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Zhou X, Lu J, Zhang Y, Guo J, Lin W, Van Norman JM, Qin Y, Zhu X, Yang Z. Membrane receptor-mediated mechano-transduction maintains cell integrity during pollen tube growth within the pistil. Dev Cell 2021; 56:1030-1042.e6. [PMID: 33756107 DOI: 10.1016/j.devcel.2021.02.030] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 01/22/2021] [Accepted: 02/26/2021] [Indexed: 12/11/2022]
Abstract
Invasive or penetrative growth is critical for developmental and reproductive processes (e.g., pollen tube penetration of pistils) and disease progression (e.g., cancer metastasis and fungal hyphae invasion). The invading or penetrating cells experience drastic changes in mechanical pressure from the surroundings and must balance growth with cell integrity. Here, we show that Arabidopsis pollen tubes sense and/or respond to mechanical changes via a cell-surface receptor kinase Buddha's Paper Seal 1 (BUPS1) while emerging from compressing female tissues. BUPS1-defective pollen tubes fail to maintain cell integrity after emergence from these tissues. The mechano-transduction function of BUPS1 is established by using a microfluidic channel device mimicking the mechanical features of the in vivo growth path. BUPS1-based mechano-transduction activates Rho-like GTPase from Plant 1 (ROP1) GTPase to promote exocytosis that facilitates secretion of BUPS1's ligands for mechanical signal amplification and cell wall rigidification in pollen tubes. These findings uncover a membrane receptor-based mechano-transduction system for cells to cope with the physical challenges during invasive or penetrative growth.
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Affiliation(s)
- Xiang Zhou
- Department of Botany and Plant Sciences and Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Jun Lu
- Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai, China; National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Shanghai 200032, People's Republic of China
| | - Yuqin Zhang
- FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Jingzhe Guo
- Department of Botany and Plant Sciences and Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Wenwei Lin
- Department of Botany and Plant Sciences and Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521, USA; FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Jaimie M Van Norman
- Department of Botany and Plant Sciences and Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Yuan Qin
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Center for Genomics and Biotechnology, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xiaoyue Zhu
- FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Zhenbiao Yang
- Department of Botany and Plant Sciences and Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521, USA.
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Khan A, Yadav NS, Morgenstern Y, Zemach A, Grafi G. Activation of Tag1 transposable elements in Arabidopsis dedifferentiating cells and their regulation by CHROMOMETHYLASE 3-mediated CHG methylation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:1289-98. [PMID: 27475038 DOI: 10.1016/j.bbagrm.2016.07.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Revised: 07/13/2016] [Accepted: 07/25/2016] [Indexed: 12/11/2022]
Abstract
Dedifferentiation, that is, the acquisition of stem cell-like state, commonly induced by stress (e.g., protoplasting), is characterized by open chromatin conformation, a chromatin state that could lead to activation of transposable elements (TEs). Here, we studied the activation of the Arabidopsis class II TE Tag1, in which two copies, situated close to each other (near genes) on chromosome 1 are found in Landsberg erecta (Ler) but not in Columbia (Col). We first transformed protoplasts with a construct in which a truncated Tag1 (ΔTag1 non-autonomous) blocks the expression of a reporter gene AtMBD5-GFP and found a relatively high ectopic excision of ΔTag1 accompanied by expression of AtMBD5-GFP in protoplasts derived from Ler compared to Col; further increase was observed in ddm1 (decrease in DNA methylation1) protoplasts (Ler background). Ectopic excision was associated with transcription of the endogenous Tag1 and changes in histone H3 methylation at the promoter region. Focusing on the endogenous Tag1 elements we found low level of excision in Ler protoplasts, which was slightly and strongly enhanced in ddm1 and cmt3 (chromomethylase3) protoplasts, respectively, concomitantly with reduction in Tag1 gene body (GB) CHG methylation and increased Tag1 transcription; strong activation of Tag1 was also observed in cmt3 leaves. Notably, in cmt3, but not in ddm1, Tag1 elements were excised out from their original sites and transposed elsewhere in the genome. Our results suggest that dedifferentiation is associated with Tag1 activation and that CMT3 rather than DDM1 plays a central role in restraining Tag1 activation via inducing GB CHG methylation.
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Affiliation(s)
- Asif Khan
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben Gurion 84990, Israel
| | - Narendra Singh Yadav
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben Gurion 84990, Israel
| | - Yaakov Morgenstern
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben Gurion 84990, Israel
| | - Assaf Zemach
- Department of Molecular Biology and Ecology of Plants, Tel-Aviv University, 69978 Tel Aviv, Israel
| | - Gideon Grafi
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben Gurion 84990, Israel.
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Fambrini M, Basile A, Salvini M, Pugliesi C. Excisions of a defective transposable CACTA element (Tetu1) generate new alleles of a CYCLOIDEA-like gene of Helianthus annuus. Gene 2014; 549:198-207. [PMID: 25046140 DOI: 10.1016/j.gene.2014.07.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 07/07/2014] [Accepted: 07/08/2014] [Indexed: 01/17/2023]
Abstract
Tubular ray flower (turf) is a sunflower mutant that caught attention because it bears actinomorphic ray flowers, due to the presence of an active, although non-autonomous CACTA transposon (Tetu1) in the TCP domain of a CYCLOIDEA-like gene, HaCYC2c, a major regulator of sunflower floral symmetry. Here, we analyzed its excision rates in F3 population deriving from independent crosses of turf with common sunflower accessions. Our results suggest that the excision rate, ranging from 1.21 to 6.29%, depends on genetic background; moreover, the absence of somatic sectors in inflorescences of revertant individuals analyzed (182) and genetic analyses suggests a tight developmental control of Tetu1 excision, likely restricted to germinal cells. We individuate events of Tetu1 excision through molecular analysis that restore the wild type (WT) HaCYC2c allele, but even transposon excisions during which footprints are left. All mutations we detected occurred at the TCP basic motif and cause a change in ray flower phenotype. In particular, we selected five mutants with a one-to-four amino acid change that influence the capacity of reproductive organ development and ray flower corolla shaping (MUT-1, -2, -3, -4, -5). Revertant alleles not affecting turf phenotype (i.e. reading frame mutations) have also been identified (MUT-6). In all mutants, Real-time quantitative PCR (qPCR) experiments revealed variations of the steady state level of HaCYC2c mRNA. MUT-1 and MUT-4 showed a significant HaCYC2c down-regulation with respect to WT. A large variation within the biological replicates of MUT-2, MUT-3 and MUT-5 was detected and not significant differences in transcription levels between mutants and WT were observed. We detected low steady state level of HaCYC2c mRNA both in turf as in MUT-6. A three dimensional (3D) structure prediction tool let us predict an incorrect folding of the TCP protein already after a single amino acid deletion. This in turn is detectable as the restore of traits that are not peculiar of WT ray flowers, such as male fertility. Our analysis of an active TE sheds light on the TCP motif of the HaCYC2c gene and suggests that Tetu1 may be useful to obtain new natural mutants and for transposon tagging in different inbred lines of sunflower.
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Affiliation(s)
- Marco Fambrini
- Dipartimento di Scienze Agrarie, Alimentari e Agro-ambientali, Università di Pisa, Pisa, Italy
| | - Alice Basile
- Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Mariangela Salvini
- Dipartimento di Scienze Agrarie, Alimentari e Agro-ambientali, Università di Pisa, Pisa, Italy; Scuola Normale Superiore, Pisa, Italy
| | - Claudio Pugliesi
- Dipartimento di Scienze Agrarie, Alimentari e Agro-ambientali, Università di Pisa, Pisa, Italy.
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Li Y, Harris L, Dooner HK. TED, an autonomous and rare maize transposon of the mutator superfamily with a high gametophytic excision frequency. THE PLANT CELL 2013; 25:3251-65. [PMID: 24038653 PMCID: PMC3809530 DOI: 10.1105/tpc.113.116517] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Mutator (Mu) elements, one of the most diverse superfamilies of DNA transposons, are found in all eukaryotic kingdoms, but are particularly numerous in plants. Most of the present knowledge on the transposition behavior of this superfamily comes from studies of the maize (Zea mays) Mu elements, whose transposition is mediated by the autonomous Mutator-Don Robertson (MuDR) element. Here, we describe the maize element TED (for Transposon Ellen Dempsey), an autonomous cousin that differs significantly from MuDR. Element excision and reinsertion appear to require both proteins encoded by MuDR, but only the single protein encoded by TED. Germinal excisions, rare with MuDR, are common with TED, but arise in one of the mitotic divisions of the gametophyte, rather than at meiosis. Instead, transposition-deficient elements arise at meiosis, suggesting that the double-strand breaks produced by element excision are repaired differently in mitosis and meiosis. Unlike MuDR, TED is a very low-copy transposon whose number and activity do not undergo dramatic changes upon inbreeding or outcrossing. Like MuDR, TED transposes mostly to unlinked sites and can form circular transposition products. Sequences closer to TED than to MuDR were detected only in the grasses, suggesting a rather recent evolutionary split from a common ancestor.
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Affiliation(s)
- Yubin Li
- Waksman Institute, Rutgers University, Piscataway, New Jersey 08854
| | - Linda Harris
- Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada K1A 0C6
| | - Hugo K. Dooner
- Waksman Institute, Rutgers University, Piscataway, New Jersey 08854
- Department of Plant Biology, Rutgers University, New Brunswick, New Jersey 08901
- Address correspondence to
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5
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McCue AD, Slotkin RK. Transposable element small RNAs as regulators of gene expression. Trends Genet 2012; 28:616-23. [PMID: 23040327 DOI: 10.1016/j.tig.2012.09.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 08/31/2012] [Accepted: 09/05/2012] [Indexed: 11/30/2022]
Abstract
Transposable elements (TEs) are a source of endogenous small RNAs in animals and plants. These TE-derived small RNAs have been traditionally treated as functionally distinct from gene-regulating small RNAs, such as miRNAs. Two recent reports in Drosophila and Arabidopsis have blurred the lines of this distinction. In both examples, epigenetically and developmentally regulated bursts in TE expression produce gene-regulating small RNAs. In the Drosophila early embryo, maternally deposited TE-derived PIWI-interacting small RNAs (piRNAs) play a role in regulating the nanos mRNA through small RNA binding sites in the nanos 3' untranslated region (UTR). In Arabidopsis, when Athila retrotransposons are epigenetically activated, their transcripts are processed into small RNAs, which directly target the 3'UTR of the genic oligouridylate binding protein 1B (UBP1b) mRNA. Based on these two examples, we suggest that other TE-derived small RNAs regulate additional genes and propose that, through small RNAs, the epigenetic status of TEs could widely influence the genic transcriptome.
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Affiliation(s)
- Andrea D McCue
- Department of Molecular Genetics & Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
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6
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Havecker ER, Wallbridge LM, Hardcastle TJ, Bush MS, Kelly KA, Dunn RM, Schwach F, Doonan JH, Baulcombe DC. The Arabidopsis RNA-directed DNA methylation argonautes functionally diverge based on their expression and interaction with target loci. THE PLANT CELL 2010; 22:321-34. [PMID: 20173091 PMCID: PMC2845420 DOI: 10.1105/tpc.109.072199] [Citation(s) in RCA: 261] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 12/31/2009] [Accepted: 01/29/2010] [Indexed: 05/18/2023]
Abstract
Argonaute (AGO) effectors of RNA silencing bind small RNA (sRNA) molecules and mediate mRNA cleavage, translational repression, or epigenetic DNA modification. In many organisms, these targeting mechanisms are devolved to different products of AGO multigene families. To investigate the basis of AGO functional diversification, we characterized three closely related Arabidopsis thaliana AGOs (AGO4, AGO6, and AGO9) implicated in RNA-directed DNA methylation. All three AGOs bound 5' adenosine 24-nucleotide sRNAs, but each exhibited different preferences for sRNAs from different heterochromatin-associated loci. This difference was reduced when AGO6 and AGO9 were expressed from the AGO4 promoter, indicating that the functional diversification was partially due to differential expression of the corresponding genes. However, the AGO4-directed pattern of sRNA accumulation and DNA methylation was not fully recapitulated with AGO6 or AGO9 expressed from the AGO4 promoter. Here, we show that sRNA length and 5' nucleotide do not account for the observed functional diversification of these AGOs. Instead, the selectivity of sRNA binding is determined by the coincident expression of the AGO and sRNA-generating loci, and epigenetic modification is influenced by interactions between the AGO protein and the different target loci. These findings highlight the importance of tissue specificity and AGO-associated proteins in influencing epigenetic modifications.
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Affiliation(s)
- Ericka R. Havecker
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Laura M. Wallbridge
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Thomas J. Hardcastle
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Maxwell S. Bush
- Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom
| | - Krystyna A. Kelly
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Ruth M. Dunn
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Frank Schwach
- Computing Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - John H. Doonan
- Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom
| | - David C. Baulcombe
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
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Slotkin RK, Vaughn M, Borges F, Tanurdzić M, Becker JD, Feijó JA, Martienssen RA. Epigenetic reprogramming and small RNA silencing of transposable elements in pollen. Cell 2009; 136:461-72. [PMID: 19203581 DOI: 10.1016/j.cell.2008.12.038] [Citation(s) in RCA: 725] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 09/15/2008] [Accepted: 12/11/2008] [Indexed: 10/21/2022]
Abstract
The mutagenic activity of transposable elements (TEs) is suppressed by epigenetic silencing and small interfering RNAs (siRNAs), especially in gametes that could transmit transposed elements to the next generation. In pollen from the model plant Arabidopsis, we show that TEs are unexpectedly reactivated and transpose, but only in the pollen vegetative nucleus, which accompanies the sperm cells but does not provide DNA to the fertilized zygote. TE expression coincides with downregulation of the heterochromatin remodeler decrease in DNA methylation 1 and of many TE siRNAs. However, 21 nucleotide siRNAs from Athila retrotransposons are generated and accumulate in pollen and sperm, suggesting that siRNA from TEs activated in the vegetative nucleus can target silencing in gametes. We propose a conserved role for reprogramming in germline companion cells, such as nurse cells in insects and vegetative nuclei in plants, to reveal intact TEs in the genome and regulate their activity in gametes.
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Affiliation(s)
- R Keith Slotkin
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
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Moon S, Jung KH, Lee DE, Jiang WZ, Koh HJ, Heu MH, Lee DS, Suh HS, An G. Identification of Active Transposon dTok , a Member of the hAT Family, in Rice. ACTA ACUST UNITED AC 2006; 47:1473-83. [PMID: 16990289 DOI: 10.1093/pcp/pcl012] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Recent completion of the sequencing of the rice genome has revealed that it contains >40% repetitive sequences, most of which are related to inactive transposable elements. During the molecular analysis of the floral organ number 1/multiple pistil 2 (fon1/mp2) mutant, we identified an active transposable element dTok0 that was inserted at the kinase domain of FON1, a homolog of CLAVATA1. Insertion of the element into FON1 generated an 8 bp duplication of its target sites, which is one of the major characteristics of the hAT family of transposons. The dTok0 element was actively transposed out of the FON1 gene, leaving 5-8 bp footprints. Reinsertion into a new location was observed at a low frequency. Analysis of the genome sequence showed that the rice cultivar 'Nipponbare' contains 25 copies of dTok elements; similar numbers were present in all the Oryza species examined. Because dTok0 does not encode a transposase, enzyme activity should be provided in trans. We identified a putative autonomous transposon, Tok1 that contains an intact open reading frame of the Ac-like transposase.
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Affiliation(s)
- Sunok Moon
- National Research Laboratory of Plant Functional Genomics, Division of Molecular and Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea
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