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Yan H, Ren Y, Zhang B, Jin J, Du F, Shan Z, Fu Y, Zhu Y, Wang X, Zhu C, Cai Y, Zhang J, Wang F, Zhang X, Wang R, Wang Y, Xu H, Jiang L, Liu X, Zhu S, Lin Q, Lei C, Cheng Z, Wang Y, Zhang W, Wan J. SUBSTANDARD STARCH GRAIN7 regulates starch grain size and endosperm development in rice. PLANT BIOTECHNOLOGY JOURNAL 2024. [PMID: 39180364 DOI: 10.1111/pbi.14444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 07/17/2024] [Accepted: 07/21/2024] [Indexed: 08/26/2024]
Abstract
Starch is synthesized as insoluble, semicrystalline particles within plant chloroplast and amyloplast, which are referred to as starch grains (SGs). The size and morphology of SGs in the cereal endosperm are diverse and species-specific, representing a key determinant of the suitability of starch for industrial applications. However, the molecular mechanisms modulating SG size in cereal endosperm remain elusive. Here, we functionally characterized the rice (Oryza sativa) mutant substandard starch grain7 (ssg7), which exhibits enlarged SGs and defective endosperm development. SSG7 encodes a plant-specific DUF1001 domain-containing protein homologous to Arabidopsis (Arabidopsis thaliana) CRUMPLED LEAF (AtCRL). SSG7 localizes to the amyloplast membrane in developing endosperm. Several lines of evidence suggest that SSG7 functions together with SSG4 and SSG6, known as two regulators essential for SG development, to control SG size, by interacting with translocon-associated components, which unveils a molecular link between SG development and protein import. Genetically, SSG7 acts synergistically with SSG4 and appears to be functional redundancy with SSG6 in modulating SG size and endosperm development. Collectively, our findings uncover a multimeric functional protein complex involved in SG development in rice. SSG7 represents a promising target gene for the biotechnological modification of SG size, particularly for breeding programs aimed at improving starch quality.
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Affiliation(s)
- Haigang Yan
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Yulong Ren
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Binglei Zhang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Jie Jin
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Feilong Du
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Zhuangzhuang Shan
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Yushuang Fu
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Yun Zhu
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xin Wang
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Changyuan Zhu
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Yue Cai
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Jie Zhang
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Fan Wang
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiao Zhang
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Rongqi Wang
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Yongxiang Wang
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Hancong Xu
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Ling Jiang
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Xi Liu
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
| | - Shanshan Zhu
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Qibing Lin
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Cailin Lei
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Zhijun Cheng
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yihua Wang
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
- Zhongshan Biological Breeding Laboratory, Nanjing, China
| | - Wenwei Zhang
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
- Zhongshan Biological Breeding Laboratory, Nanjing, China
| | - Jianmin Wan
- State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, China
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
- Zhongshan Biological Breeding Laboratory, Nanjing, China
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Shi J, Wang H, Li M, Mi L, Gao Y, Qiang S, Zhang Y, Chen D, Dai X, Ma H, Lu H, Kim C, Chen S. Alternaria TeA toxin activates a chloroplast retrograde signaling pathway to facilitate JA-dependent pathogenicity. PLANT COMMUNICATIONS 2024; 5:100775. [PMID: 38050356 PMCID: PMC10943587 DOI: 10.1016/j.xplc.2023.100775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 11/05/2023] [Accepted: 11/30/2023] [Indexed: 12/06/2023]
Abstract
The chloroplast is a critical battleground in the arms race between plants and pathogens. Among microbe-secreted mycotoxins, tenuazonic acid (TeA), produced by the genus Alternaria and other phytopathogenic fungi, inhibits photosynthesis, leading to a burst of photosynthetic singlet oxygen (1O2) that is implicated in damage and chloroplast-to-nucleus retrograde signaling. Despite the significant crop damage caused by Alternaria pathogens, our understanding of the molecular mechanism by which TeA promotes pathogenicity and cognate plant defense responses remains fragmentary. We now reveal that A. alternata induces necrotrophic foliar lesions by harnessing EXECUTER1 (EX1)/EX2-mediated chloroplast-to-nucleus retrograde signaling activated by TeA toxin-derived photosynthetic 1O2 in Arabidopsis thaliana. Mutation of the 1O2-sensitive EX1-W643 residue or complete deletion of the EX1 singlet oxygen sensor domain compromises expression of 1O2-responsive nuclear genes and foliar lesions. We also found that TeA toxin rapidly induces nuclear genes implicated in jasmonic acid (JA) synthesis and signaling, and EX1-mediated retrograde signaling appears to be critical for establishing a signaling cascade from 1O2 to JA. The present study sheds new light on the foliar pathogenicity of A. alternata, during which EX1-dependent 1O2 signaling induces JA-dependent foliar cell death.
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Affiliation(s)
- Jiale Shi
- Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095, China
| | - He Wang
- Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095, China
| | - Mengping Li
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Liru Mi
- Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095, China
| | - Yazhi Gao
- Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095, China
| | - Sheng Qiang
- Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095, China
| | - Yu Zhang
- Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095, China
| | - Dan Chen
- Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095, China
| | - Xinbin Dai
- Bioinformatics and Computational Biology Laboratory, Noble Research Institute, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Hongyu Ma
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Huan Lu
- Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095, China
| | - Chanhong Kim
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
| | - Shiguo Chen
- Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095, China.
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3
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Bali S, Gautam A, Dhiman A, Michael R, Dogra V. Salicylate and jasmonate intertwine in ROS-triggered chloroplast-to-nucleus retrograde signaling. PHYSIOLOGIA PLANTARUM 2023; 175:e14041. [PMID: 37882286 DOI: 10.1111/ppl.14041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 09/20/2023] [Accepted: 09/25/2023] [Indexed: 10/27/2023]
Abstract
Plants, being sessile, are frequently exposed to environmental perturbations, affecting their sustenance and survival. In response, distinct inherent mechanisms emerged during plant evolution to deal with environmental stresses. Among various organelles, chloroplast plays an indispensable role in plant cells. Besides providing the site for photosynthesis and biosynthesis of many important primary and secondary metabolites, including hormones, chloroplasts also act as environmental sensors. Any environmental perturbation directly influences the photosynthetic electron transport chain, leading to excess accumulation of reactive oxygen species (ROS), causing oxidative damages to biomolecules in the vicinity. To prevent excess ROS accumulation and the consequent oxidative damages, the chloroplast activates retrograde signaling (RS) pathways to reprogramme nuclear gene expression, defining plant's response to stress. Based on levels and site of ROS accumulation, distinct biomolecules are oxidized, generating specific derivatives that act as genuine signaling molecules, triggering specific RS pathways to instigate distinctive responses, including growth inhibition, acclimation, and programmed cell death. Though various RS pathways independently modulate nuclear gene expression, they also implicate the defense hormone salicylic acid (SA) and oxylipins, including 12-oxo-phytodienoic acid (OPDA) and jasmonic acid (JA), by promoting their biosynthesis and utilizing them for intra- and intercellular communications. Several studies reported the involvement of both hormones in individual RS pathways, but the precise dissection of their activation and participation in a given RS pathway remains an enigma. The present review describes the current understanding of how SA and JA intertwine in ROS-triggered RS pathways. We have also emphasized the future perspectives for elucidating stress specificity and spatiotemporal accumulation of respective hormones in a given RS pathway.
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Affiliation(s)
- Shagun Bali
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
| | - Ayushi Gautam
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
| | - Aarzoo Dhiman
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
| | - Rahul Michael
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
| | - Vivek Dogra
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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Zhao L, Wang HJ, Martins PD, van Dongen JT, Bolger AM, Schmidt RR, Jing HC, Mueller-Roeber B, Schippers JHM. The Arabidopsis thaliana onset of leaf death 12 mutation in the lectin receptor kinase P2K2 results in an autoimmune phenotype. BMC PLANT BIOLOGY 2023; 23:294. [PMID: 37264342 DOI: 10.1186/s12870-023-04300-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 05/20/2023] [Indexed: 06/03/2023]
Abstract
BACKGROUND Plant immunity relies on the perception of immunogenic signals by cell-surface and intracellular receptors and subsequent activation of defense responses like programmed cell death. Under certain circumstances, the fine-tuned innate immune system of plants results in the activation of autoimmune responses that cause constitutive defense responses and spontaneous cell death in the absence of pathogens. RESULTS Here, we characterized the onset of leaf death 12 (old12) mutant that was identified in the Arabidopsis accession Landsberg erecta. The old12 mutant is characterized by a growth defect, spontaneous cell death, plant-defense gene activation, and early senescence. In addition, the old12 phenotype is temperature reversible, thereby exhibiting all characteristics of an autoimmune mutant. Mapping the mutated locus revealed that the old12 phenotype is caused by a mutation in the Lectin Receptor Kinase P2-TYPE PURINERGIC RECEPTOR 2 (P2K2) gene. Interestingly, the P2K2 allele from Landsberg erecta is conserved among Brassicaceae. P2K2 has been implicated in pathogen tolerance and sensing extracellular ATP. The constitutive activation of defense responses in old12 results in improved resistance against Pseudomonas syringae pv. tomato DC3000. CONCLUSION We demonstrate that old12 is an auto-immune mutant and that allelic variation of P2K2 contributes to diversity in Arabidopsis immune responses.
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Affiliation(s)
- Liming Zhao
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Straße 24-25, Haus 20, 14476, Potsdam, Germany
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam-Golm, Germany
- Beijng Academy, Beijing, 100028, China
| | - Hao-Jie Wang
- Department of Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany
- Institute of Biology I, Rheinisch-Westfälische Technische Hochschule Aachen University, 52074, Aachen, Germany
| | - Patricia Dalcin Martins
- Institute of Biology I, Rheinisch-Westfälische Technische Hochschule Aachen University, 52074, Aachen, Germany
| | - Joost T van Dongen
- Institute of Biology I, Rheinisch-Westfälische Technische Hochschule Aachen University, 52074, Aachen, Germany
| | - Anthony M Bolger
- Institute of Biology I, Rheinisch-Westfälische Technische Hochschule Aachen University, 52074, Aachen, Germany
- IBG-4: Bioinformatik,Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Romy R Schmidt
- Institute of Biology I, Rheinisch-Westfälische Technische Hochschule Aachen University, 52074, Aachen, Germany
- Plant Biotechnology Group, Faculty of Biology, Bielefeld University, Universitätsstrasse 25, 33615, Bielefeld, Germany
- Center for Biotechnology, Bielefeld University, Universitätsstrasse 25, 33615, Bielefeld, Germany
| | - Hai-Chun Jing
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Bernd Mueller-Roeber
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Straße 24-25, Haus 20, 14476, Potsdam, Germany
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam-Golm, Germany
- Center of Plant Systems Biology and Biotechnology (CPSBB), Ruski 139 Blvd, Plovdiv, 4000, Bulgaria
| | - Jos H M Schippers
- Department of Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany.
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5
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Kim DB, Na C, Hwang I, Lee DW. Understanding protein translocation across chloroplast membranes: Translocons and motor proteins. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2023; 65:408-416. [PMID: 36223071 DOI: 10.1111/jipb.13385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Subcellular organelles in eukaryotes are surrounded by lipid membranes. In an endomembrane system, vesicle trafficking is the primary mechanism for the delivery of organellar proteins to specific organelles. However, organellar proteins for chloroplasts, mitochondria, the nucleus, and peroxisomes that are translated in the cytosol are directly imported into their target organelles. Chloroplasts are a plant-specific organelle with outer and inner envelope membranes, a dual-membrane structure that is similar to mitochondria. Interior chloroplast proteins translated by cytosolic ribosomes are thus translocated through TOC and TIC complexes (translocons in the outer and inner envelope of chloroplasts, respectively), with stromal ATPase motor proteins playing a critical role in pulling pre-proteins through these import channels. Over the last three decades, the identity and function of TOC/TIC components and stromal motor proteins have been actively investigated, which has shed light on the action mechanisms at a molecular level. However, there remains some disagreement over the exact composition of TIC complexes and genuine stromal motor proteins. In this review, we discuss recent findings on the mechanisms by which proteins are translocated through TOC/TIC complexes and discuss future prospects for this field of research.
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Affiliation(s)
- Da Been Kim
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Korea
| | - Changhee Na
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Korea
| | - Inhwan Hwang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Dong Wook Lee
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Korea
- Department of Bioenergy Science and Technology, Chonnam National University, Gwangju, 61186, Korea
- Kumho Life Science Laboratory, Chonnam National University, Gwangju, 61186, Korea
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Sun D, Quan W, Wang D, Cui J, Wang T, Lin M, Wang Y, Wang N, Dong Y, Li X, Liu W, Wang F. Genome-Wide Identification and Expression Analysis of Fatty Acid Desaturase ( FAD) Genes in Camelina sativa (L.) Crantz. Int J Mol Sci 2022; 23:ijms232314550. [PMID: 36498878 PMCID: PMC9738755 DOI: 10.3390/ijms232314550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/18/2022] [Accepted: 11/17/2022] [Indexed: 11/24/2022] Open
Abstract
Camelina sativa (L.) Crantz is an indispensable oilseed crop, and its seeds contain many unsaturated fatty acids. FAD (fatty acid desaturase) regulates the synthesis of unsaturated fatty acids. In this research, we performed CsFAD gene family analysis and identified 24 CsFAD genes in Camelina, which were unevenly distributed on 14 of the 19 total chromosomes. Phylogenetic analysis showed that CsFAD includes four subfamilies, supported by the conserved structures and motifs of CsFAD genes. In addition, we investigated the expression patterns of the FAD family in the different tissues of Camelina. We found that CsFAD family genes were all expressed in the stem, and CsFAD2-2 was highly expressed in the early stage of seed development. Moreover, during low temperature (4 °C) stress, we identified that the expression level of CsFAD2-2 significantly changed. By observing the transient expression of CsFAD2-2 in Arabidopsis protoplasts, we found that CsFAD2-2 was located on the nucleus. Through the detection and analysis of fatty acids, we prove that CsFAD2-2 is involved in the synthesis of linolenic acid (C18:3). In conclusion, we identified CsFAD2-2 through the phylogenetic analysis of the CsFAD gene family and further determined the fatty acid content to find that CsFAD2-2 is involved in fatty acid synthesis in Camelina.
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7
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Mohapatra S, Sirhindi G, Dogra V. Seed priming with brassinolides improves growth and reinforces antioxidative defenses under normal and heat stress conditions in seedlings of Brassica juncea. PHYSIOLOGIA PLANTARUM 2022; 174:e13814. [PMID: 36326060 DOI: 10.1111/ppl.13814] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 10/21/2022] [Accepted: 10/27/2022] [Indexed: 06/16/2023]
Abstract
Environmental stresses pose a major challenge for plant researchers to fulfill increasing food demand. Researchers are trying to generate high-yielding and stress-tolerant or resistant varieties using classical genetics and modern gene-editing tools; however, both approaches have limitations. Chemical treatments emerged as an alternative to improve yield and impart stress resilience. Brassinosteroids (BRs) are a group of phytohormones that regulate various biological processes, including stress management. With foliar spray methods, BR treatments showed promising results but are not economically feasible. We hypothesize that priming of seeds, which requires lesser amounts of BRs, could be equally effective in promoting growth and stress tolerance. Owing to this notion, we analyzed the impact of priming seeds with selected BRs, namely, 24-epibrassinolide (EBL) and 28-homobrassinolide (HBL), in Brassica juncea under normal and heat shock stress conditions. Seeds primed with BRs and grown until seedlings stage at normal conditions (20°C) were subjected to a heat shock (35°C) for a few hours, relating to what plants experience in natural conditions. Heat shock reduced the growth and biomass with an increased accumulation of reactive oxygen species. As anticipated, BRs treatments significantly improved the growth and physiological parameters with an enhanced antioxidant defense under both conditions. Transcriptional analyses revealed that BRs concomitantly induce growth and oxidative stress-responsive gene expression via the canonical BR-signaling pathway. Transfer of unstressed and heat-shock-treated seedlings to field conditions demonstrated the long-term effectivity of BR-priming. Our results showed seed priming with BRs could improve growth and resilience against heat shock; hence, it appears to be a viable strategy to enhance crop yields and stress tolerance.
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Affiliation(s)
- Sumanta Mohapatra
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | | | - Vivek Dogra
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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8
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Chevigny N, Weber-Lotfi F, Le Blevenec A, Nadiras C, Fertet A, Bichara M, Erhardt M, Dietrich A, Raynaud C, Gualberto JM. RADA-dependent branch migration has a predominant role in plant mitochondria and its defect leads to mtDNA instability and cell cycle arrest. PLoS Genet 2022; 18:e1010202. [PMID: 35550632 PMCID: PMC9129000 DOI: 10.1371/journal.pgen.1010202] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 05/24/2022] [Accepted: 04/14/2022] [Indexed: 12/21/2022] Open
Abstract
Mitochondria of flowering plants have large genomes whose structure and segregation are modulated by recombination activities. The post-synaptic late steps of mitochondrial DNA (mtDNA) recombination are still poorly characterized. Here we show that RADA, a plant ortholog of bacterial RadA/Sms, is an organellar protein that drives the major branch-migration pathway of plant mitochondria. While RadA/Sms is dispensable in bacteria, RADA-deficient Arabidopsis plants are severely impacted in their development and fertility, correlating with increased mtDNA recombination across intermediate-size repeats and accumulation of recombination-generated mitochondrial subgenomes. The radA mutation is epistatic to recG1 that affects the additional branch migration activity. In contrast, the double mutation radA recA3 is lethal, underlining the importance of an alternative RECA3-dependent pathway. The physical interaction of RADA with RECA2 but not with RECA3 further indicated that RADA is required for the processing of recombination intermediates in the RECA2-depedent recombination pathway of plant mitochondria. Although RADA is dually targeted to mitochondria and chloroplasts we found little to no effects of the radA mutation on the stability of the plastidial genome. Finally, we found that the deficient maintenance of the mtDNA in radA apparently triggers a retrograde signal that activates nuclear genes repressing cell cycle progression. In flowering plants, the mitochondrial genome is very large and dynamic, and its stability influences plant fitness and development. Rearrangements by recombination drive its very rapid evolution and can lead to valuable agronomic traits such as cytoplasmic sterility, used by breeders for the production of hybrid seeds. Here we describe RADA, a DNA helicase essential for the stability of the mitochondrial DNA in Arabidopsis. We demonstrate that RADA has branch migrating activity, accelerating the processing of recombination intermediates. radA mutants are severely affected in development and fertility. They display mitochondrial genome instability that results in uncoordinated replication of subgenomes created by recombination. Furthermore, we found that an important component of the growth defects of radA mutants is apparently a cellular response triggered by the sensing of damages to the mitochondrial genome, resulting in the activation of genes that suppress the progression of the cell cycle. Our results underline the importance of better understanding the plant mitochondrial recombination pathways and their cross-talk with nuclear gene expression.
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Affiliation(s)
- Nicolas Chevigny
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Frédérique Weber-Lotfi
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Anaïs Le Blevenec
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Cédric Nadiras
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Arnaud Fertet
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Marc Bichara
- Biotechnologie et Signalisation Cellulaire, CNRS, Université de Strasbourg, Illkirch-Graffenstaden, France
| | - Mathieu Erhardt
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - André Dietrich
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Cécile Raynaud
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), Orsay, France
- Université de Paris, CNRS, INRAE, Institute of Plant Sciences Paris-Saclay (IPS2), Orsay, France
| | - José M. Gualberto
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, Strasbourg, France
- * E-mail:
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9
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TIC236 gain-of-function mutations unveil the link between plastid division and plastid protein import. Proc Natl Acad Sci U S A 2022; 119:e2123353119. [PMID: 35275795 PMCID: PMC8931380 DOI: 10.1073/pnas.2123353119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Although plastid division is critical for plant development, how components of the plastid division machinery (PDM) are imported into plastids remains unexplored. A forward genetic screen to identify suppressors of a crumpled leaf (crl) mutant deficient in plastid division led us to find dominant gain-of-function (GF) mutations in TIC236, which significantly increases the import of PDM components and completely rescues crl phenotypes. The defective plastid division phenotypes in crl and tic236-knockdown mutants and CRL-TIC236 association in a functional complex indicate that the CRL-TIC236 module is vital for plastid division. Hence, we report the first GF translocon mutants and unveil CRL as a novel functional partner of TIC236 for PDM import. TIC236 is an essential component of the translocon for protein import into chloroplasts, as evidenced by the embryonic lethality of the knockout mutant. Here, we unveil a TIC236-allied component, the chloroplast outer membrane protein CRUMPLED LEAF (CRL), absence of which impairs plastid division and induces autoimmune responses in Arabidopsis thaliana. A forward genetic screen exploring CRL function found multiple dominant TIC236 gain-of-function (tic236-gf) mutations that abolished crl-induced phenotypes. Moreover, CRL associates with TIC236, and a tic236-knockdown mutant exhibited multiple lesions similar to the crl mutant, supporting their shared functionality. Consistent with the defective plastid division phenotype of crl, CRL interacts with the transit peptides of proteins essential in plastid division, with tic236-gf mutations reinforcing their import via increased TIC236 stability. Ensuing reverse genetic analyses further revealed genetic interaction between CRL and SP1, a RING-type ubiquitin E3 ligase, as well as with the plastid protease FTSH11, which function in TOC and TIC protein turnover, respectively. Loss of either SP1 or FTSH11 rescued crl mutant phenotypes to varying degrees due to increased translocon levels. Collectively, our data shed light on the links between plastid protein import, plastid division, and plant stress responses.
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DNA methylation-free Arabidopsis reveals crucial roles of DNA methylation in regulating gene expression and development. Nat Commun 2022; 13:1335. [PMID: 35288562 PMCID: PMC8921224 DOI: 10.1038/s41467-022-28940-2] [Citation(s) in RCA: 75] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 02/16/2022] [Indexed: 12/17/2022] Open
Abstract
A contribution of DNA methylation to defense against invading nucleic acids and maintenance of genome integrity is uncontested; however, our understanding of the extent of involvement of this epigenetic mark in genome-wide gene regulation and plant developmental control is incomplete. Here, we knock out all five known DNA methyltransferases in Arabidopsis, generating DNA methylation-free plants. This quintuple mutant exhibits a suite of developmental defects, unequivocally demonstrating that DNA methylation is essential for multiple aspects of plant development. We show that CG methylation and non-CG methylation are required for a plethora of biological processes, including pavement cell shape, endoreduplication, cell death, flowering, trichome morphology, vasculature and meristem development, and root cell fate determination. Moreover, we find that DNA methylation has a strong dose-dependent effect on gene expression and repression of transposable elements. Taken together, our results demonstrate that DNA methylation is dispensable for Arabidopsis survival but essential for the proper regulation of multiple biological processes. Our understanding of the extent of involvement of DNA methylation in genome-wide gene regulation and plant developmental control is incomplete. Here, the authors knock out all five known DNA methyltransferases and show the developmental and gene expression changes in the DNA methylation-free Arabidopsis plants.
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Dogra V, Singh RM, Li M, Li M, Singh S, Kim C. EXECUTER2 modulates the EXECUTER1 signalosome through its singlet oxygen-dependent oxidation. MOLECULAR PLANT 2022; 15:438-453. [PMID: 34968736 DOI: 10.1016/j.molp.2021.12.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 11/29/2021] [Accepted: 12/25/2021] [Indexed: 06/14/2023]
Abstract
Oxidative post-translational modifications of specific chloroplast proteins contribute to the initiation of retrograde signaling. The Arabidopsis thaliana EXECUTER1 (EX1) protein, a chloroplast-localized singlet oxygen (1O2) sensor, undergoes tryptophan (Trp) 643 oxidation by 1O2, a chloroplast-derived and light-dependent reactive oxygen species. The indole side chain of Trp is vulnerable to 1O2, leading to the generation of oxidized Trp variants and priming EX1 for degradation by a membrane-bound FtsH protease. The perception of 1O2 via Trp643 oxidation and subsequent EX1 proteolysis facilitate chloroplast-to-nucleus retrograde signaling. In this study, we discovered that the EX1-like protein EX2 also undergoes 1O2-dependent Trp530 oxidation and FtsH-dependent turnover, which attenuates 1O2 signaling by decelerating EX1-Trp643 oxidation and subsequent EX1 degradation. Consistent with this finding, the loss of EX2 function reinforces EX1-dependent retrograde signaling by accelerating EX1-Trp643 oxidation and subsequent EX1 proteolysis, whereas overexpression of EX2 produces molecular phenotypes opposite to those observed in the loss-of- function mutants of EX2. Intriguingly, phylogenetic analysis suggests that EX2 may have emerged evolutionarily to attenuate the sensitivity of EX1 toward 1O2. Collectively, these results suggest that EX2 functions as a negative regulator of the EX1 signalosome through its own 1O2-dependent oxidation, providing a new mechanistic insight into the regulation of EX1-mediated 1O2 signaling.
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Affiliation(s)
- Vivek Dogra
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Rahul Mohan Singh
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Mengping Li
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Mingyue Li
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Somesh Singh
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Chanhong Kim
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
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Luo S, Kim C. Current Understanding of Temperature Stress-Responsive Chloroplast FtsH Metalloproteases. Int J Mol Sci 2021; 22:ijms222212106. [PMID: 34829988 PMCID: PMC8622299 DOI: 10.3390/ijms222212106] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/07/2021] [Accepted: 11/08/2021] [Indexed: 12/22/2022] Open
Abstract
Low and high temperatures are life-threatening stress factors, diminishing plant productivity. One of the earliest responses of plants to stress is a rapid burst of reactive oxygen species (ROS) in chloroplasts. Widespread efforts over the past decade shed new light on the chloroplast as an environmental sensor, translating the environmental fluctuation into varying physiological responses by utilizing distinct retrograde (chloroplast-to-nucleus) signals. Recent studies have unveiled that chloroplasts mediate a similar unfolded/misfolded/damaged protein response (cpUPR) as observed in the endoplasmic reticulum and mitochondria. Although observing cpUPR is not surprising since the chloroplast is a prime organelle producing harmful ROS, the intertwined relationship among ROS, protein damage, and chloroplast protein quality controls (cpPQCs) with retrograde signaling has recently been reported. This finding also gives rise to critical attention on chloroplast proteins involved in cpPQCs, ROS detoxifiers, transcription/translation, import of precursor proteins, and assembly/maturation, the deficiency of which compromises chloroplast protein homeostasis (proteostasis). Any perturbation in the protein may require readjustment of proteostasis by transmitting retrograde signal(s) to the nucleus, whose genome encodes most of the chloroplast proteins involved in proteostasis. This review focuses on recent findings on cpUPR and chloroplast-targeted FILAMENTOUS TEMPERATURE-SENSITIVE H proteases involved in cpPQC and retrograde signaling and their impacts on plant responses to temperature stress.
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Affiliation(s)
- Shengji Luo
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Chanhong Kim
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
- Correspondence:
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Rac M, Shumbe L, Oger C, Guy A, Vigor C, Ksas B, Durand T, Havaux M. Luminescence imaging of leaf damage induced by lipid peroxidation products and its modulation by β-cyclocitral. PHYSIOLOGIA PLANTARUM 2021; 171:246-259. [PMID: 33215689 DOI: 10.1111/ppl.13279] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/30/2020] [Accepted: 11/09/2020] [Indexed: 05/26/2023]
Abstract
Lipid peroxidation is a primary event associated with oxidative stress in plants. This phenomenon secondarily generates bioactive and/or toxic compounds such as reactive carbonyl species (RCS), phytoprostanes, and phytofurans, as confirmed here in Arabidopsis plants exposed to photo-oxidative stress conditions. We analyzed the effects of exogenous applications of secondary lipid oxidation products on Arabidopsis plants by luminescence techniques. Oxidative damage to attached leaves was measured by autoluminescence imaging, using a highly sensitive CCD camera, and the activity of the detoxification pathway, dependent on the transcription regulator SCARECROW-LIKE 14 (SCL14), was monitored with a bioluminescent line expressing the firefly LUCIFERASE (LUC) gene under the control of the ALKENAL REDUCTASE (AER) gene promoter. We identified 4-hydroxynonenal (HNE), and to a lesser extent 4-hydroxyhexenal (HHE), as highly reactive compounds that are harmful to leaves and can trigger AER gene expression, contrary to other RCS (pentenal, hexenal) and to isoprostanoids. Although the levels of HNE and other RCS were enhanced in the SCL14-deficient mutant (scl14), exogenously applied HNE was similarly damaging to this mutant, its wild-type parent and a SCL14-overexpressing transgenic line (OE:SCL14). However, strongly boosting the SCL14 detoxification pathway and AER expression by a pre-treatment of OE:SCL14 with the signaling apocarotenoid β-cyclocitral canceled the damaging effects of HNE. Conversely, in the scl14 mutant, the effects of β-cyclocitral and HNE were additive, leading to enhanced leaf damage. These results indicate that the cellular detoxification pathway induced by the low-toxicity β-cyclocitral targets highly toxic compounds produced during lipid peroxidation, reminiscent of a safener-type mode of action.
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Affiliation(s)
- Marek Rac
- Institute of Biosciences and Biotechnologies, CEA/Cadarache, Aix Marseille University, CEA, CNRS, BIAM, UMR7265, Saint-Paul-lez-Durance, France
- Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Leonard Shumbe
- Institute of Biosciences and Biotechnologies, CEA/Cadarache, Aix Marseille University, CEA, CNRS, BIAM, UMR7265, Saint-Paul-lez-Durance, France
| | - Camille Oger
- Institut des Biomolécules Max Mousseron (IBMM), UMR 5247, CNRS, University of Montpellier, Montpellier, France
| | - Alexandre Guy
- Institut des Biomolécules Max Mousseron (IBMM), UMR 5247, CNRS, University of Montpellier, Montpellier, France
| | - Claire Vigor
- Institut des Biomolécules Max Mousseron (IBMM), UMR 5247, CNRS, University of Montpellier, Montpellier, France
| | - Brigitte Ksas
- Institute of Biosciences and Biotechnologies, CEA/Cadarache, Aix Marseille University, CEA, CNRS, BIAM, UMR7265, Saint-Paul-lez-Durance, France
| | - Thierry Durand
- Institut des Biomolécules Max Mousseron (IBMM), UMR 5247, CNRS, University of Montpellier, Montpellier, France
| | - Michel Havaux
- Institute of Biosciences and Biotechnologies, CEA/Cadarache, Aix Marseille University, CEA, CNRS, BIAM, UMR7265, Saint-Paul-lez-Durance, France
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Rea AC. More Than Just a FAD(5): Unsaturated Fatty Acids in Chloroplasts Elicit Protective Autoimmunity. THE PLANT CELL 2020; 32:3049-3050. [PMID: 32796125 PMCID: PMC7534481 DOI: 10.1105/tpc.20.00637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
- Anne C Rea
- MSU-DOE Plant Research LaboratoryMichigan State UniversityEast Lansing, Michigan
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