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de Felippes FF, Waterhouse PM. Plant terminators: the unsung heroes of gene expression. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:2239-2250. [PMID: 36477559 PMCID: PMC10082929 DOI: 10.1093/jxb/erac467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/25/2022] [Indexed: 06/06/2023]
Abstract
To be properly expressed, genes need to be accompanied by a terminator, a region downstream of the coding sequence that contains the information necessary for the maturation of the mRNA 3' end. The main event in this process is the addition of a poly(A) tail at the 3' end of the new transcript, a critical step in mRNA biology that has important consequences for the expression of genes. Here, we review the mechanism leading to cleavage and polyadenylation of newly transcribed mRNAs and how this process can affect the final levels of gene expression. We give special attention to an aspect often overlooked, the effect that different terminators can have on the expression of genes. We also discuss some exciting findings connecting the choice of terminator to the biogenesis of small RNAs, which are a central part of one of the most important mechanisms of regulation of gene expression in plants.
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Affiliation(s)
| | - Peter M Waterhouse
- Centre for Agriculture and the Bioeconomy, Institute for Future Environments, Queensland University of Technology (QUT), Brisbane, QLD, Australia
- ARC Centre of Excellence for Plant Success in Nature & Agriculture, QUT, Brisbane, QLD, Australia
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2
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Park HY, Lee HT, Lee JH, Kim JK. Arabidopsis U2AF65 Regulates Flowering Time and the Growth of Pollen Tubes. FRONTIERS IN PLANT SCIENCE 2019; 10:569. [PMID: 31130976 PMCID: PMC6510283 DOI: 10.3389/fpls.2019.00569] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 04/15/2019] [Indexed: 05/19/2023]
Abstract
During pre-mRNA splicing, U2 small nuclear ribonucleoprotein auxiliary factor 65 (U2AF65) interacts with U2AF35 and splicing factor 1 (SF1), allowing for the recognition of the 3'-splice site by the ternary complex. The functional characterization of U2AF65 homologs has not been performed in Arabidopsis thaliana yet. Here, we show that normal plant development, including floral transition, and male gametophyte development, requires two Arabidopsis U2AF65 isoforms (AtU2AF65a and AtU2AF65b). Loss-of-function mutants of these two isoforms displayed opposite flowering phenotypes: atu2af65a mutants showed late flowering, whereas atu2af65b mutants were characterized by slightly early flowering, as compared to that in the wild-type (Col-0) plants. These abnormal flowering phenotypes were well-correlated with the expression patterns of the flowering time genes such as FLOWERING LOCUS C (FLC) and FLOWERING LOCUS T (FT). However, the two atu2af65 mutants did not display any morphological abnormalities or alterations in abiotic stress tests. Double mutation of the AtU2AF65a and AtU2AF65b genes resulted in non-viable seeds due to defective male gametophyte. In vitro pollen germination test revealed that mutations in both AtU2AF65a and AtU2AF65b genes significantly impaired pollen tube growth. Collectively, our findings suggest that two protein isoforms of AtU2AF65 are differentially involved in regulating flowering time and display a redundant role in pollen tube growth.
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Affiliation(s)
- Hyo-Young Park
- Division of Life Sciences, Korea University, Seoul, South Korea
| | - Hee Tae Lee
- Division of Life Sciences, Korea University, Seoul, South Korea
| | - Jeong Hwan Lee
- Division of Life Science, Chonbuk National University, Jeonju, South Korea
- *Correspondence: Jeong Hwan Lee, Jeong-Kook Kim,
| | - Jeong-Kook Kim
- Division of Life Sciences, Korea University, Seoul, South Korea
- *Correspondence: Jeong Hwan Lee, Jeong-Kook Kim,
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3
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Lee KC, Jang YH, Kim SK, Park HY, Thu MP, Lee JH, Kim JK. RRM domain of Arabidopsis splicing factor SF1 is important for pre-mRNA splicing of a specific set of genes. PLANT CELL REPORTS 2017; 36:1083-1095. [PMID: 28401337 DOI: 10.1007/s00299-017-2140-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/04/2017] [Indexed: 05/20/2023]
Abstract
The RNA recognition motif of Arabidopsis splicing factor SF1 affects the alternative splicing of FLOWERING LOCUS M pre-mRNA and a heat shock transcription factor HsfA2 pre-mRNA. Splicing factor 1 (SF1) plays a crucial role in 3' splice site recognition by binding directly to the intron branch point. Although plant SF1 proteins possess an RNA recognition motif (RRM) domain that is absent in its fungal and metazoan counterparts, the role of the RRM domain in SF1 function has not been characterized. Here, we show that the RRM domain differentially affects the full function of the Arabidopsis thaliana AtSF1 protein under different experimental conditions. For example, the deletion of RRM domain influences AtSF1-mediated control of flowering time, but not the abscisic acid sensitivity response during seed germination. The alternative splicing of FLOWERING LOCUS M (FLM) pre-mRNA is involved in flowering time control. We found that the RRM domain of AtSF1 protein alters the production of alternatively spliced FLM-β transcripts. We also found that the RRM domain affects the alternative splicing of a heat shock transcription factor HsfA2 pre-mRNA, thereby mediating the heat stress response. Taken together, our results suggest the importance of RRM domain for AtSF1-mediated alternative splicing of a subset of genes involved in the regulation of flowering and adaptation to heat stress.
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Affiliation(s)
- Keh Chien Lee
- Division of Life Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Yun Hee Jang
- Division of Life Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Soon-Kap Kim
- Center for Desert Agriculture, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Hyo-Young Park
- Division of Life Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - May Phyo Thu
- Division of Life Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Jeong Hwan Lee
- Department of Life Sciences, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabuk-do, 54896, Republic of Korea.
| | - Jeong-Kook Kim
- Division of Life Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea.
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4
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Kong Y, Zhou G, Yin Y, Xu Y, Pattathil S, Hahn MG. Molecular analysis of a family of Arabidopsis genes related to galacturonosyltransferases. PLANT PHYSIOLOGY 2011; 155:1791-805. [PMID: 21300919 PMCID: PMC3091093 DOI: 10.1104/pp.110.163220] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We are studying a Galacturonosyltransferase-Like (GATL) gene family in Arabidopsis (Arabidopsis thaliana) that was identified bioinformatically as being closely related to a group of 15 genes (Galacturonosyltransferase1 [GAUT1] to -15), one of which (GAUT1) has been shown to encode a functional galacturonosyltransferase. Here, we describe the phylogeny, gene structure, evolutionary history, genomic organization, protein topology, and expression pattern of this gene family in Arabidopsis. Expression studies (reverse transcription-polymerase chain reaction) demonstrate that all 10 AtGATL genes are transcribed, albeit to varying degrees, in Arabidopsis tissues. Promoter::β-glucuronidase expression studies show that individual AtGATL gene family members have both overlapping and unique expression patterns. Nine of the 10 AtGATL genes are expressed in all major plant organs, although not always in all cell types of those organs. AtGATL4 expression appears to be confined to pollen grains. Most of the AtGATL genes are expressed strongly in vascular tissue in both the stem and hypocotyl. Subcellular localization studies of several GATL proteins using yellow fluorescent protein tagging provide evidence supporting the Golgi localization of these proteins. Plants carrying T-DNA insertions in three AtGATL genes (atgatl3, atgatl6, and atgatl9) have reduced amounts of GalA in their stem cell walls. The xylose content increased in atgatl3 and atgatl6 stem walls. Glycome profiling of cell wall fractions from these mutants using a toolkit of diverse plant glycan-directed monoclonal antibodies showed that the mutations affect both pectins and hemicelluloses and alter overall wall structure, as indicated by altered epitope extractability patterns. The data presented suggest that the AtGATL genes encode proteins involved in cell wall biosynthesis, but their precise roles in wall biosynthesis remain to be substantiated.
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5
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Sullivan M. A novel red clover hydroxycinnamoyl transferase has enzymatic activities consistent with a role in phaselic acid biosynthesis. PLANT PHYSIOLOGY 2009; 150:1866-79. [PMID: 19525325 PMCID: PMC2719126 DOI: 10.1104/pp.109.136689] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Accepted: 06/10/2009] [Indexed: 05/19/2023]
Abstract
Red clover (Trifolium pratense) leaves accumulate several mumol g(-1) fresh weight of phaselic acid [2-O-(caffeoyl)-l-malate]. Postharvest oxidation of such o-diphenols to o-quinones by endogenous polyphenol oxidases prevents breakdown of forage protein during storage. Forage crops like alfalfa (Medicago sativa) lack both polyphenol oxidase and o-diphenols, and breakdown of their protein upon harvest and storage results in economic losses and release of excess nitrogen into the environment. Understanding how red clover synthesizes o-diphenols such as phaselic acid will help in the development of forage crops utilizing this natural system of protein protection. A possible pathway for phaselic acid biosynthesis predicts a hydroxycinnamoyl transferase (HCT) capable of forming caffeoyl and/or p-coumaroyl esters with malate. Genes encoding two distinct HCTs were identified in red clover. HCT1 shares more than 75% amino acid identity with a number of well-characterized shikimate O-HCTs implicated in monolignol biosynthesis. HCT2 shares only 34% amino acid sequence identity with HCT1 and has limited sequence identity to any previously identified HCT. Expression analyses indicate that HCT1 mRNA accumulates to 4-fold higher levels in stems than in leaves, whereas HCT2 mRNA accumulates to 10-fold higher levels in leaves than in stems. Activity assays of HCT1 and HCT2 proteins expressed in Escherichia coli indicate that HCT1 transfers caffeoyl or p-coumaroyl moieties from a coenzyme A-thiolester to shikimate but not malate, whereas HCT2 transfers caffeoyl or p-coumaroyl moieties from a coenzyme A-thiolester to malate but not shikimate. Together, these results indicate that HCT1 is involved in monolignol biosynthesis and HCT2 is a novel transferase likely involved in phaselic acid biosynthesis.
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Affiliation(s)
- Michaell Sullivan
- Dairy Forage Research Center, Agricultural Research Service, United States Department of Agriculture, Madison, Wisconsin 53706, USA.
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6
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Millar AA, Gubler F. The Arabidopsis GAMYB-like genes, MYB33 and MYB65, are microRNA-regulated genes that redundantly facilitate anther development. THE PLANT CELL 2005; 17:705-21. [PMID: 15722475 PMCID: PMC1069693 DOI: 10.1105/tpc.104.027920] [Citation(s) in RCA: 455] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Accepted: 12/20/2004] [Indexed: 05/17/2023]
Abstract
The functions of the vast majority of genes encoding R2R3 MYB domain proteins remain unknown. The closely related MYB33 and MYB65 genes of Arabidopsis thaliana have high sequence similarity to the barley (Hordeum vulgare) GAMYB gene. T-DNA insertional mutants were isolated for both genes, and a myb33 myb65 double mutant was defective in anther development. In myb33 myb65 anthers, the tapetum undergoes hypertrophy at the pollen mother cell stage, resulting in premeiotic abortion of pollen development. However, myb33 myb65 sterility was conditional, where fertility increased both under higher light or lower temperature conditions. Thus, MYB33/MYB65 facilitate, but are not essential for, anther development. Neither single mutant displayed a phenotype, implying that MYB33 and MYB65 are functionally redundant. Consistent with functional redundancy, promoter-beta-glucuronidase (GUS) fusions of MYB33 and MYB65 gave identical expression patterns in flowers (sepals, style, receptacle, anther filaments, and connective but not in anthers themselves), shoot apices, and root tips. By contrast, expression of a MYB33:GUS translational fusion in flowers was solely in young anthers (consistent with the male sterile phenotype), and no staining was seen in shoot meristems or root tips. A microRNA target sequence is present in the MYB genes, and mutating this sequence in the MYB33:GUS fusion results in an expanded expression pattern, in tissues similar to that observed in the promoter-GUS lines, implying that the microRNA target sequence is restricting MYB33 expression. Arabidopsis transformed with MYB33 containing the mutated microRNA target had dramatic pleiotrophic developmental defects, suggesting that restricting MYB33 expression, especially in the shoot apices, is essential for proper plant development.
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MESH Headings
- Alleles
- Amino Acid Sequence
- Arabidopsis/genetics
- Arabidopsis/growth & development
- Base Sequence
- DNA, Bacterial/genetics
- DNA, Plant/genetics
- Enhancer Elements, Genetic
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Plant
- Genes, Plant
- Light
- MicroRNAs/genetics
- Models, Genetic
- Mutagenesis, Insertional
- Plants, Genetically Modified
- Promoter Regions, Genetic
- RNA, Plant/genetics
- Sequence Homology, Nucleic Acid
- Temperature
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Affiliation(s)
- Anthony A Millar
- Commonwealth Scientific and Industrial Research Organization, Division of Plant Industry, Canberra ACT 2601, Australia.
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7
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Brewin NJ. Plant Cell Wall Remodelling in the Rhizobium–Legume Symbiosis. CRITICAL REVIEWS IN PLANT SCIENCES 2004; 23:293-316. [PMID: 0 DOI: 10.1080/07352680490480734] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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8
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Reddy VS, Reddy ASN. Developmental and cell-specific expression of ZWICHEL is regulated by the intron and exon sequences of its gene. PLANT MOLECULAR BIOLOGY 2004; 54:273-93. [PMID: 15159628 DOI: 10.1023/b:plan.0000028793.88757.8b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Functional studies with ZWICHEL ( ZWI ), which encodes a Ca(2+)-calmodulin-regulated kinesin, have shown its involvement in trichome morphogenesis and cell division. To identify regulatory regions that control the ZWI expression pattern, we generated transgenic Arabidopsis plants with a GUS reporter driven by different lengths of the ZWI gene 5' region alone or 5' and 3' regions together. The 5' fusions contain varying lengths of the coding and non-coding regions of beta - HYDROXYISOBUTYRYL-CoA HYDROLASE 1 ( CHY1 ), which is upstream of ZWI, and a 162 bp intergenic region. In transgenic plants with 5' 460::GUS, GUS activity was observed primarily in the root hairs whereas transgenic plants with an additional 5' 266 bp region from the CHY1 gene (5' 726::GUS) showed strong GUS accumulation in the entire root including root hairs and root tip, calli and at various developmental stages in trichomes and pollen. However, very little GUS accumulation was detected in roots of dark-grown or root tips of cold-treated seedlings with 5' ZWI constructs. These results were further confirmed by quantifying GUS enzyme activity and transcripts in these seedlings. Calli and pollen transformed with the 5' distal 268 bp fused in antisense orientation to the proximal 460 bp did not show GUS expression. Further, IAA-treated dark-grown seedlings with 726::GUS, but not with 460::GUS, showed high GUS expression in specific regions (outer layer 2a cells) at the base of the lateral roots. The ZWI 3' region (3 kb) did not influence the GUS expression pattern driven by the 5' 726 bp. The absence of CHY1 transcripts in the chy1-2 mutant did not alter either ZWI expression or ZWI-mediated trichome morphogenesis. Thus, our data suggest that the 3' part of the CHY1 gene contains regulatory elements that control ZWI gene expression in dividing cells and other cells that exhibit polarized growth such as root hairs, pollen and trichomes. This is the first evidence that the regulatory regions conferring developmental and cell-specific expression of a gene reside in the introns and exons of its upstream protein-coding gene.
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Affiliation(s)
- Vaka S Reddy
- Department of Biology and Program in Cell and Molecular Biology, Colorado State University, 200 W Lake Street, Fort Collins, CO 80523, USA
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9
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Nakagawa T, Takane K, Sugimoto T, Izui K, Kouchi H, Hata S. Regulatory regions and nuclear factors involved in nodule-enhanced expression of a soybean phosphoenolpyruvate carboxylase gene: implications for molecular evolution. Mol Genet Genomics 2003; 269:163-72. [PMID: 12684874 DOI: 10.1007/s00438-002-0794-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2002] [Accepted: 12/04/2002] [Indexed: 10/25/2022]
Abstract
We have determined the genomic organization of two closely related phosphoenolpyruvate carboxylase genes in soybean, GmPEPC7, which is expressed at high levels in root nodules, and the housekeeping gene GmPEPC15. Their nucleotide sequences, including most introns and 5;-flanking regions within 600 bp upstream from the transcription start sites, are well conserved, suggesting that they were duplicated quite recently. To gain insights into the process of evolution of the tissue-specifically expressed GmPEPC7gene, we produced chimeric constructs carrying either the GmPEPC7or GmPEPC15promoter fused to the beta-glucuronidase gene. The expression patterns of the reporter observed in nodules that developed on transgenic hairy roots reflected the levels of mRNA levels produced by the genes in wild-type soybean plants, indicating that the GmPEPC7promoter directs nodule-specific expression. Loss-of-function experiments showed that the segment of GmPEPC7between -466 and -400, designated as the "switch region" (SR), was necessary for expression in nodules, although proteins that bind to SR were not detectable in a gel-retardation assay. Another gel-retardation assay indicated that putative nodule nuclear proteins bind specifically to the region of GmPEPC7between -400 and -318, designated as the "amplifier region" (AR). Both SR and AR have characteristic sequences that are not found in the GmPEPC15promoter. Furthermore, experiments using hybrid promoters derived from GmPEPC15demonstrated that AR confers high-level expression in nodules only in combination with SR. When wild-type soybean plants were subjected to prolonged darkness and subsequently illuminated, the level of GmPEPC7mRNA in nodules decreased and then recovered. This study suggests that the acquisition of two interdependent cis-acting elements resulted in molecular evolution of the nodule-enhanced GmPEPC7gene.
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Affiliation(s)
- T Nakagawa
- Laboratory of Plant Physiology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Japan
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10
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Laplaze L, Gherbi H, Duhoux E, Pawlowski K, Auguy F, Guermache F, Franche C, Bogusz D. Symbiotic and non-symbiotic expression of cgMT1, a metallothionein-like gene from the actinorhizal tree Casuarina glauca. PLANT MOLECULAR BIOLOGY 2002; 49:81-92. [PMID: 12008901 DOI: 10.1023/a:1014415003714] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A clone for a type 1 metallothionein (cgMT1) was isolated from a Casuarina glauca nodule cDNA library. The corresponding gene belongs to a small family and is highly expressed in roots and nitrogen-fixing nodules, whereas low expression was observed in aerial parts of the plant. The promoter region of cgMT1 was isolated and fused to the beta-glucuronidase (gus) gene. Transgenic Casuarinaceae plants showed that the cgMT1 promoter was most active in roots and in the oldest region of the shoot. In situ hybridization indicated that in nodules cgMT1 transcript is present in mature Frankia-infected cells and in the pericycle. Possible roles for cgMT1 in symbiotic and nonsymbiotic tissues are discussed.
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MESH Headings
- 5' Flanking Region/genetics
- Amino Acid Sequence
- Base Sequence
- Blotting, Northern
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- DNA, Complementary/isolation & purification
- DNA, Plant/chemistry
- DNA, Plant/genetics
- Gene Expression Regulation, Plant
- Glucuronidase/genetics
- Glucuronidase/metabolism
- Histocytochemistry
- In Situ Hybridization
- Magnoliopsida/genetics
- Metallothionein/genetics
- Molecular Sequence Data
- Plant Roots/genetics
- Plants, Genetically Modified
- RNA, Plant/genetics
- RNA, Plant/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Symbiosis/genetics
- Transcription, Genetic
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11
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Ali S, Taylor WC. The 3' non-coding region of a C4 photosynthesis gene increases transgene expression when combined with heterologous promoters. PLANT MOLECULAR BIOLOGY 2001; 46:325-33. [PMID: 11488479 DOI: 10.1023/a:1010669204137] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The Me1 gene of the dicot Flaveria bidentis encodes NADP malic enzyme, which catalyses the decarboxylation reaction of C4 photosynthesis in bundle sheath cells. We have previously shown that the 3' non-coding region (Me1 3') controls quantitative expression of the gene. We wondered whether Me1 3' can increase expression when combined with heterologous promoters. We tested a highly expressed, constitutive promoter, the S4 promoter from subterranean clover stunt virus, and a highly expressed, leaf-specific promoter, the light-harvesting chlorophyll a/b-binding protein gene 3 (Lhcb3) promoter of Arabidopsis thaliana. Promoter-3'-end combinations were tested in transgenic C4 Flaveria plants and C3 tobacco. We found that Me1 3' increased expression of the gusA reporter gene several-fold in leaves of both species in combination with either of the promoters. In both cases Me1 3' does not alter the expression pattern for either promoter. We conclude that Me1 3' can be used as a transcription terminator to increase transgene expression in C3 dicot plants.
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Affiliation(s)
- S Ali
- CSIRO Plant Industry, Canberra, Australia
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12
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Ali S, Taylor WC. Quantitative regulation of the Flaveria Me1 gene is controlled by the 3'-untranslated region and sequences near the amino terminus. PLANT MOLECULAR BIOLOGY 2001; 46:251-261. [PMID: 11488473 DOI: 10.1023/a:1010684509008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The Me1 gene of Flaveria bidentis codes for the C4 isoform of NADP malic enzyme, which accumulates to a high-level only in bundle sheath cells. Previous experiments demonstrated that sequences at the 5' end of the gene control cell specificity whereas sequences at the 3' end are necessary for high-level expression. To localize quantitative regulator sequences, we have analysed a series of Me1 3' deletion constructs fused to the gusA reporter gene. We show that sequences within the 3'-untranslated region (3'-UTR) control quantitative levels of expression. Analysis of 5' promoter fusions demonstrated that high-level expression also requires sequences within the N-terminal coding region of the gene, suggesting possible interactions between the 3'-UTR and 5' coding regions. Cell-specific regulatory sequences are located in a different part of the 5' end of the gene, between 1023 bp upstream of the transcription start and the start of translation.
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Affiliation(s)
- S Ali
- CSIRO Plant Industry, Canberra, Australia
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13
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No EG, Zhou Y, Loopstra CA. Sequences upstream and downstream of two xylem-specific pine genes influence their expression. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2000; 160:77-86. [PMID: 11164579 DOI: 10.1016/s0168-9452(00)00366-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The identification of regulatory elements conferring high levels of expression in differentiating pine xylem will be valuable for genetic engineering of wood properties and will contribute to our understanding of gene regulation in this important group of forest trees. We examined the roles of both upstream and downstream elements in regulating the expression of two genes with preferential expression in developing xylem of loblolly pine. Gene constructs containing a PtX3H6, PtX14A9, or CaMV 35S promoter, the uidA gene encoding beta-glucuronidase, and a PtX3H6, PtX14A9, or NOS terminator were used to transform tobacco and hybrid poplar. When combined with the NOS terminator, neither pine promoter conferred xylem-specific expression in tobacco. When combined with the PtX3H6 promoter, an element at the 3' end of PtX3H6 reduced GUS expression resulting in preferential expression in vascular tissues. This silencing effect was not observed when the pine terminator was tested in conjunction with the CaMV 35S promoter. The PtX14A9 terminator did not increase tissue specificity. In leaves of transgenic poplar, both pine promoters conferred preferential GUS expression in veins when combined with the NOS terminator. The PtX3H6 terminator greatly decreased expression in leaves and stems when combined with the PtX3H6 promoter but only slightly altered expression when combined with the CaMV 35S promoter. An element at the 3' end of PtX14A9 increased GUS expression in veins when used in conjunction with either the PtX14A9 or CaMV35S promoter.
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Affiliation(s)
- E -G. No
- Department of Forest Science and Crop Biotechnology Center, Texas A&M University, 77843-2135, College Station, TX, USA
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14
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Jeon JS, Lee S, Jung KH, Jun SH, Kim C, An G. Tissue-preferential expression of a rice alpha-tubulin gene, OsTubA1, mediated by the first intron. PLANT PHYSIOLOGY 2000; 123:1005-14. [PMID: 10889249 PMCID: PMC59063 DOI: 10.1104/pp.123.3.1005] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/1999] [Accepted: 03/13/2000] [Indexed: 05/18/2023]
Abstract
The genomic clone encoding an alpha-tubulin, OsTubA1, has been isolated from rice (Oryza sativa L.). The gene consists of four exons and three introns. RNA-blot analysis showed that the gene is strongly expressed in actively dividing tissues, including root tips, young leaves, and young flowers. Analysis of chimeric fusions between OsTubA1 and beta-glucuronidase (GUS) revealed that the intron 1 was required for high-level GUS expression in actively dividing tissues, corresponding with normal expression pattern of OsTubA1. Fusion constructs lacking the intron 1 showed more GUS staining in mature tissues rather than young tissues. When the intron 1 was placed at the distal region from 5'-upstream region or at the 3'-untranslated region, no enhancement of GUS expression was observed. Sequential deletions of the OsTubA1 intron 1 brought about a gradual reduction of GUS activity in calli. These results suggest that tissue-preferential expression of the OsTubA1 gene is mediated by the intron 1 and that it may be involved in a mechanism for an efficient RNA splicing that is position dependent.
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Affiliation(s)
- J S Jeon
- Department of Life Science and National Research Laboratory of Plant Functional Genomics, Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea
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15
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Carvalho H, Lescure N, de Billy F, Chabaud M, Lima L, Salema R, Cullimore J. Cellular expression and regulation of the Medicago truncatula cytosolic glutamine synthetase genes in root nodules. PLANT MOLECULAR BIOLOGY 2000; 42:741-56. [PMID: 10809446 DOI: 10.1023/a:1006304003770] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In this paper we have studied the localisation of expression of the two functional cytosolic glutamine synthetase (GS) genes, MtGSa and MtGSb, in root nodules of the model legume Medicago truncatula. We have used a combination of different techniques, including immunocytochemistry, in situ hybridisation and promoter beta-glucuronidase (GUS) fusions in transgenic plants, to provide the means of correlating gene expression with protein localisation. These studies revealed that transcriptional regulation (mRNA synthesis) plays an important part in controlling GS protein levels in nodules of M. truncatula. The major locations of cytosolic GS mRNA and protein are the central tissue, the parenchyma and the pericycle of the vascular bundles. These findings indicate that in nodules, GS might be involved in other physiological processes in addition to the primary assimilation of ammonia released by the bacterial nitrogenase. The two genes show different but overlapping patterns of expression with MtGSa being the major gene expressed in the infected cells of the nodule. Promoter fragments of 2.6 kb and 3.1 kb of MtGSa and MtGSb, respectively, have been sequenced and primer extension revealed that the MtGSb promoter is expressed in nodules from an additional start site that is not used in roots. Generally these fragments in the homologous transgenic system were sufficient to drive GUS expression in almost all the tissues and cell types where GS proteins and transcripts are located except that the MtGSa promoter fragment did not express GUS highly in the nodule infected cells. These results indicate that the cis-acting regulatory elements responsible for infected-cell expression are missing from the MtGSa promoter fragment.
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Affiliation(s)
- H Carvalho
- Instituto de Biologia Molecular e Celular, Porto, Portugal
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