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Ishii K, Kazama Y, Hirano T, Fawcett JA, Sato M, Hirai MY, Sakai F, Shirakawa Y, Ohbu S, Abe T. Genomic view of heavy-ion-induced deletions associated with distribution of essential genes in Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2024; 15:1352564. [PMID: 38693931 PMCID: PMC11061394 DOI: 10.3389/fpls.2024.1352564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 03/11/2024] [Indexed: 05/03/2024]
Abstract
Heavy-ion beam, a type of ionizing radiation, has been applied to plant breeding as a powerful mutagen and is a promising tool to induce large deletions and chromosomal rearrangements. The effectiveness of heavy-ion irradiation can be explained by linear energy transfer (LET; keV µm-1). Heavy-ion beams with different LET values induce different types and sizes of mutations. It has been suggested that deletion size increases with increasing LET value, and complex chromosomal rearrangements are induced in higher LET radiations. In this study, we mapped heavy-ion beam-induced deletions detected in Arabidopsis mutants to its genome. We revealed that deletion sizes were similar between different LETs (100 to 290 keV μm-1), that their upper limit was affected by the distribution of essential genes, and that the detected chromosomal rearrangements avoid disrupting the essential genes. We also focused on tandemly arrayed genes (TAGs), where two or more homologous genes are adjacent to one another in the genome. Our results suggested that 100 keV µm-1 of LET is enough to disrupt TAGs and that the distribution of essential genes strongly affects the heritability of mutations overlapping them. Our results provide a genomic view of large deletion inductions in the Arabidopsis genome.
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Affiliation(s)
- Kotaro Ishii
- RIKEN Nishina Center for Accelerator-Based Science, Wako, Japan
- Department of Radiation Measurement and Dose Assessment, Institute for Radiological Science, Quantum Life and Medical Science Directorate, National Institutes for Quantum Science and Technology, Chiba, Japan
| | - Yusuke Kazama
- RIKEN Nishina Center for Accelerator-Based Science, Wako, Japan
- Department of Bioscience and Biotechnology, Fukui Prefectural University, Eiheiji-cho, Japan
| | - Tomonari Hirano
- RIKEN Nishina Center for Accelerator-Based Science, Wako, Japan
- Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan
| | - Jeffrey A. Fawcett
- RIKEN Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), Wako, Japan
| | - Muneo Sato
- RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | - Masami Yokota Hirai
- RIKEN Center for Sustainable Resource Science, Yokohama, Japan
- Graduate School of Bioagricultural Science, Nagoya University, Nagoya, Japan
| | | | - Yuki Shirakawa
- RIKEN Nishina Center for Accelerator-Based Science, Wako, Japan
| | - Sumie Ohbu
- RIKEN Nishina Center for Accelerator-Based Science, Wako, Japan
| | - Tomoko Abe
- RIKEN Nishina Center for Accelerator-Based Science, Wako, Japan
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Watabe Y, Takahashi S. Production of Enhanced Carotenoid-Producing Strains of the Yeast Rhodotorula gracilis Using the Antibiotic Zeocin. Appl Biochem Biotechnol 2023; 195:7889-7897. [PMID: 37084031 DOI: 10.1007/s12010-023-04494-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2023] [Indexed: 04/22/2023]
Abstract
We employed genomic mutagenesis to the yeast Rhodotorula gracilis using Zeocin as a mutagen to develop enhanced carotenoid-producing mutant strains. The yeast mutant strains with enhanced carotenoid pigmentation were produced on agar plates containing Zeocin at a concentration of less than 1.5 µg/mL. The optimum concentration for producing enhanced carotenoid-pigmentation mutant strains was 0.25 µg/mL. The production of β-carotene, torulene, and torularhodin in an enhanced pigmentation strain were 1.3, 1.65, and 1.5 times higher than in the wild-type strain. These results suggested that genomic mutagenesis of the yeast using Zeocin could be applied for efficiently producing enhanced carotenoid-producing mutant strains.
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Affiliation(s)
- Yusuke Watabe
- Department of Bioengineering, Nagaoka University of Technology, Nagaoka, 940-2188, Niigata, Japan
| | - Shouji Takahashi
- Department of Bioengineering, Nagaoka University of Technology, Nagaoka, 940-2188, Niigata, Japan.
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3
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Satoh K, Hoshino W, Hase Y, Kitamura S, Hayashi H, Furuta M, Oono Y. Lethal and mutagenic effects of different LET radiations on Bacillus subtilis spores. Mutat Res 2023; 827:111835. [PMID: 37562181 DOI: 10.1016/j.mrfmmm.2023.111835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/23/2023] [Accepted: 07/27/2023] [Indexed: 08/12/2023]
Abstract
New, useful microorganism resources have been generated by ionizing radiation breeding technology. However, the mutagenic effects of ionizing radiation on microorganisms have not been systematically clarified. For a deeper understanding and characterization of ionizing radiation-induced mutations in microorganisms, we investigated the lethal effects of seven different linear energy transfer (LET) radiations based on the survival fraction (SF) and whole-genome sequencing analysis of the mutagenic effects of a dose resulting in an SF of around 1% in Bacillus subtilis spores. Consequently, the lower LET radiations (gamma [surface LET: 0.2 keV/µm] and 4He2+ [24 keV/µm]) showed low lethality and high mutation frequency (MF), resulting in the major induction of single-base substitutions. Whereas higher LET radiations (12C5+ [156 keV/µm] and 12C6+ [179 keV/µm]) showed high lethality and low MF, resulting in the preferential induction of deletion mutations. In addition, 12C6+ (111) ion beams likely possess characteristics of both low- and high-LET radiations simultaneously. A decrease in the relative biological effectiveness and an evaluation of the inactivation cross section indicated that 20Ne8+ (468 keV/µm) and 40Ar13+ (2214 keV/µm) ion beams had overkill effects. In conclusion, in the mutation breeding of microorganisms, it should be possible to regulate the proportions, types, and frequencies of induced mutations by selecting an ionizing radiation of an appropriate LET in accordance with the intended purpose.
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Affiliation(s)
- Katsuya Satoh
- Department of Quantum-Applied Biosciences, Takasaki Institute for Advanced Quantum Science, Foundational Quantum Technology Research Directorate, National Institutes for Quantum Science and Technology (QST), 1233 Watanuki, Takasaki, Gunma 370-1292, Japan.
| | - Wataru Hoshino
- Department of Quantum-Applied Biosciences, Takasaki Institute for Advanced Quantum Science, Foundational Quantum Technology Research Directorate, National Institutes for Quantum Science and Technology (QST), 1233 Watanuki, Takasaki, Gunma 370-1292, Japan; Faculty of Engineering, Maebashi Institute of Technology, 460-1 Kamisadori, Maebashi, Gunma 371-0816, Japan
| | - Yoshihiro Hase
- Department of Quantum-Applied Biosciences, Takasaki Institute for Advanced Quantum Science, Foundational Quantum Technology Research Directorate, National Institutes for Quantum Science and Technology (QST), 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
| | - Satoshi Kitamura
- Department of Quantum-Applied Biosciences, Takasaki Institute for Advanced Quantum Science, Foundational Quantum Technology Research Directorate, National Institutes for Quantum Science and Technology (QST), 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
| | - Hidenori Hayashi
- Faculty of Engineering, Maebashi Institute of Technology, 460-1 Kamisadori, Maebashi, Gunma 371-0816, Japan
| | - Masakazu Furuta
- Department of Quantum and Radiation Engineering, Graduate School of Engineering, Osaka Metropolitan University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan
| | - Yutaka Oono
- Department of Quantum-Applied Biosciences, Takasaki Institute for Advanced Quantum Science, Foundational Quantum Technology Research Directorate, National Institutes for Quantum Science and Technology (QST), 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
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4
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Chen X, Du Y, Luo S, Qu Y, Jin W, Liu S, Wang Z, Liu X, Feng Z, Qin B, Zhou L. Physiological and Transcriptomic Analyses Reveal the Effects of Carbon-Ion Beam on Taraxacum kok-saghyz Rodin Adventitious Buds. Int J Mol Sci 2023; 24:ijms24119287. [PMID: 37298239 DOI: 10.3390/ijms24119287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 04/23/2023] [Accepted: 05/15/2023] [Indexed: 06/12/2023] Open
Abstract
Taraxacum kok-saghyz Rodin (TKS) has great potential as an alternative natural-rubber (NR)-producing crop. The germplasm innovation of TKS still faces great challenges due to its self-incompatibility. Carbon-ion beam (CIB) irradiation is a powerful and non-species-specific physical method for mutation creation. Thus far, the CIB has not been utilized in TKS. To better inform future mutation breeding for TKS by the CIB and provide a basis for dose-selection, adventitious buds, which not only can avoid high levels of heterozygosity, but also further improve breeding efficiency, were irradiated here, and the dynamic changes of the growth and physiologic parameters, as well as gene expression pattern were profiled, comprehensively. The results showed that the CIB (5-40 Gy) caused significant biological effects on TKS, exhibiting inhibitory effects on the fresh weight and the number of regenerated buds and roots. Then,15 Gy was chosen for further study after comprehensive consideration. CIB-15 Gy resulted in significant oxidative damages (hydroxyl radical (OH•) generation activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and malondialdehyde (MDA) content) and activated the antioxidant system (superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX)) of TKS. Based on RNA-seq analysis, the number of differentially expressed genes (DEGs) peaked at 2 h after CIB irradiation. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that DNA-replication-/repair- (mainly up-regulated), cell-death- (mainly up-regulated), plant-hormone- (auxin and cytokinin, which are related to plant morphogenesis, were mainly down-regulated), and photosynthesis- (mainly down-regulated) related pathways were involved in the response to the CIB. Furthermore, CIB irradiation can also up-regulate the genes involved in NR metabolism, which provides an alternative strategy to elevate the NR production in TKS in the future. These findings are helpful to understand the radiation response mechanism and further guide the future mutation breeding for TKS by the CIB.
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Affiliation(s)
- Xia Chen
- Biophysics Group, Biomedical Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Du
- Biophysics Group, Biomedical Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shanwei Luo
- Guangdong Key Laboratory for New Technology Research of Vegetables, Vegetable Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
| | - Ying Qu
- Biophysics Group, Biomedical Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenjie Jin
- Biophysics Group, Biomedical Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Shizhong Liu
- Rubber Research Institute, Chinese Academy of Tropical Agricultural Science, Haikou 571101, China
| | - Zhuanzi Wang
- Biophysics Group, Biomedical Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiao Liu
- Biophysics Group, Biomedical Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhuo Feng
- Biophysics Group, Biomedical Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bi Qin
- Rubber Research Institute, Chinese Academy of Tropical Agricultural Science, Haikou 571101, China
| | - Libin Zhou
- Biophysics Group, Biomedical Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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Hase Y, Satoh K, Kitamura S. Comparative analysis of seed and seedling irradiation with gamma rays and carbon ions for mutation induction in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2023; 14:1149083. [PMID: 37089645 PMCID: PMC10117944 DOI: 10.3389/fpls.2023.1149083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 03/23/2023] [Indexed: 05/03/2023]
Abstract
The molecular nature of mutations induced by ionizing radiation and chemical mutagens in plants is becoming clearer owing to the availability of high-throughput DNA sequencing technology. However, few studies have compared the induced mutations between different radiation qualities and between different irradiated materials with the same analysis method. To compare mutation induction between dry-seeds and seedlings irradiated with carbon ions and gamma rays in Arabidopsis, in this study we detected the mutations induced by seedling irradiation with gamma rays and analyzed the data together with data previously obtained for the other irradiation treatments. Mutation frequency at the equivalent dose for survival reduction was higher with gamma rays than with carbon ions, and was higher with dry-seed irradiation than with seedling irradiation. Carbon ions induced a higher frequency of deletions (2-99 bp) than gamma rays in the case of dry-seed irradiation, but this difference was less evident in the case of seedling irradiation. This result supported the inference that dry-seed irradiation under a lower water content more clearly reflects the difference in radiation quality. However, the ratio of rearrangements (inversions, translocations, and deletions larger than 100 bp), which are considered to be derived from the rejoining of two distantly located DNA breaks, was significantly higher with carbon ions than gamma rays irrespective of the irradiated material. This finding suggested that high-linear energy transfer radiation induced closely located DNA damage, irrespective of the water content of the material, that could lead to the generation of rearrangements. Taken together, the results provide an overall picture of radiation-induced mutation in Arabidopsis and will be useful for selection of a suitable radiation treatment for mutagenesis.
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Hirao AS, Watanabe Y, Hasegawa Y, Takagi T, Ueno S, Kaneko S. Mutational effects of chronic gamma radiation throughout the life cycle of Arabidopsis thaliana: Insight into radiosensitivity in the reproductive stage. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:156224. [PMID: 35644386 DOI: 10.1016/j.scitotenv.2022.156224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 05/17/2022] [Accepted: 05/21/2022] [Indexed: 06/15/2023]
Abstract
Organisms living on Earth have always been exposed to natural sources of ionizing radiation, but following recent nuclear disasters, these background levels have often increased regionally due to the addition of man-made sources of radiation. To assess the mutational effects of ubiquitously present radiation on plants, we performed a whole-genome resequencing analysis of mutations induced by chronic irradiation throughout the life cycle of Arabidopsis thaliana grown under controlled conditions. We obtained resequencing data from 36 second generation post-mutagenesis (M2) progeny derived from 12 first generation (M1) lines grown under gamma-irradiation conditions, ranging from 0.0 to 2.0 Gray per day (Gy/day), to identify de novo mutations, including single base substitutions (SBSs) and small insertions/deletions (INDELs). The relationship between de novo mutation frequency and radiation dose rate from 0.0 to 2.0 Gy/day was assessed by statistical modeling. The increase in de novo mutations in response to irradiation dose fit the negative binomial model, which accounted for the high variability of mutation frequency observed. Among the different types of mutations, SBSs were more prevalent than INDELs, and deletions were more frequent than insertions. Furthermore, we observed that the mutational effects of chronic radiation were greater during the reproductive stage. These results will provide valuable insights into practical strategies for analyzing mutational effects in wild plants growing in environments with various mutagens.
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Affiliation(s)
- Akira S Hirao
- Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanayagawa, Fukushima, Fukushima 960-1296, Japan; National Research Institute of Fisheries Science, Japan Fisheries Research and Education Agency, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa 236-8648, Japan
| | - Yoshito Watanabe
- Fukushima Project Headquarters, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Yoichi Hasegawa
- Department of Forest Molecular Genetics and Biotechnology, Forestry and Forest Products Research Institute, Forest Research and Management Organization, 1 Matsunosato, Tsukuba, Ibaraki, Japan
| | - Toshihito Takagi
- Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 1 Kanayagawa, Fukushima, Fukushima, Japan
| | - Saneyoshi Ueno
- Department of Forest Molecular Genetics and Biotechnology, Forestry and Forest Products Research Institute, Forest Research and Management Organization, 1 Matsunosato, Tsukuba, Ibaraki, Japan
| | - Shingo Kaneko
- Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanayagawa, Fukushima, Fukushima 960-1296, Japan; Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima, Fukushima, Japan.
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Kralemann LEM, de Pater S, Shen H, Kloet SL, van Schendel R, Hooykaas PJJ, Tijsterman M. Distinct mechanisms for genomic attachment of the 5' and 3' ends of Agrobacterium T-DNA in plants. NATURE PLANTS 2022; 8:526-534. [PMID: 35534719 DOI: 10.1038/s41477-022-01147-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
Agrobacterium tumefaciens, a pathogenic bacterium capable of transforming plants through horizontal gene transfer, is nowadays the preferred vector for plant genetic engineering. The vehicle for transfer is the T-strand, a single-stranded DNA molecule bound by the bacterial protein VirD2, which guides the T-DNA into the plant's nucleus where it integrates. How VirD2 is removed from T-DNA, and which mechanism acts to attach the liberated end to the plant genome is currently unknown. Here, using newly developed technology that yields hundreds of T-DNA integrations in somatic tissue of Arabidopsis thaliana, we uncover two redundant mechanisms for the genomic capture of the T-DNA 5' end. Different from capture of the 3' end of the T-DNA, which is the exclusive action of polymerase theta-mediated end joining (TMEJ), 5' attachment is accomplished either by TMEJ or by canonical non-homologous end joining (cNHEJ). We further find that TMEJ needs MRE11, whereas cNHEJ requires TDP2 to remove the 5' end-blocking protein VirD2. As a consequence, T-DNA integration is severely impaired in plants deficient for both MRE11 and TDP2 (or other cNHEJ factors). In support of MRE11 and cNHEJ specifically acting on the 5' end, we demonstrate rescue of the integration defect of double-deficient plants by using T-DNAs that are capable of forming telomeres upon 3' capture. Our study provides a mechanistic model for how Agrobacterium exploits the plant's own DNA repair machineries to transform it.
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Affiliation(s)
| | - Sylvia de Pater
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | - Hexi Shen
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, Shandong, China
| | - Susan L Kloet
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Robin van Schendel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Paul J J Hooykaas
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | - Marcel Tijsterman
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands.
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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Kitamura S, Satoh K, Oono Y. Detection and characterization of genome-wide mutations in M1 vegetative cells of gamma-irradiated Arabidopsis. PLoS Genet 2022; 18:e1009979. [PMID: 35051177 PMCID: PMC8775353 DOI: 10.1371/journal.pgen.1009979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 12/04/2021] [Indexed: 11/20/2022] Open
Abstract
Radiation-induced mutations have been detected by whole-genome sequencing analyses of self-pollinated generations of mutagenized plants. However, large DNA alterations and mutations in non-germline cells were likely missed. In this study, in order to detect various types of mutations in mutagenized M1 plants, anthocyanin pigmentation was used as a visible marker of mutations. Arabidopsis seeds heterozygous for the anthocyanin biosynthetic genes were irradiated with gamma-rays. Anthocyanin-less vegetative sectors resulting from a loss of heterozygosity were isolated from the gamma-irradiated M1 plants. The whole-genome sequencing analysis of the sectors detected various mutations, including structural variations (SVs) and large deletions (≥100 bp), both of which have been less characterized in the previous researches using gamma-irradiated plant genomes of M2 or later generations. Various types of rejoined sites were found in SVs, including no-insertion/deletion (indel) sites, only-deletion sites, only-insertion sites, and indel sites, but the rejoined sites with 0–5 bp indels represented most of the SVs. Examinations of the junctions of rearrangements (SVs and large deletions), medium deletions (10–99 bp), and small deletions (2–9 bp) revealed unique features (i.e., frequency of insertions and microhomology) at the rejoined sites. These results suggest that they were formed preferentially via different processes. Additionally, mutations that occurred in putative single M1 cells were identified according to the distribution of their allele frequency. The estimated mutation frequencies and spectra of the M1 cells were similar to those of previously analyzed M2 cells, with the exception of the greater proportion of rearrangements in the M1 cells. These findings suggest there are no major differences in the small mutations (<100 bp) between vegetative and germline cells. Thus, this study generated valuable information that may help clarify the nature of gamma-irradiation-induced mutations and their occurrence in cells that develop into vegetative or reproductive tissues. Mutations that occur in plant genome are not only related to plant evolution and speciation in nature, and also useful to identify novel gene functions and to develop new cultivars. Ionizing radiations induce various types of mutations throughout genomes in individual cells of an irradiated/mutagenized plant. However, current knowledge on radiation-induced genome-wide mutations in plants relied on the analyses of self-pollinated generations (M2 or later generations) of the mutagenized plants (M1 generation). Thus, mutations that are hardly transmitted to the next generation and those occurred in non-germline cells could not be investigated. Here, using anthocyanin pigmentation as a visible marker to reduce the genomic complexity in M1 plants, we achieved reliable detection of radiation-induced genome-wide mutations. We demonstrated that rearrangements, which were hardly detected in previous analyses using M2 genomes, occurred substantially often in gamma-irradiated M1 cells. We also revealed that mutation profile of the M1 cells was comparable with that of M2 genomes reported in previous analyses, except for the higher proportion of rearrangements in the M1 genome. Together with unique features at rejoined sites of rearrangements, medium deletions, and small deletions in the M1 genome, our findings are helpful to know the nature of genome-wide mutations induced by gamma-irradiation.
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Affiliation(s)
- Satoshi Kitamura
- Project “Ion Beam Mutagenesis”, Department of Radiation-Applied Biology Research, Takasaki Advanced Radiation Research Institute, National Institutes for Quantum Science and Technology, Takasaki, Japan
- * E-mail:
| | - Katsuya Satoh
- Project “Ion Beam Mutagenesis”, Department of Radiation-Applied Biology Research, Takasaki Advanced Radiation Research Institute, National Institutes for Quantum Science and Technology, Takasaki, Japan
| | - Yutaka Oono
- Project “Ion Beam Mutagenesis”, Department of Radiation-Applied Biology Research, Takasaki Advanced Radiation Research Institute, National Institutes for Quantum Science and Technology, Takasaki, Japan
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9
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Frequency and Spectrum of Mutations Induced by Gamma Rays Revealed by Phenotype Screening and Whole-Genome Re-Sequencing in Arabidopsis thaliana. Int J Mol Sci 2022; 23:ijms23020654. [PMID: 35054839 PMCID: PMC8775868 DOI: 10.3390/ijms23020654] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/26/2021] [Accepted: 01/04/2022] [Indexed: 12/29/2022] Open
Abstract
Genetic variations are an important source of germplasm diversity, as it provides an allele resource that contributes to the development of new traits for plant breeding. Gamma rays have been widely used as a physical agent for mutation creation in plants, and their mutagenic effect has attracted extensive attention. However, few studies are available on the comprehensive mutation profile at both the large-scale phenotype mutation screening and whole-genome mutation scanning. In this study, biological effects on M1 generation, large-scale phenotype screening in M2 generation, as well as whole-genome re-sequencing of seven M3 phenotype-visible lines were carried out to comprehensively evaluate the mutagenic effects of gamma rays on Arabidopsis thaliana. A total of 417 plants with visible mutated phenotypes were isolated from 20,502 M2 plants, and the phenotypic mutation frequency of gamma rays was 2.03% in Arabidopsis thaliana. On average, there were 21.57 single-base substitutions (SBSs) and 11.57 small insertions and deletions (InDels) in each line. Single-base InDels accounts for 66.7% of the small InDels. The genomic mutation frequency was 2.78 × 10−10/bp/Gy. The ratio of transition/transversion was 1.60, and 64.28% of the C > T events exhibited the pyrimidine dinucleotide sequence; 69.14% of the small InDels were located in the sequence with 1 to 4 bp terminal microhomology that was used for DNA end rejoining, while SBSs were less dependent on terminal microhomology. Nine genes, on average, were predicted to suffer from functional alteration in each re-sequenced line. This indicated that a suitable mutation gene density was an advantage of gamma rays when trying to improve elite materials for one certain or a few traits. These results will aid the full understanding of the mutagenic effects and mechanisms of gamma rays and provide a basis for suitable mutagen selection and parameter design, which can further facilitate the development of more controlled mutagenesis methods for plant mutation breeding.
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