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Ellison EL, Zhou P, Hermanson P, Chu YH, Read A, Hirsch CN, Grotewold E, Springer NM. Mutator transposon insertions within maize genes often provide a novel outward reading promoter. Genetics 2023; 225:iyad171. [PMID: 37815810 DOI: 10.1093/genetics/iyad171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 09/04/2023] [Indexed: 10/11/2023] Open
Abstract
The highly active family of Mutator (Mu) DNA transposons has been widely used for forward and reverse genetics in maize. There are examples of Mu-suppressible alleles that result in conditional phenotypic effects based on the activity of Mu. Phenotypes from these Mu-suppressible mutations are observed in Mu-active genetic backgrounds, but absent when Mu activity is lost. For some Mu-suppressible alleles, phenotypic suppression likely results from an outward-reading promoter within Mu that is only active when the autonomous Mu element is silenced or lost. We isolated 35 Mu alleles from the UniformMu population that represent insertions in 24 different genes. Most of these mutant alleles are due to insertions within gene coding sequences, but several 5' UTR and intron insertions were included. RNA-seq and de novo transcript assembly were utilized to document the transcripts produced from 33 of these Mu insertion alleles. For 20 of the 33 alleles, there was evidence of transcripts initiating within the Mu sequence reading through the gene. This outward-reading promoter activity was detected in multiple types of Mu elements and does not depend on the orientation of Mu. Expression analyses of Mu-initiated transcripts revealed the Mu promoter often provides gene expression levels and patterns that are similar to the wild-type gene. These results suggest the Mu promoter may represent a minimal promoter that can respond to gene cis-regulatory elements. Findings from this study have implications for maize researchers using the UniformMu population, and more broadly highlight a strategy for transposons to co-exist with their host.
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Affiliation(s)
- Erika L Ellison
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Peng Zhou
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Peter Hermanson
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Yi-Hsuan Chu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Andrew Read
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
- Department of Agronomy and Plant Genetics, University of Minnesota, Saint Paul, MN 55108, USA
| | - Candice N Hirsch
- Department of Agronomy and Plant Genetics, University of Minnesota, Saint Paul, MN 55108, USA
| | - Erich Grotewold
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Nathan M Springer
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
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Wang PH, Kumar S, Zeng J, McEwan R, Wright TR, Gupta M. Transcription Terminator-Mediated Enhancement in Transgene Expression in Maize: Preponderance of the AUGAAU Motif Overlapping With Poly(A) Signals. FRONTIERS IN PLANT SCIENCE 2020; 11:570778. [PMID: 33178242 PMCID: PMC7591816 DOI: 10.3389/fpls.2020.570778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 09/11/2020] [Indexed: 05/08/2023]
Abstract
The selection of transcription terminators (TTs) for pairing with high expressing constitutive promoters in chimeric constructs is crucial to deliver optimal transgene expression in plants. In this study, the use of the native combinations of four polyubiquitin gene promoters and corresponding TTs resulted in up to >3-fold increase in transgene expression in maize. Of the eight polyubiquitin promoter and TT regulatory elements utilized, seven were novel and identified from the polyubiquitin genes of Brachypodium distachyon, Setaria italica, and Zea mays. Furthermore, gene expression driven by the Cassava mosaic virus promoter was studied by pairing the promoter with distinct TTs derived from the high expressing genes of Arabidopsis. Of the three TTs studied, the polyubiquitin10 gene TT produced the highest transgene expression in maize. Polyadenylation patterns and mRNA abundance from eight distinct TTs were analyzed using 3'-RACE and next-generation sequencing. The results exhibited one to three unique polyadenylation sites in the TTs. The poly(A) site patterns for the StPinII TT were consistent when the same TT was deployed in chimeric constructs irrespective of the reporter gene and promoter used. Distal to the poly(A) sites, putative polyadenylation signals were identified in the near-upstream regions of the TTs based on previously reported mutagenesis and bioinformatics studies in rice and Arabidopsis. The putative polyadenylation signals were 9 to 11 nucleotides in length. Six of the eight TTs contained the putative polyadenylation signals that were overlaps of either canonical AAUAAA or AAUAAA-like polyadenylation signals and AUGAAU, a top-ranking-hexamer of rice and Arabidopsis gene near-upstream regions. Three of the polyubiquitin gene TTs contained the identical 9-nucleotide overlap, AUGAAUAAG, underscoring the functional significance of such overlaps in mRNA 3' end processing. In addition to identifying new combinations of regulatory elements for high constitutive trait gene expression in maize, this study demonstrated the importance of TTs for optimizing gene expression in plants. Learning from this study could be applied to other dicotyledonous and monocotyledonous plant species for transgene expression. Research on TTs is not limited to transgene expression but could be extended to the introduction of appropriate mutations into TTs via genome editing, paving the way for expression modulation of endogenous genes.
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Affiliation(s)
- Po-Hao Wang
- Applied Science & Technology, Corteva Agriscience, Johnston, IA, United States
| | - Sandeep Kumar
- Applied Science & Technology, Corteva Agriscience, Johnston, IA, United States
- *Correspondence: Sandeep Kumar,
| | - Jia Zeng
- Data Science & Informatics, Corteva Agriscience, Indianapolis, IN, United States
| | - Robert McEwan
- Applied Science & Technology, Corteva Agriscience, Johnston, IA, United States
| | - Terry R. Wright
- Trait Discovery, Corteva Agriscience, Indianapolis, IN, United States
| | - Manju Gupta
- Trait Product Development, Dow Agrosciences, Indianapolis, IN, United States
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Sahebi M, Hanafi MM, van Wijnen AJ, Rice D, Rafii MY, Azizi P, Osman M, Taheri S, Bakar MFA, Isa MNM, Noor YM. Contribution of transposable elements in the plant's genome. Gene 2018; 665:155-166. [PMID: 29684486 DOI: 10.1016/j.gene.2018.04.050] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 04/04/2018] [Accepted: 04/18/2018] [Indexed: 12/26/2022]
Abstract
Plants maintain extensive growth flexibility under different environmental conditions, allowing them to continuously and rapidly adapt to alterations in their environment. A large portion of many plant genomes consists of transposable elements (TEs) that create new genetic variations within plant species. Different types of mutations may be created by TEs in plants. Many TEs can avoid the host's defense mechanisms and survive alterations in transposition activity, internal sequence and target site. Thus, plant genomes are expected to utilize a variety of mechanisms to tolerate TEs that are near or within genes. TEs affect the expression of not only nearby genes but also unlinked inserted genes. TEs can create new promoters, leading to novel expression patterns or alternative coding regions to generate alternate transcripts in plant species. TEs can also provide novel cis-acting regulatory elements that act as enhancers or inserts within original enhancers that are required for transcription. Thus, the regulation of plant gene expression is strongly managed by the insertion of TEs into nearby genes. TEs can also lead to chromatin modifications and thereby affect gene expression in plants. TEs are able to generate new genes and modify existing gene structures by duplicating, mobilizing and recombining gene fragments. They can also facilitate cellular functions by sharing their transposase-coding regions. Hence, TE insertions can not only act as simple mutagens but can also alter the elementary functions of the plant genome. Here, we review recent discoveries concerning the contribution of TEs to gene expression in plant genomes and discuss the different mechanisms by which TEs can affect plant gene expression and reduce host defense mechanisms.
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Affiliation(s)
- Mahbod Sahebi
- Laboratory of Climate-Smart Food Crop Production, Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
| | - Mohamed M Hanafi
- Laboratory of Climate-Smart Food Crop Production, Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia; Laboratory of Plantation Science and Technology, Institute of Plantation Studies, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia; Department of Land Management, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
| | | | - David Rice
- Department of Molecular Biology & Biotecnology, University of Sheffield, United Kingdom
| | - M Y Rafii
- Laboratory of Climate-Smart Food Crop Production, Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Parisa Azizi
- Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Mohamad Osman
- Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Sima Taheri
- Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
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Hirsch CD, Springer NM. Transposable element influences on gene expression in plants. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1860:157-165. [PMID: 27235540 DOI: 10.1016/j.bbagrm.2016.05.010] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 05/17/2016] [Accepted: 05/18/2016] [Indexed: 01/29/2023]
Abstract
Transposable elements (TEs) comprise a major portion of many plant genomes and bursts of TE movements cause novel genomic variation within species. In order to maintain proper gene function, plant genomes have evolved a variety of mechanisms to tolerate the presence of TEs within or near genes. Here, we review our understanding of the interactions between TEs and gene expression in plants by assessing three ways that transposons can influence gene expression. First, there is growing evidence that TE insertions within introns or untranslated regions of genes are often tolerated and have minimal impact on expression level or splicing. However, there are examples in which TE insertions within genes can result in aberrant or novel transcripts. Second, TEs can provide novel alternative promoters, which can lead to new expression patterns or original coding potential of an alternate transcript. Third, TE insertions near genes can influence regulation of gene expression through a variety of mechanisms. For example, TEs may provide novel cis-acting regulatory sites behaving as enhancers or insert within existing enhancers to influence transcript production. Alternatively, TEs may change chromatin modifications in regions near genes, which in turn can influence gene expression levels. Together, the interactions of genes and TEs provide abundant evidence for the role of TEs in changing basic functions within plant genomes beyond acting as latent genomic elements or as simple insertional mutagens. This article is part of a Special Issue entitled: Plant Gene Regulatory Mechanisms and Networks, edited by Dr. Erich Grotewold and Dr. Nathan Springer.
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Affiliation(s)
- Cory D Hirsch
- Department of Plant Pathology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Nathan M Springer
- Department of Plant Biology, University of Minnesota, Saint Paul, MN 55108, USA.
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Abstract
The Mutator system of transposable elements (TEs) is a highly mutagenic family of transposons in maize. Because they transpose at high rates and target genic regions, these transposons can rapidly generate large numbers of new mutants, which has made the Mutator system a favored tool for both forward and reverse mutagenesis in maize. Low copy number versions of this system have also proved to be excellent models for understanding the regulation and behavior of Class II transposons in plants. Notably, the availability of a naturally occurring locus that can heritably silence autonomous Mutator elements has provided insights into the means by which otherwise active transposons are recognized and silenced. This chapter will provide a review of the biology, regulation, evolution and uses of this remarkable transposon system, with an emphasis on recent developments in our understanding of the ways in which this TE system is recognized and epigenetically silenced as well as recent evidence that Mu-like elements (MULEs) have had a significant impact on the evolution of plant genomes.
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Hunter CT, Suzuki M, Saunders J, Wu S, Tasi A, McCarty DR, Koch KE. Phenotype to genotype using forward-genetic Mu-seq for identification and functional classification of maize mutants. FRONTIERS IN PLANT SCIENCE 2014; 4:545. [PMID: 24432026 PMCID: PMC3882665 DOI: 10.3389/fpls.2013.00545] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 12/12/2013] [Indexed: 05/08/2023]
Abstract
In pursuing our long-term goals of identifying causal genes for mutant phenotypes in maize, we have developed a new, phenotype-to-genotype approach for transposon-based resources, and used this to identify candidate genes that co-segregate with visible kernel mutants. The strategy incorporates a redesigned Mu-seq protocol (sequence-based, transposon mapping) for high-throughput identification of individual plants carrying Mu insertions. Forward-genetic Mu-seq also involves a genetic pipeline for generating families that segregate for mutants of interest, and grid designs for concurrent analysis of genotypes in multiple families. Critically, this approach not only eliminates gene-specific PCR genotyping, but also profiles all Mu-insertions in hundreds of individuals simultaneously. Here, we employ this scalable approach to study 12 families that showed Mendelian segregation of visible seed mutants. These families were analyzed in parallel, and 7 showed clear co-segregation between the selected phenotype and a Mu insertion in a specific gene. Results were confirmed by PCR. Mutant genes that associated with kernel phenotypes include those encoding: a new allele of Whirly1 (a transcription factor with high affinity for organellar and single-stranded DNA), a predicted splicing factor with a KH domain, a small protein with unknown function, a putative mitochondrial transcription-termination factor, and three proteins with pentatricopeptide repeat domains (predicted mitochondrial). Identification of such associations allows mutants to be prioritized for subsequent research based on their functional annotations. Forward-genetic Mu-seq also allows a systematic dissection of mutant classes with similar phenotypes. In the present work, a high proportion of kernel phenotypes were associated with mutations affecting organellar gene transcription and processing, highlighting the importance and non-redundance of genes controlling these aspects of seed development.
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Affiliation(s)
- Charles T. Hunter
- *Correspondence: Charles T. Hunter, Horticultural Sciences, University of Florida, 2550 Hull Rd., Gainesville, FL 32611, USA e-mail:
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Uchiyama T, Hiura S, Ebinuma I, Senda M, Mikami T, Martin C, Kishima Y. A pair of transposons coordinately suppresses gene expression, independent of pathways mediated by siRNA in Antirrhinum. THE NEW PHYTOLOGIST 2013; 197:431-440. [PMID: 23190182 DOI: 10.1111/nph.12041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 10/07/2012] [Indexed: 05/22/2023]
Abstract
Our knowledge is limited regarding mechanisms by which transposable elements control host gene expression. Two Antirrhinum lines, HAM2 and HAM5, show different petal colors, pale-red and white, respectively, although these lines contain the same insertion of transposon Tam3 in the promoter region of the nivea (niv) locus encoding chalcone synthase. Among 1000 progeny from HAM5 grown under the preferred conditions for the Tam3 transposition, a few showed an intermediate petal color between HAM2 and HAM5. Transposon tagging using these progeny identified a causative insertion of Tam3 for the HAM5 type (white) petal color, which was found 1.6 kb downstream of the niv gene. Insertion of Tam3 at the position 1.6 kb downstream of niv alone showed nearly wildtype petal pigmentation, and the niv expression reduced by only 50%. Severe suppression of niv observed in HAM5 required interaction of two Tam3 copies on either side of the niv coding sequence. DNA methylation and small interfering RNAs (siRNAs) were not associated with the suppression of niv expression in HAM5. Insertion of a pair of transposons in close proximity can interfere with the expression of gene located between the two copies, and also provide evidence that this interference is not directly associated with pathways mediated by siRNAs.
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Affiliation(s)
- Takako Uchiyama
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Satoshi Hiura
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Izuru Ebinuma
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Mineo Senda
- Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Japan
| | - Tetsuo Mikami
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Cathie Martin
- Department of Cell and Developmental Biology, John Innes Centre, Norwich, UK
| | - Yuji Kishima
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
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8
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Goettel W, Messing J. Divergence of gene regulation through chromosomal rearrangements. BMC Genomics 2010; 11:678. [PMID: 21118519 PMCID: PMC3014980 DOI: 10.1186/1471-2164-11-678] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 11/30/2010] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND The molecular mechanisms that modify genome structures to give birth and death to alleles are still not well understood. To investigate the causative chromosomal rearrangements, we took advantage of the allelic diversity of the duplicated p1 and p2 genes in maize. Both genes encode a transcription factor involved in maysin synthesis, which confers resistance to corn earworm. However, p1 also controls accumulation of reddish pigments in floral tissues and has therefore acquired a new function after gene duplication. p1 alleles vary in their tissue-specific expression, which is indicated in their allele designation: the first suffix refers to red or white pericarp pigmentation and the second to red or white glume pigmentation. RESULTS Comparing chromosomal regions comprising p1-ww[4Co63], P1-rw1077 and P1-rr4B2 alleles with that of the reference genome, P1-wr[B73], enabled us to reconstruct additive events of transposition, chromosome breaks and repairs, and recombination that resulted in phenotypic variation and chimeric regulatory signals. The p1-ww[4Co63] null allele is probably derived from P1-wr[B73] by unequal crossover between large flanking sequences. A transposon insertion in a P1-wr-like allele and NHEJ (non-homologous end-joining) could have resulted in the formation of the P1-rw1077 allele. A second NHEJ event, followed by unequal crossover, probably led to the duplication of an enhancer region, creating the P1-rr4B2 allele. Moreover, a rather dynamic picture emerged in the use of polyadenylation signals by different p1 alleles. Interestingly, p1 alleles can be placed on both sides of a large retrotransposon cluster through recombination, while functional p2 alleles have only been found proximal to the cluster. CONCLUSIONS Allelic diversity of the p locus exemplifies how gene duplications promote phenotypic variability through composite regulatory signals. Transposition events increase the level of genomic complexity based not only on insertions but also on excisions that cause DNA double-strand breaks and trigger illegitimate recombination.
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Affiliation(s)
- Wolfgang Goettel
- Waksman Institute of Microbiology, Rutgers University, 190 Frelinghuysen Road, Piscataway, NJ 08854, USA
| | - Joachim Messing
- Waksman Institute of Microbiology, Rutgers University, 190 Frelinghuysen Road, Piscataway, NJ 08854, USA
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Shapiro JA. Mobile DNA and evolution in the 21st century. Mob DNA 2010; 1:4. [PMID: 20226073 PMCID: PMC2836002 DOI: 10.1186/1759-8753-1-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Accepted: 01/25/2010] [Indexed: 01/05/2023] Open
Abstract
Scientific history has had a profound effect on the theories of evolution. At the beginning of the 21st century, molecular cell biology has revealed a dense structure of information-processing networks that use the genome as an interactive read-write (RW) memory system rather than an organism blueprint. Genome sequencing has documented the importance of mobile DNA activities and major genome restructuring events at key junctures in evolution: exon shuffling, changes in cis-regulatory sites, horizontal transfer, cell fusions and whole genome doublings (WGDs). The natural genetic engineering functions that mediate genome restructuring are activated by multiple stimuli, in particular by events similar to those found in the DNA record: microbial infection and interspecific hybridization leading to the formation of allotetraploids. These molecular genetic discoveries, plus a consideration of how mobile DNA rearrangements increase the efficiency of generating functional genomic novelties, make it possible to formulate a 21st century view of interactive evolutionary processes. This view integrates contemporary knowledge of the molecular basis of genetic change, major genome events in evolution, and stimuli that activate DNA restructuring with classical cytogenetic understanding about the role of hybridization in species diversification.
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Affiliation(s)
- James A Shapiro
- Department of Biochemistry and Molecular Biology, University of Chicago, Gordon Center for Integrative Science W123B, 929 E 57th Street, Chicago, IL 60637, USA.
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10
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Wei F, Stein JC, Liang C, Zhang J, Fulton RS, Baucom RS, De Paoli E, Zhou S, Yang L, Han Y, Pasternak S, Narechania A, Zhang L, Yeh CT, Ying K, Nagel DH, Collura K, Kudrna D, Currie J, Lin J, Kim H, Angelova A, Scara G, Wissotski M, Golser W, Courtney L, Kruchowski S, Graves TA, Rock SM, Adams S, Fulton LA, Fronick C, Courtney W, Kramer M, Spiegel L, Nascimento L, Kalyanaraman A, Chaparro C, Deragon JM, Miguel PS, Jiang N, Wessler SR, Green PJ, Yu Y, Schwartz DC, Meyers BC, Bennetzen JL, Martienssen RA, McCombie WR, Aluru S, Clifton SW, Schnable PS, Ware D, Wilson RK, Wing RA. Detailed analysis of a contiguous 22-Mb region of the maize genome. PLoS Genet 2009; 5:e1000728. [PMID: 19936048 PMCID: PMC2773423 DOI: 10.1371/journal.pgen.1000728] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Accepted: 10/16/2009] [Indexed: 12/20/2022] Open
Abstract
Most of our understanding of plant genome structure and evolution has come from the careful annotation of small (e.g., 100 kb) sequenced genomic regions or from automated annotation of complete genome sequences. Here, we sequenced and carefully annotated a contiguous 22 Mb region of maize chromosome 4 using an improved pseudomolecule for annotation. The sequence segment was comprehensively ordered, oriented, and confirmed using the maize optical map. Nearly 84% of the sequence is composed of transposable elements (TEs) that are mostly nested within each other, of which most families are low-copy. We identified 544 gene models using multiple levels of evidence, as well as five miRNA genes. Gene fragments, many captured by TEs, are prevalent within this region. Elimination of gene redundancy from a tetraploid maize ancestor that originated a few million years ago is responsible in this region for most disruptions of synteny with sorghum and rice. Consistent with other sub-genomic analyses in maize, small RNA mapping showed that many small RNAs match TEs and that most TEs match small RNAs. These results, performed on approximately 1% of the maize genome, demonstrate the feasibility of refining the B73 RefGen_v1 genome assembly by incorporating optical map, high-resolution genetic map, and comparative genomic data sets. Such improvements, along with those of gene and repeat annotation, will serve to promote future functional genomic and phylogenomic research in maize and other grasses.
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Affiliation(s)
- Fusheng Wei
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
| | - Joshua C. Stein
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Chengzhi Liang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Jianwei Zhang
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
| | - Robert S. Fulton
- The Genome Center and Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Regina S. Baucom
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
| | - Emanuele De Paoli
- Department of Plant and Soil Sciences and Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, United States of America
| | - Shiguo Zhou
- Laboratory for Molecular and Computational Genomics, Department of Chemistry, Laboratory of Genetics, University of Wisconsin Madison, Madison, Wisconsin, United States of America
| | - Lixing Yang
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
| | - Yujun Han
- Department of Plant Biology, University of Georgia, Athens, Georgia, United States of America
| | - Shiran Pasternak
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Apurva Narechania
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Lifang Zhang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Cheng-Ting Yeh
- Department of Agronomy and Center for Plant Genomics, Iowa State University, Ames, Iowa, United States of America
| | - Kai Ying
- Department of Agronomy and Center for Plant Genomics, Iowa State University, Ames, Iowa, United States of America
| | - Dawn H. Nagel
- Department of Plant Biology, University of Georgia, Athens, Georgia, United States of America
| | - Kristi Collura
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
| | - David Kudrna
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
| | - Jennifer Currie
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
| | - Jinke Lin
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
| | - HyeRan Kim
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
| | - Angelina Angelova
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
| | - Gabriel Scara
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
| | - Marina Wissotski
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
| | - Wolfgang Golser
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
| | - Laura Courtney
- The Genome Center and Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Scott Kruchowski
- The Genome Center and Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Tina A. Graves
- The Genome Center and Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Susan M. Rock
- The Genome Center and Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Stephanie Adams
- The Genome Center and Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Lucinda A. Fulton
- The Genome Center and Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Catrina Fronick
- The Genome Center and Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - William Courtney
- The Genome Center and Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Melissa Kramer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Lori Spiegel
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Lydia Nascimento
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Ananth Kalyanaraman
- School of Electrical Engineering and Computer Science, Washington State University, Pullman, Washington, United States of America
| | - Cristian Chaparro
- Université de Perpignan Via Domitia, CNRS UMR 5096, Perpignan, France
| | - Jean-Marc Deragon
- Université de Perpignan Via Domitia, CNRS UMR 5096, Perpignan, France
| | - Phillip San Miguel
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America
| | - Ning Jiang
- Department of Horticulture, Michigan State University, East Lansing, Michigan, United States of America
| | - Susan R. Wessler
- Department of Plant Biology, University of Georgia, Athens, Georgia, United States of America
| | - Pamela J. Green
- Department of Plant and Soil Sciences and Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, United States of America
| | - Yeisoo Yu
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
| | - David C. Schwartz
- Laboratory for Molecular and Computational Genomics, Department of Chemistry, Laboratory of Genetics, University of Wisconsin Madison, Madison, Wisconsin, United States of America
| | - Blake C. Meyers
- Department of Plant and Soil Sciences and Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, United States of America
| | - Jeffrey L. Bennetzen
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
| | - Robert A. Martienssen
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - W. Richard McCombie
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Srinivas Aluru
- Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa, United States of America
| | - Sandra W. Clifton
- The Genome Center and Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Patrick S. Schnable
- Department of Agronomy and Center for Plant Genomics, Iowa State University, Ames, Iowa, United States of America
| | - Doreen Ware
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Richard K. Wilson
- The Genome Center and Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Rod A. Wing
- Arizona Genomics Institute, School of Plant Sciences and Department of Ecology and Evolutionary Biology, BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona, United States of America
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11
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Uchiyama T, Fujino K, Ogawa T, Wakatsuki A, Kishima Y, Mikami T, Sano Y. Stable transcription activities dependent on an orientation of Tam3 transposon insertions into Antirrhinum and yeast promoters occur only within chromatin. PLANT PHYSIOLOGY 2009; 151:1557-69. [PMID: 19759347 PMCID: PMC2773084 DOI: 10.1104/pp.109.142356] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Accepted: 09/09/2009] [Indexed: 05/28/2023]
Abstract
Transposon insertions occasionally occur in the promoter regions of plant genes, many of which are still capable of being transcribed. However, it remains unclear how transcription of such promoters is able to occur. Insertion of the Tam3 transposon into various genes of Antirrhinum majus can confer leaky phenotypes without its excision. These genes, named Tam3-permissible alleles, often contain Tam3 in their promoter regions. Two alleles at different anthocyanin biosynthesis loci, nivea(recurrensTam3) (niv(rec)) and pallida(recurrensTam3) (pal(rec)), both contain Tam3 at a similar position immediately upstream of the promoter TATA-box; however, these insertions had different phenotypic consequences. Under conditions where the inserted Tam3 is immobilized, the niv(rec) line produces pale red petals, whereas the pal(rec) line produces no pigment. These pigmentation patterns are correlated with the level of transcripts from the niv(rec) or pal(rec) alleles, and these transcriptional activities are independent of DNA methylation in their promoter regions. In niv(rec), Tam3 is inserted in an orientation that results in the 3' end of Tam3 adjacent to the 5' region of the gene coding sequence. In contrast, the pal(rec) allele contains a Tam3 insertion in the opposite orientation. Four of five different nonrelated genes that are also Tam3-permissible alleles and contain Tam3 within the promoter region share the same Tam3 orientation as niv(rec). The different transcriptional activities dependent on Tam3 orientation in the Antirrhinum promoters were consistent with expression of luciferase reporter constructs introduced into yeast chromosomes but not with transient expression of these constructs in Antirrhinum cells. These results suggest that for Tam3 to sustain stable transcriptional activity in various promoters it must be embedded in chromatin.
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Affiliation(s)
| | | | | | | | - Yuji Kishima
- Laboratories of Plant Breeding (T.U., T.O., Y.K., Y.S.), Crop Physiology (K.F.), and Genetic Engineering (A.W., T.M.), Research Faculty of Agriculture, Hokkaido University, Sapporo 060–8589, Japan
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12
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Disruption of imprinting by mutator transposon insertions in the 5' proximal regions of the Zea mays Mez1 locus. Genetics 2009; 181:1229-37. [PMID: 19204379 DOI: 10.1534/genetics.108.093666] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Imprinting is a form of epigenetic gene regulation in which alleles are differentially regulated according to the parent of origin. The Mez1 gene in maize is imprinted such that the maternal allele is expressed in the endosperm while the paternal allele is not expressed. Three novel Mez1 alleles containing Mutator transposon insertions within the promoter were identified. These mez1-mu alleles do not affect vegetative expression levels or result in morphological phenotypes. However, these alleles can disrupt imprinted expression of Mez1. Maternal inheritance of the mez-m1 or mez1-m4 alleles results in activation of the normally silenced paternal allele of Mez1. Paternal inheritance of the mez1-m2 or mez1-m4 alleles can also result in a loss of silencing of the paternal Mez1 allele. The paternal disruption of imprinting by transposon insertions may reflect a requirement for sequence elements involved in targeting silencing of the paternal allele. The maternal disruption of imprinting by transposon insertions within the Mez1 promoter suggests that maternally produced MEZ1 protein may be involved in silencing of the paternal Mez1 allele. The endosperms with impaired imprinting did not exhibit phenotypic consequences associated with bi-allelic Mez1 expression.
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13
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Hochholdinger F, Wen TJ, Zimmermann R, Chimot-Marolle P, da Costa e Silva O, Bruce W, Lamkey KR, Wienand U, Schnable PS. The maize (Zea mays L.) roothairless3 gene encodes a putative GPI-anchored, monocot-specific, COBRA-like protein that significantly affects grain yield. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 54:888-98. [PMID: 18298667 PMCID: PMC2440564 DOI: 10.1111/j.1365-313x.2008.03459.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 01/24/2008] [Accepted: 02/07/2008] [Indexed: 05/18/2023]
Abstract
The rth3 (roothairless 3) mutant is specifically affected in root hair elongation. We report here the cloning of the rth3 gene via a PCR-based strategy (amplification of insertion mutagenized sites) and demonstrate that it encodes a COBRA-like protein that displays all the structural features of a glycosylphosphatidylinositol anchor. Genes of the COBRA family are involved in various types of cell expansion and cell wall biosynthesis. The rth3 gene belongs to a monocot-specific clade of the COBRA gene family comprising two maize and two rice genes. While the rice (Oryza sativa) gene OsBC1L1 appears to be orthologous to rth3 based on sequence similarity (86% identity at the protein level) and maize/rice synteny, the maize (Zea mays L.) rth3-like gene does not appear to be a functional homolog of rth3 based on their distinct expression profiles. Massively parallel signature sequencing analysis detected rth3 expression in all analyzed tissues, but at relatively low levels, with the most abundant expression in primary roots where the root hair phenotype is manifested. In situ hybridization experiments confine rth3 expression to root hair-forming epidermal cells and lateral root primordia. Remarkably, in replicated field trials involving near-isogenic lines, the rth3 mutant conferred significant losses in grain yield.
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Affiliation(s)
- Frank Hochholdinger
- Center for Plant Molecular Biology, Department of General Genetics, Eberhard-Karls-University Tuebingen72076 Tuebingen, Germany
| | - Tsui-Jung Wen
- Department of Agronomy, Iowa State UniversityAmes, IA 50011, USA
| | - Roman Zimmermann
- Center for Plant Molecular Biology, Department of General Genetics, Eberhard-Karls-University Tuebingen72076 Tuebingen, Germany
| | - Patricia Chimot-Marolle
- Institute for General Botany and Botanical Garden, University of Hamburg22609 Hamburg, Germany
| | | | - Wesley Bruce
- Pioneer Hi-Bred International, Inc. – a DuPont CompanyJohnston, IA 50131, USA
| | - Kendall R Lamkey
- Department of Agronomy, Iowa State UniversityAmes, IA 50011, USA
| | - Udo Wienand
- Institute for General Botany and Botanical Garden, University of Hamburg22609 Hamburg, Germany
| | - Patrick S Schnable
- Department of Agronomy, Iowa State UniversityAmes, IA 50011, USA
- Pioneer Hi-Bred International, Inc. – a DuPont CompanyJohnston, IA 50131, USA
- Department of Genetics, Development, and Cell Biology, Iowa State UniversityAmes, IA 50011, USA
- Center for Plant Genomics, Iowa State University, Ames, IA 50011-36506, USA
- *For correspondence (fax +1 515 294 5256; e-mail )
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14
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Robbins ML, Sekhon RS, Meeley R, Chopra S. A Mutator transposon insertion is associated with ectopic expression of a tandemly repeated multicopy Myb gene pericarp color1 of maize. Genetics 2008; 178:1859-74. [PMID: 18430921 PMCID: PMC2323782 DOI: 10.1534/genetics.107.082503] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Accepted: 01/28/2008] [Indexed: 12/17/2022] Open
Abstract
The molecular basis of tissue-specific pigmentation of maize carrying a tandemly repeated multicopy allele of pericarp color1 (p1) was examined using Mutator (Mu) transposon-mediated mutagenesis. The P1-wr allele conditions a white or colorless pericarp and a red cob glumes phenotype. However, a Mu-insertion allele, designated as P1-wr-mum6, displayed an altered phenotype that was first noted as occasional red stripes on pericarp tissue. This gain-of-pericarp-pigmentation phenotype was heritable, yielding families that displayed variable penetrance and expressivity. In one fully penetrant family, deep red pericarp pigmentation was observed. Several reports on Mu suppressible alleles have shown that Mu transposons can affect gene expression by mechanisms that depend on transposase activity. Conversely, the P1-wr-mum6 phenotype is not affected by transposase activity. The increased pigmentation was associated with elevated mRNA expression of P1-wr-mum6 copy (or copies) that was uninterrupted by the transposons. Genomic bisulfite sequencing analysis showed that the elevated expression was associated with hypomethylation of a floral-specific enhancer that is approximately 4.7 kb upstream of the Mu1 insertion site and may be proximal to an adjacent repeated copy. We propose that the Mu1 insertion interferes with the DNA methylation and related chromatin packaging of P1-wr, thereby inducing expression from gene copy (or copies) that is otherwise suppressed.
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Affiliation(s)
- Michael L Robbins
- Department of Crop and Soil Sciences, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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15
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Abstract
Rates of Mu transposon insertions and excisions are both high in late somatic cells of maize. In contrast, although high rates of insertions are observed in germinal cells, germinal excisions are recovered only rarely. Plants doubly homozygous for deletion alleles of rad51A1 and rad51A2 do not encode functional RAD51 protein (RAD51-). Approximately 1% of the gametes from RAD51+ plants that carry the MuDR-insertion allele a1-m5216 include at least partial deletions of MuDR and the a1 gene. The structures of these deletions suggest they arise via the repair of MuDR-induced double-strand breaks via nonhomologous end joining. In RAD51- plants these germinal deletions are recovered at rates that are at least 40-fold higher. These rates are not substantially affected by the presence or absence of an a1-containing homolog. Together, these findings indicate that in RAD51+ germinal cells MuDR-induced double-strand breaks (DSBs) are efficiently repaired via RAD51-directed homologous recombination with the sister chromatid. This suggests that RAD51- plants may offer an efficient means to generate deletion alleles for functional genomic studies. Additionally, the high proportion of Mu-active, RAD51- plants that exhibit severe developmental defects suggest that RAD51 plays a critical role in the repair of MuDR-induced DSBs early in vegetative development.
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16
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Schmidt S, Lombardi M, Gardiner DM, Ayliffe M, Anderson PA. The M flax rust resistance pre-mRNA is alternatively spliced and contains a complex upstream untranslated region. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2007; 115:373-82. [PMID: 17534592 DOI: 10.1007/s00122-007-0571-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Accepted: 04/27/2007] [Indexed: 05/15/2023]
Abstract
Alternative splicing is an important step in controlling gene expression and has been shown to occur for a number of plant disease resistance (R) genes. The specific biological role of alternatively spliced transcripts from most R genes is unknown, yet in two cases it is clear that functional disease resistance cannot be activated without them. We report 12 splice isoforms of the M flax rust resistance gene, a TIR-NBS-LRR class of R gene. Collectively, these isoforms are predicted to encode at least nine different polypeptide products, only one of which is a full length peptide believed to confer functional M gene-specific disease resistance. An additional intron to that previously described was found in the 5' untranslated region. Splicing of this leader intron removes an upstream ORF (muORF) sequence. In some transcripts the leader intron is retained and in this case we predict negligible translation initiation of the full length M gene-encoding ORF. The majority of the alternatively spliced isoforms of M would encode truncated TIR and TIR-NBS containing proteins. Although the role of alternative splicing and the existence and function of the products they encode is still unclear, the complexities of the splicing profile, and the 5' UTR of the M gene, are likely to serve in mechanisms to regulate R protein levels.
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Affiliation(s)
- Simon Schmidt
- School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
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17
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Li J, Harper LC, Golubovskaya I, Wang CR, Weber D, Meeley RB, McElver J, Bowen B, Cande WZ, Schnable PS. Functional analysis of maize RAD51 in meiosis and double-strand break repair. Genetics 2007; 176:1469-82. [PMID: 17507687 PMCID: PMC1931559 DOI: 10.1534/genetics.106.062604] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In Saccharomyces cerevisiae, Rad51p plays a central role in homologous recombination and the repair of double-strand breaks (DSBs). Double mutants of the two Zea mays L. (maize) rad51 homologs are viable and develop well under normal conditions, but are male sterile and have substantially reduced seed set. Light microscopic analyses of male meiosis in these plants reveal reduced homologous pairing, synapsis of nonhomologous chromosomes, reduced bivalents at diakinesis, numerous chromosome breaks at anaphase I, and that >33% of quartets carry cells that either lack an organized nucleolus or have two nucleoli. This indicates that RAD51 is required for efficient chromosome pairing and its absence results in nonhomologous pairing and synapsis. These phenotypes differ from those of an Arabidopsis rad51 mutant that exhibits completely disrupted chromosome pairing and synapsis during meiosis. Unexpectedly, surviving female gametes produced by maize rad51 double mutants are euploid and exhibit near-normal rates of meiotic crossovers. The finding that maize rad51 double mutant embryos are extremely susceptible to radiation-induced DSBs demonstrates a conserved role for RAD51 in the repair of mitotic DSBs in plants, vertebrates, and yeast.
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Affiliation(s)
- Jin Li
- Department of Genetics, Development and Cell Biology, Iowa State Unversity, Ames, Iowa 50011, USA
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18
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Ivanov MK, Dymshits GM. Cytoplasmic male sterility and restoration of pollen fertility in higher plants. RUSS J GENET+ 2007. [DOI: 10.1134/s1022795407040023] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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19
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Tang S, Hass CG, Knapp SJ. Ty3/gypsy-like retrotransposon knockout of a 2-methyl-6-phytyl-1,4-benzoquinone methyltransferase is non-lethal, uncovers a cryptic paralogous mutation, and produces novel tocopherol (vitamin E) profiles in sunflower. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2006; 113:783-99. [PMID: 16902787 DOI: 10.1007/s00122-006-0321-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Accepted: 05/13/2006] [Indexed: 05/11/2023]
Abstract
The m (Tph(1)) mutation partially disrupts the synthesis of alpha-tocopherol (vitamin E) in sunflower (Helianthus annuus L.) seeds and was predicted to disrupt a methyltransferase activity necessary for the synthesis of alpha- and gamma-tocopherol. We identified and isolated two 2-methyl-6-phytyl-1,4-benzoquinone/2-methyl-6-solanyl-1,4-benzoquinone methyltransferase (MPBQ/MSBQ-MT) paralogs from sunflower (MT-1 and MT-2), resequenced MT-1 and MT-2 alleles from wildtype (m(+) m(+)) and mutant (m m) inbred lines, identified m as a non-lethal knockout mutation of MT-1 caused by the insertion of a 5.2 kb Ty3/gypsy-like retrotransposon in exon 1, and uncovered a cryptic codominant mutation (d) in a wildtype x mutant F(2) population predicted to be segregating for the m mutation only. MT-1 and m cosegregated and mapped to linkage group 1 and MT-1 was not transcribed in mutant homozygotes (m m). The m locus was epistatic to the d locus--the d locus had no effect in m(+) m(+) and m(+) m individuals, but significantly increased beta-tocopherol percentages in m m individuals. MT-2 and d cosegregated, MT-2 alleles isolated from mutant homozygotes (d d) carried a 30 bp insertion at the start of the 5'-UTR, and MT-2 was more strongly transcribed in seeds and leaves of wildtype (d(+) d(+)) than mutant (d d) homozygotes (transcripts were 2.2- to 5.0-fold more abundant in the former than the latter). The double mutant (m m d d) was non-lethal and produced 24-45% alpha- and 55-74% beta-tocopherol (the wildtype produced 96% alpha- and 4% beta-tocopherol). MT-2 compensated for the loss of the MT-1 function, and the MT-2 mutation profoundly affected the synthesis of tocopherols without adversely affecting the synthesis of plastoquinone crucial for normal plant growth and development.
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Affiliation(s)
- Shunxue Tang
- Center for Applied Genetic Technologies, The University of Georgia, 111 Riverbend Road, Athens, GA 30602, USA
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20
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Hass CG, Tang S, Leonard S, Traber MG, Miller JF, Knapp SJ. Three non-allelic epistatically interacting methyltransferase mutations produce novel tocopherol (vitamin E) profiles in sunflower. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2006; 113:767-82. [PMID: 16896719 DOI: 10.1007/s00122-006-0320-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Accepted: 05/13/2006] [Indexed: 05/11/2023]
Abstract
Wildtype sunflower (Helianthus annuus L.) seeds are a rich source of alpha-tocopherol (vitamin E). The g = Tph(2) mutation disrupts the synthesis of alpha-tocopherol, enhances the synthesis of gamma-tocopherol, and was predicted to knock out a gamma-tocopherol methyltransferase (gamma-TMT) necessary for the synthesis of alpha-tocopherol in sunflower seeds--wildtype (g(+) g(+)) lines accumulated > 90% alpha-tocopherol, whereas mutant (g g) lines accumulated > 90% gamma-tocopherol. We identified and isolated two gamma-TMT paralogs (gamma-TMT-1 and gamma-TMT-2). Both mapped to linkage group 8, cosegregated with the g locus, and were transcribed in developing seeds of wildtype lines. The g mutation greatly decreased gamma-TMT-1 transcription, caused alternative splicing of gamma-TMT-1, disrupted gamma-TMT-2 transcription, and knocked out one of two transcription initiation sites identified in the wildtype; gamma-TMT transcription was 36 to 51-fold greater in developing seeds of wildtype (g(+) g(+)) than mutant (g g) lines. F(2) populations (B109 x LG24 and R112 x LG24) developed for mapping the g locus segregated for a previously unidentified locus (d). B109, R112, and LG24 were homozygous for a null mutation (m = Tph(1)) in MT-1, one of two 2-methyl-6-phytyl-1,4-benzoquinone/2-methyl-6-solanyl-1,4-benzoquinone methyltransferase (MPBQ/MSBQ-MT) paralogs identified in sunflower. The d mutations segregating in B109 x LG24 and R112 x LG24 were allelic to a cryptic mutation identified in the other MPBQ/MSBQ-MT paralog (MT-2) and disrupted the synthesis of alpha- and gamma-tocopherol in F(2) progeny carrying m or g mutations--m m g(+) g(+) d d homozygotes accumulated 41.5% alpha- and 58.5% beta-T, whereas m m g g d d homozygotes accumulated 58.1% gamma- and 41.9% delta-T. MT-2 cosegregated with d and mapped to linkage group 4. Hence, novel tocopherol profiles are produced in sunflower seed oil by three non-allelic epistatically interacting methyltransferase mutations.
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Affiliation(s)
- Catherine G Hass
- Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331, USA
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21
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May BP, Liu H, Vollbrecht E, Senior L, Rabinowicz PD, Roh D, Pan X, Stein L, Freeling M, Alexander D, Martienssen R. Maize-targeted mutagenesis: A knockout resource for maize. Proc Natl Acad Sci U S A 2003; 100:11541-6. [PMID: 12954979 PMCID: PMC208794 DOI: 10.1073/pnas.1831119100] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2003] [Indexed: 11/18/2022] Open
Abstract
We describe an efficient system for site-selected transposon mutagenesis in maize. A total of 43,776 F1 plants were generated by using Robertson's Mutator (Mu) pollen parents and self-pollinated to establish a library of transposon-mutagenized seed. The frequency of new seed mutants was between 10-4 and 10-5 per F1 plant. As a service to the maize community, maize-targeted mutagenesis selects insertions in genes of interest from this library by using the PCR. Pedigree, knockout, sequence, phenotype, and other information is stored in a powerful interactive database (maize-targeted mutagenesis database) that enables analysis of the entire population and the handling of knockout requests. By inhibiting Mu activity in most F1 plants, we sought to reduce somatic insertions that may cause false positives selected from pooled tissue. By monitoring the remaining Mu activity in the F2, however, we demonstrate that seed phenotypes depend on it, and false positives occur in lines that appear to lack it. We conclude that more than half of all mutations arising in this population are suppressed on losing Mu activity. These results have implications for epigenetic models of inbreeding and for functional genomics.
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Affiliation(s)
- Bruce P May
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
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22
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Liu F, Schnable PS. Functional specialization of maize mitochondrial aldehyde dehydrogenases. PLANT PHYSIOLOGY 2002; 130:1657-74. [PMID: 12481049 PMCID: PMC166681 DOI: 10.1104/pp.012336] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2002] [Revised: 08/28/2002] [Accepted: 09/25/2002] [Indexed: 05/18/2023]
Abstract
The maize (Zea mays) rf2a and rf2b genes both encode homotetrameric aldehyde dehydrogenases (ALDHs). The RF2A protein was shown previously to accumulate in the mitochondria. In vitro import experiments and ALDH assays on mitochondrial extracts from rf2a mutant plants established that the RF2B protein also accumulates in the mitochondria. RNA gel-blot analyses and immunohistolocation experiments revealed that these two proteins have only partially redundant expression patterns in organs and cell types. For example, RF2A, but not RF2B, accumulates to high levels in the tapetal cells of anthers. Kinetic analyses established that RF2A and RF2B have quite different substrate specificities; although RF2A can oxidize a broad range of aldehydes, including aliphatic aldehydes and aromatic aldehydes, RF2B can oxidize only short-chain aliphatic aldehydes. These two enzymes also have different pH optima and responses to changes in substrate concentration. In addition, RF2A, but not RF2B or any other natural ALDHs, exhibits positive cooperativity. These functional specializations may explain why many species have two mitochondrial ALDHs. This study provides data that serve as a basis for identifying the physiological pathway by which the rf2a gene participates in normal anther development and the restoration of Texas cytoplasm-based male sterility. For example, the observations that Texas cytoplasm anthers do not accumulate elevated levels of reactive oxygen species or lipid peroxidation and the kinetic features of RF2A make it unlikely that rf2a restores fertility by preventing premature programmed cell death.
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Affiliation(s)
- Feng Liu
- Department of Zoology and Genetics, Iowa State University, Ames, Iowa 50011, USA
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