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Sidorenko LV, Chandler VL, Wang X, Peterson T. Transcribed enhancer sequences are required for maize p1 paramutation. Genetics 2024; 226:iyad178. [PMID: 38169343 PMCID: PMC10763531 DOI: 10.1093/genetics/iyad178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 08/27/2023] [Indexed: 01/05/2024] Open
Abstract
Paramutation is a transfer of heritable silencing states between interacting endogenous alleles or between endogenous alleles and homologous transgenes. Prior results demonstrated that paramutation occurs at the P1-rr (red pericarp and red cob) allele of the maize p1 (pericarp color 1) gene when exposed to a transgene containing a 1.2-kb enhancer fragment (P1.2) of P1-rr. The paramutable P1-rr allele undergoes transcriptional silencing resulting in a paramutant light-pigmented P1-rr' state. To define more precisely the sequences required to elicit paramutation, the P1.2 fragment was further subdivided, and the fragments transformed into maize plants and crossed with P1-rr. Analysis of the progeny plants showed that the sequences required for paramutation are located within a ∼600-bp segment of P1.2 and that this segment overlaps with a previously identified enhancer that is present in 4 direct repeats in P1-rr. The paramutagenic segment is transcribed in both the expressed P1-rr and the silenced P1-rr'. Transcription is sensitive to α-amanitin, indicating that RNA polymerase II mediates most of the transcription of this sequence. Although transcription within the paramutagenic sequence was similar in all tested genotypes, small RNAs were more abundant in the silenced P1-rr' epiallele relative to the expressed P1-rr allele. In agreement with prior results indicating the association of RNA-mediated DNA methylation in p1 paramutation, DNA blot analyses detected increased cytosine methylation of the paramutant P1-rr' sequences homologous to the transgenic P1.2 subfragments. Together these results demonstrate that the P1-rr enhancer repeats mediate p1 paramutation.
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Affiliation(s)
- Lyudmila V Sidorenko
- Department of Plant Sciences, The University of Arizona, Tucson, AZ 85721, USA
- Corteva Agriscience, 7300 NW 62nd Ave, Johnston, IA 50131, USA
| | - Vicki L Chandler
- Department of Plant Sciences, The University of Arizona, Tucson, AZ 85721, USA
- Minerva University, 14 Mint Plaza, Suite 300, San Francisco, CA 94103, USA
| | - Xiujuan Wang
- Corteva Agriscience, 7300 NW 62nd Ave, Johnston, IA 50131, USA
- Department of Genetics, Development, and Cellular Biology, Department of Agronomy, Iowa State University, Ames, IA 50010, USA
| | - Thomas Peterson
- Department of Genetics, Development, and Cellular Biology, Department of Agronomy, Iowa State University, Ames, IA 50010, USA
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Rashmi R, Nandi C, Majumdar S. Bioinformatic analysis of THAP9 transposase homolog: conserved regions, novel motifs. Curr Res Struct Biol 2023; 7:100113. [PMID: 38292821 PMCID: PMC10824691 DOI: 10.1016/j.crstbi.2023.100113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/10/2023] [Accepted: 11/13/2023] [Indexed: 02/01/2024] Open
Abstract
THAP9 is a transposable element-derived gene that encodes the THAP9 protein, which is homologous to the Drosophila P-element transposase (DmTNP) and can cut and paste DNA. However, the exact functional role of THAP9 is unknown. Here, we perform structure prediction, evolutionary analysis and extensive in silico characterization of THAP9, including predicting domains and putative post-translational modification sites. Comparison of the AlphaFold-predicted structure of THAP9 with the DmTNP CryoEM structure, provided insights about the C2CH motif and other DNA binding residues, RNase H-like catalytic domain and insertion domain of the THAP9 protein. We also predicted previously unreported mammalian-specific post-translational modification sites that may play a role in the subcellular localization of THAP9. Furthermore, we observed that there are distinct organism class-specific conservation patterns of key functional residues in certain THAP9 domains.
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Affiliation(s)
- Richa Rashmi
- Discipline of Biological Engineering, IIT Gandhinagar, Gandhinagar, Gujarat, India
| | - Chandan Nandi
- Discipline of Biological Engineering, IIT Gandhinagar, Gandhinagar, Gujarat, India
| | - Sharmistha Majumdar
- Discipline of Biological Engineering, IIT Gandhinagar, Gandhinagar, Gujarat, India
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Sharma SP, Peterson T. Complex chromosomal rearrangements induced by transposons in maize. Genetics 2022; 223:6702042. [PMID: 36111993 PMCID: PMC9910405 DOI: 10.1093/genetics/iyac124] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
Eukaryotic genomes are large and complex, and gene expression can be affected by multiple regulatory elements and their positions within the dynamic chromatin architecture. Transposable elements are known to play important roles in genome evolution, yet questions remain as to how transposable elements alter genome structure and affect gene expression. Previous studies have shown that genome rearrangements can be induced by Reversed Ends Transposition involving termini of Activator and related transposable elements in maize and other plants. Here, we show that complex alleles can be formed by the rapid and progressive accumulation of Activator-induced duplications and rearrangements. The p1 gene enhancer in maize can induce ectopic expression of the nearby p2 gene in pericarp tissue when placed near it via different structural rearrangements. By screening for p2 expression, we identified and studied 5 cases in which multiple sequential transposition events occurred and increased the p1 enhancer copy number. We see active p2 expression due to multiple copies of the p1 enhancer present near p2 in all 5 cases. The p1 enhancer effects are confirmed by the observation that loss of p2 expression is correlated with transposition-induced excision of the p1 enhancers. We also performed a targeted Chromosome Conformation Capture experiment to test the physical interaction between the p1 enhancer and p2 promoter region. Together, our results show that transposon-induced rearrangements can accumulate rapidly and progressively increase genetic variation important for genomic evolution.
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Affiliation(s)
- Sharu Paul Sharma
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Thomas Peterson
- Corresponding author: Department of Genetics, Development and Cell Biology, Iowa State University, 2258 Molecular Biology, Iowa State University, Ames, IA 50011, USA.
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Zanini SF, Bayer PE, Wells R, Snowdon RJ, Batley J, Varshney RK, Nguyen HT, Edwards D, Golicz AA. Pangenomics in crop improvement-from coding structural variations to finding regulatory variants with pangenome graphs. THE PLANT GENOME 2022; 15:e20177. [PMID: 34904403 DOI: 10.1002/tpg2.20177] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 10/07/2021] [Indexed: 05/15/2023]
Abstract
Since the first reported crop pangenome in 2014, advances in high-throughput and cost-effective DNA sequencing technologies facilitated multiple such studies including the pangenomes of oilseed rape (Brassica napus L.), soybean [Glycine max (L.) Merr.], rice (Oryza sativa L.), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.). Compared with single-reference genomes, pangenomes provide a more accurate representation of the genetic variation present in a species. By combining the genomic data of multiple accessions, pangenomes allow for the detection and annotation of complex DNA polymorphisms such as structural variations (SVs), one of the major determinants of genetic diversity within a species. In this review we summarize the current literature on crop pangenomics, focusing on their application to find candidate SVs involved in traits of agronomic interest. We then highlight the potential of pangenomes in the discovery and functional characterization of noncoding regulatory sequences and their variations. We conclude with a summary and outlook on innovative data structures representing the complete content of plant pangenomes including annotations of coding and noncoding elements and outcomes of transcriptomic and epigenomic experiments.
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Affiliation(s)
- Silvia F Zanini
- Dep. of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig Univ. Giessen, Giessen, 35392, Germany
| | - Philipp E Bayer
- School of Biological Sciences and Institute of Agriculture, Univ. of Western Australia, Perth, Western Australia, Australia
| | - Rachel Wells
- Dep. of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, NR47UH, UK
| | - Rod J Snowdon
- Dep. of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig Univ. Giessen, Giessen, 35392, Germany
| | - Jacqueline Batley
- School of Biological Sciences and Institute of Agriculture, Univ. of Western Australia, Perth, Western Australia, Australia
| | - Rajeev K Varshney
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India
- State Agricultural Biotechnology Centre, Centre for Crop Food Innovation, Food Futures Institute, Murdoch Univ., Murdoch, WA, Australia
| | - Henry T Nguyen
- Division of Plant Sciences, Univ. of Missouri, Columbia, MO, USA
| | - David Edwards
- School of Biological Sciences and Institute of Agriculture, Univ. of Western Australia, Perth, Western Australia, Australia
| | - Agnieszka A Golicz
- Dep. of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig Univ. Giessen, Giessen, 35392, Germany
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Sharma SP, Zuo T, Peterson T. Transposon-induced inversions activate gene expression in the maize pericarp. Genetics 2021; 218:iyab062. [PMID: 33905489 PMCID: PMC8225341 DOI: 10.1093/genetics/iyab062] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 04/09/2021] [Indexed: 11/28/2022] Open
Abstract
Chromosomal inversions can have considerable biological and agronomic impacts including disrupted gene function, change in gene expression, and inhibited recombination. Here, we describe the molecular structure and functional impact of six inversions caused by Alternative Transpositions between p1 and p2 genes responsible for floral pigmentation in maize. In maize line p1-wwB54, the p1 gene is null and the p2 gene is expressed in anther and silk but not in pericarp, making the kernels white. By screening for kernels with red pericarp, we identified inversions in this region caused by transposition of Ac and fractured Ac (fAc) transposable elements. We hypothesize that these inversions place the p2 gene promoter near a p1 gene enhancer, thereby activating p2 expression in kernel pericarp. To our knowledge, this is the first report of multiple recurrent inversions that change the position of a gene promoter relative to an enhancer to induce ectopic expression in a eukaryote.
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Affiliation(s)
- Sharu Paul Sharma
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Tao Zuo
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Thomas Peterson
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
- Department of Agronomy, Iowa State University, Ames, IA 50011, USA
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