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Waneka G, Broz AK, Wold-McGimsey F, Zou Y, Wu Z, Sloan DB. Disruption of recombination machinery alters the mutational landscape in plant organellar genomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.03.597120. [PMID: 38895361 PMCID: PMC11185577 DOI: 10.1101/2024.06.03.597120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Land plant organellar genomes have extremely low rates of point mutation yet also experience high rates of recombination and genome instability. Characterizing the molecular machinery responsible for these patterns is critical for understanding the evolution of these genomes. While much progress has been made towards understanding recombination activity in land plant organellar genomes, the relationship between recombination pathways and point mutation rates remains uncertain. The organellar targeted mutS homolog MSH1 has previously been shown to suppress point mutations as well as non-allelic recombination between short repeats in Arabidopsis thaliana. We therefore implemented high-fidelity Duplex Sequencing to test if other genes that function in recombination and maintenance of genome stability also affect point mutation rates. We found small to moderate increases in the frequency of single nucleotide variants (SNVs) and indels in mitochondrial and/or plastid genomes of A. thaliana mutant lines lacking radA, recA1, or recA3. In contrast, osb2 and why2 mutants did not exhibit an increase in point mutations compared to wild type (WT) controls. In addition, we analyzed the distribution of SNVs in previously generated Duplex Sequencing data from A. thaliana organellar genomes and found unexpected strand asymmetries and large effects of flanking nucleotides on mutation rates in WT plants and msh1 mutants. Finally, using long-read Oxford Nanopore sequencing, we characterized structural variants in organellar genomes of the mutant lines and show that different short repeat sequences become recombinationally active in different mutant backgrounds. Together, these complementary sequencing approaches shed light on how recombination may impact the extraordinarily low point mutation rates in plant organellar genomes.
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Affiliation(s)
- Gus Waneka
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Amanda K Broz
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
| | | | - Yi Zou
- Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China
| | - Zhiqiang Wu
- Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China
| | - Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
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UPL5 modulates WHY2 protein distribution in a Kub-site dependent ubiquitination in response to [Ca2+]cyt-induced leaf senescence. iScience 2023; 26:106216. [PMID: 36994183 PMCID: PMC10040967 DOI: 10.1016/j.isci.2023.106216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 01/08/2023] [Accepted: 02/13/2023] [Indexed: 03/08/2023] Open
Abstract
The translocation of proteins between various compartments of cells is the simplest and most direct way of an/retrograde communication. However, the mechanism of protein trafficking is far understood. In this study, we showed that the alteration of WHY2 protein abundance in various compartments of cells was dependent on a HECT-type ubiquitin E3 ligase UPL5 interacting with WHY2 in the cytoplasm, plastid, and nucleus, as well as mitochondrion to selectively ubiquitinate various Kub-sites (Kub 45 and Kub 227) of WHY2. Plastid genome stability can be maintained by the UPL5-WHY2 module, accompany by the alteration of photosystem activity and senescence-associated gene expression. In addition, the specificity of UPL5 ubiquitinating various Kub-sites of WHY2 was responded to cold or CaCl2 stress, in a dose [Ca2+]cyt-dependent manner. This demonstrates the integration of the UPL5 ubiquitination with the regulation of WHY2 distribution and retrograde communication between organelle and nuclear events of leaf senescence.
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Taylor RE, West CE, Foyer CH. WHIRLY protein functions in plants. Food Energy Secur 2023; 12:e379. [PMID: 38440693 PMCID: PMC10909546 DOI: 10.1002/fes3.379] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 02/22/2022] [Accepted: 03/04/2022] [Indexed: 03/06/2024] Open
Abstract
Environmental stresses pose a significant threat to food security. Understanding the function of proteins that regulate plant responses to biotic and abiotic stresses is therefore pivotal in developing strategies for crop improvement. The WHIRLY (WHY) family of DNA-binding proteins are important in this regard because they fulfil a portfolio of important functions in organelles and nuclei. The WHY1 and WHY2 proteins function as transcription factors in the nucleus regulating phytohormone synthesis and associated growth and stress responses, as well as fulfilling crucial roles in DNA and RNA metabolism in plastids and mitochondria. WHY1, WHY2 (and WHY3 proteins in Arabidopsis) maintain organelle genome stability and serve as auxiliary factors for homologous recombination and double-strand break repair. Our understanding of WHY protein functions has greatly increased in recent years, as has our knowledge of the flexibility of their localization and overlap of functions but there is no review of the topic in the literature. Our aim in this review was therefore to provide a comprehensive overview of the topic, discussing WHY protein functions in nuclei and organelles and highlighting roles in plant development and stress responses. In particular, we consider areas of uncertainty such as the flexible localization of WHY proteins in terms of retrograde signalling connecting mitochondria, plastids, and the nucleus. Moreover, we identify WHY proteins as important targets in plant breeding programmes designed to increase stress tolerance and the sustainability of crop yield in a changing climate.
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Affiliation(s)
- Rachel E. Taylor
- Faculty of Biological SciencesThe Centre for Plant SciencesUniversity of LeedsLeedsUK
| | - Christopher E. West
- Faculty of Biological SciencesThe Centre for Plant SciencesUniversity of LeedsLeedsUK
| | - Christine H. Foyer
- School of BiosciencesCollege of Life and Environmental SciencesUniversity of BirminghamBirminghamUK
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Krupinska K, Desel C, Frank S, Hensel G. WHIRLIES Are Multifunctional DNA-Binding Proteins With Impact on Plant Development and Stress Resistance. FRONTIERS IN PLANT SCIENCE 2022; 13:880423. [PMID: 35528945 PMCID: PMC9070903 DOI: 10.3389/fpls.2022.880423] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 03/24/2022] [Indexed: 06/01/2023]
Abstract
WHIRLIES are plant-specific proteins binding to DNA in plastids, mitochondria, and nucleus. They have been identified as significant components of nucleoids in the organelles where they regulate the structure of the nucleoids and diverse DNA-associated processes. WHIRLIES also fulfil roles in the nucleus by interacting with telomers and various transcription factors, among them members of the WRKY family. While most plants have two WHIRLY proteins, additional WHIRLY proteins evolved by gene duplication in some dicot families. All WHIRLY proteins share a conserved WHIRLY domain responsible for ssDNA binding. Structural analyses revealed that WHIRLY proteins form tetramers and higher-order complexes upon binding to DNA. An outstanding feature is the parallel localization of WHIRLY proteins in two or three cell compartments. Because they translocate from organelles to the nucleus, WHIRLY proteins are excellent candidates for transducing signals between organelles and nucleus to allow for coordinated activities of the different genomes. Developmental cues and environmental factors control the expression of WHIRLY genes. Mutants and plants with a reduced abundance of WHIRLY proteins gave insight into their multiple functionalities. In chloroplasts, a reduction of the WHIRLY level leads to changes in replication, transcription, RNA processing, and DNA repair. Furthermore, chloroplast development, ribosome formation, and photosynthesis are impaired in monocots. In mitochondria, a low level of WHIRLIES coincides with a reduced number of cristae and a low rate of respiration. The WHIRLY proteins are involved in the plants' resistance toward abiotic and biotic stress. Plants with low levels of WHIRLIES show reduced responsiveness toward diverse environmental factors, such as light and drought. Consequently, because such plants are impaired in acclimation, they accumulate reactive oxygen species under stress conditions. In contrast, several plant species overexpressing WHIRLIES were shown to have a higher resistance toward stress and pathogen attacks. By their multiple interactions with organelle proteins and nuclear transcription factors maybe a comma can be inserted here? and their participation in organelle-nucleus communication, WHIRLY proteins are proposed to serve plant development and stress resistance by coordinating processes at different levels. It is proposed that the multifunctionality of WHIRLY proteins is linked to the plasticity of land plants that develop and function in a continuously changing environment.
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Affiliation(s)
- Karin Krupinska
- Institute of Botany, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Christine Desel
- Institute of Botany, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Susann Frank
- Institute of Botany, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Götz Hensel
- Centre for Plant Genome Engineering, Institute of Plant Biochemistry, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
- Centre of Region Haná for Biotechnological and Agricultural Research, Czech Advanced Technology and Research Institute, Palacký University Olomouc, Olomouc, Czechia
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Han SH, Kim JY, Lee JH, Park CM. Safeguarding genome integrity under heat stress in plants. JOURNAL OF EXPERIMENTAL BOTANY 2021:erab355. [PMID: 34343307 DOI: 10.1093/jxb/erab355] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Indexed: 06/13/2023]
Abstract
Heat stress adversely affects an array of molecular and cellular events in plant cells, such as denaturation of protein and lipid molecules and malformation of cellular membranes and cytoskeleton networks. Genome organization and DNA integrity are also disturbed under heat stress, and accordingly, plants have evolved sophisticated adaptive mechanisms that either protect their genomes from deleterious heat-induced damages or stimulate genome restoration responses. In particular, it is emerging that DNA damage responses are a critical defense process that underlies the acquirement of thermotolerance in plants, during which molecular players constituting the DNA repair machinery are rapidly activated. In recent years, thermotolerance genes that mediate the maintenance of genome integrity or trigger DNA repair responses have been functionally characterized in various plant species. Furthermore, accumulating evidence supports that genome integrity is safeguarded through multiple layers of thermoinduced protection routes in plant cells, including transcriptome adjustment, orchestration of RNA metabolism, protein homeostasis, and chromatin reorganization. In this review, we summarize topical progresses and research trends in understanding how plants cope with heat stress to secure genome intactness. We focus on molecular regulatory mechanisms by which plant genomes are secured against the DNA-damaging effects of heat stress and DNA damages are effectively repaired. We will also explore the practical interface between heat stress response and securing genome integrity in view of developing biotechnological ways of improving thermotolerance in crop species under global climate changes, a worldwide ecological concern in agriculture.
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Affiliation(s)
- Shin-Hee Han
- Department of Chemistry, Seoul National University, Seoul, Korea
| | - Jae Young Kim
- Department of Chemistry, Seoul National University, Seoul, Korea
| | - June-Hee Lee
- Department of Chemistry, Seoul National University, Seoul, Korea
| | - Chung-Mo Park
- Department of Chemistry, Seoul National University, Seoul, Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul, Korea
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Brambilla S, Soto G, Odorizzi A, Arolfo V, McCormick W, Primo E, Giordano W, Jozefkowicz C, Ayub N. Spontaneous Mutations in the Nitrate Reductase Gene napC Drive the Emergence of Eco-friendly Low-N 2O-Emitting Alfalfa Rhizobia in Regions with Different Climates. MICROBIAL ECOLOGY 2020; 79:1044-1053. [PMID: 31828388 DOI: 10.1007/s00248-019-01473-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 12/03/2019] [Indexed: 06/10/2023]
Abstract
We have recently shown that commercial alfalfa inoculants (e.g., Sinorhizobium meliloti B399), which are closely related to the denitrifier model strain Sinorhizobium meliloti 1021, have conserved nitrate, nitrite, and nitric oxide reductases associated with the production of the greenhouse gas nitrous oxide (N2O) from nitrate but lost the N2O reductase related to the degradation of N2O to gas nitrogen. Here, we screened a library of nitrogen-fixing alfalfa symbionts originating from different ecoregions and containing N2O reductase genes and identified novel rhizobia (Sinorhizobium meliloti INTA1-6) exhibiting exceptionally low N2O emissions. To understand the genetic basis of this novel eco-friendly phenotype, we sequenced and analyzed the genomes of these strains, focusing on their denitrification genes, and found mutations only in the nitrate reductase structural gene napC. The evolutionary analysis supported that, in these natural strains, the denitrification genes were inherited by vertical transfer and that their defective nitrate reductase napC alleles emerged by independent spontaneous mutations. In silico analyses showed that mutations in this gene occurred in ssDNA loop structures with high negative free energy (-ΔG) and that the resulting mutated stem-loop structures exhibited increased stability, suggesting the occurrence of transcription-associated mutation events. In vivo assays supported that at least one of these ssDNA sites is a mutational hot spot under denitrification conditions. Similar benefits from nitrogen fixation were observed when plants were inoculated with the commercial inoculant B399 and strains INTA4-6, suggesting that the low-N2O-emitting rhizobia can be an ecological alternative to the current inoculants without resigning economic profitability.
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Affiliation(s)
- Silvina Brambilla
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO-CONICET), Buenos Aires, Argentina
- Instituto de Genética (IGEAF-INTA), Buenos Aires, Argentina
| | - Gabriela Soto
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO-CONICET), Buenos Aires, Argentina
- Instituto de Genética (IGEAF-INTA), Buenos Aires, Argentina
| | - Ariel Odorizzi
- Estación Experimental Agropecuaria Manfredi (INTA), Córdoba, Argentina
| | - Valeria Arolfo
- Estación Experimental Agropecuaria Manfredi (INTA), Córdoba, Argentina
| | - Wayne McCormick
- Ottawa Research and Development Centre (AAFC), Ottawa, ON, Canada
| | - Emiliano Primo
- Departamento de Biología Molecular (UNRC), Córdoba, Argentina
| | - Walter Giordano
- Departamento de Biología Molecular (UNRC), Córdoba, Argentina
| | - Cintia Jozefkowicz
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO-CONICET), Buenos Aires, Argentina
- Instituto de Genética (IGEAF-INTA), Buenos Aires, Argentina
| | - Nicolás Ayub
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO-CONICET), Buenos Aires, Argentina.
- Instituto de Genética (IGEAF-INTA), Buenos Aires, Argentina.
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