC bait identified a thaumatin-like protein that we named GCTLP1, some homologs of which bind and/or digest β-1,3-glucans, the main constituent of callose. GCTLP1 is expressed in a germline-specific manner and colocalizes with SGC during pollen development, indicating that GCTLP1 is a putative SGC interactor. Collectively, our results show that SGC suppresses callose deposition in the nascent generative cell, thereby allowing the generative cell to fully internalize into the vegetative cell and correctly differentiate as the germline progenitor, with the potential involvement of the GCTLP1 protein, during pollen development in Arabidopsis.
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Affiliation(s)
- Sung-Aeong Oh
- School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Hyo-Jin Park
- School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Myung-Hee Kim
- School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Soon-Ki Park
- School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Republic of Korea
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9
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Li Y, Li L, Wang Y, Wang YC, Wang NN, Lu R, Wu YW, Li XB. Pollen-Specific Protein PSP231 Activates Callose Synthesis to Govern Male Gametogenesis and Pollen Germination. PLANT PHYSIOLOGY 2020; 184:1024-1041. [PMID: 32663166 PMCID: PMC7536655 DOI: 10.1104/pp.20.00297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 06/25/2020] [Indexed: 05/05/2023]
Abstract
Spatiotemporally regulated callose deposition is an essential, genetically programmed phenomenon that promotes pollen development and functionality. Severe male infertility is associated with deficient callose biosynthesis, highlighting the significance of intact callose deposition in male gametogenesis. The molecular mechanism that regulates the crucial role of callose in production of functional male gametophytes remains completely unexplored. Here, we provide evidence that the gradual upregulation of a previously uncharacterized cotton (Gossypium hirsutum) pollen-specific SKS-like protein (PSP231), specifically at the post pollen-mitosis stage, activates callose biosynthesis to promote pollen maturation. Aberrant PSP231 expression levels caused by either silencing or overexpression resulted in late pollen developmental abnormalities and male infertility phenotypes in a dose-dependent manner, highlighting the importance of fine-tuned PSP231 expression. Mechanistic analyses revealed that PSP231 plays a central role in triggering and fine-tuning the callose synthesis and deposition required for pollen development. Specifically, PSP231 protein sequesters the cellular pool of RNA-binding protein GhRBPL1 to destabilize GhWRKY15 mRNAs, turning off GhWRKY15-mediated transcriptional repression of GhCalS4/GhCalS8 and thus activating callose biosynthesis in pollen. This study showed that PSP231 is a key molecular switch that activates the molecular circuit controlling callose deposition toward pollen maturation and functionality and thereby safeguards agricultural crops against male infertility.
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Affiliation(s)
- Yang Li
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, China
| | - Li Li
- Department of Genetics and Genome Biology, The Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children and the University of Toronto, Toronto, Ontario M5G 0A4, Canada
| | - Yao Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, China
| | - Ya-Chao Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, China
| | - Na-Na Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, China
| | - Rui Lu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, China
| | - Yu-Wei Wu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, China
| | - Xue-Bao Li
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, China
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10
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Pereira PA, Boavida LC, Santos MR, Becker JD. AtNOT1 is required for gametophyte development in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:1289-1303. [PMID: 32369648 DOI: 10.1111/tpj.14801] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 04/15/2020] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Abstract
In flowering plants, pollen development is under a dynamic and well-orchestrated transcriptional control, characterized by an early phase with high transcript diversity and a late post-mitotic phase skewed to a cell-type-specific transcriptome. Such transcriptional changes require a balance between synthesis and degradation of mRNA transcripts, the latter being initiated by deadenylation. The CCR4-NOT complex is the main evolutionary conserved deadenylase complex in eukaryotes, and its function is essential during germline specification in animals. We hypothesized that the CCR4-NOT complex might play a central role in mRNA turnover during microgametogenesis in Arabidopsis. Disruption of NOT1 gene, which encodes the scaffold protein of the CCR4-NOT complex, showed abnormal seed set. Genetic analysis failed to recover homozygous progeny, and reciprocal crosses confirmed reduced transmission through the male and female gametophytes. Concordantly, not1 embryo sacs showed delayed development and defects in embryogenesis. not1 pollen grains exhibited abnormal male germ unit configurations and failed to germinate. Transcriptome analysis of pollen from not1/+ mutants revealed that lack of NOT1 leads to an extensive transcriptional deregulation during microgametogenesis. Therefore, our work establishes NOT1 as an important player during gametophyte development in Arabidopsis.
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Affiliation(s)
- Patrícia A Pereira
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras, 2780-156, Portugal
| | - Leonor C Boavida
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras, 2780-156, Portugal
| | - Mário R Santos
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras, 2780-156, Portugal
| | - Jörg D Becker
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras, 2780-156, Portugal
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, Oeiras, 2780-157, Portugal
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11
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Ks R, Ra L, Rd W, Ha O, A M. Callose in sporogenesis: Novel composition of the inner spore wall in hornworts. PLANT SYSTEMATICS AND EVOLUTION = ENTWICKLUNGSGESCHICHTE UND SYSTEMATIK DER PFLANZEN 2020; 306:16. [PMID: 34079158 PMCID: PMC8167838 DOI: 10.1007/s00606-020-01631-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 01/08/2020] [Indexed: 05/06/2023]
Abstract
Sporogenesis is a developmental process that defines embryophytes and involves callose, especially in the production of the highly protective and recalcitrant spore/pollen wall. Until now, hornworts, leptosporangiate ferns and homosporous lycophytes are the only major plant groups in which the involvement of callose in spore development is equivocal. Through aniline blue fluorescence and immunogold labeling in the transmission electron microscope, we provide indisputable evidence for the presence of callose in the spore wall of five hornwort genera, but not in the derived Dendroceros, an epiphyte that produces multicellular spores. We present evidence that callose appears in the developing spore wall and is retained throughout development as a wall constituent of the intine or inner spore wall, a novel location for this polysaccharide in embryophytes. In endosporic and multicellular spores/pollen of Dendroceros, the liverwort Pellia, and Arabidopsis, callose appears in the newly formed cell walls only following the first mitotic division. Further probing for other wall polymers in hornworts reveals the presence of cellulose (Calcofluor fluorescence) in the spore intine, aperture and around the equatorial girdle. Further immunogold labeling with monoclonal antibodies identifies pectin and hemicellulose in hornwort intines. The persistence of callose, a typically transient cell wall constituent, with cellulose, pectins and hemicellulose in the intine, supports specialized functions of callose in spores of hornworts that include reduced water loss when spores are dry and mechanical flexibility to withstand desiccation.
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Affiliation(s)
- Renzaglia Ks
- Department of Plant Biology, Southern Illinois University Carbondale, Carbondale, Illinois, USA
| | - Lopez Ra
- Department of Plant Biology, Southern Illinois University Carbondale, Carbondale, Illinois, USA
| | - Welsh Rd
- Department of Plant Biology, Southern Illinois University Carbondale, Carbondale, Illinois, USA
| | - Owen Ha
- Department of Biological Sciences, University of Wisconsin Milwaukee, Milwaukee, Wisconsin, USA
| | - Merced A
- Institute of Neurobiology, University of Puerto Rico, San Juan, Puerto Rico, USA
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Zheng Y, Deng X, Qu A, Zhang M, Tao Y, Yang L, Liu Y, Xu J, Zhang S. Regulation of pollen lipid body biogenesis by MAP kinases and downstream WRKY transcription factors in Arabidopsis. PLoS Genet 2018; 14:e1007880. [PMID: 30586356 PMCID: PMC6324818 DOI: 10.1371/journal.pgen.1007880] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 01/08/2019] [Accepted: 12/05/2018] [Indexed: 11/18/2022] Open
Abstract
Signaling pathways that control the activities in non-photosynthetic plastids, important sites of plant metabolism, are largely unknown. Previously, we demonstrated that WRKY2 and WRKY34 transcription factors play an essential role in pollen development downstream of mitogen-activated protein kinase 3 (MPK3) and MPK6 in Arabidopsis. Here, we report that GLUCOSE-6-PHOSPHATE/PHOSPHATE TRANSLOCATOR 1 (GPT1) is a key target gene of WRKY2/WRKY34. GPT1 transports glucose-6-phosphate (Glc6P) into plastids for starch and/or fatty acid biosynthesis depending on the plant species. Loss of function of WRKY2/WRKY34 results in reduced GPT1 expression, and concomitantly, reduced accumulation of lipid bodies in mature pollen, which leads to compromised pollen viability, germination, pollen tube growth, and male transmission in Arabidopsis. Pollen-specific overexpression of GPT1 rescues the pollen defects of wrky2 wrky34 double mutant. Furthermore, gain-of-function activation of MPK3/MPK6 enhances GPT1 expression; whereas GPT1 expression is reduced in mkk4 mkk5 double mutant. Together, this study revealed a cytoplasmic/nuclear signaling pathway capable of coordinating the metabolic activities in plastids. High-level expression of GPT1 at late stages of pollen development drives Glc6P from cytosol into plastids, where Glc6P is used for fatty acid biosynthesis, an important step of lipid body biogenesis. The accumulation of lipid bodies during pollen maturation is essential to pollen fitness and successful reproduction. Plastids are important sites of plant metabolism including fatty acid and starch biosynthesis. At present, how the activities in the plastids are coordinated with those in the cytoplasm and the signaling pathway(s) involved are largely unknown. Previously, we demonstrated that WRKY2 and WRKY34 transcription factors play an essential role in pollen development downstream of mitogen-activated protein kinase 3 (MPK3) and MPK6 in Arabidopsis. Here, we report that GLUCOSE-6-PHOSPHATE/PHOSPHATE TRANSLOCATOR 1 (GPT1) is a key target gene of WRKY2/WRKY34. GPT1 is localized on the membrane of plastids and transports glucose-6-phosphate (Glc6P) into plastids for starch and/or fatty acid biosynthesis depending on the plant species. Genetic analyses demonstrated that WRKY2/WRKY34 and their upstream MPK3/MPK6 are involved in regulating GPT1 expression, therefore, the accumulation of lipid bodies in mature pollen, which is critical to pollen viability, pollen germination, pollen tube growth, and male transmission in Arabidopsis. This study revealed a cytoplasmic/nuclear signaling pathway capable of coordinating the metabolic activities in plastids. High-level expression of GPT1 at late stages of pollen development drives Glc6P from cytosol into plastids, where Glc6P is used for fatty acid biosynthesis, an important step of lipid body biogenesis. The accumulation of lipid bodies during pollen maturation is essential to pollen fitness and successful reproduction.
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Affiliation(s)
- Yueping Zheng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiangxiong Deng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Aili Qu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Mengmeng Zhang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yuan Tao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Liuyi Yang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yidong Liu
- Division of Biochemistry, Interdisciplinary Plant Group, Bond Life Sciences Center, University of Missouri, Columbia, MO, United States of America
| | - Juan Xu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- * E-mail: (JX); (SZ)
| | - Shuqun Zhang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- Division of Biochemistry, Interdisciplinary Plant Group, Bond Life Sciences Center, University of Missouri, Columbia, MO, United States of America
- * E-mail: (JX); (SZ)
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Fan M, Zhang C, Shi L, Liu C, Ma W, Chen M, Liu K, Cai F, Wang G, Wei Z, Jiang M, Liu Z, Javeed A, Lin F. ZmSTK1 and ZmSTK2, encoding receptor-like cytoplasmic kinase, are involved in maize pollen development with additive effect. PLANT BIOTECHNOLOGY JOURNAL 2018; 16:1402-1414. [PMID: 29327510 PMCID: PMC6041449 DOI: 10.1111/pbi.12880] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 12/26/2017] [Accepted: 01/05/2018] [Indexed: 05/11/2023]
Abstract
Pollen germination and pollen tube growth are important physiological processes of sexual reproduction of plants and also are involved in signal transduction. Our previous study reveals that ZmSTK1 and ZmSTK2 are two receptor-like cytoplasmic kinases (RLCK) homologs in Zea mays as members of receptor-like protein kinase (RLK) subfamily, sharing 86% identity at the amino acid level. Here, we report that ZmSTK1 and ZmSTK2, expressed at late stages of pollen development, regulate maize pollen development with additive effect. ZmSTK1 or ZmSTK2 mutation exhibited severe pollen transmission deficiency, which thus influenced pollen fertility. Moreover, the kinase domains of ZmSTKs were cross-interacted with C-terminus of enolases detected by co-immunoprecipitation (Co-IP) and yeast two-hybrid system (Y2H), respectively. Further, the detective ZmSTK1 or ZmSTK2 was associated with decreased activity of enolases and also reduced downstream metabolite contents, which enolases are involved in glycolytic pathway, such as phosphoenolpyruvate (PEP), pyruvate, ADP/ATP, starch, glucose, sucrose and fructose. This study reveals that ZmSTK1 and ZmSTK2 regulate maize pollen development and indirectly participate in glycolytic pathway.
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Affiliation(s)
- Mingxia Fan
- College of Bioscience and BiotechnologyShenyang Agricultural UniversityShenyangLiaoningChina
| | - Chunyu Zhang
- College of Bioscience and BiotechnologyShenyang Agricultural UniversityShenyangLiaoningChina
| | - Lei Shi
- Corn Research InstituteLiaoning Academy of Agricultural SciencesShenyangLiaoningChina
| | - Chen Liu
- College of Bioscience and BiotechnologyShenyang Agricultural UniversityShenyangLiaoningChina
| | - Wenjuan Ma
- College of Bioscience and BiotechnologyShenyang Agricultural UniversityShenyangLiaoningChina
| | - Meiming Chen
- College of Bioscience and BiotechnologyShenyang Agricultural UniversityShenyangLiaoningChina
| | - Kuichen Liu
- College of Bioscience and BiotechnologyShenyang Agricultural UniversityShenyangLiaoningChina
| | - Fengchun Cai
- College of Bioscience and BiotechnologyShenyang Agricultural UniversityShenyangLiaoningChina
| | - Guohong Wang
- Corn Research InstituteLiaoning Academy of Agricultural SciencesShenyangLiaoningChina
| | - Zhengyi Wei
- Laboratory of Plant Bioreactor and Genetics EngineeringJilin Provincial Key Laboratory of Agricultural BiotechnologyAgro‐Biotechnology Research InstituteJilin Academy of Agricultural SciencesJilinChangchunChina
| | - Min Jiang
- Corn Research InstituteLiaoning Academy of Agricultural SciencesShenyangLiaoningChina
| | - Zaochang Liu
- Shanghai Agrobiological Gene CenterShanghai Academy of Agricultural SciencesShanghaiChina
| | - Ansar Javeed
- College of Bioscience and BiotechnologyShenyang Agricultural UniversityShenyangLiaoningChina
| | - Feng Lin
- College of Bioscience and BiotechnologyShenyang Agricultural UniversityShenyangLiaoningChina
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14
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Liu L. Ultramicroscopic examination of mature massulae of Habenaria arinaria (Orchidaceae). Micron 2015; 74:1-7. [PMID: 25910428 DOI: 10.1016/j.micron.2015.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 04/02/2015] [Accepted: 04/02/2015] [Indexed: 12/01/2022]
Abstract
The mature massula of H. arinaria was examined by means of transmission electron microscopy, with the aim to understand the nature of cohesion between grains, the accumulation of pollen storage reserves, and the behavior of the nucleus of the vegetative cell in this composite type of pollen. The massula was a union of a large number of polygonal pollen grains that were tightly linked together. The exine within the massula were highly simplified, consisting of a single layer of nexine-2, lacking tectum, bacula, and nexine-1, while all the four layers comprised the exine on the massula surface. The two layers of nexine-2 of adjacent grains fused into a seamless whole. Undoubtedly the fusion of the nexine-2 was the mechanism by which the grains of the massula were linked together. No starch grains, lipid bodies, or storage proteins were present in the mature massula, and so the composite pollen of this species belonged to a novel type with regard to storage reserves. The vegetative nucleus was not lobed and revealed a huge amount of highly condensed chromatin, indicating a quiescent status. The condensed status of the vegetative nuclei in this composite type of pollen system is in striking contrast to the highly decondensed status reported in the free type of pollen grains.
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Affiliation(s)
- Lin Liu
- School of Pharmacy, Linyi University, Linyi 276000, China.
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15
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Parra-Vega V, Corral-Martínez P, Rivas-Sendra A, Seguí-Simarro JM. Induction of Embryogenesis in Brassica Napus Microspores Produces a Callosic Subintinal Layer and Abnormal Cell Walls with Altered Levels of Callose and Cellulose. FRONTIERS IN PLANT SCIENCE 2015; 6:1018. [PMID: 26635844 PMCID: PMC4658426 DOI: 10.3389/fpls.2015.01018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 11/04/2015] [Indexed: 05/05/2023]
Abstract
The induction of microspore embryogenesis produces dramatic changes in different aspects of the cell physiology and structure. Changes at the cell wall level are among the most intriguing and poorly understood. In this work, we used high pressure freezing and freeze substitution, immunolocalization, confocal, and electron microscopy to analyze the structure and composition of the first cell walls formed during conventional Brassica napus microspore embryogenesis, and in cultures treated to alter the intracellular Ca(2+) levels. Our results revealed that one of the first signs of embryogenic commitment is the formation of a callose-rich, cellulose-deficient layer beneath the intine (the subintinal layer), and of irregular, incomplete cell walls. In these events, Ca(2+) may have a role. We propose that abnormal cell walls are due to a massive callose synthesis and deposition of excreted cytoplasmic material, and the parallel inhibition of cellulose synthesis. These features were absent in pollen-like structures and in microspore-derived embryos, few days after the end of the heat shock, where abnormal cell walls were no longer produced. Together, our results provide an explanation to a series of relevant aspects of microspore embryogenesis including the role of Ca(2+) and the occurrence of abnormal cell walls. In addition, our discovery may be the explanation to why nuclear fusions take place during microspore embryogenesis.
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16
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Borg M, Rutley N, Kagale S, Hamamura Y, Gherghinoiu M, Kumar S, Sari U, Esparza-Franco MA, Sakamoto W, Rozwadowski K, Higashiyama T, Twell D. An EAR-Dependent Regulatory Module Promotes Male Germ Cell Division and Sperm Fertility in Arabidopsis. THE PLANT CELL 2014; 26:2098-2113. [PMID: 24876252 PMCID: PMC4079371 DOI: 10.1105/tpc.114.124743] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The production of the sperm cells in angiosperms requires coordination of cell division and cell differentiation. In Arabidopsis thaliana, the germline-specific MYB protein DUO1 integrates these processes, but the regulatory hierarchy in which DUO1 functions is unknown. Here, we identify an essential role for two germline-specific DUO1 target genes, DAZ1 and DAZ2, which encode EAR motif-containing C2H2-type zinc finger proteins. We show that DAZ1/DAZ2 are required for germ cell division and for the proper accumulation of mitotic cyclins. Importantly, DAZ1/DAZ2 are sufficient to promote G2- to M-phase transition and germ cell division in the absence of DUO1. DAZ1/DAZ2 are also required for DUO1-dependent cell differentiation and are essential for gamete fusion at fertilization. We demonstrate that the two EAR motifs in DAZ1/DAZ2 mediate their function in the male germline and are required for transcriptional repression and for physical interaction with the corepressor TOPLESS. Our findings uncover an essential module in a regulatory hierarchy that drives mitotic transition in male germ cells and implicates gene repression pathways in sperm cell formation and fertility.
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Affiliation(s)
- Michael Borg
- Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Nicholas Rutley
- Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Sateesh Kagale
- Agriculture and Agri-Food Canada, Saskatoon SK S7N OX2, Canada
| | - Yuki Hamamura
- JST, ERATO, Higashiyama Live-Holonics Project, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
| | - Mihai Gherghinoiu
- Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Sanjeev Kumar
- Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Ugur Sari
- Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
| | | | - Wataru Sakamoto
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan
| | | | - Tetsuya Higashiyama
- JST, ERATO, Higashiyama Live-Holonics Project, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
| | - David Twell
- Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
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17
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Evolutionarily conserved mechanisms of male germline development in flowering plants and animals. Biochem Soc Trans 2014; 42:377-82. [DOI: 10.1042/bst20130261] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Sexual reproduction is the main reproductive strategy of the overwhelming majority of eukaryotes. This suggests that the last eukaryotic common ancestor was able to reproduce sexually. Sexual reproduction reflects the ability to perform meiosis, and ultimately generating gametes, which are cells that carry recombined half sets of the parental genome and are able to fertilize. These functions have been allocated to a highly specialized cell lineage: the germline. Given its significant evolutionary conservation, it is to be expected that the germline programme shares common molecular bases across extremely divergent eukaryotic species. In the present review, we aim to identify the unifying principles of male germline establishment and development by comparing two very disparate kingdoms: plants and animals. We argue that male meiosis defines two temporally regulated gene expression programmes: the first is required for meiotic commitment, and the second is required for the acquisition of fertilizing ability. Small RNA pathways are a further key communality, ultimately ensuring the epigenetic stability of the information conveyed by the male germline.
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18
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Daghma DES, Hensel G, Rutten T, Melzer M, Kumlehn J. Cellular dynamics during early barley pollen embryogenesis revealed by time-lapse imaging. FRONTIERS IN PLANT SCIENCE 2014; 5:675. [PMID: 25538715 PMCID: PMC4259004 DOI: 10.3389/fpls.2014.00675] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 11/12/2014] [Indexed: 05/10/2023]
Abstract
Plants display a remarkable capacity for cellular totipotency. An intriguing and useful example is that immature pollen cultured in vitro can pass through embryogenic development to form haploid or doubled haploid plants. However, a lack of understanding the initial mechanisms of pollen embryogenesis hampers the improvement and more effective and widespread employment of haploid technology in plant research and breeding. To investigate the cellular dynamics during the onset of pollen embryogenesis, we used time-lapse imaging along with transgenic barley expressing nuclear localized Green Fluorescent Protein. The results enabled us to identify nine distinct embryogenic and non-embryogenic types of pollen response to the culture conditions. Cell proliferation in embryogenic pollen normally started via a first symmetric mitosis (54.3% of pollen observed) and only rarely did so via asymmetric pollen mitosis I (4.3% of pollen observed). In the latter case, proliferation generally originated from the vegetative-like cell, albeit the division of the generative-like cell was observed in few types of pollen. Under the culture conditions used, fusion of cell nuclei was the only mechanism of genome duplication observed.
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Affiliation(s)
- Diaa Eldin S. Daghma
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
- Department of National Gene Bank and Genetic Resources, Agriculture Research CenterGiza, Egypt
| | - Goetz Hensel
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
| | - Twan Rutten
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
| | - Michael Melzer
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
| | - Jochen Kumlehn
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant ResearchGatersleben, Germany
- *Correspondence: Jochen Kumlehn, Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Correnstr 3, Gatersleben 06466, Germany e-mail:
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19
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Tanaka Y, Nishimura K, Kawamukai M, Oshima A, Nakagawa T. Redundant function of two Arabidopsis COPII components, AtSec24B and AtSec24C, is essential for male and female gametogenesis. PLANTA 2013; 238:561-75. [PMID: 23779001 DOI: 10.1007/s00425-013-1913-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 06/05/2013] [Indexed: 05/08/2023]
Abstract
Anterograde vesicle transport from the endoplasmic reticulum to the Golgi apparatus is the start of protein transport through the secretory pathway, in which the transport is mediated by coat protein complex II (COPII)-coated vesicles. Therefore, most proteins synthesized on the endoplasmic reticulum are loaded as cargo into COPII vesicles. The COPII is composed of the small GTPase Sar1 and two types of protein complexes (Sec23/24 and Sec13/31). Of these five COPII components, Sec24 is thought to recognize cargo that is incorporated into COPII vesicles by directly interacting with the cargo. The Arabidopsis genome encodes three types of Sec24 homologs (AtSec24A, AtSec24B, and AtSec24C). The subcellular dynamics and function of AtSec24A have been characterized. The intracellular distributions and functions of other AtSec24 proteins are not known, and the functional differences among the three AtSec24s remain unclear. Here, we found that all three AtSec24s were expressed in similar parts of the plant body and showed the same subcellular localization pattern. AtSec24B knockout plant, but not AtSec24C knockdown plant, showed mild male sterility with reduction of pollen germination. Significant decrease of AtSec24B and AtSec24C expression affected male and female gametogenesis in Arabidopsis thaliana. Our results suggested that the redundant function of AtSec24B and AtSec24C is crucial for the development of plant reproductive cells. We propose that the COPII transport is involved in male and female gametogenesis in planta.
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Affiliation(s)
- Yuji Tanaka
- Department of Molecular and Functional Genomics, Center for Integrated Research in Science, Shimane University, Nishikawatsu 1060, Matsue, 690-8504, Japan
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20
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Jiang J, Zhang Z, Cao J. Pollen wall development: the associated enzymes and metabolic pathways. PLANT BIOLOGY (STUTTGART, GERMANY) 2013; 15:249-63. [PMID: 23252839 DOI: 10.1111/j.1438-8677.2012.00706.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Accepted: 10/22/2012] [Indexed: 05/18/2023]
Abstract
Pollen grains are surrounded by a sculpted wall, which protects male gametophytes from various environmental stresses and microbial attacks, and also facilitates pollination. Pollen wall development requires lipid and polysaccharide metabolism, and some key genes and proteins that participate in these processes have recently been identified. Here, we summarise the genes and describe their functions during pollen wall development via several metabolic pathways. A working model involving substances and catalytic enzyme reactions that occur during pollen development is also presented. This model provides information on the complete process of pollen wall development with respect to metabolic pathways.
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Affiliation(s)
- J Jiang
- Laboratory of Cell & Molecular Biology, Institute of Vegetable Science, Zhejiang University, Hangzhou, China
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21
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Forsthoefel NR, Dao TP, Vernon DM. PIRL1 and PIRL9, encoding members of a novel plant-specific family of leucine-rich repeat proteins, are essential for differentiation of microspores into pollen. PLANTA 2010; 232:1101-1114. [PMID: 20697737 DOI: 10.1007/s00425-010-1242-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Accepted: 07/26/2010] [Indexed: 05/29/2023]
Abstract
Plant intracellular Ras-group-related leucine-rich repeat proteins (PIRLs) are a plant-specific class of leucine-rich repeat (LRR) proteins related to animal and fungal LRRs that take part in developmental signaling and gene regulation. As part of a systematic functional study of the Arabidopsis thaliana PIRL gene family, T-DNA knockout mutants defective in the closely related PIRL1 and PIRL9 genes were identified and characterized. Pirl1 and pirl9 single mutants displayed normal transmission and did not exhibit an obvious developmental phenotype. To investigate the possibility of functional redundancy, crosses to generate double mutants were carried out; however, pirl1;pirl9 plants were not recovered. Reciprocal crosses between wild type and pirl1/PIRL1;pirl9 plants, which produce 50% pirl1;pirl9 gametophytes, indicated male-specific transmission failure of the double-mutant allele combination. Scanning electron microscopy and viability staining showed that approximately half of the pollen produced by pirl1/PIRL1;pirl9 plants was inviable and severely malformed. Tetrad analyses with qrt1 indicated that pollen defects segregated with the double-mutant allele combination, thus demonstrating that PIRL1 and PIRL9 function after meiosis. Pollen development was characterized with bright field, fluorescence, and transmission electron microscopy. Pirl1;pirl9 mutants stopped growing as microspores, failed to initiate vacuolar fission, aborted, and underwent cytoplasmic degeneration. Development consistently arrested at the late microspore stage, just prior to pollen mitosis I. Thus, PIRL1 and PIRL9 have redundant roles essential at a key transition point early in pollen development. Together, these results define a functional context for these two members of this distinct class of plant LRR genes.
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22
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Backues SK, Korasick DA, Heese A, Bednarek SY. The Arabidopsis dynamin-related protein2 family is essential for gametophyte development. THE PLANT CELL 2010; 22:3218-31. [PMID: 20959563 PMCID: PMC2990125 DOI: 10.1105/tpc.110.077727] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2010] [Revised: 08/20/2010] [Accepted: 09/27/2010] [Indexed: 05/20/2023]
Abstract
Clathrin-mediated membrane trafficking is critical for multiple stages of plant growth and development. One key component of clathrin-mediated trafficking in animals is dynamin, a polymerizing GTPase that plays both regulatory and mechanical roles. Other eukaryotes use various dynamin-related proteins (DRP) in clathrin-mediated trafficking. Plants are unique in the apparent involvement of both a family of classical dynamins (DRP2) and a family of dynamin-related proteins (DRP1) in clathrin-mediated membrane trafficking. Our analysis of drp2 insertional mutants demonstrates that, similar to the DRP1 family, the DRP2 family is essential for Arabidopsis thaliana development. Gametophytes lacking both DRP2A and DRP2B were inviable, arresting prior to the first mitotic division in both male and female gametogenesis. Mutant pollen displayed a variety of defects, including branched or irregular cell plates, altered Golgi morphology and ectopic callose deposition. Ectopic callose deposition was also visible in the pollen-lethal drp1c-1 mutant and appears to be a specific feature of pollen-defective mutants with impaired membrane trafficking. However, drp2ab pollen arrested at earlier stages in development than drp1c-1 pollen and did not accumulate excess plasma membrane or display other gross defects in plasma membrane morphology. Therefore, the DRP2 family, but not DRP1C, is necessary for cell cycle progression during early gametophyte development. This suggests a possible role for DRP2-dependent clathrin-mediated trafficking in the transduction of developmental signals in the gametophyte.
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Affiliation(s)
- Steven K. Backues
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - David A. Korasick
- Division of Biochemistry, Interdisciplinary Plant Group, University of Missouri, Columbia, Missouri 65211
| | - Antje Heese
- Division of Biochemistry, Interdisciplinary Plant Group, University of Missouri, Columbia, Missouri 65211
| | - Sebastian Y. Bednarek
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
- Address correspondence to
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23
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Xie B, Wang X, Hong Z. Precocious pollen germination in Arabidopsis plants with altered callose deposition during microsporogenesis. PLANTA 2010; 231:809-23. [PMID: 20039178 DOI: 10.1007/s00425-009-1091-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Accepted: 12/14/2009] [Indexed: 05/22/2023]
Abstract
Pollination is essential for seed reproduction and for exchanges of genetic information between individual plants. In angiosperms, mature pollen grains released from dehisced anthers are transferred to the stigma where they become hydrated and begin to germinate. Pollen grains of wild-type Arabidopsis thaliana do not germinate inside the anther under normal growth conditions. We report two Arabidopsis lines that produced pollen grains able to in situ precociously germinate inside the anther. One of them was a callose synthase 9 (cs9) knockout mutant with a T-DNA insertion in the Callose Synthase 9 gene (CalS9). Male gametophytes carrying a cs9 mutant allele were defective and no homozygous progeny could be produced. Heterozygous mutant plants (cs9/+) produced approximately 50% defective pollen grains with an altered male germ unit (MGU) and aberrant callose deposition in bicellular pollen. Bicellular pollen grains germinated precociously inside the anther. Another line, a transgenic plant expressing callose synthase 5 (CalS5) under the CaMV 35S promoter, also contained abnormal callose deposition during microsporogenesis and displaced MGUs in pollen grains. We also observed that precocious pollen germination could be induced in wild-type plants by incubation with medium containing sucrose and calcium ion and by wounding in the anther. These results demonstrate that precocious pollen germination in Arabidopsis could be triggered by a genetic alteration and a physiological condition.
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Affiliation(s)
- Bo Xie
- Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, ID 83844-3052, USA
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24
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Li T, Gong C, Wang T. RA68 is required for postmeiotic pollen development in Oryza sativa. PLANT MOLECULAR BIOLOGY 2010; 72:265-277. [PMID: 19888555 DOI: 10.1007/s11103-009-9566-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 10/25/2009] [Indexed: 05/27/2023]
Abstract
Postmeiotic development is a unique characteristic of flowering plants. During the development, microspores undergo two cycles of mitosis (PMI and PMII) and a subsequent maturation process to finally produce the mature pollen, but the mechanism underlying the development is still largely unknown. Here, we report on the roles of a novel gene, RA68, in postmeiotic pollen development in Oryza sativa. RA68 was expressed preferentially in shoots and flowers. In flowers, the transcript persisted from the floral organ differentiation to the mature pollen stages and showed preferential accumulation in male meiocytes, developing pollen and tapetal cells. RA68-deficient RNAi lines showed reduced seed setting and pollen viability but not an aberrant phenotype in vegetative organs. Knockdown of RA68 led to arrested PMI, smaller pollen grains with little or no starch, and aborted pollen but not severely distruped male meiosis. Additionally, no abnormality of anther wall development was observed in RA68-RNAi lines. RA68 may be required for postmeiotic pollen development by affecting PMI and starch accumulation.
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Affiliation(s)
- Tang Li
- Research Center of Molecular and Developmental Biology, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Haidianqu, Beijing, 100093, China
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Oh SA, Pal MD, Park SK, Johnson JA, Twell D. The tobacco MAP215/Dis1-family protein TMBP200 is required for the functional organization of microtubule arrays during male germline establishment. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:969-81. [PMID: 20022922 PMCID: PMC2826647 DOI: 10.1093/jxb/erp367] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 11/09/2009] [Accepted: 11/18/2009] [Indexed: 05/19/2023]
Abstract
The haploid microspore division during pollen development in flowering plants is an intrinsically asymmetric division which establishes the male germline for sexual reproduction. Arabidopsis gem1 mutants lack the male germline as a result of disturbed microspore polarity, division asymmetry, and cytokinesis and represent loss-of-function mutants in MOR1/GEM1, a plant orthologue of the conserved MAP215/Dis1 microtubule associated protein (MAP) family. This provides genetic evidence for the role of MAP215/Dis1 in the organization of gametophytic microtubule arrays, but it has remained unknown how microtubule arrays are affected in gem1 mutant microspores. Here, novel male gametophytic microtubule-reporter Nicotiana tabacum plants were constructed, expressing a green fluorescent protein-alpha-TUBULIN fusion protein (GFP-TUA6) under the control of a microspore-specific promoter. These plants allow effective visualization of all major male gametophytic microtubule arrays and provide useful tools to study the regulation of microtubule arrays by MAPs and other effectors. Depletion of TMBP200, a tobacco homologue of MOR1/GEM1 in gametophytic microtubule-reporter plants using microspore-targeted RNA interference, induced defects in microspore polarity, division asymmetry and cytokinesis that were associated with striking defects in phragmoplast position, orientation, and structure. Our observations further reveal a requirement for TMBP200 in gametophytic spindle organization and a novel role in spindle position and orientation in polarized microspores. These results provide direct evidence for the function of MAP215/Dis1 family protein TMBP200 in the organization of microtubule arrays critical for male germline formation in plants.
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Affiliation(s)
- Sung Aeong Oh
- Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
- Division of Plant Biosciences, Kyungpook National University, Daegu 702-701, South Korea
| | - Madhumita Das Pal
- Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - Soon Ki Park
- Division of Plant Biosciences, Kyungpook National University, Daegu 702-701, South Korea
| | - James Andrew Johnson
- Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - David Twell
- Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
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Zhang M, Fan J, Taylor DC, Ohlrogge JB. DGAT1 and PDAT1 acyltransferases have overlapping functions in Arabidopsis triacylglycerol biosynthesis and are essential for normal pollen and seed development. THE PLANT CELL 2009; 21:3885-901. [PMID: 20040537 PMCID: PMC2814504 DOI: 10.1105/tpc.109.071795] [Citation(s) in RCA: 341] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2009] [Revised: 11/20/2009] [Accepted: 12/11/2009] [Indexed: 05/15/2023]
Abstract
Triacylglycerol (TAG) biosynthesis is a principal metabolic pathway in most organisms, and TAG is the major form of carbon storage in many plant seeds. Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is the only acyltransferase enzyme that has been confirmed to contribute to TAG biosynthesis in Arabidopsis thaliana seeds. However, dgat1 null mutants display only a 20 to 40% decrease in seed oil content. To determine whether other enzymes contribute to TAG synthesis, candidate genes were expressed in TAG-deficient yeast, candidate mutants were crossed with the dgat1-1 mutant, and target genes were suppressed by RNA interference (RNAi). An in vivo role for phospholipid:diacylglycerol acyltransferase 1 (PDAT1; At5g13640) in TAG synthesis was revealed in this study. After failing to obtain double homozygous plants from crossing dgat1-1 and pdat1-2, further investigation showed that the dgat1-1 pdat1-2 double mutation resulted in sterile pollen that lacked visible oil bodies. RNAi silencing of PDAT1 in a dgat1-1 background or DGAT1 in pdat1-1 background resulted in 70 to 80% decreases in oil content per seed and in disruptions of embryo development. These results establish in vivo involvement of PDAT1 in TAG biosynthesis, rule out major contributions by other candidate enzymes, and indicate that PDAT1 and DGAT1 have overlapping functions that are essential for normal pollen and seed development of Arabidopsis.
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Affiliation(s)
- Meng Zhang
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Jilian Fan
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - David C. Taylor
- National Research Council of Canada, Plant Biotechnology Institute, Saskatoon S7N 0W9, Canada
| | - John B. Ohlrogge
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
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Dinis AM, Coutinho AP. Interaction of lipid bodies with other cell organelles in the maturing pollen of Magnolia x soulangeana (Magnoliaceae). PROTOPLASMA 2009; 238:35-46. [PMID: 19763782 DOI: 10.1007/s00709-009-0071-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 08/27/2009] [Indexed: 05/28/2023]
Abstract
The pollen grain maturation in Magnolia x soulangeana was studied ultrastructurally and cytochemically using both the light and transmission electron microscope. Emphasis was given on the storage lipid bodies of the vegetative cell (VC) and their interaction with other cell organelles. Stereological analysis of electron micrographs was performed to evaluate the variation in volume density (V(V)), surface density, and surface-to-volume ratio (S/V) of various cell organelles during pollen maturation. The size and numerical density of the lipid bodies, and their frequency of association with other cell organelles, were also determined. It was noted that during pollen ontogeny and maturation, the lipid bodies changed their pattern of distribution in the VC cytoplasm, which may be a good marker for the succeeding stages of pollen development. Also, the size, osmiophily, and V(V) of the lipid bodies were progressively reduced during pollen maturation whereas the S/V was significantly increased. This seems to indicate that the lipid bodies are mobilized in part during this period of pollen maturation. In particular, the intermediate and mature pollen showed a high percentage of lipid bodies establishing a physical contact with either glyoxysomes, either protein storage vacuoles, or small vesicles presumably originated from dictyosomes. This physical contact was found in both the chemically fixed and rapid freeze-fixed pollen indicating that it is neither artifactual nor casual. On the basis of this intimate association with other cell organelles and the morphometric analysis performed, we suggest that the mobilization of lipid bodies is likely mediated not only by glyoxysomes but also by other catabolic pathways involving the interaction of lipid bodies with either protein storage vacuoles or small Golgi vesicles.
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Affiliation(s)
- Augusto M Dinis
- Laboratory of Electron Microscopy and Palynology, and Center for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
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Brownfield L, Hafidh S, Durbarry A, Khatab H, Sidorova A, Doerner P, Twell D. Arabidopsis DUO POLLEN3 is a key regulator of male germline development and embryogenesis. THE PLANT CELL 2009; 21:1940-56. [PMID: 19638475 PMCID: PMC2729611 DOI: 10.1105/tpc.109.066373] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 06/19/2009] [Accepted: 07/14/2009] [Indexed: 05/19/2023]
Abstract
Male germline development in angiosperms produces the pair of sperm cells required for double fertilization. A key regulator of this process in Arabidopsis thaliana is the male germline-specific transcription factor DUO POLLEN1 (DUO1) that coordinates germ cell division and gamete specification. Here, we uncover the role of DUO3, a nuclear protein that has a distinct, but overlapping role with DUO1 in male germline development. DUO3 is a conserved protein in land plants and is related to GON-4, a cell lineage regulator of gonadogenesis in Caenorhabditis elegans. Mutant duo3-1 germ cells either fail to divide or show a delay in division, and we show that, unlike DUO1, DUO3 promotes entry into mitosis independent of the G2/M regulator CYCB1;1. We also show that DUO3 is required for the expression of a subset of germline genes under DUO1 control and that like DUO1, DUO3 is essential for sperm cell specification and fertilization. Furthermore, we demonstrate an essential sporophytic role for DUO3 in cell division and embryo patterning. Our findings demonstrate essential developmental roles for DUO3 in cell cycle progression and cell specification in both gametophytic and sporophytic tissues.
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Affiliation(s)
- Lynette Brownfield
- Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
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Zeng CJT, Lee YRJ, Liu B. The WD40 repeat protein NEDD1 functions in microtubule organization during cell division in Arabidopsis thaliana. THE PLANT CELL 2009; 21:1129-40. [PMID: 19383896 PMCID: PMC2685624 DOI: 10.1105/tpc.109.065953] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2009] [Revised: 03/27/2009] [Accepted: 04/08/2009] [Indexed: 05/23/2023]
Abstract
Although cells of flowering plants lack a structurally defined microtubule-organizing center like the centrosome, organization of the spindles and phragmoplasts in mitosis is known to involve the evolutionarily conserved gamma-tubulin complex. We have investigated the function of Arabidopsis thaliana NEDD1, a WD40 repeat protein related to the animal NEDD1/GCP-WD protein, which interacts with the gamma-tubulin complex. The NEDD1 protein decorates spindle microtubules (MTs) preferentially toward spindle poles and phragmoplast MTs toward their minus ends. A T-DNA insertional allele of the single NEDD1 gene was isolated and maintained in heterozygous sporophytes, and NEDD1's function in cell division was analyzed in haploid microspores produced by the heterozygote. In approximately half of the dividing microspores exhibiting aberrant MT organization, spindles were no longer restricted to the cell periphery and became abnormally elongated. After mitosis, MTs aggregated between reforming nuclei but failed to appear in a bipolar configuration. Consequently, defective microspores did not form a continuous cell plate, and two identical nuclei were produced with no differentiation into generative and vegetative cells. Our results support the notion that the plant NEDD1 homolog plays a critical role in MT organization during mitosis, and its function is likely linked to that of the gamma-tubulin complex.
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Affiliation(s)
- C J Tracy Zeng
- Department of Plant Biology, University of California, Davis, California 95616, USA
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Kim HJ, Oh SA, Brownfield L, Hong SH, Ryu H, Hwang I, Twell D, Nam HG. Control of plant germline proliferation by SCF(FBL17) degradation of cell cycle inhibitors. Nature 2008; 455:1134-7. [PMID: 18948957 DOI: 10.1038/nature07289] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Accepted: 07/24/2008] [Indexed: 01/23/2023]
Abstract
Flowering plants possess a unique reproductive strategy, involving double fertilization by twin sperm cells. Unlike animal germ lines, the male germ cell lineage in plants only forms after meiosis and involves asymmetric division of haploid microspores, to produce a large, non-germline vegetative cell and a germ cell that undergoes one further division to produce the twin sperm cells. Although this switch in cell cycle control is critical for sperm cell production and delivery, the underlying molecular mechanisms are unknown. Here we identify a novel F-box protein of Arabidopsis thaliana, designated FBL17 (F-box-like 17), that enables this switch by targeting the degradation of cyclin-dependent kinase A;1 inhibitors specifically in male germ cells. We show that FBL17 is transiently expressed in the male germ line after asymmetric division and forms an SKP1-Cullin1-F-box protein (SCF) E3 ubiquitin ligase complex (SCF(FBL17)) that targets the cyclin-dependent kinase inhibitors KRP6 and KRP7 for proteasome-dependent degradation. Accordingly, the loss of FBL17 function leads to the stabilization of KRP6 and inhibition of germ cell cycle progression. Our results identify SCF(FBL17) as an essential male germ cell proliferation complex that promotes twin sperm cell production and double fertilization in flowering plants.
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Affiliation(s)
- Hyo Jung Kim
- Division of Molecular Life Sciences, Pohang University of Science and Technology, Pohang 790-784, South Korea
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Oh SA, Bourdon V, Das 'Pal M, Dickinson H, Twell D. Arabidopsis kinesins HINKEL and TETRASPORE act redundantly to control cell plate expansion during cytokinesis in the male gametophyte. MOLECULAR PLANT 2008; 1:794-9. [PMID: 19825582 DOI: 10.1093/mp/ssn042] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Asymmetric cell division at pollen mitosis I (PMI) is required to specify the differential fate of the daughter vegetative and generative cells. Cytokinesis at PMI displays specialized features, and it has been suggested that there might be distinct molecular pathways underpinning different modes of cytokinesis in plants. Activation of the NACK-PQR MAP kinase signaling pathway, which is essential for somatic cell cytokinesis in tobacco, depends upon the NACK1 and NACK2 kinesin-related proteins. Their Arabidopsis orthologs, HINKEL (HIK) and TETRASPORE (TES), were reported to be essential for cytokinesis in somatic cells and in microsporocytes, respectively. More recently, HIK and TES were shown to have a functionally redundant role in female gametophytic cytokinesis. We report here that HIK and TES are co-expressed in microspores and developing pollen, and, through analysis of microspore and pollen development in double heterozygote mutants, the occurrence of cell plate expansion defects during cytokinesis at PMI. The data demonstrate a functionally redundant role for HIK and TES in cell plate expansion during male gametophytic cytokinesis, extending the concept that different modes of cytokinesis are executed by a common signaling pathway, but reinforcing the individuality of gametophytic cytokinesis in its requirement for either TES or HIK.
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Affiliation(s)
- Sung-Aeong Oh
- Department of Biology, University of Leicester, Leicester LE1 7RH, UK
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Verelst W, Twell D, de Folter S, Immink R, Saedler H, Münster T. MADS-complexes regulate transcriptome dynamics during pollen maturation. Genome Biol 2008; 8:R249. [PMID: 18034896 PMCID: PMC2258202 DOI: 10.1186/gb-2007-8-11-r249] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 10/15/2007] [Accepted: 11/22/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Differentiation processes are responsible for the diversity and functional specialization of the cell types that compose an organism. The outcome of these processes can be studied at molecular, physiologic, and biochemical levels by comparing different cell types, but the complexity and dynamics of the regulatory processes that specify the differentiation are largely unexplored. RESULTS Here we identified the pollen-specific MIKC* class of MADS-domain transcription factors as major regulators of transcriptome dynamics during male reproductive cell development in Arabidopsis thaliana. Pollen transcript profiling of mutants deficient in different MIKC* protein complexes revealed that they control a transcriptional switch that directs pollen maturation and that is essential for pollen competitive ability. We resolved the functional redundancy among the MIKC* proteins and uncovered part of the underlying network by identifying the non-MIKC* MADS-box genes AGL18 and AGL29 as downstream regulators of a subset of the MIKC* MADS-controlled genes. CONCLUSION Our results provide a first, unique, and compelling insight into the complexity of a transcription factor network that directs cellular differentiation during pollen maturation, a process that is essential for male reproductive fitness in flowering plants.
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Affiliation(s)
- Wim Verelst
- Department of Molecular Plant Genetics, Max-Planck-Institute for Plant Breeding Research, Carl-von-Linné-Weg, 50829 Cologne, Germany.
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Liu J, Qu LJ. Meiotic and mitotic cell cycle mutants involved in gametophyte development in Arabidopsis. MOLECULAR PLANT 2008; 1:564-74. [PMID: 19825562 DOI: 10.1093/mp/ssn033] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The alternation between diploid and haploid generations is fundamental in the life cycles of both animals and plants. The meiotic cell cycle is common to both animals and plants gamete formation, but in animals the products of meiosis are gametes, whereas for most plants, subsequent mitotic cell cycles are needed for their formation. Clarifying the regulatory mechanisms of mitotic cell cycle progression during gametophyte development will help understanding of sexual reproduction in plants. Many mutants defective in gametophyte development and, in particular, many meiotic and mitotic cell cycle mutants in Arabidopsis male and female gametophyte development were identified through both forward and reverse genetics approaches.
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Affiliation(s)
- Jingjing Liu
- National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
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Töller A, Brownfield L, Neu C, Twell D, Schulze-Lefert P. Dual function of Arabidopsis glucan synthase-like genes GSL8 and GSL10 in male gametophyte development and plant growth. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 54:911-23. [PMID: 18315544 DOI: 10.1111/j.1365-313x.2008.03462.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Members of the glucan synthase-like (GSL) family are believed to be involved in synthesis of the cell-wall component callose in specialized locations throughout the plant. We identified two members of the Arabidopsis GSL gene family, GSL8 and GSL10, that are independently required for male gametophyte development and plant growth. Analysis of gsl8 and gsl10 mutant pollen during development revealed specific malfunctions associated with asymmetric microspore division. GSL8 and GSL10 are not essential for normal microspore growth and polarity, but play a role in entry of microspores into mitosis. Impaired function of GSL10 also leads to perturbation of microspore division symmetry, irregular callose deposition and failure of generative-cell engulfment by the cytoplasm of the vegetative cell. Silencing of GSL8 or GSL10 in transgenic lines expressing gene-specific dsRNAi constructs resulted in a dwarfed growth habit, thereby revealing additional and independent wild-type gene functions for normal plant growth.
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Affiliation(s)
- Armin Töller
- Department of Plant-Microbe Interactions, Max-Planck-Institut für Züchtungsforschung, Carl-von-Linné-Weg 10, D-50829 Köln, Germany
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Seguí-Simarro J, Nuez F. Pathways to doubled haploidy: chromosome doubling during androgenesis. Cytogenet Genome Res 2008; 120:358-69. [DOI: 10.1159/000121085] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2007] [Indexed: 01/04/2023] Open
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Backues SK, Konopka CA, McMichael CM, Bednarek SY. Bridging the divide between cytokinesis and cell expansion. CURRENT OPINION IN PLANT BIOLOGY 2007; 10:607-15. [PMID: 17936678 DOI: 10.1016/j.pbi.2007.08.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Revised: 08/15/2007] [Accepted: 08/23/2007] [Indexed: 05/14/2023]
Abstract
Two of the most fundamental processes in plant development are cytokinesis, by which new cells are formed, and cell expansion, by which existing cells grow and establish their functional morphology. In this review we summarize recent progress in understanding the pathways necessary for cytokinesis and cell expansion, including the role of the cytoskeleton, cell wall biogenesis, and membrane trafficking. Here, we focus on genes and lipids that are involved in both cytokinesis and cell expansion and bridge the divide between these two processes. In addition, we discuss our understanding of and controversies surrounding the role of endocytosis in both of these processes.
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Affiliation(s)
- Steven K Backues
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
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Lee YRJ, Li Y, Liu B. Two Arabidopsis phragmoplast-associated kinesins play a critical role in cytokinesis during male gametogenesis. THE PLANT CELL 2007; 19:2595-605. [PMID: 17720869 PMCID: PMC2002617 DOI: 10.1105/tpc.107.050716] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
In plant cells, cytokinesis is brought about by the phragmoplast. The phragmoplast has a dynamic microtubule array of two mirrored sets of microtubules, which are aligned perpendicularly to the division plane with their plus ends located at the division site. It is not well understood how the phragmoplast microtubule array is organized. In Arabidopsis thaliana, two homologous microtubule motor kinesins, PAKRP1/Kinesin-12A and PAKRP1L/Kinesin-12B, localize exclusively at the juxtaposing plus ends of the antiparallel microtubules in the middle region of the phragmoplast. When either kinesin was knocked out by T-DNA insertions, mutant plants did not show a noticeable defect. However, in the absence of both kinesins, postmeiotic development of the male gametophyte was severely inhibited. In dividing microspores of the double mutant, microtubules often became disorganized following chromatid segregation and failed to form an antiparallel microtubule array between reforming nuclei. Consequently, the first postmeiotic cytokinesis was abolished without the formation of a cell plate, which led to failures in the birth of the generative cell and, subsequently, the sperm. Thus, our results indicate that Kinesin-12A and Kinesin-12B jointly play a critical role in the organization of phragmoplast microtubules during cytokinesis in the microspore that is essential for cell plate formation. Furthermore, we conclude that Kinesin-12 members serve as dynamic linkers of the plus ends of antiparallel microtubules in the phragmoplast.
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Affiliation(s)
- Yuh-Ru Julie Lee
- Section of Plant Biology, University of California, Davis, California 95616, USA
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38
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Footitt S, Dietrich D, Fait A, Fernie AR, Holdsworth MJ, Baker A, Theodoulou FL. The COMATOSE ATP-binding cassette transporter is required for full fertility in Arabidopsis. PLANT PHYSIOLOGY 2007; 144:1467-80. [PMID: 17468211 PMCID: PMC1914130 DOI: 10.1104/pp.107.099903] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
COMATOSE (CTS) encodes a peroxisomal ATP-binding cassette transporter required not only for beta-oxidation of storage lipids during germination and establishment, but also for biosynthesis of jasmonic acid and conversion of indole butyric acid to indole acetic acid. cts mutants exhibited reduced fertilization, which was rescued by genetic complementation, but not by exogenous application of jasmonic acid or indole acetic acid. Reduced fertilization was also observed in thiolase (kat2-1) and peroxisomal acyl-Coenzyme A synthetase mutants (lacs6-1,lacs7-1), indicating a general role for beta-oxidation in fertility. Genetic analysis revealed reduced male transmission of cts alleles and both cts pollen germination and tube growth in vitro were impaired in the absence of an exogenous carbon source. Aniline blue staining of pollinated pistils demonstrated that pollen tube growth was affected only when both parents bore the cts mutation, indicating that expression of CTS in either male or female tissues was sufficient to support pollen tube growth in vivo. Accordingly, abundant peroxisomes were detected in a range of maternal tissues. Although gamma-aminobutyric acid levels were reduced in flowers of cts mutants, they were unchanged in kat2-1, suggesting that alterations in gamma-aminobutyric acid catabolism do not contribute to the reduced fertility phenotype through altered pollen tube targeting. Taken together, our data support an important role for beta-oxidation in fertility in Arabidopsis (Arabidopsis thaliana) and suggest that this pathway could play a role in the mobilization of lipids in both pollen and female tissues.
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Affiliation(s)
- Steven Footitt
- Crop Performance and Improvement Division, Rothamsted Research, Harpenden, Hertfordshire, UK
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Drakakaki G, Zabotina O, Delgado I, Robert S, Keegstra K, Raikhel N. Arabidopsis reversibly glycosylated polypeptides 1 and 2 are essential for pollen development. PLANT PHYSIOLOGY 2006; 142:1480-92. [PMID: 17071651 PMCID: PMC1676068 DOI: 10.1104/pp.106.086363] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Reversibly glycosylated polypeptides (RGPs) have been implicated in polysaccharide biosynthesis. To date, to our knowledge, no direct evidence exists for the involvement of RGPs in a particular biochemical process. The Arabidopsis (Arabidopsis thaliana) genome contains five RGP genes out of which RGP1 and RGP2 share the highest sequence identity. We characterized the native expression pattern of Arabidopsis RGP1 and RGP2 and used reverse genetics to investigate their respective functions. Although both genes are ubiquitously expressed, the highest levels are observed in actively growing tissues and in mature pollen, in particular. RGPs showed cytoplasmic and transient association with Golgi. In addition, both proteins colocalized in the same compartments and coimmunoprecipitated from plant cell extracts. Single-gene disruptions did not show any obvious morphological defects under greenhouse conditions, whereas the double-insertion mutant could not be recovered. We present evidence that the double mutant is lethal and demonstrate the critical role of RGPs, particularly in pollen development. Detailed analysis demonstrated that mutant pollen development is associated with abnormally enlarged vacuoles and a poorly defined inner cell wall layer, which consequently results in disintegration of the pollen structure during pollen mitosis I. Taken together, our results indicate that RGP1 and RGP2 are required during microspore development and pollen mitosis, either affecting cell division and/or vacuolar integrity.
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Affiliation(s)
- Georgia Drakakaki
- The Center for Plant Cell Biology and Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA
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Kawamura E, Himmelspach R, Rashbrooke MC, Whittington AT, Gale KR, Collings DA, Wasteneys GO. MICROTUBULE ORGANIZATION 1 regulates structure and function of microtubule arrays during mitosis and cytokinesis in the Arabidopsis root. PLANT PHYSIOLOGY 2006; 140:102-14. [PMID: 16377747 PMCID: PMC1326035 DOI: 10.1104/pp.105.069989] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
MICROTUBULE ORGANIZATION 1 (MOR1) is a plant member of the highly conserved MAP215/Dis1 family of microtubule-associated proteins. Prior studies with the temperature-sensitive mor1 mutants of Arabidopsis (Arabidopsis thaliana), which harbor single amino acid substitutions in an N-terminal HEAT repeat, proved that MOR1 regulates cortical microtubule organization and function. Here we demonstrate by use of live cell imaging and immunolabeling that the mor1-1 mutation generates specific defects in the microtubule arrays of dividing vegetative cells. Unlike the universal cortical microtubule disorganization in elongating mor1-1 cells, disruption of mitotic and cytokinetic microtubule arrays was not detected in all dividing cells. Nevertheless, quantitative analysis identified distinct defects in preprophase bands (PPBs), spindles, and phragmoplasts. In nearly one-half of dividing cells at the restrictive temperature of 30 degrees C, PPBs were not detected prior to spindle formation, and those that did form were often disrupted. mor1-1 spindles and phragmoplasts were short and abnormally organized and persisted for longer times than in wild-type cells. The reduced length of these arrays predicts that the component microtubule lengths are also reduced, suggesting that microtubule length is a critical determinant of spindle and phragmoplast structure, orientation, and function. Microtubule organizational defects led to aberrant chromosomal arrangements, misaligned or incomplete cell plates, and multinucleate cells. Antiserum raised against an N-terminal MOR1 sequence labeled the full length of microtubules in interphase arrays, PPBs, spindles, and phragmoplasts. Continued immunolabeling of the disorganized and short microtubules of mor1-1 at the restrictive temperature demonstrated that the mutant mor1-1(L174F) protein loses function without dissociating from microtubules, providing important insight into the mechanism by which MOR1 may regulate microtubule length.
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Affiliation(s)
- Eiko Kawamura
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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Risso-Pascotto C, Pagliarini MS, Valle CB, Jank L. Symmetric pollen mitosis I and suppression of pollen mitosis II prevent pollen development in Brachiaria jubata (Gramineae). Braz J Med Biol Res 2005; 38:1603-8. [PMID: 16258628 DOI: 10.1590/s0100-879x2005001100006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Microsporogenesis and pollen development were analyzed in a tetraploid (2n = 4x = 36) accession of the forage grass Brachiaria jubata (BRA 007820) from the Embrapa Beef Cattle Brachiaria collection that showed partial male sterility. Microsporocytes and pollen grains were prepared by squashing and staining with 0.5% propionic carmine. The meiotic process was typical of polyploids, with precocious chromosome migration to the poles and laggards in both meiosis I and II, resulting in tetrads with micronuclei in some microspores. After callose dissolution, microspores were released into the anther locule and appeared to be normal. Although each microspore initiated its differentiation into a pollen grain, in 11.1% of them nucleus polarization was not observed, i.e., pollen mitosis I was symmetric and the typical hemispherical cell plate was not detected. After a central cytokinesis, two equal-sized cells showing equal chromatin condensation and the same nuclear shape and size were formed. Generative cells and vegetative cells could not be distinguished. These cells did not undergo the second pollen mitosis and after completion of pollen wall synthesis each gave rise to a sterile and uninucleate pollen grain. The frequency of abnormal pollen mitosis varied among flowers and also among inflorescences. All plants were equally affected. The absence of fertile sperm cells in a considerable amount of pollen grains in this accession of B. jubata may compromise its use in breeding and could explain, at least in part, why seed production is low when compared with the amount of flowers per raceme.
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Affiliation(s)
- C Risso-Pascotto
- Departamento de Biologia Celular e Genética, Universidade Estadual de Maringá, Maringá, PR, Brazil
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González-Melendi P, Ramírez C, Testillano PS, Kumlehn J, Risueño MC. Three dimensional confocal and electron microscopy imaging define the dynamics and mechanisms of diploidisation at early stages of barley microspore-derived embryogenesis. PLANTA 2005; 222:47-57. [PMID: 15809862 DOI: 10.1007/s00425-005-1515-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2004] [Accepted: 01/31/2005] [Indexed: 05/20/2023]
Abstract
In order to determine the timing and mechanisms of the spontaneous diploidisation throughout microspore-derived embryogenesis in barley, we have estimated the ploidy level of individual nuclei within young pro-embryos, from the first androgenetic division up to multinuclear structures still surrounded by the exine. Our methodological approach was based on the measure of the intensity of fluorescence after 4,6-Diamidino-2-phenylindole dihydrochloride staining, nuclear size and number of nucleoli in the confocal microscope. This method avoids the overlapping of the fluorescence signal in multinuclear pro-embryos, which cannot be studied using cytophotometer methods based on other types of fluorescence microscopes. The identification of haploid and diploid nuclei enabled us to determine the timing of diploidisation at early stages throughout androgenetic development. We found that diploidisation is an ongoing process that can start after the first embryogenic division and continues in multinuclear pro-embryos. Reconstruction of 3D-images of entire pro-embryos and the observation of cross and longitudinal sections across stacks of optical sections, together with correlative light and electron microscopy, provided evidences of nuclear fusion as the main mechanism of diploidisation.
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Cole RA, Synek L, Zarsky V, Fowler JE. SEC8, a subunit of the putative Arabidopsis exocyst complex, facilitates pollen germination and competitive pollen tube growth. PLANT PHYSIOLOGY 2005; 138:2005-18. [PMID: 16040664 PMCID: PMC1183391 DOI: 10.1104/pp.105.062273] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The exocyst, a complex of eight proteins, contributes to the morphogenesis of polarized cells in a broad range of eukaryotes. In these organisms, the exocyst appears to facilitate vesicle docking at the plasma membrane during exocytosis. Although we had identified orthologs for each of the eight exocyst components in Arabidopsis (Arabidopsis thaliana), no function has been demonstrated for any of them in plants. The gene encoding one exocyst component ortholog, AtSEC8, is expressed in pollen and vegetative tissues of Arabidopsis. Genetic studies utilizing an allelic series of six independent T-DNA mutations reveal a role for SEC8 in male gametophyte function. Three T-DNA insertions in SEC8 cause an absolute, male-specific transmission defect that can be complemented by expression of SEC8 from the LAT52 pollen promoter. Microscopic analysis shows no obvious abnormalities in the microgametogenesis of the SEC8 mutants, and the mutant pollen grains appear to respond to the signals that initiate germination. However, in vivo assays indicate that these mutant pollen grains are unable to germinate a pollen tube. The other three T-DNA insertions are associated with a partial transmission defect, such that the mutant allele is transmitted through the pollen at a reduced frequency. The partial transmission defect is only evident when mutant gametophytes must compete with wild-type gametophytes, and arises in part from a reduced pollen tube growth rate. These data support the hypothesis that one function of the putative plant exocyst is to facilitate the initiation and maintenance of the polarized growth of pollen tubes.
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Affiliation(s)
- Rex A Cole
- Department of Botany and Plant Pathology and Center for Gene Research and Biotechnology, Oregon State University, Corvallis, Oregon 97331, USA
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Eleftheriou EP, Baskin TI, Hepler PK. Aberrant cell plate formation in the Arabidopsis thaliana microtubule organization 1 mutant. PLANT & CELL PHYSIOLOGY 2005; 46:671-675. [PMID: 15753108 DOI: 10.1093/pcp/pci068] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
MICROTUBULE ORGANIZATION 1 encodes a microtubule-associated protein in Arabidopsis thaliana but different alleles have contradictory phenotypes. The original mutant mor1 alleles were reported to have disrupted cortical microtubules, swollen organs and normal cytokinesis, whereas other alleles, embryo-lethal gemini pollen 1 (gem1), have defective pollen cytokinesis. To determine whether MOR1 functions generally in cytokinesis, we examined the ultrastructure of cell division in roots of the original mor1-1 allele. Cell plates are misaligned, branched and meandering; the forming cell plates remain partly vesicular, with electron-dense or lamellar content. Phragmoplast microtubules are abundant but organized aberrantly. Thus, MOR1 functions in both phragmoplast and cortical arrays.
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Lalanne E, Michaelidis C, Moore JM, Gagliano W, Johnson A, Patel R, Howden R, Vielle-Calzada JP, Grossniklaus U, Twell D. Analysis of transposon insertion mutants highlights the diversity of mechanisms underlying male progamic development in Arabidopsis. Genetics 2005; 167:1975-86. [PMID: 15342534 PMCID: PMC1471024 DOI: 10.1534/genetics.104.030270] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To identify genes with essential roles in male gametophytic development, including postpollination (progamic) events, we have undertaken a genetic screen based on segregation ratio distortion of a transposon-borne kanamycin-resistance marker. In a population of 3359 Arabidopsis Ds transposon insertion lines, we identified 20 mutants with stably reduced segregation ratios arising from reduced gametophytic transmission. All 20 mutants showed strict cosegregation of Ds and the reduced gametophytic transmission phenotype. Among these, 10 mutants affected both male and female transmission and 10 mutants showed male-specific transmission defects. Four male and female (ungud) mutants and 1 male-specific mutant showed cellular defects in microspores and/or in developing pollen. The 6 remaining ungud mutants and 9 male-specific (seth) mutants affected pollen functions during progamic development. In vitro and in vivo analyses are reported for 5 seth mutants. seth6 completely blocked pollen germination, while seth7 strongly reduced pollen germination efficiency and tube growth. In contrast, seth8, seth9, or seth10 pollen showed reduced competitive ability that was linked to slower rates of pollen tube growth. Gene sequences disrupted in seth insertions suggest essential functions for putative SETH proteins in diverse processes including protein anchoring, cell wall biosynthesis, signaling, and metabolism.
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Affiliation(s)
- Eric Lalanne
- Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
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Mendes-Bonato AB, Pagliarini MS, do Valle CB, Jank L. Abnormal pollen mitoses (PM I and PM II) in an interspecific hybrid of Brachiaria ruziziensis and Brachiaria decumbens (Gramineae). J Genet 2005; 83:279-83. [PMID: 15689630 DOI: 10.1007/bf02717897] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Park SK, Rahman D, Oh SA, Twell D. gemini pollen 2, a male and female gametophytic cytokinesis defective mutation. ACTA ACUST UNITED AC 2004; 17:63-70. [PMID: 17464359 PMCID: PMC1855439 DOI: 10.1007/s00497-004-0216-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Gametophytic cytokinesis is essential for the development and function of the male and female gametophytes. We have previously described the isolation and characterisation of the gemini pollen 1 (gem1) that acts gametophytically to disturb asymmetric division and cytokinesis at pollen mitosis I in Arabidopsis. Here we describe the genetic and cytological analysis of an independent gametophytic mutant, gem2, with similar characteristics to gem1, but which maps to a different genetic locus. gem2 shows reduced genetic transmission through both male and female gametes and leads to the production of divided or twin-celled pollen. Developmental analysis revealed that gem2 does not affect karyokinesis at pollen mitosis I, but leads to repositioning of the cell plate and partial or complete failure of cytokinesis, resulting in symmetrical divisions or binucleate pollen grains respectively. Symmetrical divisions lead to altered pollen cell fate with both sister cells displaying vegetative cell fate. Moreover, we demonstrate that the predominant female defect in gem2 is a lack of cellularization of the embryo sac during megagametogenesis. GEM2 therefore defines an independent genetic locus that is involved in the correct specification of both male and female gametophytic cytokinesis.
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Affiliation(s)
- Soon Ki Park
- Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
- Division of Plant Biosciences, Kyungpook National University, Daegu 702-701, Korea
| | - Daisy Rahman
- Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - Sung Aeong Oh
- Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - David Twell
- Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
- Author for correspondance Tel: +44-116-252-2281 Fax: +44-116-252-2791
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Cheng H, Qin L, Lee S, Fu X, Richards DE, Cao D, Luo D, Harberd NP, Peng J. Gibberellin regulates Arabidopsis floral development via suppression of DELLA protein function. Development 2004; 131:1055-64. [PMID: 14973286 DOI: 10.1242/dev.00992] [Citation(s) in RCA: 344] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The phytohormone gibberellin (GA) regulates the development and fertility of Arabidopsis flowers. The mature flowers of GA-deficient mutant plants typically exhibit reduced elongation growth of petals and stamens. In addition, GA-deficiency blocks anther development, resulting in male sterility. Previous analyses have shown that GA promotes the elongation of plant organs by opposing the function of the DELLA proteins, a family of nuclear growth repressors. However, it was not clear that the DELLA proteins are involved in the GA-regulation of stamen and anther development. We show that GA regulates cell elongation rather than cell division during Arabidopsis stamen filament elongation. In addition, GA regulates the cellular developmental pathway of anthers leading from microspore to mature pollen grain. Genetic analysis shows that the Arabidopsis DELLA proteins RGA and RGL2 jointly repress petal, stamen and anther development in GA-deficient plants, and that this function is enhanced by RGL1 activity. GA thus promotes Arabidopsis petal, stamen and anther development by opposing the function of the DELLA proteins RGA, RGL1 and RGL2.
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Affiliation(s)
- Hui Cheng
- Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609
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Lalanne E, Honys D, Johnson A, Borner GHH, Lilley KS, Dupree P, Grossniklaus U, Twell D. SETH1 and SETH2, two components of the glycosylphosphatidylinositol anchor biosynthetic pathway, are required for pollen germination and tube growth in Arabidopsis. THE PLANT CELL 2004; 16:229-40. [PMID: 14671020 PMCID: PMC301407 DOI: 10.1105/tpc.014407] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2003] [Accepted: 10/23/2003] [Indexed: 05/17/2023]
Abstract
Glycosylphosphatidylinositol (GPI) anchoring provides an alternative to transmembrane domains for anchoring proteins to the cell surface in eukaryotes. GPI anchors are synthesized in the endoplasmic reticulum via the sequential addition of monosaccharides, fatty acids, and phosphoethanolamines to phosphatidylinositol. Deficiencies in GPI biosynthesis lead to embryonic lethality in animals and to conditional lethality in eukaryotic microbes by blocking cell growth, cell division, or morphogenesis. We report the genetic and phenotypic analysis of insertional mutations disrupting SETH1 and SETH2, which encode Arabidopsis homologs of two conserved proteins involved in the first step of the GPI biosynthetic pathway. seth1 and seth2 mutations specifically block male transmission and pollen function. This results from reduced pollen germination and tube growth, which are associated with abnormal callose deposition. This finding suggests an essential role for GPI anchor biosynthesis in pollen tube wall deposition or metabolism. Using transcriptomic and proteomic approaches, we identified 47 genes that encode potential GPI-anchored proteins that are expressed in pollen and demonstrated that at least 11 of these proteins are associated with pollen membranes by GPI anchoring. Many of the identified candidate proteins are homologous with proteins involved in cell wall synthesis and remodeling or intercellular signaling and adhesion, and they likely play important roles in the establishment and maintenance of polarized pollen tube growth.
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Affiliation(s)
- Eric Lalanne
- Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
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Falbel TG, Koch LM, Nadeau JA, Segui-Simarro JM, Sack FD, Bednarek SY. SCD1 is required for cytokinesis and polarized cell expansion in Arabidopsis thaliana [corrected]. Development 2003; 130:4011-24. [PMID: 12874123 DOI: 10.1242/dev.00619] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the leaf epidermis, guard mother cells undergo a stereotyped symmetric division to form the guard cells of stomata. We have identified a temperature-sensitive Arabidopsis mutant, stomatal cytokinesis-defective 1-1 (scd1-1), which affects this specialized division. At the non-permissive temperature, 22 degrees C, defective scd1-1 guard cells are binucleate, and the formation of their ventral cell walls is incomplete. Cytokinesis was also disrupted in other types of epidermal cells such as pavement cells. Further phenotypic analysis of scd1-1 indicated a role for SCD1 in seedling growth, root elongation and flower morphogenesis. More severe scd1 T-DNA insertion alleles (scd1-2 and scd1-3) markedly affect polar cell expansion, most notably in trichomes and root hairs. SCD1 is a unique gene in Arabidopsis that encodes a protein related to animal proteins that regulate intracellular protein transport and/or mitogen-activated protein kinase signaling pathways. Consistent with a role for SCD1 in membrane trafficking, secretory vesicles were found to accumulate in cytokinesis-defective scd1 cells. In addition the scd1 mutant phenotype was enhanced by low doses of inhibitors of cell plate consolidation and vesicle secretion. We propose that SCD1 functions in polarized vesicle trafficking during plant cytokinesis and cell expansion.
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Affiliation(s)
- Tanya G Falbel
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
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