1
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Tourdot E, Martin PGP, Maza E, Mauxion JP, Djari A, Gévaudant F, Chevalier C, Pirrello J, Gonzalez N. Ploidy-specific transcriptomes shed light on the heterogeneous identity and metabolism of developing tomato pericarp cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 118:997-1015. [PMID: 38281284 DOI: 10.1111/tpj.16646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 11/20/2023] [Accepted: 01/05/2024] [Indexed: 01/30/2024]
Abstract
Endoreduplication, during which cells increase their DNA content through successive rounds of full genome replication without cell division, is the major source of endopolyploidy in higher plants. Endoreduplication plays pivotal roles in plant growth and development and is associated with the activation of specific transcriptional programmes that are characteristic of each cell type, thereby defining their identity. In plants, endoreduplication is found in numerous organs and cell types, especially in agronomically valuable ones, such as the fleshy fruit (pericarp) of tomato presenting high ploidy levels. We used the tomato pericarp tissue as a model system to explore the transcriptomes associated with endoreduplication progression during fruit growth. We confirmed that expression globally scales with ploidy level and identified sets of differentially expressed genes presenting only developmental-specific, only ploidy-specific expression patterns or profiles resulting from an additive effect of ploidy and development. When comparing ploidy levels at a specific developmental stage, we found that non-endoreduplicated cells are defined by cell division state and cuticle synthesis while endoreduplicated cells are mainly defined by their metabolic activity changing rapidly over time. By combining this dataset with publicly available spatiotemporal pericarp expression data, we proposed a map describing the distribution of ploidy levels within the pericarp. These transcriptome-based predictions were validated by quantifying ploidy levels within the pericarp tissue. This in situ ploidy quantification revealed the dynamic progression of endoreduplication and its cell layer specificity during early fruit development. In summary, the study sheds light on the complex relationship between endoreduplication, cell differentiation and gene expression patterns in the tomato pericarp.
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Affiliation(s)
- Edouard Tourdot
- Université de Bordeaux, INRAE, UMR1332 Biologie du Fruit et Pathologie, F-33882, Villenave d'Ornon, France
| | - Pascal G P Martin
- Université de Bordeaux, INRAE, UMR1332 Biologie du Fruit et Pathologie, F-33882, Villenave d'Ornon, France
| | - Elie Maza
- Laboratoire de Recherche en Sciences Végétales-Génomique et Biotechnologie des Fruits-UMR5546, Université de Toulouse, CNRS, UPS, Toulouse-INP, F-31326, Castanet-Tolosan, France
| | - Jean-Philippe Mauxion
- Université de Bordeaux, INRAE, UMR1332 Biologie du Fruit et Pathologie, F-33882, Villenave d'Ornon, France
| | - Anis Djari
- Laboratoire de Recherche en Sciences Végétales-Génomique et Biotechnologie des Fruits-UMR5546, Université de Toulouse, CNRS, UPS, Toulouse-INP, F-31326, Castanet-Tolosan, France
| | - Frédéric Gévaudant
- Université de Bordeaux, INRAE, UMR1332 Biologie du Fruit et Pathologie, F-33882, Villenave d'Ornon, France
| | - Christian Chevalier
- Université de Bordeaux, INRAE, UMR1332 Biologie du Fruit et Pathologie, F-33882, Villenave d'Ornon, France
| | - Julien Pirrello
- Laboratoire de Recherche en Sciences Végétales-Génomique et Biotechnologie des Fruits-UMR5546, Université de Toulouse, CNRS, UPS, Toulouse-INP, F-31326, Castanet-Tolosan, France
| | - Nathalie Gonzalez
- Université de Bordeaux, INRAE, UMR1332 Biologie du Fruit et Pathologie, F-33882, Villenave d'Ornon, France
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2
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Tourdot E, Mauxion JP, Gonzalez N, Chevalier C. Endoreduplication in plant organogenesis: a means to boost fruit growth. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:6269-6284. [PMID: 37343125 DOI: 10.1093/jxb/erad235] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 06/16/2023] [Indexed: 06/23/2023]
Abstract
Endoreduplication is the major source of somatic endopolyploidy in higher plants, and leads to variation in cell ploidy levels due to iterative rounds of DNA synthesis in the absence of mitosis. Despite its ubiquitous occurrence in many plant organs, tissues, and cells, the physiological meaning of endoreduplication is not fully understood, although several roles during plant development have been proposed, mostly related to cell growth, differentiation, and specialization via transcriptional and metabolic reprogramming. Here, we review recent advances in our knowledge of the molecular mechanisms and cellular characteristics of endoreduplicated cells, and provide an overview of the multi-scale effects of endoreduplication on supporting growth in plant development. In addition, the effects of endoreduplication in fruit development are discussed, since it is highly prominent during fruit organogenesis where it acts as a morphogenetic factor supporting rapid fruit growth, as illustrated by case of the model fleshy fruit, tomato (Solanum lycopersicum).
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Affiliation(s)
- Edouard Tourdot
- Université de Bordeaux, INRAE, UMR1332 Biologie du Fruit et Pathologie, F-33140 Villenave d'Ornon, France
| | - Jean-Philippe Mauxion
- Université de Bordeaux, INRAE, UMR1332 Biologie du Fruit et Pathologie, F-33140 Villenave d'Ornon, France
| | - Nathalie Gonzalez
- Université de Bordeaux, INRAE, UMR1332 Biologie du Fruit et Pathologie, F-33140 Villenave d'Ornon, France
| | - Christian Chevalier
- Université de Bordeaux, INRAE, UMR1332 Biologie du Fruit et Pathologie, F-33140 Villenave d'Ornon, France
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3
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Nowicka A, Ferková Ľ, Said M, Kovacik M, Zwyrtková J, Baroux C, Pecinka A. Non-Rabl chromosome organization in endoreduplicated nuclei of barley embryo and endosperm tissues. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:2527-2541. [PMID: 36705553 DOI: 10.1093/jxb/erad036] [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: 10/26/2022] [Accepted: 01/25/2023] [Indexed: 06/06/2023]
Abstract
Rabl organization is a type of interphase chromosome arrangement with centromeres and telomeres clustering at opposite nuclear poles. Here, we analyzed nuclear morphology and chromosome organization in cycling and endoreduplicated nuclei isolated from embryo and endosperm tissues of developing barley seeds. We show that endoreduplicated nuclei have an irregular shape, less sister chromatid cohesion at 5S rDNA loci, and a reduced amount of centromeric histone CENH3. While the chromosomes of the embryo and endosperm nuclei are initially organized in Rabl configuration, the centromeres and telomeres are intermingled within the nuclear space in the endoreduplicated nuclei with an increasing endoreduplication level. Such a loss of chromosome organization suggests that Rabl configuration is introduced and further reinforced by mitotic divisions in barley cell nuclei in a tissue- and seed age-dependent manner.
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Affiliation(s)
- Anna Nowicka
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany of the Czech Academy of Sciences, Šlechtitelů 31, 779 00 Olomouc, Czech Republic
- The Polish Academy of Sciences, The Franciszek Górski Institute of Plant Physiology, Niezapominajek 21, 30-239 Krakow, Poland
| | - Ľuboslava Ferková
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany of the Czech Academy of Sciences, Šlechtitelů 31, 779 00 Olomouc, Czech Republic
| | - Mahmoud Said
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany of the Czech Academy of Sciences, Šlechtitelů 31, 779 00 Olomouc, Czech Republic
- Field Crops Research Institute, Agricultural Research Centre, 9 Gamma Street, Giza, Cairo, 12619, Egypt
| | - Martin Kovacik
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany of the Czech Academy of Sciences, Šlechtitelů 31, 779 00 Olomouc, Czech Republic
| | - Jana Zwyrtková
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany of the Czech Academy of Sciences, Šlechtitelů 31, 779 00 Olomouc, Czech Republic
| | - Célia Baroux
- Department of Plant and Microbial Biology, Zürich-Basel Plant Science Center, University of Zürich, Zollikerstrasse 107, 8008 Zürich, Switzerland
| | - Ales Pecinka
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany of the Czech Academy of Sciences, Šlechtitelů 31, 779 00 Olomouc, Czech Republic
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4
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Mauxion JP, Chevalier C, Gonzalez N. Complex cellular and molecular events determining fruit size. TRENDS IN PLANT SCIENCE 2021; 26:1023-1038. [PMID: 34158228 DOI: 10.1016/j.tplants.2021.05.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 05/24/2021] [Accepted: 05/28/2021] [Indexed: 06/13/2023]
Abstract
The understanding of plant organ-size determination represents an important challenge, especially because of the significant role of plants as food and renewable energy sources and the increasing need for plant-derived products. Most of the knowledge on the regulation of organ growth and the molecular network controlling cell division and cell expansion, the main drivers of growth, is derived from arabidopsis. The increasing use of crops such as tomato for research is now bringing essential information on the mechanisms underlying size control in agronomically important organs. This review describes our current knowledge, still very scarce, of the cellular and molecular mechanisms governing tomato fruit size and proposes future research to better understand the regulation of growth in this important crop.
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Affiliation(s)
- Jean-Philippe Mauxion
- INRAE, Univ. Bordeaux, UMR1332 Biologie du fruit et Pathologie, F33882 Villenave d'Ornon, France
| | - Christian Chevalier
- INRAE, Univ. Bordeaux, UMR1332 Biologie du fruit et Pathologie, F33882 Villenave d'Ornon, France
| | - Nathalie Gonzalez
- INRAE, Univ. Bordeaux, UMR1332 Biologie du fruit et Pathologie, F33882 Villenave d'Ornon, France. @inrae.fr
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5
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Narukawa H, Yokoyama R, Kuroha T, Nishitani K. Host-produced ethylene is required for marked cell expansion and endoreduplication in dodder search hyphae. PLANT PHYSIOLOGY 2021; 185:491-502. [PMID: 33721891 PMCID: PMC8133569 DOI: 10.1093/plphys/kiaa010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 09/28/2020] [Indexed: 05/13/2023]
Abstract
The genus Cuscuta comprises stem holoparasitic plant species with wide geographic distribution. Cuscuta spp. obtain water, nutrients, proteins, and mRNA from their host plants via a parasitic organ called the haustorium. As the haustorium penetrates into the host tissue, search hyphae elongate within the host tissue and finally connect with the host's vascular system. Invasion by Cuscuta spp. evokes various reactions within the host plant's tissues. Here, we show that, when Arabidopsis (Arabidopsis thaliana) is invaded by Cuscuta campestris, ethylene biosynthesis by the host plant promotes elongation of the parasite's search hyphae. The expression of genes encoding 1-aminocylclopropane-1-carboxylic acid (ACC) synthases, ACC SYNTHASE2 (AtACS2) and ACC SYNTHASE6 (AtACS6), was activated in the stem of Arabidopsis plants upon invasion by C. campestris. When the ethylene-deficient Arabidopsis acs octuple mutant was invaded by C. campestris, cell elongation and endoreduplication of the search hyphae were significantly reduced, and the inhibition of search hyphae growth was complemented by exogenous application of ACC. In contrast, in the C. campestris-infected Arabidopsis ethylene-insensitive mutant etr1-3, no growth inhibition of search hyphae was observed, indicating that ETHYLENE RESPONSE1-mediated ethylene signaling in the host plant is not essential for parasitism by C. campestris. Overall, our results suggest that C. campestris recognizes host-produced ethylene as a stimulatory signal for successful invasion.
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Affiliation(s)
- Hideki Narukawa
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Ryusuke Yokoyama
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Takeshi Kuroha
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Kazuhiko Nishitani
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan
- Author for communication: (K.N.)
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6
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Chen H, Feng X, Jiang M, Xiao B, Zhang J, Zhang W, Hu Y, Sui Z. Estimating the ploidy of Gracilariopsis lemaneiformis at both the cellular and genomic level 1. JOURNAL OF PHYCOLOGY 2020; 56:1339-1348. [PMID: 32464702 DOI: 10.1111/jpy.13035] [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: 02/13/2020] [Accepted: 05/17/2020] [Indexed: 06/11/2023]
Abstract
The determination of the ploidy level of an organism is a prerequisite for studies of evolution, cellular function, and genomic construction. Identification of the ploidy of the economically important red alga Gracilariopsis lemaneiformis has been hindered by its small genome and large number of chromosomes. Therefore, in the current study, PloidyNGS, a tool that calculates the number of reads supporting different alleles at each position along the genome sequence, and fluorescence in situ hybridization coupled with tyramide signal amplification (TSA-FISH) were used to clarify the ploidy of G. lemaneiformis. In addition, flow cytometry (FCM) was used to estimate the ploidy of different somatic cells. The PloidyNGS results showed that most of the alleles in the gametophyte were monomorphic, whereas the TSA-FISH results showed that one hybridization signal was observed in gametophytic nuclei and two in tetrasporophytic nuclei when the nuclei were hybridized by single copy gene probes. These results confirmed that G. lemaneiformis is a haploid in the gametophytic generation and diploid in the sporophytic generation. Moreover, the FCM result suggested that G. lemaneiformis was not an endopolyploid. Based on previous studies, we hypothesize that the nuclear number is important for the cellular differentiation and function of this species. We also suggest that G. lemaneiformis evolved from a paleopolyploid, the genome of which has been diploidized, and that traces of genomic doubling are no longer apparent. Thus, this study provides important evidence for further studies on the evolution and genomes of red algae.
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Affiliation(s)
- Haihong Chen
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China
| | - Xiaoqing Feng
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China
| | - Minjie Jiang
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China
| | - Baoheng Xiao
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China
| | - Jingyu Zhang
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China
| | - Wei Zhang
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China
| | - Yiyi Hu
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China
| | - Zhenghong Sui
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, Qingdao, 266003, China
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7
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Baldazzi V, Valsesia P, Génard M, Bertin N. Organ-wide and ploidy-dependent regulation both contribute to cell-size determination: evidence from a computational model of tomato fruit. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:6215-6228. [PMID: 31504751 PMCID: PMC6859726 DOI: 10.1093/jxb/erz398] [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: 01/15/2019] [Accepted: 08/01/2019] [Indexed: 05/10/2023]
Abstract
The development of a new organ is the result of coordinated events of cell division and expansion, in strong interaction with each other. This study presents a dynamic model of tomato fruit development that includes cell division, endoreduplication, and expansion processes. The model is used to investigate the potential interactions among these developmental processes within the context of the neo-cellular theory. In particular, different control schemes (either cell-autonomous or organ-controlled) are tested and compared to experimental data from two contrasting genotypes. The model shows that a pure cell-autonomous control fails to reproduce the observed cell-size distribution, and that an organ-wide control is required in order to get realistic cell-size variations. The model also supports the role of endoreduplication as an important determinant of the final cell size and suggests that a direct effect of endoreduplication on cell expansion is needed in order to obtain a significant correlation between size and ploidy, as observed in real data.
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Affiliation(s)
- Valentina Baldazzi
- INRA, PSH, 228 route de l'Aerodrome, Avignon, France
- Université Côte d'Azur, INRA, CNRS, ISA, 400 route des Chappes, Sophia-Antipolis, France
- Université Côte d'Azur, Inria, INRA, CNRS, Sorbonne Université, BIOCORE, 2004 route des Lucioles, Sophia-Antipolis, France
| | | | - Michel Génard
- INRA, PSH, 228 route de l'Aerodrome, Avignon, France
| | - Nadia Bertin
- INRA, PSH, 228 route de l'Aerodrome, Avignon, France
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8
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Bhosale R, Maere S, De Veylder L. Endoreplication as a potential driver of cell wall modifications. CURRENT OPINION IN PLANT BIOLOGY 2019; 51:58-65. [PMID: 31071565 DOI: 10.1016/j.pbi.2019.04.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 03/29/2019] [Accepted: 04/02/2019] [Indexed: 05/06/2023]
Abstract
Endoreplication represents a variant of the mitotic cell cycle during which cells replicate their DNA without mitosis and/or cytokinesis, resulting in an increase in the cells' ploidy level. This process is especially prominent in higher plants, where it has been correlated with cell differentiation, metabolic output and rapid cell growth. However, different reports argue against a ploidy-dependent contribution to cell growth. Here, we review accumulating data suggesting that endocycle onset might exert an effect on cell growth through transcriptional control of cell wall-modifying genes to drive cell wall changes required to accommodate turgor-driven rapid cell expansion, consistent with the idea that vacuolar expansion rather than a ploidy-driven increase in cellular volume represents the major force driving cell growth.
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Affiliation(s)
- Rahul Bhosale
- Plant and Crop Sciences, School of Biosciences, University of Nottingham, Nottingham, LE12 5RD, United Kingdom; Center for Plant Integrative Biology (CPIB), University of Nottingham, Sutton Bonington, LE12 5RD, United Kingdom
| | - Steven Maere
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, B-9052, Belgium; VIB Center for Plant Systems Biology, B-9052 Ghent, Belgium; Bioinformatics Institute Ghent, Ghent University, B-9052 Ghent, Belgium
| | - Lieven De Veylder
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, B-9052, Belgium; VIB Center for Plant Systems Biology, B-9052 Ghent, Belgium.
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9
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Carotenuto G, Sciascia I, Oddi L, Volpe V, Genre A. Size matters: three methods for estimating nuclear size in mycorrhizal roots of Medicago truncatula by image analysis. BMC PLANT BIOLOGY 2019; 156:265-273. [PMID: 31054574 DOI: 10.1046/j.1469-8137.2002.00508.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
BACKGROUND The intracellular accommodation of arbuscular mycorrhizal (AM) fungi involves a profound molecular reprogramming of the host cell architecture and metabolism, based on the activation of a symbiotic signaling pathway. In analogy with other plant biotrophs, AM fungi are reported to trigger cell cycle reactivation in their host tissues, possibly in support of the enhanced metabolic demand required for the symbiosis. RESULTS We here compare the efficiency of three Fiji/ImageJ image analysis plugins in localizing and quantifying the increase in nuclear size - a hallmark of recursive events of endoreduplication - in M. truncatula roots colonized by the AM fungus Gigaspora margarita. All three approaches proved to be versatile and upgradeable, allowing the investigation of nuclear changes in a complex tissue; 3D Object Counter provided more detailed information than both TrackMate and Round Surface Detector plugins. On this base we challenged 3D Object Counter with two case studies: verifying the lack of endoreduplication-triggering responses in Medicago truncatula mutants with a known non-symbiotic phenotype; and analysing the correlation in space and time between the induction of cortical cell division and endoreduplication upon AM colonization. Both case studies revealed important biological aspects. Mutant phenotype analyses have demonstrated that the knock-out mutation of different key genes in the symbiotic signaling pathway block AM-associated endoreduplication. Furthermore, our data show that cell divisions occur during initial stages of root colonization and are followed by recursive activation of the endocycle in preparation for arbuscule accommodation. CONCLUSIONS In conclusion, our results indicate 3D Object Counter as the best performing Fiji/ImageJ image analysis script in plant root thick sections and its application highlighted endoreduplication as a major feature of the AM pre-penetration response in root cortical cells.
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Affiliation(s)
- Gennaro Carotenuto
- Department of Life Sciences and Systems Biology, University of Turin, 10125, Torino, Italy
| | - Ivan Sciascia
- Department of Life Sciences and Systems Biology, University of Turin, 10125, Torino, Italy
| | - Ludovica Oddi
- Department of Life Sciences and Systems Biology, University of Turin, 10125, Torino, Italy
| | - Veronica Volpe
- Department of Life Sciences and Systems Biology, University of Turin, 10125, Torino, Italy
| | - Andrea Genre
- Department of Life Sciences and Systems Biology, University of Turin, 10125, Torino, Italy.
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10
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Carotenuto G, Sciascia I, Oddi L, Volpe V, Genre A. Size matters: three methods for estimating nuclear size in mycorrhizal roots of Medicago truncatula by image analysis. BMC PLANT BIOLOGY 2019; 19:180. [PMID: 31054574 PMCID: PMC6500585 DOI: 10.1186/s12870-019-1791-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 04/18/2019] [Indexed: 05/10/2023]
Abstract
BACKGROUND The intracellular accommodation of arbuscular mycorrhizal (AM) fungi involves a profound molecular reprogramming of the host cell architecture and metabolism, based on the activation of a symbiotic signaling pathway. In analogy with other plant biotrophs, AM fungi are reported to trigger cell cycle reactivation in their host tissues, possibly in support of the enhanced metabolic demand required for the symbiosis. RESULTS We here compare the efficiency of three Fiji/ImageJ image analysis plugins in localizing and quantifying the increase in nuclear size - a hallmark of recursive events of endoreduplication - in M. truncatula roots colonized by the AM fungus Gigaspora margarita. All three approaches proved to be versatile and upgradeable, allowing the investigation of nuclear changes in a complex tissue; 3D Object Counter provided more detailed information than both TrackMate and Round Surface Detector plugins. On this base we challenged 3D Object Counter with two case studies: verifying the lack of endoreduplication-triggering responses in Medicago truncatula mutants with a known non-symbiotic phenotype; and analysing the correlation in space and time between the induction of cortical cell division and endoreduplication upon AM colonization. Both case studies revealed important biological aspects. Mutant phenotype analyses have demonstrated that the knock-out mutation of different key genes in the symbiotic signaling pathway block AM-associated endoreduplication. Furthermore, our data show that cell divisions occur during initial stages of root colonization and are followed by recursive activation of the endocycle in preparation for arbuscule accommodation. CONCLUSIONS In conclusion, our results indicate 3D Object Counter as the best performing Fiji/ImageJ image analysis script in plant root thick sections and its application highlighted endoreduplication as a major feature of the AM pre-penetration response in root cortical cells.
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Affiliation(s)
- Gennaro Carotenuto
- Department of Life Sciences and Systems Biology, University of Turin, 10125, Torino, Italy
| | - Ivan Sciascia
- Department of Life Sciences and Systems Biology, University of Turin, 10125, Torino, Italy
| | - Ludovica Oddi
- Department of Life Sciences and Systems Biology, University of Turin, 10125, Torino, Italy
| | - Veronica Volpe
- Department of Life Sciences and Systems Biology, University of Turin, 10125, Torino, Italy
| | - Andrea Genre
- Department of Life Sciences and Systems Biology, University of Turin, 10125, Torino, Italy.
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11
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Baroux C, Schubert V. Technical Review: Microscopy and Image Processing Tools to Analyze Plant Chromatin: Practical Considerations. Methods Mol Biol 2018; 1675:537-589. [PMID: 29052212 DOI: 10.1007/978-1-4939-7318-7_31] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
In situ nucleus and chromatin analyses rely on microscopy imaging that benefits from versatile, efficient fluorescent probes and proteins for static or live imaging. Yet the broad choice in imaging instruments offered to the user poses orientation problems. Which imaging instrument should be used for which purpose? What are the main caveats and what are the considerations to best exploit each instrument's ability to obtain informative and high-quality images? How to infer quantitative information on chromatin or nuclear organization from microscopy images? In this review, we present an overview of common, fluorescence-based microscopy systems and discuss recently developed super-resolution microscopy systems, which are able to bridge the resolution gap between common fluorescence microscopy and electron microscopy. We briefly present their basic principles and discuss their possible applications in the field, while providing experience-based recommendations to guide the user toward best-possible imaging. In addition to raw data acquisition methods, we discuss commercial and noncommercial processing tools required for optimal image presentation and signal evaluation in two and three dimensions.
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Affiliation(s)
- Célia Baroux
- Department of Plant and Microbial Biology, Zürich-Basel Plant Science Center, University of Zürich, Zollikerstrasse 107, 8008, Zürich, Switzerland.
| | - Veit Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany
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12
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Pirrello J, Deluche C, Frangne N, Gévaudant F, Maza E, Djari A, Bourge M, Renaudin JP, Brown S, Bowler C, Zouine M, Chevalier C, Gonzalez N. Transcriptome profiling of sorted endoreduplicated nuclei from tomato fruits: how the global shift in expression ascribed to DNA ploidy influences RNA-Seq data normalization and interpretation. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 93:387-398. [PMID: 29172253 DOI: 10.1111/tpj.13783] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/09/2017] [Accepted: 11/14/2017] [Indexed: 06/07/2023]
Abstract
As part of normal development most eukaryotic organisms, ranging from insects and mammals to plants, display variations in nuclear ploidy levels resulting from somatic endopolyploidy. Endoreduplication is the major source of endopolyploidy in higher plants. Endoreduplication is a remarkable characteristic of the fleshy pericarp tissue of developing tomato fruits, where it establishes a highly integrated cellular system that acts as a morphogenetic factor supporting cell growth. However, the functional significance of endoreduplication is not fully understood. Although endoreduplication is thought to increase metabolic activity due to a global increase in transcription, the issue of gene-specific ploidy-regulated transcription remains open. To investigate the influence of endoreduplication on transcription in tomato fruit, we tested the feasibility of a RNA sequencing (RNA-Seq) approach using total nuclear RNA extracted from purified populations of flow cytometry-sorted nuclei based on their DNA content. Here we show that cell-based approaches to the study of RNA-Seq profiles need to take into account the putative global shift in expression between samples for correct analysis and interpretation of the data. From ploidy-specific expression profiles we found that the activity of cells inside the pericarp is related both to the ploidy level and their tissue location.
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Affiliation(s)
- Julien Pirrello
- UMR1332 BFP, INRA, Univ. Bordeaux, 33882, Villenave d'Ornon Cedex, France
- GBF, Université de Toulouse, INRA, 31326, Castanet-Tolosan Cedex, France
| | - Cynthia Deluche
- UMR1332 BFP, INRA, Univ. Bordeaux, 33882, Villenave d'Ornon Cedex, France
| | - Nathalie Frangne
- UMR1332 BFP, INRA, Univ. Bordeaux, 33882, Villenave d'Ornon Cedex, France
| | - Frédéric Gévaudant
- UMR1332 BFP, INRA, Univ. Bordeaux, 33882, Villenave d'Ornon Cedex, France
| | - Elie Maza
- GBF, Université de Toulouse, INRA, 31326, Castanet-Tolosan Cedex, France
| | - Anis Djari
- GBF, Université de Toulouse, INRA, 31326, Castanet-Tolosan Cedex, France
| | - Mickaël Bourge
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Université Paris-Saclay, 91198, Gif-sur-Yvette, France
| | | | - Spencer Brown
- Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Université Paris-Saclay, 91198, Gif-sur-Yvette, France
| | - Chris Bowler
- Département de Biologie, IBENS, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, F-75005, Paris, France
| | - Mohamed Zouine
- GBF, Université de Toulouse, INRA, 31326, Castanet-Tolosan Cedex, France
| | | | - Nathalie Gonzalez
- UMR1332 BFP, INRA, Univ. Bordeaux, 33882, Villenave d'Ornon Cedex, France
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13
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Robin GP, Kleemann J, Neumann U, Cabre L, Dallery JF, Lapalu N, O’Connell RJ. Subcellular Localization Screening of Colletotrichum higginsianum Effector Candidates Identifies Fungal Proteins Targeted to Plant Peroxisomes, Golgi Bodies, and Microtubules. FRONTIERS IN PLANT SCIENCE 2018; 9:562. [PMID: 29770142 PMCID: PMC5942036 DOI: 10.3389/fpls.2018.00562] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 04/10/2018] [Indexed: 05/20/2023]
Abstract
The genome of the hemibiotrophic anthracnose fungus, Colletotrichum higginsianum, encodes a large inventory of putative secreted effector proteins that are sequentially expressed at different stages of plant infection, namely appressorium-mediated penetration, biotrophy and necrotrophy. However, the destinations to which these proteins are addressed inside plant cells are unknown. In the present study, we selected 61 putative effector genes that are highly induced in appressoria and/or biotrophic hyphae. We then used Agrobacterium-mediated transformation to transiently express them as N-terminal fusions with fluorescent proteins in cells of Nicotiana benthamiana for imaging by confocal microscopy. Plant compartments labeled by the fusion proteins in N. benthamiana were validated by co-localization with specific organelle markers, by transient expression of the proteins in the true host plant, Arabidopsis thaliana, and by transmission electron microscopy-immunogold labeling. Among those proteins for which specific subcellular localizations could be verified, nine were imported into plant nuclei, three were imported into the matrix of peroxisomes, three decorated cortical microtubule arrays and one labeled Golgi stacks. Two peroxisome-targeted proteins harbored canonical C-terminal tripeptide signals for peroxisome import via the PTS1 (peroxisomal targeting signal 1) pathway, and we showed that these signals are essential for their peroxisome localization. Our findings provide valuable information about which host processes are potentially manipulated by this pathogen, and also reveal plant peroxisomes, microtubules, and Golgi as novel targets for fungal effectors.
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Affiliation(s)
- Guillaume P. Robin
- UMR BIOGER, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Versailles, France
| | - Jochen Kleemann
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Ulla Neumann
- Central Microscopy, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Lisa Cabre
- UMR BIOGER, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Versailles, France
| | - Jean-Félix Dallery
- UMR BIOGER, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Versailles, France
| | - Nicolas Lapalu
- UMR BIOGER, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Versailles, France
| | - Richard J. O’Connell
- UMR BIOGER, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Versailles, France
- *Correspondence: Richard J. O’Connell,
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14
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Laimbeer FPE, Holt SH, Makris M, Hardigan MA, Robin Buell C, Veilleux RE. Protoplast isolation prior to flow cytometry reveals clear patterns of endoreduplication in potato tubers, related species, and some starchy root crops. PLANT METHODS 2017; 13:27. [PMID: 28413433 PMCID: PMC5391561 DOI: 10.1186/s13007-017-0177-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Accepted: 04/02/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND Endoreduplication, the process of DNA replication in the absence of cell division, is associated with specialized cellular function and increased cell size. Genes controlling endoreduplication in tomato fruit have been shown to affect mature fruit size. An efficient method of estimating endoreduplication is required to study its role in plant organ development. Flow cytometry is often utilized to evaluate endoreduplication, yet some tissues and species, among them the tubers of Solanum tuberosum, remain intractable to routine tissue preparation for flow cytometry. We aimed to develop a method through the use of protoplast extraction preceding flow cytometry, specifically for the assessment of endoreduplication in potato tubers. RESULTS We present a method for appraising endoreduplication in potato (Solanum tuberosum) tuber tissues. We evaluated this method and observed consistent differences between pith and cortex of tubers and between different cultivars, but no apparent relationship with whole tuber size. Furthermore, we were able to observe distinct patterns of endoreduplication in 16 of 20 wild potato relatives, with mean endoreduplication index (EI) ranging from 0.94 to 2.62 endocycles per cell. The protocol was also applied to a panel of starchy root crop species and, while only two of five yielded reliable flow histograms, the two (sweet potato and turnip) exhibited substantially lower EIs than wild and cultivated potato accessions. CONCLUSIONS The protocol reported herein has proven effective on tubers of a variety of potato cultivars and related species, as well as storage roots of other starchy crops. This method provides an important tool for the study of potato morphology and development while revealing natural variation for endoreduplication which may have agricultural relevance.
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Affiliation(s)
| | - Sarah H. Holt
- Department of Horticulture, Virginia Tech, Blacksburg, VA 24061 USA
| | - Melissa Makris
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24061 USA
| | | | - C. Robin Buell
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824 USA
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15
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Brown SC, Bourge M, Maunoury N, Wong M, Wolfe Bianchi M, Lepers-Andrzejewski S, Besse P, Siljak-Yakovlev S, Dron M, Satiat-Jeunemaître B. DNA Remodeling by Strict Partial Endoreplication in Orchids, an Original Process in the Plant Kingdom. Genome Biol Evol 2017; 9:1051-1071. [PMID: 28419219 PMCID: PMC5546068 DOI: 10.1093/gbe/evx063] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2017] [Indexed: 12/12/2022] Open
Abstract
DNA remodeling during endoreplication appears to be a strong developmental characteristic in orchids. In this study, we analyzed DNA content and nuclei in 41 species of orchids to further map the genome evolution in this plant family. We demonstrate that the DNA remodeling observed in 36 out of 41 orchids studied corresponds to strict partial endoreplication. Such process is developmentally regulated in each wild species studied. Cytometry data analyses allowed us to propose a model where nuclear states 2C, 4E, 8E, etc. form a series comprising a fixed proportion, the euploid genome 2C, plus 2-32 additional copies of a complementary part of the genome. The fixed proportion ranged from 89% of the genome in Vanilla mexicana down to 19% in V. pompona, the lowest value for all 148 orchids reported. Insterspecific hybridization did not suppress this phenomenon. Interestingly, this process was not observed in mass-produced epiphytes. Nucleolar volumes grow with the number of endocopies present, coherent with high transcription activity in endoreplicated nuclei. Our analyses suggest species-specific chromatin rearrangement. Towards understanding endoreplication, V. planifolia constitutes a tractable system for isolating the genomic sequences that confer an advantage via endoreplication from those that apparently suffice at diploid level.
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Affiliation(s)
- Spencer C. Brown
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université
Paris‐Sud, Université Paris‐Saclay, Gif‐sur‐Yvette Cedex, France
| | - Mickaël Bourge
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université
Paris‐Sud, Université Paris‐Saclay, Gif‐sur‐Yvette Cedex, France
| | - Nicolas Maunoury
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université
Paris‐Sud, Université Paris‐Saclay, Gif‐sur‐Yvette Cedex, France
| | - Maurice Wong
- Service du Développement Rural, Papeete Tahiti, French Polynesia,
France
| | - Michele Wolfe Bianchi
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université
Paris‐Sud, Université Paris‐Saclay, Gif‐sur‐Yvette Cedex, France
| | | | - Pascale Besse
- UMR 53, PVBMT Université de la Réunion – Cirad, Pôle de Protection des
Plantes, St Pierre, France
| | - Sonja Siljak-Yakovlev
- Ecologie Systématique Evolution, Université Paris-Sud, CNRS, AgroParisTech,
Université Paris-Saclay, Orsay Cedex, France
| | - Michel Dron
- Institute of Plant Sciences Paris Saclay IPS2, Université Paris-Sud, CNRS,
INRA, Université Evry, Université Paris Diderot, Sorbonne Paris-Cité, Université
Paris-Saclay, Orsay, France
| | - Béatrice Satiat-Jeunemaître
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université
Paris‐Sud, Université Paris‐Saclay, Gif‐sur‐Yvette Cedex, France
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16
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Renaudin JP, Deluche C, Cheniclet C, Chevalier C, Frangne N. Cell layer-specific patterns of cell division and cell expansion during fruit set and fruit growth in tomato pericarp. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:1613-1623. [PMID: 28369617 PMCID: PMC5444452 DOI: 10.1093/jxb/erx058] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In angiosperms, the ovary wall resumes growth after pollination through a balanced combination of cell division and cell expansion. The quantitative pattern of these events remains poorly known in fleshy fruits such as tomato (Solanum spp.), in which dramatic growth of the pericarp occurs together with endoreduplication. Here, this pattern is reported at the level of each of the cell layers or groups of cell layers composing the pericarp, except for vascular bundles. Overall, cell division and cell expansion occurred at similar rates for 9 days post anthesis (DPA), with very specific patterns according to the layers. Subsequently, only cell expansion continued for up to 3-4 more weeks. New cell layers in the pericarp originated from periclinal cell divisions in the two sub-epidermal cell layers. The shortest doubling times for cell number and for cell volume were both detected early, at 4 DPA, in epicarp and mesocarp respectively, and were both found to be close to 14 h. Endoreduplication started before anthesis in pericarp and was stimulated at fruit set. It is proposed that cell division, endoreduplication, and cell expansion are triggered simultaneously in specific cell layers by the same signals issuing from pollination and fertilization, which contribute to the fastest relative fruit growth early after fruit set.
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Affiliation(s)
- Jean-Pierre Renaudin
- UMR 1332 BFP, INRA National Institute for Agronomic Research, University of Bordeaux, F-33882 Villenave d'Ornon Cedex, France
| | - Cynthia Deluche
- UMR 1332 BFP, INRA National Institute for Agronomic Research, University of Bordeaux, F-33882 Villenave d'Ornon Cedex, France
| | - Catherine Cheniclet
- UMR 1332 BFP, INRA National Institute for Agronomic Research, University of Bordeaux, F-33882 Villenave d'Ornon Cedex, France
- UMS 3420, Bordeaux Imaging Center, CNRS, US4, INSERM, University of Bordeaux, F-33000 Bordeaux, France
| | - Christian Chevalier
- UMR 1332 BFP, INRA National Institute for Agronomic Research, University of Bordeaux, F-33882 Villenave d'Ornon Cedex, France
| | - Nathalie Frangne
- UMR 1332 BFP, INRA National Institute for Agronomic Research, University of Bordeaux, F-33882 Villenave d'Ornon Cedex, France
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17
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Kliot A, Ghanim M. Fluorescent in situ hybridization for the localization of viruses, bacteria and other microorganisms in insect and plant tissues. Methods 2016; 98:74-81. [PMID: 26678796 DOI: 10.1016/j.ymeth.2015.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 12/03/2015] [Accepted: 12/06/2015] [Indexed: 12/21/2022] Open
Abstract
Methods for the localization of cellular components such as nucleic acids, proteins, cellular vesicles and more, and the localization of microorganisms including viruses, bacteria and fungi have become an important part of any research program in biological sciences that enable the visualization of these components in fixed and live tissues without the need for complex processing steps. The rapid development of microscopy tools and technologies as well as related fluorescent markers and fluorophores for many cellular components, and the ability to design DNA and RNA sequence-based molecular probes and antibodies which can be visualized fluorescently, have rapidly advanced this field. This review will focus on some of the localizations methods which have been used in plants and insect pests in agriculture, and other microorganisms, which are rapidly advancing the research in agriculture-related fields.
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Affiliation(s)
- Adi Kliot
- Department of Entomology, The Volcani Center, Bet Dagan 50250, Israel
| | - Murad Ghanim
- Department of Entomology, The Volcani Center, Bet Dagan 50250, Israel.
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18
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Katagiri Y, Hasegawa J, Fujikura U, Hoshino R, Matsunaga S, Tsukaya H. The coordination of ploidy and cell size differs between cell layers in leaves. Development 2016; 143:1120-5. [PMID: 26903507 PMCID: PMC4852493 DOI: 10.1242/dev.130021] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 02/15/2016] [Indexed: 12/12/2022]
Abstract
Growth and developmental processes are occasionally accompanied by multiple rounds of DNA replication, known as endoreduplication. Coordination between endoreduplication and cell size regulation often plays a crucial role in proper organogenesis and cell differentiation. Here, we report that the level of correlation between ploidy and cell volume is different in the outer and inner cell layers of leaves of Arabidopsis thaliana using a novel imaging technique. Although there is a well-known, strong correlation between ploidy and cell volume in pavement cells of the epidermis, this correlation was extremely weak in palisade mesophyll cells. Induction of epidermis cell identity based on the expression of the homeobox gene ATML1 in mesophyll cells enhanced the level of correlation between ploidy and cell volume to near that of wild-type epidermal cells. We therefore propose that the correlation between ploidy and cell volume is regulated by cell identity. Summary: The well-known correlation between ploidy and cell volume in the leaf epidermis is not seen in leaf palisade mesophyll cells, indicating that cell identity influences this correlation.
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Affiliation(s)
- Yohei Katagiri
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Junko Hasegawa
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Ushio Fujikura
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Rina Hoshino
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Sachihiro Matsunaga
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Hirokazu Tsukaya
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan Bio-Next Project, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Yamate Build. #3, 5-1, Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
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19
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Sliwinska E, Mathur J, Bewley JD. On the relationship between endoreduplication and collet hair initiation and tip growth, as determined using six Arabidopsis thaliana root-hair mutants. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:3285-3295. [PMID: 25873686 DOI: 10.1093/jxb/erv136] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A positive correlation between nuclear DNA content and cell size, as postulated by the karyoplasmic theory, has been confirmed in many plant tissues. However, there is also evidence suggesting that there are exceptions. While in previous reports the cell size:ploidy relationship was studied in intact tissues containing cells of different sizes, here simultaneously developing single cells of collet hairs were used to study endoreduplication in Arabidopsis thaliana mutants that produce hairs of variable size and morphology. Endoreduplication in the root and collet zones of six different root-hair mutants was analysed before and after collet hair development using flow cytometry and confocal microscopy. Additionally, the changes in nuclear size (ploidy), shape, and movement in developing collet hairs of a hybrid between Arabidopsis transgenic line NLS-GFP-GUS and the rhd3 (root hair defective3) mutant were followed using time-lapse confocal microscopy. In this hybrid endoreduplication in the collet hairs was disturbed. However, based on the analyses of all mutants, no correlation was found between hair length and the ploidy of the cells in the collet and root regions. The results indicate that the karyoplasmic ratio is maintained at the beginning of collet-hair development, but tip growth proceeds in a DNA-amount-independent manner. The final size of a collet hair appears to be dependent more on genetic modifiers governing general cell physiology than on its DNA content.
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Affiliation(s)
- Elwira Sliwinska
- Laboratory of Molecular Biology and Cytometry, Department of Plant Genetics, Physiology and Biotechnology, UTP University of Science and Technology, Kaliskiego Ave. 7, 85-789 Bydgoszcz, Poland Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Jaideep Mathur
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - J Derek Bewley
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
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20
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Azzi L, Deluche C, Gévaudant F, Frangne N, Delmas F, Hernould M, Chevalier C. Fruit growth-related genes in tomato. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:1075-86. [PMID: 25573859 DOI: 10.1093/jxb/eru527] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Tomato (Solanum lycopersicum Mill.) represents a model species for all fleshy fruits due to its biological cycle and the availability of numerous genetic and molecular resources. Its importance in human nutrition has made it one of the most valuable worldwide commodities. Tomato fruit size results from the combination of cell number and cell size, which are determined by both cell division and expansion. As fruit growth is mainly driven by cell expansion, cells from the (fleshy) pericarp tissue become highly polyploid according to the endoreduplication process, reaching a DNA content rarely encountered in other plant species (between 2C and 512C). Both cell division and cell expansion are under the control of complex interactions between hormone signalling and carbon partitioning, which establish crucial determinants of the quality of ripe fruit, such as the final size, weight, and shape, and organoleptic and nutritional traits. This review describes the genes known to contribute to fruit growth in tomato.
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Affiliation(s)
- Lamia Azzi
- University of Bordeaux, UMR1332 Biologie du Fruit et Pathologie, INRA Bordeaux Aquitaine, CS20032, F-33882 Villenave d'Ornon cedex, France
| | - Cynthia Deluche
- University of Bordeaux, UMR1332 Biologie du Fruit et Pathologie, INRA Bordeaux Aquitaine, CS20032, F-33882 Villenave d'Ornon cedex, France
| | - Frédéric Gévaudant
- University of Bordeaux, UMR1332 Biologie du Fruit et Pathologie, INRA Bordeaux Aquitaine, CS20032, F-33882 Villenave d'Ornon cedex, France
| | - Nathalie Frangne
- University of Bordeaux, UMR1332 Biologie du Fruit et Pathologie, INRA Bordeaux Aquitaine, CS20032, F-33882 Villenave d'Ornon cedex, France
| | - Frédéric Delmas
- University of Bordeaux, UMR1332 Biologie du Fruit et Pathologie, INRA Bordeaux Aquitaine, CS20032, F-33882 Villenave d'Ornon cedex, France
| | - Michel Hernould
- University of Bordeaux, UMR1332 Biologie du Fruit et Pathologie, INRA Bordeaux Aquitaine, CS20032, F-33882 Villenave d'Ornon cedex, France
| | - Christian Chevalier
- INRA, UMR1332 Biologie du Fruit et Pathologie, INRA Bordeaux Aquitaine, CS20032, F-33882, Villenave d'Ornon cedex, France
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21
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Schubert V. RNA polymerase II forms transcription networks in rye and Arabidopsis nuclei and its amount increases with endopolyploidy. Cytogenet Genome Res 2014; 143:69-77. [PMID: 25060696 DOI: 10.1159/000365233] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
RNA polymerase II (RNAPII) is responsible for the transcription of most eukaryotic genes. In mammalian nuclei, RNAPII is mainly localized in relatively few distinct transcription factories. In this study--applying super-resolution microscopy--it is shown that in plants, inactive (non-phosphorylated) and active (phosphorylated) RNAPII modifications compose distinct 'transcription networks' within the euchromatin. These reticulate structures sometimes attach to each other, but they are absent from heterochromatin and nucleoli. The global RNAPII distribution within nuclei is not influenced by interphase chromatin organization such as Rabl (rye) versus non-Rabl (Arabidopsis thaliana) orientation. Replication of sister chromatids without cell division causes endopolyploidy, a phenomenon widespread in plants and animals. Endopolyploidy raises the number of gene copies per nucleus. Here, it is shown that the amounts of active and inactive RNAPII enzymes in differentiated 2-32C leaf nuclei of A. thaliana proportionally increase with rising endopolyploidy. Thus, increasing the transcriptional activity of cells and tissues seems to be an important function of endopolyploidy.
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Affiliation(s)
- Veit Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
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22
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Blondel C, Melesan M, San Miguel A, Veyrenc S, Meresse P, Pezet M, Reynaud S, Raveton M. Cell cycle disruption and apoptosis as mechanisms of toxicity of organochlorines in Zea mays roots. JOURNAL OF HAZARDOUS MATERIALS 2014; 276:312-322. [PMID: 24892778 DOI: 10.1016/j.jhazmat.2014.05.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 05/13/2014] [Accepted: 05/15/2014] [Indexed: 06/03/2023]
Abstract
Organochlorine pesticides (OCPs) are widespread environmental pollutants; two of them are highly persistent: lindane (γHCH) and chlordecone (CLD). Maize plants cope with high levels of OCP-environmental pollution, however little is known about cellular mechanisms involved in plant response to such OCP-exposures. This research was aimed at understanding the physiological pathways involved in the plant response to OCPs in function of a gradient of exposure. Here we provide the evidences that OCPs might disrupt root cell cycle leading to a rise in the level of polyploidy possibly through mechanisms of endoreduplication. In addition, low-to-high doses of γHCH were able to induce an accumulation of H2O2 without modifying NO contents, while CLD modulated neither H2O2 nor NO production. [Ca(2+)]cytosolic, the caspase-3-like activity as well as TUNEL-positive nuclei and IP-positive cells increased after exposure to low-to-high doses of OCPs. These data strongly suggest a cascade mechanism of the OCP-induced toxic effect, notably with an increase in [Ca(2+)]cytosolic and caspase-3-like activity, suggesting the activation of programmed cell death pathway.
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Affiliation(s)
- Claire Blondel
- Laboratoire d'Ecologie Alpine, UMR CNRS n°5553, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 09, France; Université de Grenoble - Alpes, France
| | - Marc Melesan
- Laboratoire d'Ecologie Alpine, UMR CNRS n°5553, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 09, France; Université de Grenoble - Alpes, France
| | - Angélique San Miguel
- Laboratoire d'Ecologie Alpine, UMR CNRS n°5553, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 09, France; Université de Grenoble - Alpes, France
| | - Sylvie Veyrenc
- Laboratoire d'Ecologie Alpine, UMR CNRS n°5553, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 09, France; Université de Grenoble - Alpes, France
| | - Patrick Meresse
- Université de Grenoble - Alpes, France; Centre Universitaire de Biologie Expérimentale, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 09, France
| | - Mylène Pezet
- Centre de Recherche Inserm/UJF U823, Institut Albert Bonniot, BP 170, 38042 Grenoble Cedex 09, France
| | - Stephane Reynaud
- Laboratoire d'Ecologie Alpine, UMR CNRS n°5553, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 09, France; Université de Grenoble - Alpes, France
| | - Muriel Raveton
- Laboratoire d'Ecologie Alpine, UMR CNRS n°5553, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 09, France; Université de Grenoble - Alpes, France.
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Chevalier C, Bourdon M, Pirrello J, Cheniclet C, Gévaudant F, Frangne N. Endoreduplication and fruit growth in tomato: evidence in favour of the karyoplasmic ratio theory. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2731-46. [PMID: 24187421 DOI: 10.1093/jxb/ert366] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The growth of a plant organ depends upon the developmental processes of cell division and cell expansion. The activity of cell divisions sets the number of cells that will make up the organ; the cell expansion activity then determines its final size. Among the various mechanisms that may influence the determination of cell size, endopolyploidy by means of endoreduplication appears to be of great importance in plants. Endoreduplication is widespread in plants and supports the process of differentiation of cells and organs. Its functional role in plant cells is not fully understood, although it is commonly associated with ploidy-dependent cell expansion. During the development of tomato fruit, cells from the (fleshy) pericarp tissue become highly polyploid, reaching a DNA content barely encountered in other plant species (between 2C and 512C). Recent investigations using tomato fruit development as a model provided new data in favour of the long-standing karyoplasmic ratio theory, stating that cells tend to adjust their cytoplasmic volume to the nuclear DNA content. By establishing a highly structured cellular system where multiple physiological functions are integrated, endoreduplication does act as a morphogenetic factor supporting cell growth during tomato fruit development.
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Affiliation(s)
- Christian Chevalier
- INRA, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France
| | - Matthieu Bourdon
- INRA, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France University of Bordeaux, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France
| | - Julien Pirrello
- INRA, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France
| | - Catherine Cheniclet
- INRA, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France CNRS, Bordeaux Imaging Center, UMS 3420, F-33000 Bordeaux, France
| | - Frédéric Gévaudant
- University of Bordeaux, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France
| | - Nathalie Frangne
- University of Bordeaux, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France
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Suzaki T, Ito M, Yoro E, Sato S, Hirakawa H, Takeda N, Kawaguchi M. Endoreduplication-mediated initiation of symbiotic organ development in Lotus japonicus. Development 2014; 141:2441-5. [PMID: 24850853 DOI: 10.1242/dev.107946] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Many leguminous plants have a unique ability to reset and alter the fate of differentiated root cortical cells to form new organs of nitrogen-fixing root nodules during legume-Rhizobium symbiosis. Recent genetic studies on the role of cytokinin signaling reveal that activation of cytokinin signaling is crucial to the nodule organogenesis process. However, the genetic mechanism underlying the initiation of nodule organogenesis is poorly understood due to the low number of genes that have been identified. Here, we have identified a novel nodulation-deficient mutant named vagrant infection thread 1 (vag1) after suppressor mutant screening of spontaneous nodule formation 2, a cytokinin receptor gain-of-function mutant in Lotus japonicus. The VAG1 gene encodes a protein that is putatively orthologous to Arabidopsis ROOT HAIRLESS 1/HYPOCOTYL 7, a component of the plant DNA topoisomerase VI that is involved in the control of endoreduplication. Nodule phenotype of the vag1 mutant shows that VAG1 is required for the ploidy-dependent cell growth of rhizobial-infected cells. Furthermore, VAG1 mediates the onset of endoreduplication in cortical cells during early nodule development, which may be essential for the initiation of cortical cell proliferation that leads to nodule primordium formation. In addition, cortical infection is severely impaired in the vag1 mutants, whereas the epidermal infection threads formation is normal. This suggests that the VAG1-mediated endoreduplication of cortical cells may be required for the guidance of symbiotic bacteria to host meristematic cells.
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Affiliation(s)
- Takuya Suzaki
- National Institute for Basic Biology, Okazaki 444-8585, Japan School of Life Science, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan
| | - Momoyo Ito
- National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Emiko Yoro
- National Institute for Basic Biology, Okazaki 444-8585, Japan School of Life Science, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan
| | - Shusei Sato
- Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | | | - Naoya Takeda
- National Institute for Basic Biology, Okazaki 444-8585, Japan School of Life Science, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan
| | - Masayoshi Kawaguchi
- National Institute for Basic Biology, Okazaki 444-8585, Japan School of Life Science, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan
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Breuer C, Braidwood L, Sugimoto K. Endocycling in the path of plant development. CURRENT OPINION IN PLANT BIOLOGY 2014; 17:78-85. [PMID: 24507498 DOI: 10.1016/j.pbi.2013.11.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/11/2013] [Accepted: 11/12/2013] [Indexed: 05/29/2023]
Abstract
Genome duplication is a widespread phenomenon in many eukaryotes. In plants numeric changes of chromosome sets have tremendous impact on growth performance and yields, hence, are of high importance for agriculture. In contrast to polyploidisation in which the genome is duplicated throughout the entire organism and stably inherited by the offspring, endopolyploidy relies on endocycles in which cells multiply the genome in specific tissues and cell types. During the endocycle cells repeatedly replicate their DNA but skip mitosis, leading to genome duplication after each round. Endocycles are common in multicellular eukaryotes and are often involved in the regulation of cell and organ growth. In plants, changes in cellular ploidy have also been associated with other developmental processes as well as physiological interactions with the surrounding environment. Thus, endocycles play pivotal roles throughout the life cycle of many plant species.
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Affiliation(s)
- Christian Breuer
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Luke Braidwood
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Keiko Sugimoto
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan.
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26
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Galbraith DW. Endoreduplicative standards for calibration of flow cytometric C-Value measurements. Cytometry A 2014; 85:368-74. [PMID: 24415326 DOI: 10.1002/cyto.a.22440] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 12/05/2013] [Accepted: 12/27/2013] [Indexed: 01/13/2023]
Abstract
It has been estimated that there are, globally, as many as 400,000 species of the angiosperms (the flowering plants). Of these, a minimal proportion has been characterized at the cytological level. Urgency is required in initiating a systematic and comprehensive census, due to species extinction as a consequence of anthropogenic activities. Fundamental to eukaryotes is the 2C-value, the amount of DNA contained within the nucleus of the unreduced gametes. Flow cytometry provides an ideal method for determining C-values, but the values archived in the Kew Plant C-value Database represent <2% of these species. Complicating the issue is a proliferation of different, and inconsistent standards for C-value measurements utilizing flow cytometry, and variability associated with different instrument platforms and using different staining procedures. In previous work, the use of flow cytometry for analysis of plant nuclear DNA contents for species spanning much of the range of genome sizes found in the angiosperms was described. For this work, an endoreduplicative species (Arabidopsis thaliana L.) was particularly helpful as an internal standard for genome size calibration. Such a standard is compromised if it overlaps in DNA content than that of the species whose genome size is sought. This report describes the use of a second species displaying endoreduplication, Capsicum annuum L., for similar standardization. The results (a) indicate accurate reporting of nuclear DNA contents across a range 0.32-423.68 pg, (b) confirm that endoreduplication increases nuclear DNA contents by complete replication of the genome, and (c) provide a means for quality control of linearity in instrumentation over defined dynamic ranges.
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Affiliation(s)
- David W Galbraith
- School of Plant Sciences, BIO5 Institute, University of Arizona, Tucson, Arizona
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28
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Pirrello J, Bourdon M, Cheniclet C, Bourge M, Brown SC, Renaudin JP, Frangne N, Chevalier C. How fruit developmental biology makes use of flow cytometry approaches. Cytometry A 2013; 85:115-25. [PMID: 24273206 DOI: 10.1002/cyto.a.22417] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 09/20/2013] [Accepted: 10/26/2013] [Indexed: 12/15/2022]
Abstract
Fleshy fruit species such as tomato are important because of their nutritional and economic value. Several stages of fruit development such as ovary formation, fruit set, and fruit maturation have already been the subject of many developmental studies. However, fruit growth per se has been much less addressed. Fruit growth like all plant organs depends upon the developmental processes of cell division and cell expansion. The activity of cell divisions sets the number of cells that will compose the fruit; the cell expansion activity then determines its final size. Among the various mechanisms that may influence the determination of cell size, endopolyploidy by the means of endoreduplication, i.e. genome amplification in the absence of mitosis, appears to be of great importance in fleshy fruits. In tomato fruit, endoreduplication is associated with DNA-dependent cell expansion: cell size can reach spectacular levels such as hundreds of times its initial size (e.g. >0.5 mm in diameter), with as much as a 256-fold increase in nuclear DNA content. Using tomato fruit development as a model, recent investigations combining the use of flow cytometry, cellular imaging and molecular analyses have provided new data in favor of the long-standing karyoplasmic ratio theory, stating that cells tend to adjust their cytoplasmic volume to the nuclear DNA content. By establishing a highly structured cellular system where multiple physiological functions are integrated, endoreduplication acts as a morphogenetic factor supporting cell growth during tomato fruit development. In the context of plant breeding, deciphering the mechanisms controlling fruit growth, in particular those connecting the process of nuclear endoreduplication with modulation of gene expression, the regulation of cell size and final fruit size and composition, is necessary to understand better the establishment of fleshy fruit quality traits.
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Affiliation(s)
- Julien Pirrello
- INRA, Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France
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29
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Bourdon M, Pirrello J, Cheniclet C, Coriton O, Bourge M, Brown S, Moïse A, Peypelut M, Rouyère V, Renaudin JP, Chevalier C, Frangne N. Evidence for karyoplasmic homeostasis during endoreduplication and a ploidy-dependent increase in gene transcription during tomato fruit growth. Development 2012; 139:3817-26. [PMID: 22991446 DOI: 10.1242/dev.084053] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Endopolyploidy is a widespread process that corresponds to the amplification of the genome in the absence of mitosis. In tomato, very high ploidy levels (up to 256C) are reached during fruit development, concomitant with very large cell sizes. Using cellular approaches (fluorescence and electron microscopy) we provide a structural analysis of endoreduplicated nuclei at the level of chromatin and nucleolar organisation, nuclear shape and relationship with other cellular organelles such as mitochondria. We demonstrate that endopolyploidy in pericarp leads to the formation of polytene chromosomes and markedly affects nuclear structure. Nuclei manifest a complex shape, with numerous deep grooves that are filled with mitochondria, affording a fairly constant ratio between nuclear surface and nuclear volume. We provide the first direct evidence that endopolyploidy plays a role in increased transcription of rRNA and mRNA on a per-nucleus basis. Overall, our results provide quantitative evidence in favour of the karyoplasmic theory and show that endoreduplication is associated with complex cellular organisation during tomato fruit development.
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Affiliation(s)
- Matthieu Bourdon
- University of Bordeaux, UMR1332 Biologie du Fruit et Pathologie, BP 81, F-33140 Villenave d'Ornon, France
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LEGLAND D, DEVAUX MF, BOUCHET B, GUILLON F, LAHAYE M. Cartography of cell morphology in tomato pericarp at the fruit scale. J Microsc 2012; 247:78-93. [DOI: 10.1111/j.1365-2818.2012.03623.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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31
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Interphase chromatin organisation in Arabidopsis nuclei: constraints versus randomness. Chromosoma 2012; 121:369-87. [PMID: 22476443 DOI: 10.1007/s00412-012-0367-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 02/09/2012] [Accepted: 03/12/2012] [Indexed: 12/22/2022]
Abstract
The spatial chromatin organisation and molecular interactions within and between chromatin domains and chromosome territories (CTs) are essential for fundamental processes such as replication, transcription and DNA repair via homologous recombination. To analyse the distribution and interaction of whole CTs, centromeres, (sub)telomeres and ~100-kb interstitial chromatin segments in endopolyploid nuclei, specific FISH probes from Arabidopsis thaliana were applied to 2-64C differentiated leaf nuclei. Whereas CTs occupy a distinct and defined volume of the nucleus and do not obviously intermingle with each other in 2-64C nuclei, ~100-kb sister chromatin segments within these CTs become more non-cohesive with increasing endopolyploidy. Centromeres, preferentially located at the nuclear periphery, may show ring- or half-moon like shapes in 2C and 4C nuclei. Sister centromeres tend to associate up to the 8C level. From 16C nuclei on, they become progressively separated. The higher the polyploidy level gets, the more separate chromatids are present. Due to sister chromatid separation in highly endopolyploid nuclei, the centromeric histone variant CENH3, the 180-bp centromeric repeats and pericentromeric heterochromatin form distinct subdomains at adjacent but not intermingling positions. The (sub)telomeres are frequently associated with each other and with the nucleolus and less often with centromeres. The extent of chromatid separation and of chromatin decondensation at subtelomeric chromatin segments varies between chromosome arms. A mainly random distribution and similar shapes of CTs even at higher ploidy levels indicate that in general no substantial CT reorganisation occurs during endopolyploidisation. Non-cohesive sister chromatid regions at chromosome arms and at the (peri)centromere are accompanied by a less dense chromatin conformation in highly endopolyploid nuclei. We discuss the possible function of this conformation in comparison to transcriptionally active regions at insect polytene chromosomes.
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De Veylder L, Larkin JC, Schnittger A. Molecular control and function of endoreplication in development and physiology. TRENDS IN PLANT SCIENCE 2011; 16:624-34. [PMID: 21889902 DOI: 10.1016/j.tplants.2011.07.001] [Citation(s) in RCA: 202] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 07/19/2011] [Accepted: 07/21/2011] [Indexed: 05/03/2023]
Abstract
Endoreplication, also called endoreduplication, is a cell cycle variant of multicellular eukaryotes in which mitosis is skipped and cells repeatedly replicate their DNA, resulting in cellular polyploidy. In recent years, research results have shed light on the molecular mechanism of endoreplication control, but the function of this cell-cycle variant has remained elusive. However, new evidence is at last providing insight into the biological relevance of cellular polyploidy, demonstrating that endoreplication is essential for developmental processes, such as cell fate maintenance, and is a prominent response to physiological conditions, such as pathogen attack or DNA damage. Thus, endoreplication is being revealed as an important module in plant growth that contributes to the robustness of plant life.
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