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Zhang J, Sun L, Wang Y, Li B, Li X, Ye Z, Zhang J. A Calcium-Dependent Protein Kinase Regulates the Defense Response in Citrus sinensis. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2024; 37:459-466. [PMID: 38597923 DOI: 10.1094/mpmi-12-23-0208-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Citrus Huanglongbing (HLB), which is caused by 'Candidatus Liberibacter asiaticus' (CLas), is one of the most destructive citrus diseases worldwide, and defense-related Citrus sinensis gene resources remain largely unexplored. Calcium signaling plays an important role in diverse biological processes. In plants, a few calcium-dependent protein kinases (CDPKs/CPKs) have been shown to contribute to defense against pathogenic microbes. The genome of C. sinensis encodes dozens of CPKs. In this study, the role of C. sinensis calcium-dependent protein kinases (CsCPKs) in C. sinensis defense was investigated. Silencing of CsCPK6 compromised the induction of defense-related genes in C. sinensis. Expression of a constitutively active form of CsCPK6 (CsCPK6CA) triggered the activation of defense-related genes in C. sinensis. Complementation of CsCPK6 rescued the defense-related gene induction in an Arabidopsis thaliana cpk4/11 mutant, indicating that CsCPK6 carries CPK activity and is capable of functioning as a CPK in Arabidopsis. Moreover, an effector derived from CLas inhibits defense induced by the expression of CsCPK6CA and autophosphorylation of CsCPK6, which suggests the involvement of CsCPK6 and calcium signaling in defense. These results support a positive role for CsCPK6 in C. sinensis defense against CLas, and the autoinhibitory regulation of CsCPK6 provides a potential genome-editing target for improving C. sinensis defense. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Jinghan Zhang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- School of Life Sciences, Hebei University, Baoding, Hebei 071002, China
| | - Lifan Sun
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yu Wang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Baiyang Li
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiangguo Li
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- College of Agronomy, Shanxi Agricultural University, Taigu 030801, China
| | - Ziqin Ye
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jie Zhang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
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Jia H, Omar AA, Xu J, Dalmendray J, Wang Y, Feng Y, Wang W, Hu Z, Grosser JW, Wang N. Generation of transgene-free canker-resistant Citrus sinensis cv. Hamlin in the T0 generation through Cas12a/CBE co-editing. FRONTIERS IN PLANT SCIENCE 2024; 15:1385768. [PMID: 38595767 PMCID: PMC11002166 DOI: 10.3389/fpls.2024.1385768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 03/15/2024] [Indexed: 04/11/2024]
Abstract
Citrus canker disease affects citrus production. This disease is caused by Xanthomonas citri subsp. citri (Xcc). Previous studies confirmed that during Xcc infection, PthA4, a transcriptional activator like effector (TALE), is translocated from the pathogen to host plant cells. PthA4 binds to the effector binding elements (EBEs) in the promoter region of canker susceptibility gene LOB1 (EBEPthA4-LOBP) to activate its expression and subsequently cause canker symptoms. Previously, the Cas12a/CBE co-editing method was employed to disrupt EBEPthA4-LOBP of pummelo, which is highly homozygous. However, most commercial citrus cultivars are heterozygous hybrids and more difficult to generate homozygous/biallelic mutants. Here, we employed Cas12a/CBE co-editing method to edit EBEPthA4-LOBP of Hamlin (Citrus sinensis), a commercial heterozygous hybrid citrus cultivar grown worldwide. Binary vector GFP-p1380N-ttLbCas12a:LOBP1-mPBE:ALS2:ALS1 was constructed and shown to be functional via Xcc-facilitated agroinfiltration in Hamlin leaves. This construct allows the selection of transgene-free regenerants via GFP, edits ALS to generate chlorsulfuron-resistant regenerants as a selection marker for genome editing resulting from transient expression of the T-DNA via nCas9-mPBE:ALS2:ALS1, and edits gene(s) of interest (i.e., EBEPthA4-LOBP in this study) through ttLbCas12a, thus creating transgene-free citrus. Totally, 77 plantlets were produced. Among them, 8 plantlets were transgenic plants (#HamGFP1 - #HamGFP8), 4 plantlets were transgene-free (#HamNoGFP1 - #HamNoGFP4), and the rest were wild type. Among 4 transgene-free plantlets, three lines (#HamNoGFP1, #HamNoGFP2 and #HamNoGFP3) contained biallelic mutations in EBEpthA4, and one line (#HamNoGFP4) had homozygous mutations in EBEpthA4. We achieved 5.2% transgene-free homozygous/biallelic mutation efficiency for EBEPthA4-LOBP in C. sinensis cv. Hamlin, compared to 1.9% mutation efficiency for pummelo in a previous study. Importantly, the four transgene-free plantlets and 3 transgenic plantlets that survived were resistant against citrus canker. Taken together, Cas12a/CBE co-editing method has been successfully used to generate transgene-free canker-resistant C. sinensis cv. Hamlin in the T0 generation via biallelic/homozygous editing of EBEpthA4 of the canker susceptibility gene LOB1.
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Affiliation(s)
- Hongge Jia
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Ahmad A. Omar
- Citrus Research and Education Center, Horticultural Sciences Department, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
- Biochemistry Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
| | - Jin Xu
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Javier Dalmendray
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Yuanchun Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Yu Feng
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Wenting Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Zhuyuan Hu
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Jude W. Grosser
- Citrus Research and Education Center, Horticultural Sciences Department, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
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Cardi T, Murovec J, Bakhsh A, Boniecka J, Bruegmann T, Bull SE, Eeckhaut T, Fladung M, Galovic V, Linkiewicz A, Lukan T, Mafra I, Michalski K, Kavas M, Nicolia A, Nowakowska J, Sági L, Sarmiento C, Yıldırım K, Zlatković M, Hensel G, Van Laere K. CRISPR/Cas-mediated plant genome editing: outstanding challenges a decade after implementation. TRENDS IN PLANT SCIENCE 2023; 28:1144-1165. [PMID: 37331842 DOI: 10.1016/j.tplants.2023.05.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 05/09/2023] [Accepted: 05/15/2023] [Indexed: 06/20/2023]
Abstract
The discovery of the CRISPR/Cas genome-editing system has revolutionized our understanding of the plant genome. CRISPR/Cas has been used for over a decade to modify plant genomes for the study of specific genes and biosynthetic pathways as well as to speed up breeding in many plant species, including both model and non-model crops. Although the CRISPR/Cas system is very efficient for genome editing, many bottlenecks and challenges slow down further improvement and applications. In this review we discuss the challenges that can occur during tissue culture, transformation, regeneration, and mutant detection. We also review the opportunities provided by new CRISPR platforms and specific applications related to gene regulation, abiotic and biotic stress response improvement, and de novo domestication of plants.
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Affiliation(s)
- Teodoro Cardi
- Consiglio Nazionale delle Ricerche (CNR), Institute of Biosciences and Bioresources (IBBR), Portici, Italy; CREA Research Centre for Vegetable and Ornamental Crops, Pontecagnano, Italy
| | - Jana Murovec
- University of Ljubljana, Biotechnical Faculty, Ljubljana, Slovenia
| | - Allah Bakhsh
- Department of Agricultural Genetic Engineering, Faculty of Agricultural Sciences and Technologies, Nigde Omer Halisdemir University, Nigde, Turkey; Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Justyna Boniecka
- Department of Genetics, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, Toruń, Poland; Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Toruń, Poland
| | | | - Simon E Bull
- Molecular Plant Breeding, Institute of Agricultural Sciences, Eidgenössische Technische Hochschule (ETH) Zurich, Switzerland; Plant Biochemistry, Institute of Molecular Plant Biology, ETH, Zurich, Switzerland
| | - Tom Eeckhaut
- Flanders Research Institute for Agricultural, Fisheries and Food, Melle, Belgium
| | | | - Vladislava Galovic
- University of Novi Sad, Institute of Lowland Forestry and Environment (ILFE), Novi Sad, Serbia
| | - Anna Linkiewicz
- Molecular Biology and Genetics Department, Institute of Biological Sciences, Faculty of Biology and Environmental Sciences, Cardinal Stefan Wyszyński University, Warsaw, Poland
| | - Tjaša Lukan
- National Institute of Biology, Department of Biotechnology and Systems Biology, Ljubljana, Slovenia
| | - Isabel Mafra
- Rede de Química e Tecnologia (REQUIMTE) Laboratório Associado para a Química Verde (LAQV), Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | - Krzysztof Michalski
- Plant Breeding and Acclimatization Institute, National Research Institute, Błonie, Poland
| | - Musa Kavas
- Department of Molecular Biology and Genetics, Faculty of Science, Ondokuz Mayis University, Samsun, Turkey
| | - Alessandro Nicolia
- CREA Research Centre for Vegetable and Ornamental Crops, Pontecagnano, Italy
| | - Justyna Nowakowska
- Molecular Biology and Genetics Department, Institute of Biological Sciences, Faculty of Biology and Environmental Sciences, Cardinal Stefan Wyszyński University, Warsaw, Poland
| | - Laszlo Sági
- Centre for Agricultural Research, Loránd Eötvös Research Network, Martonvásár, Hungary
| | - Cecilia Sarmiento
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Kubilay Yıldırım
- Department of Molecular Biology and Genetics, Faculty of Science, Ondokuz Mayis University, Samsun, Turkey
| | - Milica Zlatković
- University of Novi Sad, Institute of Lowland Forestry and Environment (ILFE), Novi Sad, Serbia
| | - Goetz Hensel
- Heinrich-Heine-University, Institute of Plant Biochemistry, Centre for Plant Genome Engineering, Düsseldorf, Germany; Division of Molecular Biology, Centre of the Region Hana for Biotechnological and Agriculture Research, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Katrijn Van Laere
- Flanders Research Institute for Agricultural, Fisheries and Food, Melle, Belgium.
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Ma Z, Ma L, Zhou J. Applications of CRISPR/Cas genome editing in economically important fruit crops: recent advances and future directions. MOLECULAR HORTICULTURE 2023; 3:1. [PMID: 37789479 PMCID: PMC10515014 DOI: 10.1186/s43897-023-00049-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 01/10/2023] [Indexed: 10/05/2023]
Abstract
Fruit crops, consist of climacteric and non-climacteric fruits, are the major sources of nutrients and fiber for human diet. Since 2013, CRISPR/Cas (Clustered Regularly Interspersed Short Palindromic Repeats and CRISPR-Associated Protein) genome editing system has been widely employed in different plants, leading to unprecedented progress in the genetic improvement of many agronomically important fruit crops. Here, we summarize latest advancements in CRISPR/Cas genome editing of fruit crops, including efforts to decipher the mechanisms behind plant development and plant immunity, We also highlight the potential challenges and improvements in the application of genome editing tools to fruit crops, including optimizing the expression of CRISPR/Cas cassette, improving the delivery efficiency of CRISPR/Cas reagents, increasing the specificity of genome editing, and optimizing the transformation and regeneration system. In addition, we propose the perspectives on the application of genome editing in crop breeding especially in fruit crops and highlight the potential challenges. It is worth noting that efforts to manipulate fruit crops with genome editing systems are urgently needed for fruit crops breeding and demonstration.
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Affiliation(s)
- Zhimin Ma
- Peking University Institute of Advanced Agricultural Sciences, Weifang, 261000, Shandong, China
| | - Lijing Ma
- Peking University Institute of Advanced Agricultural Sciences, Weifang, 261000, Shandong, China
| | - Junhui Zhou
- Peking University Institute of Advanced Agricultural Sciences, Weifang, 261000, Shandong, China.
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Khan FS, Goher F, Zhang D, Shi P, Li Z, Htwe YM, Wang Y. Is CRISPR/Cas9 a way forward to fast-track genetic improvement in commercial palms? Prospects and limits. FRONTIERS IN PLANT SCIENCE 2022; 13:1042828. [PMID: 36578341 PMCID: PMC9791139 DOI: 10.3389/fpls.2022.1042828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Commercially important palms (oil palm, coconut, and date palm) are widely grown perennial trees with tremendous commercial significance due to food, edible oil, and industrial applications. The mounting pressure on the human population further reinforces palms' importance, as they are essential crops to meet vegetable oil needs around the globe. Various conventional breeding methods are used for the genetic improvement of palms. However, adopting new technologies is crucial to accelerate breeding and satisfy the expanding population's demands. CRISPR/Cas9 is an efficient genome editing tool that can incorporate desired traits into the existing DNA of the plant without losing common traits. Recent progress in genome editing in oil palm, coconut and date palm are preliminarily introduced to potential readers. Furthermore, detailed information on available CRISPR-based genome editing and genetic transformation methods are summarized for researchers. We shed light on the possibilities of genome editing in palm crops, especially on the modification of fatty acid biosynthesis in oil palm. Moreover, the limitations in genome editing, including inadequate target gene screening due to genome complexities and low efficiency of genetic transformation, are also highlighted. The prospects of CRISPR/Cas9-based gene editing in commercial palms to improve sustainable production are also addressed in this review paper.
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Affiliation(s)
- Faiza Shafique Khan
- Hainan Key Laboratory for Biosafety Monitoring and Molecular Breeding in Off-Season Reproduction Regions/Sanya Research Institute of Chinese Academy of Tropical Agricultural Sciences, Sanya, Hainan, China
- Hainan Yazhou Bay Seed Laboratory, Sanya, Hainan, China
- Hainan Key Laboratory of Tropical Oil Crops Biology, Coconut Research Institute of Chinese Academy of Tropical Agricultural Sciences, Wenchang, Hainan, China
| | - Farhan Goher
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Dapeng Zhang
- Hainan Key Laboratory for Biosafety Monitoring and Molecular Breeding in Off-Season Reproduction Regions/Sanya Research Institute of Chinese Academy of Tropical Agricultural Sciences, Sanya, Hainan, China
- Hainan Key Laboratory of Tropical Oil Crops Biology, Coconut Research Institute of Chinese Academy of Tropical Agricultural Sciences, Wenchang, Hainan, China
| | - Peng Shi
- Hainan Key Laboratory for Biosafety Monitoring and Molecular Breeding in Off-Season Reproduction Regions/Sanya Research Institute of Chinese Academy of Tropical Agricultural Sciences, Sanya, Hainan, China
- Hainan Key Laboratory of Tropical Oil Crops Biology, Coconut Research Institute of Chinese Academy of Tropical Agricultural Sciences, Wenchang, Hainan, China
| | - Zhiying Li
- Hainan Key Laboratory for Biosafety Monitoring and Molecular Breeding in Off-Season Reproduction Regions/Sanya Research Institute of Chinese Academy of Tropical Agricultural Sciences, Sanya, Hainan, China
- Hainan Key Laboratory of Tropical Oil Crops Biology, Coconut Research Institute of Chinese Academy of Tropical Agricultural Sciences, Wenchang, Hainan, China
| | - Yin Min Htwe
- Hainan Key Laboratory for Biosafety Monitoring and Molecular Breeding in Off-Season Reproduction Regions/Sanya Research Institute of Chinese Academy of Tropical Agricultural Sciences, Sanya, Hainan, China
- Hainan Yazhou Bay Seed Laboratory, Sanya, Hainan, China
- Hainan Key Laboratory of Tropical Oil Crops Biology, Coconut Research Institute of Chinese Academy of Tropical Agricultural Sciences, Wenchang, Hainan, China
| | - Yong Wang
- Hainan Key Laboratory for Biosafety Monitoring and Molecular Breeding in Off-Season Reproduction Regions/Sanya Research Institute of Chinese Academy of Tropical Agricultural Sciences, Sanya, Hainan, China
- Hainan Key Laboratory of Tropical Oil Crops Biology, Coconut Research Institute of Chinese Academy of Tropical Agricultural Sciences, Wenchang, Hainan, China
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CRISPR/Cas Genome Editing Technologies for Plant Improvement against Biotic and Abiotic Stresses: Advances, Limitations, and Future Perspectives. Cells 2022; 11:cells11233928. [PMID: 36497186 PMCID: PMC9736268 DOI: 10.3390/cells11233928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 11/28/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022] Open
Abstract
Crossbreeding, mutation breeding, and traditional transgenic breeding take much time to improve desirable characters/traits. CRISPR/Cas-mediated genome editing (GE) is a game-changing tool that can create variation in desired traits, such as biotic and abiotic resistance, increase quality and yield in less time with easy applications, high efficiency, and low cost in producing the targeted edits for rapid improvement of crop plants. Plant pathogens and the severe environment cause considerable crop losses worldwide. GE approaches have emerged and opened new doors for breeding multiple-resistance crop varieties. Here, we have summarized recent advances in CRISPR/Cas-mediated GE for resistance against biotic and abiotic stresses in a crop molecular breeding program that includes the modification and improvement of genes response to biotic stresses induced by fungus, virus, and bacterial pathogens. We also discussed in depth the application of CRISPR/Cas for abiotic stresses (herbicide, drought, heat, and cold) in plants. In addition, we discussed the limitations and future challenges faced by breeders using GE tools for crop improvement and suggested directions for future improvements in GE for agricultural applications, providing novel ideas to create super cultivars with broad resistance to biotic and abiotic stress.
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Duan S, Long Y, Cheng S, Li J, Ouyang Z, Wang N. Rapid Evaluation of the Resistance of Citrus Germplasms Against Xanthomonas citri subsp. citri. PHYTOPATHOLOGY 2022; 112:765-774. [PMID: 34495678 DOI: 10.1094/phyto-04-21-0175-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Xanthomonas citri subsp. citri (Xcc) is the causal agent of citrus bacterial canker (CBC), one of the most devastating citrus diseases. Most commercial citrus varieties are susceptible to CBC. However, some citrus varieties and wild citrus germplasms are CBC resistant and are promising in genetic increases in citrus resistance against CBC. We aimed to evaluate citrus germplasms for resistance against CBC. First, we developed a rapid evaluation method based on enhanced yellow fluorescent protein (eYFP)-labeled Xcc. The results demonstrated that eYFP does not affect the growth and virulence of Xcc. Xcc-eYFP allows measurement of bacterial titers but is more efficient and rapid than the plate colony counting method. Next, we evaluated citrus germplasms collected in China. Based on symptoms and bacterial titers, we identified that two citrus germplasms ('Ichang' papeda and 'Huapi' kumquat) are resistant, whereas eight citrus germplasms ('Chongyi' wild mandarin, 'Mangshan' wild mandarin, 'Ledong' kumquat, 'Dali' citron, 'Yiliang' citron, 'Longyan' kumquat, 'Bawang' kumquat, and 'Daoxian' wild mandarin) are tolerant. In summary, we have developed a rapid evaluation method to test the resistance of citrus plants against CBC. This method was successfully used to identify two highly canker-resistant citrus germplasms and eight citrus germplasms with canker tolerance. These results could be leveraged in traditional breeding contexts or be used to identify canker resistance genes to increase the disease resistance of commercial citrus varieties via biotechnological approaches.
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Affiliation(s)
- Shuo Duan
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi 341000, China
| | - Yunfei Long
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi 341000, China
| | - Shuyuan Cheng
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi 341000, China
| | - Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850, U.S.A
| | - Zhigang Ouyang
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi 341000, China
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850, U.S.A
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Huang X, Wang Y, Wang N. Base Editors for Citrus Gene Editing. Front Genome Ed 2022; 4:852867. [PMID: 35296063 PMCID: PMC8919994 DOI: 10.3389/fgeed.2022.852867] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/10/2022] [Indexed: 11/22/2022] Open
Abstract
Base editors, such as adenine base editors (ABE) and cytosine base editors (CBE), provide alternatives for precise genome editing without generating double-strand breaks (DSBs), thus avoiding the risk of genome instability and unpredictable outcomes caused by DNA repair. Precise gene editing mediated by base editors in citrus has not been reported. Here, we have successfully adapted the ABE to edit the TATA box in the promoter region of the canker susceptibility gene LOB1 from TATA to CACA in grapefruit (Citrus paradise) and sweet orange (Citrus sinensis). TATA-edited plants are resistant to the canker pathogen Xanthomonas citri subsp. citri (Xcc). In addition, CBE was successfully used to edit the acetolactate synthase (ALS) gene in citrus. ALS-edited plants were resistant to the herbicide chlorsulfuron. Two ALS-edited plants did not show green fluorescence although the starting construct for transformation contains a GFP expression cassette. The Cas9 gene was undetectable in the herbicide-resistant citrus plants. This indicates that the ALS edited plants are transgene-free, representing the first transgene-free gene-edited citrus using the CRISPR technology. In summary, we have successfully adapted the base editors for precise citrus gene editing. The CBE base editor has been used to generate transgene-free citrus via transient expression.
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Jia H, Omar AA, Orbović V, Wang N. Biallelic Editing of the LOB1 Promoter via CRISPR/Cas9 Creates Canker-Resistant 'Duncan' Grapefruit. PHYTOPATHOLOGY 2022; 112:308-314. [PMID: 34213958 DOI: 10.1094/phyto-04-21-0144-r] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Citrus canker caused by Xanthomonas citri subsp. citri is one of the most devastating citrus diseases worldwide. Generating disease-resistant citrus varieties is considered one of the most efficient and environmentally friendly measures for controlling canker. X. citri subsp. citri causes canker symptoms by inducing the expression of canker susceptibility gene LOB1 via PthA4, a transcription activator-like (TAL) effector, by binding to the effector binding element (EBE) in the promoter region. In previous studies, canker-resistant plants were generated by mutating the coding region or the EBE of LOB1. However, homozygous or biallelic canker-resistant plants have not been generated for commercial citrus varieties, such as grapefruit (Citrus paradisi), which usually contain two alleles of LOB1 and thus, have two types of LOB1 promoter sequences: TI LOBP and TII LOBP. Two different sgRNAs were used to target both EBE types. Both 35S promoter and Yao promoter were used to drive the expression of SpCas9p to modify EBEPthA4-LOBP in grapefruit. Using 'Duncan' grapefruit epicotyls as explants, 19 genome-edited grapefruit plants were generated with one biallelic mutant line (#DunYao7). X. citri subsp. citri caused canker symptoms on wild-type and nonbiallelic mutant plants but not on #DunYao7. XccPthA4 mutant containing the designer TAL effector dLOB1.5, which recognizes a conserved sequence in both wild-type and #DunYao7, caused canker symptoms on both wild-type and #DunYao7. No off-target mutations were detected in #DunYao7. This study represents the first time that CRISPR-mediated genome editing has been successfully used to generate disease-resistant plants for 'Duncan' grapefruit, paving the way for using disease-resistant varieties to control canker.
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Affiliation(s)
- Hongge Jia
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred 33850, U.S.A
| | - Ahmad A Omar
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred 33850, U.S.A
- Biochemistry Department, Faculty of Agriculture, Zagazig University, Zagazig 44519, Egypt
| | - Vladimir Orbović
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred 33850, U.S.A
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred 33850, U.S.A
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Jia H, Wang Y, Su H, Huang X, Wang N. LbCas12a-D156R Efficiently Edits LOB1 Effector Binding Elements to Generate Canker-Resistant Citrus Plants. Cells 2022; 11:cells11030315. [PMID: 35159125 PMCID: PMC8834406 DOI: 10.3390/cells11030315] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/07/2022] [Accepted: 01/14/2022] [Indexed: 12/17/2022] Open
Abstract
Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) is an economically important disease in most citrus production regions worldwide. Xcc secretes a transcriptional activator like effector (TALE) PthA4 to bind to the effector binding elements (EBEs) in the promoter region of canker susceptibility gene LOB1 to activate its expression, which in turn causes canker symptoms. Editing the EBE region with Cas9/gRNA has been used to generate canker resistant citrus plants. However, most of the EBE-edited lines generated contain indels of 1–2 bp, which has higher possibility to be overcome by PthA4 adaptation. The adaptation capacity of TALEs inversely correlates with the number of mismatches with the EBE. LbCas12a/crRNA is known to generate longer deletion than Cas9. In this study, we used a temperature-tolerant and more efficient LbCas12a variant (ttLbCas12a), harboring the single substitution D156R, to modify the EBE region of LOB1. We first constructed GFP-p1380N-ttLbCas12a:LOBP, which was shown to be functional via Xcc-facilitated agroinfiltration in Pummelo (Citrus maxima) leaves. Subsequently, we stably expressed ttLbCas12a:LOBP in Pummelo. Eight transgenic lines were generated, with seven lines showing 100% mutations of the EBE, among which one line is homozygous. The EBE-edited lines had the ttLbCas12a-mediated deletions of up to 10 bp. Importantly, the seven lines were canker resistant and no off-targets were detected. In summary, ttLbCas12a can be used to efficiently generate biallelic/homozygous citrus mutant lines with short deletions, thus providing a useful tool for the functional study and breeding of citrus.
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Huang X, Wang Y, Wang N. Highly Efficient Generation of Canker-Resistant Sweet Orange Enabled by an Improved CRISPR/Cas9 System. FRONTIERS IN PLANT SCIENCE 2022; 12:769907. [PMID: 35087548 PMCID: PMC8787272 DOI: 10.3389/fpls.2021.769907] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 12/09/2021] [Indexed: 06/02/2023]
Abstract
Sweet orange (Citrus sinensis) is the most economically important species for the citrus industry. However, it is susceptible to many diseases including citrus bacterial canker caused by Xanthomonas citri subsp. citri (Xcc) that triggers devastating effects on citrus production. Conventional breeding has not met the challenge to improve disease resistance of sweet orange due to the long juvenility and other limitations. CRISPR-mediated genome editing has shown promising potentials for genetic improvements of plants. Generation of biallelic/homozygous mutants remains difficult for sweet orange due to low transformation rate, existence of heterozygous alleles for target genes, and low biallelic editing efficacy using the CRISPR technology. Here, we report improvements in the CRISPR/Cas9 system for citrus gene editing. Based on the improvements we made previously [dicot codon optimized Cas9, tRNA for multiplexing, a modified sgRNA scaffold with high efficiency, citrus U6 (CsU6) to drive sgRNA expression], we further improved our CRISPR/Cas9 system by choosing superior promoters [Cestrum yellow leaf curling virus (CmYLCV) or Citrus sinensis ubiquitin (CsUbi) promoter] to drive Cas9 and optimizing culture temperature. This system was able to generate a biallelic mutation rate of up to 89% for Carrizo citrange and 79% for Hamlin sweet orange. Consequently, this system was used to generate canker-resistant Hamlin sweet orange by mutating the effector binding element (EBE) of canker susceptibility gene CsLOB1, which is required for causing canker symptoms by Xcc. Six biallelic Hamlin sweet orange mutant lines in the EBE were generated. The biallelic mutants are resistant to Xcc. Biallelic mutation of the EBE region abolishes the induction of CsLOB1 by Xcc. This study represents a significant improvement in sweet orange gene editing efficacy and generating disease-resistant varieties via CRISPR-mediated genome editing. This improvement in citrus genome editing makes genetic studies and manipulations of sweet orange more feasible.
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12
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Gupta P, Hirschberg J. The Genetic Components of a Natural Color Palette: A Comprehensive List of Carotenoid Pathway Mutations in Plants. FRONTIERS IN PLANT SCIENCE 2022; 12:806184. [PMID: 35069664 PMCID: PMC8770946 DOI: 10.3389/fpls.2021.806184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 12/08/2021] [Indexed: 05/16/2023]
Abstract
Carotenoids comprise the most widely distributed natural pigments. In plants, they play indispensable roles in photosynthesis, furnish colors to flowers and fruit and serve as precursor molecules for the synthesis of apocarotenoids, including aroma and scent, phytohormones and other signaling molecules. Dietary carotenoids are vital to human health as a source of provitamin A and antioxidants. Hence, the enormous interest in carotenoids of crop plants. Over the past three decades, the carotenoid biosynthesis pathway has been mainly deciphered due to the characterization of natural and induced mutations that impair this process. Over the year, numerous mutations have been studied in dozens of plant species. Their phenotypes have significantly expanded our understanding of the biochemical and molecular processes underlying carotenoid accumulation in crops. Several of them were employed in the breeding of crops with higher nutritional value. This compendium of all known random and targeted mutants available in the carotenoid metabolic pathway in plants provides a valuable resource for future research on carotenoid biosynthesis in plant species.
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Affiliation(s)
| | - Joseph Hirschberg
- Department of Genetics, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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13
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Conti G, Xoconostle-Cázares B, Marcelino-Pérez G, Hopp HE, Reyes CA. Citrus Genetic Transformation: An Overview of the Current Strategies and Insights on the New Emerging Technologies. FRONTIERS IN PLANT SCIENCE 2021; 12:768197. [PMID: 34917104 PMCID: PMC8670418 DOI: 10.3389/fpls.2021.768197] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/14/2021] [Indexed: 05/04/2023]
Abstract
Citrus are among the most prevailing fruit crops produced worldwide. The implementation of effective and reliable breeding programs is essential for coping with the increasing demands of satisfactory yield and quality of the fruit as well as to deal with the negative impact of fast-spreading diseases. Conventional methods are time-consuming and of difficult application because of inherent factors of citrus biology, such as their prolonged juvenile period and a complex reproductive stage, sometimes presenting infertility, self-incompatibility, parthenocarpy, or polyembryony. Moreover, certain desirable traits are absent from cultivated or wild citrus genotypes. All these features are challenging for the incorporation of the desirable traits. In this regard, genetic engineering technologies offer a series of alternative approaches that allow overcoming the difficulties of conventional breeding programs. This review gives a detailed overview of the currently used strategies for the development of genetically modified citrus. We describe different aspects regarding genotype varieties used, including elite cultivars or extensively used scions and rootstocks. Furthermore, we discuss technical aspects of citrus genetic transformation procedures via Agrobacterium, regular physical methods, and magnetofection. Finally, we describe the selection of explants considering young and mature tissues, protoplast isolation, etc. We also address current protocols and novel approaches for improving the in vitro regeneration process, which is an important bottleneck for citrus genetic transformation. This review also explores alternative emerging transformation strategies applied to citrus species such as transient and tissue localized transformation. New breeding technologies, including cisgenesis, intragenesis, and genome editing by clustered regularly interspaced short palindromic repeats (CRISPR), are also discussed. Other relevant aspects comprising new promoters and reporter genes, marker-free systems, and strategies for induction of early flowering, are also addressed. We provided a future perspective on the use of current and new technologies in citrus and its potential impact on regulatory processes.
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Affiliation(s)
- Gabriela Conti
- Instituto de Agrobiotecnología y Biología Molecular, UEDD INTA-CONICET, Hurlingham, Argentina
- Cátedra de Genética, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Beatriz Xoconostle-Cázares
- Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Gabriel Marcelino-Pérez
- Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Horacio Esteban Hopp
- Instituto de Agrobiotecnología y Biología Molecular, UEDD INTA-CONICET, Hurlingham, Argentina
- Laboratorio de Agrobiotecnología, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Molecular y Celular (FBMC), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Carina A. Reyes
- Instituto de Biotecnología y Biología Molecular, CCT-La Plata, CONICET-UNLP, Buenos Aires, Argentina
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Mathiazhagan M, Chidambara B, Hunashikatti LR, Ravishankar KV. Genomic Approaches for Improvement of Tropical Fruits: Fruit Quality, Shelf Life and Nutrient Content. Genes (Basel) 2021; 12:1881. [PMID: 34946829 PMCID: PMC8701245 DOI: 10.3390/genes12121881] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/23/2021] [Accepted: 11/16/2021] [Indexed: 12/17/2022] Open
Abstract
The breeding of tropical fruit trees for improving fruit traits is complicated, due to the long juvenile phase, generation cycle, parthenocarpy, polyploidy, polyembryony, heterozygosity and biotic and abiotic factors, as well as a lack of good genomic resources. Many molecular techniques have recently evolved to assist and hasten conventional breeding efforts. Molecular markers linked to fruit development and fruit quality traits such as fruit shape, size, texture, aroma, peel and pulp colour were identified in tropical fruit crops, facilitating Marker-assisted breeding (MAB). An increase in the availability of genome sequences of tropical fruits further aided in the discovery of SNP variants/Indels, QTLs and genes that can ascertain the genetic determinants of fruit characters. Through multi-omics approaches such as genomics, transcriptomics, metabolomics and proteomics, the identification and quantification of transcripts, including non-coding RNAs, involved in sugar metabolism, fruit development and ripening, shelf life, and the biotic and abiotic stress that impacts fruit quality were made possible. Utilizing genomic assisted breeding methods such as genome wide association (GWAS), genomic selection (GS) and genetic modifications using CRISPR/Cas9 and transgenics has paved the way to studying gene function and developing cultivars with desirable fruit traits by overcoming long breeding cycles. Such comprehensive multi-omics approaches related to fruit characters in tropical fruits and their applications in breeding strategies and crop improvement are reviewed, discussed and presented here.
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Affiliation(s)
| | | | | | - Kundapura V. Ravishankar
- Division of Basic Sciences, ICAR Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bengaluru 560089, India; (M.M.); (B.C.); (L.R.H.)
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15
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Kaur M, Manchanda P, Kalia A, Ahmed FK, Nepovimova E, Kuca K, Abd-Elsalam KA. Agroinfiltration Mediated Scalable Transient Gene Expression in Genome Edited Crop Plants. Int J Mol Sci 2021; 22:10882. [PMID: 34639221 PMCID: PMC8509792 DOI: 10.3390/ijms221910882] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 09/23/2021] [Accepted: 10/03/2021] [Indexed: 02/07/2023] Open
Abstract
Agrobacterium-mediated transformation is one of the most commonly used genetic transformation method that involves transfer of foreign genes into target plants. Agroinfiltration, an Agrobacterium-based transient approach and the breakthrough discovery of CRISPR/Cas9 holds trending stature to perform targeted and efficient genome editing (GE). The predominant feature of agroinfiltration is the abolishment of Transfer-DNA (T-DNA) integration event to ensure fewer biosafety and regulatory issues besides showcasing the capability to perform transcription and translation efficiently, hence providing a large picture through pilot-scale experiment via transient approach. The direct delivery of recombinant agrobacteria through this approach carrying CRISPR/Cas cassette to knockout the expression of the target gene in the intercellular tissue spaces by physical or vacuum infiltration can simplify the targeted site modification. This review aims to provide information on Agrobacterium-mediated transformation and implementation of agroinfiltration with GE to widen the horizon of targeted genome editing before a stable genome editing approach. This will ease the screening of numerous functions of genes in different plant species with wider applicability in future.
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Affiliation(s)
- Maninder Kaur
- School of Agricultural Biotechnology, College of Agriculture, Punjab Agricultural University, Ludhiana, Punjab 141004, India;
| | - Pooja Manchanda
- School of Agricultural Biotechnology, College of Agriculture, Punjab Agricultural University, Ludhiana, Punjab 141004, India;
| | - Anu Kalia
- Electron Microscopy and Nanoscience Laboratory, Department of Soil Science, College of Agriculture, Punjab Agricultural University, Ludhiana, Punjab 141004, India;
| | - Farah K. Ahmed
- Biotechnology English Program, Faculty of Agriculture, Cairo University, Giza 12613, Egypt;
| | - Eugenie Nepovimova
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, 50003 Hradec Kralove, Czech Republic;
| | - Kamil Kuca
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, 50003 Hradec Kralove, Czech Republic;
- Biomedical Research Center, University Hospital Hradec Kralove, 50005 Hradec Kralove, Czech Republic
| | - Kamel A. Abd-Elsalam
- Plant Pathology Research Institute, Agricultural Research Center (ARC), 9-Gamaa St., Giza 12619, Egypt;
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16
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Teper D, Xu J, Pandey SS, Wang N. PthAW1, a Transcription Activator-Like Effector of Xanthomonas citri subsp. citri, Promotes Host-Specific Immune Responses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:1033-1047. [PMID: 33970668 DOI: 10.1094/mpmi-01-21-0026-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Citrus canker disease caused by Xanthomonas citri subsp. citri is one of the most destructive diseases in citrus. X. citri subsp. citri pathotypes display different host ranges. X. citri subsp. citri strain A (XccA) causes canker disease in most commercial citrus varieties, whereas strain AW (XccAW), which is genetically similar to XccA, infects only lime and alemow. Understanding the mechanism that determines the host range of pathogens is critical to investigating and utilizing host resistance. We hypothesized that XccAW would undergo mutations in genes that restrict its host range when artificially inoculated into incompatible citrus varieties. To test this hypothesis, we used an experimental evolution approach to identify phenotypic traits and genetic loci associated with the adaptation of XccAW to incompatible sweet orange. Repeated inoculation and reisolation cycles improved the ability of three independent XccAW strains to colonize sweet orange. Adapted XccAW strains displayed increased expression of type III secretion system and effector genes. Genome sequencing analysis indicated that two of the adapted strains harbored mutations in pthAW1, a transcription activator-like effector (TALE) gene, that corresponded to the removal of one or two repeats from the central DNA-binding repeat region. Introduction of the original but not the adapted pthAW1 variants into XccA abolished its ability to cause canker symptoms in sweet orange, Meyer lemon, and clementine but not in other XccAW-resistant citrus varieties. The original pthAW1, when expressed in XccA, induced ion leakage and the expression of pathogenesis-related genes but had no effect on CsLOB1 expression in sweet orange. Our study has identified a novel host-specific avirulence TALE and demonstrated active adaptive rearrangements of the TALE repeat array during host adaptation.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Doron Teper
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
| | - Jin Xu
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
| | - Sheo Shankar Pandey
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
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17
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Yuan X, Chen C, Bassanezi RB, Wu F, Feng Z, Shi D, Li J, Du Y, Zhong L, Zhong B, Lu Z, Song X, Hu Y, Ouyang Z, Liu X, Xie J, Rao X, Wang X, Wu DO, Guan Z, Wang N. Region-Wide Comprehensive Implementation of Roguing Infected Trees, Tree Replacement, and Insecticide Applications Successfully Controls Citrus Huanglongbing. PHYTOPATHOLOGY 2021; 111:1361-1368. [PMID: 33356429 DOI: 10.1094/phyto-09-20-0436-r] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Huanglongbing (HLB) is a devastating citrus disease worldwide. A three-pronged approach to controlling HLB has been suggested, namely, removal of HLB-symptomatic trees, psyllid control, and replacement with HLB-free trees. However, such a strategy did not lead to successful HLB control in many citrus-producing regions, such as Florida. We hypothesize that this is because of the small-scale or incomprehensive implementation of the program; conversely, a comprehensive implementation of such a strategy at the regional level can successfully control HLB. To test our hypothesis, we investigated the effects of region-wide comprehensive implementation of this scheme to control HLB in Gannan region, China, with a total planted citrus acreage of over 110,000 ha from 2013 to 2019. With the region-wide implementation of comprehensive HLB management, the overall HLB incidence in Gannan decreased from 19.71% in 2014 to 3.86% in 2019. A partial implementation of such a program (without a comprehensive inoculum removal) at the regional level in Brazil resulted in HLB incidence increasing from 1.89% in 2010 to 19.02% in 2019. Using dynamic regression model analyses with data from both Brazil and China, we constructed a model to predict HLB incidence when all three components were applied at 100%. It was predicated that in a region-wide comprehensive implementation of such a program, HLB incidence would be controlled to a level of less than 1%. We conducted economic feasibility analyses and showed that average net profits were positive for groves that implemented the comprehensive strategy, but groves that did not implement it had negative net profits over a 10-year period. Overall, the key for the three-pronged program to successfully control HLB is the large scale (region-wide) and comprehensiveness in implementation. This study provides valuable information to control HLB and other economically important endemic diseases worldwide.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Xiaoyong Yuan
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Cixiang Chen
- Ganzhou Plant Protection Department of Fruit Industry/Jiangxi Navel Orange Engineering Research Center, Ganzhou, Jiangxi, China
| | | | - Feng Wu
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, U.S.A
| | - Zheng Feng
- Department of Electrical & Computer Engineering, University of Florida, Gainesville, FL, U.S.A
| | - Damin Shi
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, U.S.A
| | - Yimin Du
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Ling Zhong
- Plant Protection Bureau, Department of Agriculture, Nanchang, Jiangxi, China
| | - Balian Zhong
- National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Zhanjun Lu
- National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Xiang Song
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Yan Hu
- Ganzhou Plant Protection Department of Fruit Industry/Jiangxi Navel Orange Engineering Research Center, Ganzhou, Jiangxi, China
| | - Zhigang Ouyang
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Xinjun Liu
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Jinzhao Xie
- Ganzhou Plant Protection Department of Fruit Industry/Jiangxi Navel Orange Engineering Research Center, Ganzhou, Jiangxi, China
| | - Xi Rao
- Plant Protection Bureau, Department of Agriculture, Nanchang, Jiangxi, China
| | - Xi Wang
- Plant Protection Bureau, Department of Agriculture, Nanchang, Jiangxi, China
| | - Dapeng Oliver Wu
- Department of Electrical & Computer Engineering, University of Florida, Gainesville, FL, U.S.A
| | - Zhengfei Guan
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, U.S.A
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, U.S.A
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18
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Ribeiro C, Xu J, Teper D, Lee D, Wang N. The transcriptome landscapes of citrus leaf in different developmental stages. PLANT MOLECULAR BIOLOGY 2021; 106:349-366. [PMID: 33871796 DOI: 10.1007/s11103-021-01154-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/12/2021] [Indexed: 06/12/2023]
Abstract
The temporal expression profiles of citrus leaves explain the sink-source transition of immature leaves to mature leaves and provide knowledge regarding the differential responses of mature and immature leaves to biotic stress such as citrus canker and Asian citrus psyllid (Diaphorina citri). Citrus is an important fruit crop worldwide. Different developmental stages of citrus leaves are associated with distinct features, such as differences in susceptibilities to pathogens and insects, as well as photosynthetic capacity. Here, we investigated the mechanisms underlying these distinctions by comparing the gene expression profiles of mature and immature citrus leaves. Immature (stages V3 and V4), transition (stage V5), and mature (stage V6) Citrus sinensis leaves were chosen for RNA-seq analyses. Carbohydrate biosynthesis, photosynthesis, starch biosynthesis, and disaccharide metabolic processes were enriched among the upregulated differentially expressed genes (DEGs) in the V5 and V6 stages compared with that in the V3 and V4 stages. Glucose level was found to be higher in V5 and V6 than in V3 and V4. Among the four stages, the largest number of DEGs between contiguous stages were identified between V5 and V4, consistent with a change from sink to source, as well as with the sucrose and starch quantification data. The differential expression profiles related to cell wall synthesis, secondary metabolites such as flavonoids and terpenoids, amino acid biosynthesis, and immunity between immature and mature leaves may contribute to their different responses to Asian citrus psyllid infestation. The expression data suggested that both the constitutive and induced gene expression of immunity-related genes plays important roles in the greater resistance of mature leaves against Xanthomonas citri compared with immature leaves. The gene expression profiles in the different stages can help identify stage-specific promoters for the manipulation of the expression of citrus traits according to the stage. The temporal expression profiles explain the sink-source transition of immature leaves to mature leaves and provide knowledge regarding the differential responses to biotic stress.
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Affiliation(s)
- Camila Ribeiro
- Citrus Research & Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, 33850, USA
| | - Jin Xu
- Citrus Research & Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, 33850, USA
| | - Doron Teper
- Citrus Research & Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, 33850, USA
| | - Donghwan Lee
- Citrus Research & Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, 33850, USA
| | - Nian Wang
- Citrus Research & Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, 33850, USA.
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Sattar MN, Iqbal Z, Al-Khayri JM, Jain SM. Induced Genetic Variations in Fruit Trees Using New Breeding Tools: Food Security and Climate Resilience. PLANTS (BASEL, SWITZERLAND) 2021; 10:1347. [PMID: 34371550 PMCID: PMC8309169 DOI: 10.3390/plants10071347] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 06/23/2021] [Accepted: 06/28/2021] [Indexed: 12/22/2022]
Abstract
Fruit trees provide essential nutrients to humans by contributing to major agricultural outputs and economic growth globally. However, major constraints to sustainable agricultural productivity are the uncontrolled proliferation of the population, and biotic and abiotic stresses. Tree mutation breeding has been substantially improved using different physical and chemical mutagens. Nonetheless, tree plant breeding has certain crucial bottlenecks including a long life cycle, ploidy level, occurrence of sequence polymorphisms, nature of parthenocarpic fruit development and linkage. Genetic engineering of trees has focused on boosting quality traits such as productivity, wood quality, and resistance to biotic and abiotic stresses. Recent technological advances in genome editing provide a unique opportunity for the genetic improvement of woody plants. This review examines application of the CRISPR-Cas system to reduce disease susceptibility, alter plant architecture, enhance fruit quality, and improve yields. Examples are discussed of the contemporary CRISPR-Cas system to engineer easily scorable PDS genes, modify lignin, and to alter the flowering onset, fertility, tree architecture and certain biotic stresses.
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Affiliation(s)
- Muhammad Naeem Sattar
- Central Laboratories, King Faisal University, Al-Ahsa 31982, Saudi Arabia; (M.N.S.); (Z.I.)
| | - Zafar Iqbal
- Central Laboratories, King Faisal University, Al-Ahsa 31982, Saudi Arabia; (M.N.S.); (Z.I.)
| | - Jameel M. Al-Khayri
- Department of Agricultural Biotechnology, College of Agriculture and Food Sciences, King Faisal University, Al-Ahsa 31982, Saudi Arabia
| | - S. Mohan Jain
- Department of Agricultural Sciences, PL-27, University of Helsinki, 00014 Helsinki, Finland;
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20
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Li J, Kolbasov VG, Lee D, Pang Z, Huang Y, Collins N, Wang N. Residue Dynamics of Streptomycin in Citrus Delivered by Foliar Spray and Trunk Injection and Effect on ' Candidatus Liberibacter asiaticus' Titer. PHYTOPATHOLOGY 2021; 111:1095-1103. [PMID: 33267628 DOI: 10.1094/phyto-09-20-0427-r] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Streptomycin (STR) has been used to control citrus huanglongbing (HLB) caused by 'Candidatus Liberibacter asiaticus' (CLas) via foliar spray. Here, we studied the residue dynamics of STR and its effect on CLas titers in planta applied by foliar spray and trunk injection of 3-year-old citrus trees that were naturally infected by CLas in the field. After foliar spray, STR levels in leaves peaked at 2 to 7 days postapplication (dpa) and gradually declined thereafter. The STR spray did not significantly affect CLas titers in leaves of treated plants as determined by quantitative PCR. After trunk injection, peak levels of STR were observed 7 to 14 dpa in the leaf and root tissues, and near-peak levels were sustained for another 14 days before significantly declining. At 12 months after injection, moderate to low or undetectable levels of STR were observed in the leaf, root, and fruit, depending on the doses of STR injected, with a residue level of 0.28 µg/g in harvested fruit at the highest injection concentration of 2.0 µg/tree. CLas titers in leaves were significantly reduced by trunk injection of STR at 1.0 or 2.0 g/tree, starting from 7 dpa and throughout the experimental period. The reduction of CLas titers was positively correlated with STR residue levels in leaves. The in planta minimum effective concentration of STR needed to suppress the CLas titer to an undetectable level (cycle threshold ≥36.0) was 1.92 µg/g fresh weight. Determination of the in planta minimum effective concentration of STR against CLas and its spatiotemporal residue levels in planta provides the guidance to use STR for HLB management.
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Affiliation(s)
- Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Vladimir G Kolbasov
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Donghwan Lee
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Zhiqian Pang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Yixiao Huang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Nicole Collins
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
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21
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Acanda Y, Welker S, Orbović V, Levy A. A simple and efficient agroinfiltration method for transient gene expression in Citrus. PLANT CELL REPORTS 2021; 40:1171-1179. [PMID: 33948685 DOI: 10.1007/s00299-021-02700-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/19/2021] [Indexed: 05/21/2023]
Abstract
Microwounding pre-treatment facilitates agroinfiltration and transient gene expression in hard-to-agroinfiltrate citrus varieties. Agrobacterium infiltration is a widely used method for transient expression studies in plants, but this method is not used extensively in citrus because of its low efficiency. In this study, we developed an easy, cheap, and reliable agroinfiltration method for transient gene expression in citrus. A microneedle roller was used to create microscopic wounds in the leaf epidermis to facilitate agroinfiltration. Several optimization parameters were explored in this study, including the density of wounds per cm2 of abaxial leaf area, the leaf maturity grade, the effect of the Agrobacterium strain, and the length of the incubation period. Increasing the density of wounds on the leaf surface had a positive effect on transient expression. Higher transient expression levels were observed in well-expanded young leaves in comparison with older leaves. The Agrobacterium strain GV2260 was the most suitable to express a large amount of recombinant protein, and an eight- to ten-day incubation period resulted in the highest expression. Endoplasmic reticulum and cytoskeleton-targeted GFP were both successfully localized, confirming that this protocol can be used for protein subcellular localization in citrus. Finally, up to 100 ng of GFP per milligram of agroinfiltrated leaf tissue was estimated to be expressed using this method. This protocol was tested for GFP expression in five different citrus varieties with no significant statistical differences among them. This simple and easy method can speed up functional genomic studies in citrus and may be applied to other recalcitrant species with extensive epidermal cuticular wax.
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Affiliation(s)
- Yosvanis Acanda
- Citrus Research and Education Center, University of Florida/IFAS, Lake Alfred, FL, USA
| | - Stacy Welker
- Citrus Research and Education Center, University of Florida/IFAS, Lake Alfred, FL, USA
- Plant Pathology Department, University of Florida, Gainesville, FL, USA
| | - Vladimir Orbović
- Citrus Research and Education Center, University of Florida/IFAS, Lake Alfred, FL, USA
| | - Amit Levy
- Citrus Research and Education Center, University of Florida/IFAS, Lake Alfred, FL, USA.
- Plant Pathology Department, University of Florida, Gainesville, FL, USA.
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22
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Pandey SS, Nogales da Costa Vasconcelos F, Wang N. Spatiotemporal Dynamics of ' Candidatus Liberibacter asiaticus' Colonization Inside Citrus Plant and Huanglongbing Disease Development. PHYTOPATHOLOGY 2021; 111:921-928. [PMID: 33174821 DOI: 10.1094/phyto-09-20-0407-r] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
'Candidatus Liberibacter asiaticus' (CLas), the causal agent of citrus huanglongbing (HLB), colonizes inside the phloem and is naturally transmitted by the Asian citrus psyllid (ACP). Here, we investigated spatiotemporal CLas colonization in different tissues after ACP transmission. Of the nine plants successfully infected via ACP transmission, CLas was detected in the roots of all trees at 75 days postremoval of ACPs (DPR) but in the mature leaf of only one tree; this finding is consistent with the model that CLas moves passively from source to sink tissues. At 75 and 365 DPR, CLas was detected in 11.1 and 43.1% of mature leaves not fed on by ACPs during transmission, respectively, unveiling active movement to the source tissue. The difference in colonization timing of sink and source tissues indicates that CLas is capable of both passive and active movement, with passive movement being dominant. At 225 DPR, leaves fed on by ACPs during the young stage showed the highest ratio of HLB symptomatic leaves and the highest CLas titer, followed by leaves that emerged after ACP removal and mature leaves not fed on by ACPs. Importantly, our data showed that ACPs were unable to transmit CLas via feeding on mature leaves. It is estimated that it takes 3 years at most for CLas to infect the whole tree. Overall, spatiotemporal detection of CLas in different tissues after ACP transmission helps visualize the infection process of CLas in planta and subsequent HLB symptom development and provides evidence showing that young leaves should be the focus of HLB management.
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Affiliation(s)
- Sheo Shankar Pandey
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850
| | | | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850
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23
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Chuang YF, Phipps AJ, Lin FL, Hecht V, Hewitt AW, Wang PY, Liu GS. Approach for in vivo delivery of CRISPR/Cas system: a recent update and future prospect. Cell Mol Life Sci 2021; 78:2683-2708. [PMID: 33388855 PMCID: PMC11072787 DOI: 10.1007/s00018-020-03725-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/19/2020] [Accepted: 11/26/2020] [Indexed: 12/14/2022]
Abstract
The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) system provides a groundbreaking genetic technology that allows scientists to modify genes by targeting specific genomic sites. Due to the relative simplicity and versatility of the CRISPR/Cas system, it has been extensively applied in human genetic research as well as in agricultural applications, such as improving crops. Since the gene editing activity of the CRISPR/Cas system largely depends on the efficiency of introducing the system into cells or tissues, an efficient and specific delivery system is critical for applying CRISPR/Cas technology. However, there are still some hurdles remaining for the translatability of CRISPR/Cas system. In this review, we summarized the approaches used for the delivery of the CRISPR/Cas system in mammals, plants, and aquacultures. We further discussed the aspects of delivery that can be improved to elevate the potential for CRISPR/Cas translatability.
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Affiliation(s)
- Yu-Fan Chuang
- Shenzhen Key Laboratory of Biomimetic Materials and Cellular Immunomodulation, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Avenue, Shenzhen University Town, Shenzhen, 518055, China
- Menzies Institute for Medical Research, University of Tasmania, 17 Liverpool Street, Hobart, TAS, 7000, Australia
| | - Andrew J Phipps
- Wicking Dementia Research and Education Centre, College of Health and Medicine, University of Tasmania, Hobart, TAS, Australia
| | - Fan-Li Lin
- Shenzhen Key Laboratory of Biomimetic Materials and Cellular Immunomodulation, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Avenue, Shenzhen University Town, Shenzhen, 518055, China
- Menzies Institute for Medical Research, University of Tasmania, 17 Liverpool Street, Hobart, TAS, 7000, Australia
| | - Valerie Hecht
- School of Natural Sciences, University of Tasmania, Hobart, TAS, Australia
| | - Alex W Hewitt
- Menzies Institute for Medical Research, University of Tasmania, 17 Liverpool Street, Hobart, TAS, 7000, Australia
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, VIC, Australia
| | - Peng-Yuan Wang
- Shenzhen Key Laboratory of Biomimetic Materials and Cellular Immunomodulation, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Avenue, Shenzhen University Town, Shenzhen, 518055, China.
- Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, VIC, Australia.
| | - Guei-Sheung Liu
- Menzies Institute for Medical Research, University of Tasmania, 17 Liverpool Street, Hobart, TAS, 7000, Australia.
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, VIC, Australia.
- Aier Eye Institute, Changsha, Hunan, China.
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Teper D, Wang N. Consequences of adaptation of TAL effectors on host susceptibility to Xanthomonas. PLoS Genet 2021; 17:e1009310. [PMID: 33465093 PMCID: PMC7845958 DOI: 10.1371/journal.pgen.1009310] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 01/29/2021] [Accepted: 12/11/2020] [Indexed: 12/03/2022] Open
Abstract
Transcription activator-like effectors (TALEs) are virulence factors of Xanthomonas that induce the expression of host susceptibility (S) genes by specifically binding to effector binding elements (EBEs) in their promoter regions. The DNA binding specificity of TALEs is dictated by their tandem repeat regions, which are highly variable between different TALEs. Mutation of the EBEs of S genes is being utilized as a key strategy to generate resistant crops against TALE-dependent pathogens. However, TALE adaptations through rearrangement of their repeat regions is a potential obstacle for successful implementation of this strategy. We investigated the consequences of TALE adaptations in the citrus pathogen Xanthomonas citri subsp. citri (Xcc), in which PthA4 is the TALE required for pathogenicity, whereas CsLOB1 is the corresponding susceptibility gene, on host resistance. Seven TALEs, containing two-to-nine mismatching-repeats to the EBEPthA4 that were unable to induce CsLOB1 expression, were introduced into Xcc pthA4:Tn5 and adaptation was simulated by repeated inoculations into and isolations from sweet orange for a duration of 30 cycles. While initially all strains failed to promote disease, symptoms started to appear between 9–28 passages in four TALEs, which originally harbored two-to-five mismatches. Sequence analysis of adapted TALEs identified deletions and mutations within the TALE repeat regions which enhanced putative affinity to the CsLOB1 promoter. Sequence analyses suggest that TALEs adaptations result from recombinations between repeats of the TALEs. Reintroduction of these adapted TALEs into Xcc pthA4:Tn5 restored the ability to induce the expression of CsLOB1, promote disease symptoms and colonize host plants. TALEs harboring seven-to-nine mismatches were unable to adapt to overcome the incompatible interaction. Our study experimentally documented TALE adaptations to incompatible EBE and provided strategic guidance for generation of disease resistant crops against TALE-dependent pathogens. Mutation of the EBEs of susceptibility (S) genes via genome editing and utilization of naturally occurring EBE variants have been used to generate disease resistant plants. However, TALE adaptations may lead to resistance loss, limiting the long-term efficacy of the strategy. We utilized an experimental evolution approach to test TALEs adaptations in the Xanthomonas citri-citrus pathosystem using designer TALEs that cannot recognize the EBE of host targets. We identified adaptive TALE mutations and deletions that occurred during less than 30 cycles of repeated infections, which reconstituted the virulence on the host. Adaptive variants originated from TALEs that harbored a small number of mismatches (≤5) to the EBE, whereas designer TALEs that harbored larger number of mismatches (≥7) to the EBE failed to adapt in the duration of this study. Our study experimentally demonstrates adaptive rearrangements of TALEs during host adaptation and suggests that the potential durability in the resistance of modified crops should be a significant factor to be considered prior to their introduction into the field.
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Affiliation(s)
- Doron Teper
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida, United States of America
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida, United States of America
- * E-mail:
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25
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Hussain SB, Shi CY, Guo LX, Du W, Bai YX, Kamran HM, Fernie AR, Liu YZ. Type I H+-pyrophosphatase regulates the vacuolar storage of sucrose in citrus fruit. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:5935-5947. [PMID: 32589717 DOI: 10.1093/jxb/eraa298] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 06/19/2020] [Indexed: 06/11/2023]
Abstract
The aim of this work was to evaluate the general role of the vacuolar pyrophosphatase proton pump (V-PPase) in sucrose accumulation in citrus species. First, three citrus V-PPase genes, designated CsVPP-1, CsVPP-2, and CsVPP-4, were identified in the citrus genome. CsVPP-1 and CsVPP-2 belonging to citrus type I V-PPase genes are targeted to the tonoplast, and CsVPP-4 belonging to citrus type II V-PPase genes is located in the Golgi bodies. Moreover, there was a significantly positive correlation between transcript levels of type I V-PPase genes and sucrose, rather than hexose, content in fruits of seven citrus cultivars. Drought and abscisic acid treatments significantly induced the CsVPP-1 and CsVPP-2 transcript levels, as well as the sucrose content. The overexpression of type I V-PPase genes significantly increased PPase activity, decreased pyrophosphate contents, and increased sucrose contents, whereas V-PPase inhibition produced the opposite effect in both citrus fruits and leaves. Furthermore, altering the expression levels of type I V-PPase genes significantly influenced the transcript levels of sucrose transporter genes. Taken together, this study demonstrated that CsVPP-1 and CsVPP-2 play key roles in sucrose storage in the vacuole by regulating pyrophosphate homeostasis, ultimately the sucrose biosynthesis and transcript levels of sucrose transport genes, providing a novel lead for engineering or breeding modified taste in citrus and other fruits.
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Affiliation(s)
- Syed Bilal Hussain
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, PR China
- College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, PR China
| | - Cai-Yun Shi
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, PR China
- College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, PR China
| | - Ling-Xia Guo
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, PR China
- College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, PR China
| | - Wei Du
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, PR China
- College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, PR China
| | - Ying-Xing Bai
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, PR China
- College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, PR China
| | - Hafiz Muhammad Kamran
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, PR China
- College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, PR China
| | - Alisdair R Fernie
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Yong-Zhong Liu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, PR China
- College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, PR China
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26
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Poles L, Licciardello C, Distefano G, Nicolosi E, Gentile A, La Malfa S. Recent Advances of In Vitro Culture for the Application of New Breeding Techniques in Citrus. PLANTS (BASEL, SWITZERLAND) 2020; 9:E938. [PMID: 32722179 PMCID: PMC7465985 DOI: 10.3390/plants9080938] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 07/21/2020] [Accepted: 07/22/2020] [Indexed: 12/15/2022]
Abstract
Citrus is one of the most important fruit crops in the world. This review will discuss the recent findings related to citrus transformation and regeneration protocols of juvenile and adult explants. Despite the many advances that have been made in the last years (including the use of inducible promoters and site-specific recombination systems), transformation efficiency, and regeneration potential still represent a bottleneck in the application of the new breeding techniques in commercial citrus varieties. The influence of genotype, explant type, and other factors affecting the regeneration and transformation of the most used citrus varieties will be described, as well as some examples of how these processes can be applied to improve fruit quality and resistance to various pathogens and pests, including the potential of using genome editing in citrus. The availability of efficient regeneration and transformation protocols, together with the availability of the source of resistance, is made even more important in light of the fast diffusion of emerging diseases, such as Huanglongbing (HLB), which is seriously challenging citriculture worldwide.
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Affiliation(s)
- Lara Poles
- Food and Environment (Di3A), Department of Agriculture, University of Catania, Via Valdisavoia 5, 95123 Catania, Italy; (L.P.); (G.D.); (E.N.); (S.L.M.)
- CREA, Research Centre for Olive, Fruit and Citrus Crops, Corso Savoia 190, 95024 Acireale, Italy;
| | - Concetta Licciardello
- CREA, Research Centre for Olive, Fruit and Citrus Crops, Corso Savoia 190, 95024 Acireale, Italy;
| | - Gaetano Distefano
- Food and Environment (Di3A), Department of Agriculture, University of Catania, Via Valdisavoia 5, 95123 Catania, Italy; (L.P.); (G.D.); (E.N.); (S.L.M.)
| | - Elisabetta Nicolosi
- Food and Environment (Di3A), Department of Agriculture, University of Catania, Via Valdisavoia 5, 95123 Catania, Italy; (L.P.); (G.D.); (E.N.); (S.L.M.)
| | - Alessandra Gentile
- Food and Environment (Di3A), Department of Agriculture, University of Catania, Via Valdisavoia 5, 95123 Catania, Italy; (L.P.); (G.D.); (E.N.); (S.L.M.)
- College of Horticulture and Landscape, Hunan Agricultural University, Changsha 410128, China
| | - Stefano La Malfa
- Food and Environment (Di3A), Department of Agriculture, University of Catania, Via Valdisavoia 5, 95123 Catania, Italy; (L.P.); (G.D.); (E.N.); (S.L.M.)
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27
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Zhou J, Li D, Wang G, Wang F, Kunjal M, Joldersma D, Liu Z. Application and future perspective of CRISPR/Cas9 genome editing in fruit crops. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2020; 62:269-286. [PMID: 30791200 PMCID: PMC6703982 DOI: 10.1111/jipb.12793] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Accepted: 02/18/2019] [Indexed: 05/24/2023]
Abstract
Fruit crops, including apple, orange, grape, banana, strawberry, watermelon, kiwifruit and tomato, not only provide essential nutrients for human life but also contribute to the major agricultural output and economic growth of many countries and regions in the world. Recent advancements in genome editing provides an unprecedented opportunity for the genetic improvement of these agronomically important fruit crops. Here, we summarize recent reports of applying CRISPR/Cas9 to fruit crops, including efforts to reduce disease susceptibility, change plant architecture or flower morphology, improve fruit quality traits, and increase fruit yield. We discuss challenges facing fruit crops as well as new improvements and platforms that could be used to facilitate genome editing in fruit crops, including dCas9-base-editing to introduce desirable alleles and heat treatment to increase editing efficiency. In addition, we highlight what we see as potentially revolutionary development ranging from transgene-free genome editing to de novo domestication of wild relatives. Without doubt, we now see only the beginning of what will eventually be possible with the use of the CRISPR/Cas9 toolkit. Efforts to communicate with the public and an emphasis on the manipulation of consumer-friendly traits will be critical to facilitate public acceptance of genetically engineered fruits with this new technology.
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Affiliation(s)
- Junhui Zhou
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Dongdong Li
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
- Zhejiang Key Laboratory for Agri-Food Processing, Zhejiang University, Hangzhou 310058, China
| | - Guoming Wang
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Centre of Pear Engineering Technology
Research, Nanjing Agricultural University, Nanjing 210095, China
| | - Fuxi Wang
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Merixia Kunjal
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Dirk Joldersma
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Zhongchi Liu
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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Sun L, Ke F, Nie Z, Wang P, Xu J. Citrus Genetic Engineering for Disease Resistance: Past, Present and Future. Int J Mol Sci 2019; 20:E5256. [PMID: 31652763 PMCID: PMC6862092 DOI: 10.3390/ijms20215256] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/20/2019] [Accepted: 10/21/2019] [Indexed: 11/16/2022] Open
Abstract
Worldwide, citrus is one of the most important fruit crops and is grown in more than 130 countries, predominantly in tropical and subtropical areas. The healthy progress of the citrus industry has been seriously affected by biotic and abiotic stresses. Several diseases, such as canker and huanglongbing, etc., rigorously affect citrus plant growth, fruit quality, and yield. Genetic engineering technologies, such as genetic transformation and genome editing, represent successful and attractive approaches for developing disease-resistant crops. These genetic engineering technologies have been widely used to develop citrus disease-resistant varieties against canker, huanglongbing, and many other fungal and viral diseases. Recently, clustered regularly interspaced short palindromic repeats (CRISPR)-based systems have made genome editing an indispensable genetic manipulation tool that has been applied to many crops, including citrus. The improved CRISPR systems, such as CRISPR/CRISPR-associated protein (Cas)9 and CRISPR/Cpf1 systems, can provide a promising new corridor for generating citrus varieties that are resistant to different pathogens. The advances in biotechnological tools and the complete genome sequence of several citrus species will undoubtedly improve the breeding for citrus disease resistance with a much greater degree of precision. Here, we attempt to summarize the recent successful progress that has been achieved in the effective application of genetic engineering and genome editing technologies to obtain citrus disease-resistant (bacterial, fungal, and virus) crops. Furthermore, we also discuss the opportunities and challenges of genetic engineering and genome editing technologies for citrus disease resistance.
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Affiliation(s)
- Lifang Sun
- Institute of Citrus Research, Zhejiang Academy of Agricultural Sciences, Taizhou 318026, China.
- National Center for Citrus Variety Improvement, Zhejiang Branch, Taizhou 318026, China.
| | - Fuzhi Ke
- Institute of Citrus Research, Zhejiang Academy of Agricultural Sciences, Taizhou 318026, China.
- National Center for Citrus Variety Improvement, Zhejiang Branch, Taizhou 318026, China.
| | - Zhenpeng Nie
- Institute of Citrus Research, Zhejiang Academy of Agricultural Sciences, Taizhou 318026, China.
- National Center for Citrus Variety Improvement, Zhejiang Branch, Taizhou 318026, China.
| | - Ping Wang
- Institute of Citrus Research, Zhejiang Academy of Agricultural Sciences, Taizhou 318026, China.
- National Center for Citrus Variety Improvement, Zhejiang Branch, Taizhou 318026, China.
| | - Jianguo Xu
- Institute of Citrus Research, Zhejiang Academy of Agricultural Sciences, Taizhou 318026, China.
- National Center for Citrus Variety Improvement, Zhejiang Branch, Taizhou 318026, China.
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29
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Jia H, Orbović V, Wang N. CRISPR-LbCas12a-mediated modification of citrus. PLANT BIOTECHNOLOGY JOURNAL 2019; 17:1928-1937. [PMID: 30908830 PMCID: PMC6737016 DOI: 10.1111/pbi.13109] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 03/06/2019] [Accepted: 03/11/2019] [Indexed: 05/14/2023]
Abstract
Recently, CRISPR-Cas12a (Cpf1) from Prevotella and Francisella was engineered to modify plant genomes. In this report, we employed CRISPR-LbCas12a (LbCpf1), which is derived from Lachnospiraceae bacterium ND2006, to edit a citrus genome for the first time. First, LbCas12a was used to modify the CsPDS gene successfully in Duncan grapefruit via Xcc-facilitated agroinfiltration. Next, LbCas12a driven by either the 35S or Yao promoter was used to edit the PthA4 effector binding elements in the promoter (EBEPthA4 -CsLOBP) of CsLOB1. A single crRNA was selected to target a conserved region of both Type I and Type II CsLOBPs, since the protospacer adjacent motif of LbCas12a (TTTV) allows crRNA to act on the conserved region of these two types of CsLOBP. CsLOB1 is the canker susceptibility gene, and it is induced by the corresponding pathogenicity factor PthA4 in Xanthomonas citri by binding to EBEPthA4 -CsLOBP. A total of seven 35S-LbCas12a-transformed Duncan plants were generated, and they were designated as #D35 s1 to #D35 s7, and ten Yao-LbCas12a-transformed Duncan plants were created and designated as #Dyao 1 to #Dyao 10. LbCas12a-directed EBEPthA4 -CsLOBP modifications were observed in three 35S-LbCas12a-transformed Duncan plants (#D35 s1, #D35 s4 and #D35 s7). However, no LbCas12a-mediated indels were observed in the Yao-LbCas12a-transformed plants. Notably, transgenic line #D35 s4, which contains the highest mutation rate, alleviates XccΔpthA4:dCsLOB1.4 infection. Finally, no potential off-targets were observed. Therefore, CRISPR-LbCas12a can readily be used as a powerful tool for citrus genome editing.
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Affiliation(s)
- Hongge Jia
- Department of Microbiology and Cell ScienceCitrus Research and Education CenterInstitute of Food and Agricultural Sciences (IFAS)University of FloridaLake AlfredFLUSA
| | - Vladimir Orbović
- Citrus Research and Education CenterIFASUniversity of FloridaLake AlfredFLUSA
| | - Nian Wang
- Department of Microbiology and Cell ScienceCitrus Research and Education CenterInstitute of Food and Agricultural Sciences (IFAS)University of FloridaLake AlfredFLUSA
- China‐USA Citrus Huanglongbing Joint Laboratory (A joint laboratory of The University of Florida’s Institute of Food and Agricultural Sciences and Gannan Normal University)National Navel Orange Engineering Research CenterGannan Normal UniversityGanzhouJiangxiChina
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CRISPR-Cas9 system: A new-fangled dawn in gene editing. Life Sci 2019; 232:116636. [DOI: 10.1016/j.lfs.2019.116636] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 06/30/2019] [Accepted: 07/05/2019] [Indexed: 12/24/2022]
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Shimo HM, Terassi C, Lima Silva CC, Zanella JDL, Mercaldi GF, Rocco SA, Benedetti CE. Role of the Citrus sinensis RNA deadenylase CsCAF1 in citrus canker resistance. MOLECULAR PLANT PATHOLOGY 2019; 20:1105-1118. [PMID: 31115151 PMCID: PMC6640180 DOI: 10.1111/mpp.12815] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Poly(A) tail shortening is a critical step in messenger RNA (mRNA) decay and control of gene expression. The carbon catabolite repressor 4 (CCR4)-associated factor 1 (CAF1) component of the CCR4-NOT deadenylase complex plays an essential role in mRNA deadenylation in most eukaryotes. However, while CAF1 has been extensively investigated in yeast and animals, its role in plants remains largely unknown. Here, we show that the Citrus sinensis CAF1 (CsCAF1) is a magnesium-dependent deadenylase implicated in resistance against the citrus canker bacteria Xanthomonas citri. CsCAF1 interacted with proteins of the CCR4-NOT complex, including CsVIP2, a NOT2 homologue, translin-associated factor X (CsTRAX) and the poly(A)-binding proteins CsPABPN and CsPABPC. CsCAF1 also interacted with PthA4, the main X. citri effector required for citrus canker elicitation. We also present evidence suggesting that PthA4 inhibits CsCAF1 deadenylase activity in vitro and stabilizes the mRNA encoded by the citrus canker susceptibility gene CsLOB1, which is transcriptionally activated by PthA4 during canker formation. Moreover, we show that an inhibitor of CsCAF1 deadenylase activity significantly enhanced canker development, despite causing a reduction in PthA4-dependent CsLOB1 transcription. These results thus link CsCAF1 with canker development and PthA4-dependent transcription in citrus plants.
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Affiliation(s)
- Hugo Massayoshi Shimo
- Brazilian Biosciences National Laboratory (LNBio)Brazilian Center for Research in Energy and Materials (CNPEM)CEP 13083‐100CampinasSPBrazil
| | - Carolina Terassi
- Brazilian Biosciences National Laboratory (LNBio)Brazilian Center for Research in Energy and Materials (CNPEM)CEP 13083‐100CampinasSPBrazil
| | - Caio Cesar Lima Silva
- Brazilian Biosciences National Laboratory (LNBio)Brazilian Center for Research in Energy and Materials (CNPEM)CEP 13083‐100CampinasSPBrazil
| | - Jackeline de Lima Zanella
- Brazilian Biosciences National Laboratory (LNBio)Brazilian Center for Research in Energy and Materials (CNPEM)CEP 13083‐100CampinasSPBrazil
| | - Gustavo Fernando Mercaldi
- Brazilian Biosciences National Laboratory (LNBio)Brazilian Center for Research in Energy and Materials (CNPEM)CEP 13083‐100CampinasSPBrazil
| | - Silvana Aparecida Rocco
- Brazilian Biosciences National Laboratory (LNBio)Brazilian Center for Research in Energy and Materials (CNPEM)CEP 13083‐100CampinasSPBrazil
| | - Celso Eduardo Benedetti
- Brazilian Biosciences National Laboratory (LNBio)Brazilian Center for Research in Energy and Materials (CNPEM)CEP 13083‐100CampinasSPBrazil
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Mei P, Song Z, Li ZA, Zhou C. Functional study of Csrbohs in defence response against Xanthomonas citri ssp. citri. FUNCTIONAL PLANT BIOLOGY : FPB 2019; 46:543-554. [PMID: 30940334 DOI: 10.1071/fp18243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 02/01/2019] [Indexed: 06/09/2023]
Abstract
NADPH oxidases, encoded by rbohs (respiratory burst oxidase homologues), transfer electrons from NADPH to molecular oxygen (O2) to generate superoxide anion (O2•-), which is the first step in the formation of hydrogen peroxide (H2O2) in the plant-pathogen interaction system. In the present work, six citrus rbohs (Csrbohs) genes were identified in citrus, and their possible involvement in resistance to Xanthomonas citri ssp. citri (Xcc) was examined. Inoculation with Xcc promoted the H2O2 production and induced expression of the Csrbohs, especially CsrbohD. Results showed that CsrbohD was markedly induced in the resistant genotype kumquat 'Luofu' [Fortunella margarita (Lour.) Swingle] compared with grapefruit 'Duncan' [Citrus paradisi (Linn.) Macf.]. Virus-induced gene silencing (VIGS) of CsrbohD resulted in reduced resistance to Xcc in grapefruit, but not in kumquat. Compared with non-silenced plants, canker-like symptoms were observed earlier, and they were more extensive in the CsrbohD-silenced grapefruit. Silencing of CsrbohD also suppressed the Xcc induced reactive oxygen species (ROS) burst, and resulted in accumulation of more Xcc bacterial colonies. Taken together, these data indicate that CsrbohD promotes resistance to Xcc, especially in grapefruit.
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Affiliation(s)
- Pengying Mei
- College of Plant Protection, Southwest University, Chongqing 400715, China
| | - Zhen Song
- Citrus Research Institute, Southwest University, Chongqing 400712, China
| | - Zhong An Li
- Citrus Research Institute, Southwest University, Chongqing 400712, China
| | - Changyong Zhou
- Citrus Research Institute, Southwest University, Chongqing 400712, China; and Corresponding author.
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Goulin EH, Galdeano DM, Granato LM, Matsumura EE, Dalio RJD, Machado MA. RNA interference and CRISPR: Promising approaches to better understand and control citrus pathogens. Microbiol Res 2019; 226:1-9. [PMID: 31284938 DOI: 10.1016/j.micres.2019.03.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 02/16/2019] [Accepted: 03/16/2019] [Indexed: 12/26/2022]
Abstract
Citrus crops have great economic importance worldwide. However, citrus production faces many diseases caused by different pathogens, such as bacteria, oomycetes, fungi and viruses. To overcome important plant diseases in general, new technologies have been developed and applied to crop protection, including RNA interference (RNAi) and clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) systems. RNAi has been demonstrated to be a powerful tool for application in plant defence mechanisms against different pathogens as well as their respective vectors, and CRISPR/Cas system has become widely used in gene editing or reprogramming or knocking out any chosen DNA/RNA sequence. In this article, we provide an overview of the use of RNAi and CRISPR/Cas technologies in management strategies to control several plants diseases, and we discuss how these strategies can be potentially used against citrus pathogens.
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Affiliation(s)
- Eduardo Henrique Goulin
- Centro de Citricultura Sylvio Moreira/IAC, Rodovia Anhanguera, Km 158, Cordeiropolis, SP, Brazil.
| | - Diogo Manzano Galdeano
- Centro de Citricultura Sylvio Moreira/IAC, Rodovia Anhanguera, Km 158, Cordeiropolis, SP, Brazil
| | - Laís Moreira Granato
- Centro de Citricultura Sylvio Moreira/IAC, Rodovia Anhanguera, Km 158, Cordeiropolis, SP, Brazil
| | | | | | - Marcos Antonio Machado
- Centro de Citricultura Sylvio Moreira/IAC, Rodovia Anhanguera, Km 158, Cordeiropolis, SP, Brazil
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Yu Q, Huang M, Jia H, Yu Y, Plotto A, Baldwin EA, Bai J, Wang N, Gmitter Jr FG. Deficiency of valencene in mandarin hybrids is associated with a deletion in the promoter region of the valencene synthase gene. BMC PLANT BIOLOGY 2019; 19:101. [PMID: 30866831 PMCID: PMC6417135 DOI: 10.1186/s12870-019-1701-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 03/06/2019] [Indexed: 05/20/2023]
Abstract
BACKGROUND Valencene is a major sesquiterpene in citrus oil and biosynthesized by valencene synthase (Cstps1; EC: 4.2.3.73) from the 15-carbon substrate farnesyl diphosphate. It is abundant in juice of some mandarins (e.g. Citrus reticulata Blanco cv. Fortune), however, it is undetectable in others (e.g. C. reticulata Blanco cv. Murcott), We have discovered that the Murcott mandarin Cstps1 gene expression is severely reduced. A previous genetic mapping study using an F1 population of Fortune × Murcott found that the segregation of valencene production in fruit exhibited a Mendelian inheritance ratio of 1:1. There was only one dominant locus associated with valencene content detected on the mandarin genetic map. The goal of this study was to understand the molecular mechanism underlying the valencene deficiency observed in some citrus hybrids. RESULTS There was a clear relationship between presence or absence of the valencene synthase gene (Cstps1) expression, and presence or absence of valencene among randomly selected mandarin hybrids. Cloning the coding regions of Cstps1 from Fortune and Murcott mandarin, and aligning with previous reported Valencia orange Cstps1 sequence, showed that they both exhibited extremely high similarity with the known Cstps1. By further cloning and analyzing the promoter region of Cstps1 from Valencia, Fortune and Murcott, a 12-nucleotide deletion at approximately - 270 bp from the Cstps1 coding region was only found in Murcott. Three binary vectors, designated as p1380-FortP-GUSin, p1380-MurcP-GUSin and p1380-MurcP(+ 12)-GUSin, were developed for promoter activity analysis. Transient over-expression of Fortune Cstps1 promoter in sweet orange showed notable GUS activity, but the Murcott Cstps1 promoter did not. In addition, by re-inserting the 12-nucleotide fragment, the activity of the Murcott Cstps1 promoter was mostly recovered. CONCLUSION The deficiency of valencene production in some mandarins is probably due to a 12-nucleotide deletion in the promoter region of the Cstps1, which could be a crucial switch of Cstps1 transcription. Our results further enhanced the understanding of valencene biosynthesis in citrus.
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Affiliation(s)
- Qibin Yu
- University of Florida, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, Lake Alfred, FL 33850 USA
| | - Ming Huang
- University of Florida, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, Lake Alfred, FL 33850 USA
| | - Hongge Jia
- University of Florida, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, Lake Alfred, FL 33850 USA
| | - Yuan Yu
- University of Florida, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, Lake Alfred, FL 33850 USA
| | - Anne Plotto
- USDA-ARS Horticultural Research Laboratory, Fort Pierce, FL 34945 USA
| | | | - Jinhe Bai
- USDA-ARS Horticultural Research Laboratory, Fort Pierce, FL 34945 USA
| | - Nian Wang
- University of Florida, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, Lake Alfred, FL 33850 USA
| | - Frederick G. Gmitter Jr
- University of Florida, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, Lake Alfred, FL 33850 USA
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Abstract
CRISPR/Cas9 has been widely employed to edit genome in most of the organisms, including animal, plant, fungus, and microbe. Here we describe the modification of citrus gene CsLOB1 in transgenic citrus by Cas9/sgRNA, a two-component system derived from CRISPR-Cas9. Transgenic citrus plants can be created by Agrobacterium-mediated epicotyl transformation.
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Levy A, El-Mochtar C, Wang C, Goodin M, Orbovic V. A new toolset for protein expression and subcellular localization studies in citrus and its application to citrus tristeza virus proteins. PLANT METHODS 2018; 14:2. [PMID: 29339969 PMCID: PMC5759842 DOI: 10.1186/s13007-017-0270-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 12/19/2017] [Indexed: 05/21/2023]
Abstract
BACKGROUND Transient gene expression is a powerful tool to study gene function in plants. In citrus, Agrobacterium transformation is the method of choice for transient expression studies, but this method does not work efficiently with many gene constructs, and there is a need for a more robust transient expression system in citrus leaves. Biolistic particle delivery is an alternative to Agrobacterium transformation, and in some plants, such as Arabidopsis, gives higher transformation rates in leaf tissues than Agrobacterium. RESULTS Here we describe an improved method for gene expression in epidermal cells of citrus leaves, using the Bio-Rad Helios gene-gun. Gene-gun bombardment of GFP-HDEL produced highly efficient gene expression in large number of cells and in different citrus varieties. We show here that transiently expressed proteins have maintained their functions in plants, and this is demonstrated by the subcellular localization of different organelle markers, and by a functional assay of Xanthomonas citri effector AvrGF1. To further expand the available tools for subcellular localization studies in citrus, we also generated a new set of transgenic citrus plants that contain organelle markers labelling the nuclei, actin and endoplasmic reticulum. Using these new tools, we were able to show that the coat protein of citrus tristeza virus localizes to the cytoplasm and nuclei when expressed in epidermal cells fused to GFP. CONCLUSION We have optimized a new method for transient expression in citrus leaves, to give highly reproducible and efficient transformation without producing a high level of injury or artifacts to the bombarded tissue. We also generated the first set organelle markers for use in citrus. These fluorescent protein markers label the nucleus and the actin. With these new resources, protein activity and subcellular localization can be studied in citrus rapidly and in high throughput. The handheld gene-gun device can also be used in the grove to deliver therapies for citrus diseases, such as canker and Huanglongbing, into trees.
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Affiliation(s)
- Amit Levy
- Department of Plant Pathology, Citrus Research and Education Center, University of Florida, Gainesville, FL USA
| | - Choaa El-Mochtar
- Department of Plant Pathology, Citrus Research and Education Center, University of Florida, Gainesville, FL USA
| | - Chunxia Wang
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL USA
| | - Michael Goodin
- Department of Plant Pathology, University of Kentucky, Lexington, KY USA
| | - Vladimir Orbovic
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL USA
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Jia H, Zhang Y, Orbović V, Xu J, White FF, Jones JB, Wang N. Genome editing of the disease susceptibility gene CsLOB1 in citrus confers resistance to citrus canker. PLANT BIOTECHNOLOGY JOURNAL 2017; 15:817-823. [PMID: 27936512 PMCID: PMC5466436 DOI: 10.1111/pbi.12677] [Citation(s) in RCA: 207] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/09/2016] [Accepted: 11/24/2016] [Indexed: 05/19/2023]
Abstract
Citrus is a highly valued tree crop worldwide, while, at the same time, citrus production faces many biotic challenges, including bacterial canker and Huanglongbing (HLB). Breeding for disease-resistant varieties is the most efficient and sustainable approach to control plant diseases. Traditional breeding of citrus varieties is challenging due to multiple limitations, including polyploidy, polyembryony, extended juvenility and long crossing cycles. Targeted genome editing technology has the potential to shorten varietal development for some traits, including disease resistance. Here, we used CRISPR/Cas9/sgRNA technology to modify the canker susceptibility gene CsLOB1 in Duncan grapefruit. Six independent lines, DLOB 2, DLOB 3, DLOB 9, DLOB 10, DLOB 11 and DLOB 12, were generated. Targeted next-generation sequencing of the six lines showed the mutation rate was 31.58%, 23.80%, 89.36%, 88.79%, 46.91% and 51.12% for DLOB 2, DLOB 3, DLOB 9, DLOB 10, DLOB 11 and DLOB 12, respectively, of the cells in each line. DLOB 2 and DLOB 3 showed canker symptoms similar to wild-type grapefruit, when inoculated with the pathogen Xanthomonas citri subsp. citri (Xcc). No canker symptoms were observed on DLOB 9, DLOB 10, DLOB 11 and DLOB 12 at 4 days postinoculation (DPI) with Xcc. Pustules caused by Xcc were observed on DLOB 9, DLOB 10, DLOB 11 and DLOB 12 in later stages, which were much reduced compared to that on wild-type grapefruit. The pustules on DLOB 9 and DLOB 10 did not develop into typical canker symptoms. No side effects and off-target mutations were detected in the mutated plants. This study indicates that genome editing using CRISPR technology will provide a promising pathway to generate disease-resistant citrus varieties.
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Affiliation(s)
- Hongge Jia
- Citrus Research and Education CenterDepartment of Microbiology and Cell ScienceInstitute of Food and Agricultural Sciences (IFAS)University of FloridaLake AlfredFLUSA
| | - Yunzeng Zhang
- Citrus Research and Education CenterDepartment of Microbiology and Cell ScienceInstitute of Food and Agricultural Sciences (IFAS)University of FloridaLake AlfredFLUSA
| | - Vladimir Orbović
- Citrus Research and Education CenterIFASUniversity of FloridaLake AlfredFLUSA
| | - Jin Xu
- Citrus Research and Education CenterDepartment of Microbiology and Cell ScienceInstitute of Food and Agricultural Sciences (IFAS)University of FloridaLake AlfredFLUSA
| | - Frank F. White
- Department of Plant PathologyIFASUniversity of FloridaGainesvilleFLUSA
| | - Jeffrey B. Jones
- Department of Plant PathologyIFASUniversity of FloridaGainesvilleFLUSA
| | - Nian Wang
- Citrus Research and Education CenterDepartment of Microbiology and Cell ScienceInstitute of Food and Agricultural Sciences (IFAS)University of FloridaLake AlfredFLUSA
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Demirci Y, Zhang B, Unver T. CRISPR/Cas9: An RNA-guided highly precise synthetic tool for plant genome editing. J Cell Physiol 2017; 233:1844-1859. [PMID: 28430356 DOI: 10.1002/jcp.25970] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 04/20/2017] [Indexed: 12/17/2022]
Abstract
CRISPR/Cas9 is a newly developed and naturally occurred genome editing tool, which is originally used by bacteria for immune defence. In the past years, it has been quickly employed and modified to precisely edit genome sequences in both plants and animals. Compared with the well-developed zinc finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs), CRISPR/Cas9 has lots of advantages, including easier to design and implement, higher targeting efficiency, and less expensive. Thus, it is becoming one of the most powerful tools for knockout of an individual gene as well as insertion of one gene and/or control of gene transcription. Studies have shown that CRISPR/Cas9 is a great tool to edit many genes in a variety of plant species, including the model plant species as well as agriculturally important crops, such as cotton, maize, wheat, and rice. CRISPR/Cas9-based genome editing can be used for plant functional studies and plant improvement to yield, quality, and tolerance to environmental stress.
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Affiliation(s)
- Yeliz Demirci
- Izmir International Biomedicine and Genome Institute (iBG-izmir), Dokuz Eylul University, Izmir, Turkey
| | - Baohong Zhang
- Department of Biology, East Carolina University, Greenville, North Carolina
| | - Turgay Unver
- Izmir International Biomedicine and Genome Institute (iBG-izmir), Dokuz Eylul University, Izmir, Turkey
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Ran Y, Liang Z, Gao C. Current and future editing reagent delivery systems for plant genome editing. SCIENCE CHINA-LIFE SCIENCES 2017; 60:490-505. [PMID: 28527114 DOI: 10.1007/s11427-017-9022-1] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 03/22/2017] [Indexed: 01/01/2023]
Abstract
Many genome editing tools have been developed and new ones are anticipated; some have been extensively applied in plant genetics, biotechnology and breeding, especially the CRISPR/Cas9 system. These technologies have opened up a new era for crop improvement due to their precise editing of user-specified sequences related to agronomic traits. In this review, we will focus on an update of recent developments in the methodologies of editing reagent delivery, and consider the pros and cons of current delivery systems. Finally, we will reflect on possible future directions.
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Affiliation(s)
- Yidong Ran
- Genovo Biotechnology Co., Ltd., Tianjin, 301700, China.
| | - Zhen Liang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Caixia Gao
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
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Jia H, Xu J, Orbović V, Zhang Y, Wang N. Editing Citrus Genome via SaCas9/sgRNA System. FRONTIERS IN PLANT SCIENCE 2017; 8:2135. [PMID: 29312390 PMCID: PMC5732962 DOI: 10.3389/fpls.2017.02135] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/01/2017] [Indexed: 05/22/2023]
Abstract
SaCas9/sgRNA, derived from Staphylococcus aureus, is an alternative system for genome editing to Streptococcus pyogenes SpCas9/sgRNA. The smaller SaCas9 recognizes a different protospacer adjacent motif (PAM) sequence from SpCas9. SaCas9/sgRNA has been employed to edit the genomes of Arabidopsis, tobacco and rice. In this study, we aimed to test its potential in genome editing of citrus. Transient expression of SaCas9/sgRNA in Duncan grapefruit via Xcc-facilitated agroinfiltration showed it can successfully modify CsPDS and Cs2g12470. Subsequently, binary vector GFP-p1380N-SaCas9/35S-sgRNA1:AtU6-sgRNA2 was developed to edit two target sites of Cs7g03360 in transgenic Carrizo citrange. Twelve GFP-positive Carrizo transformants were successfully established, designated as #Cz1 to #Cz12. Based on targeted next generation sequencing results, the mutation rates for the two targets ranged from 15.55 to 39.13% for sgRNA1 and 49.01 to 79.67% for sgRNA2. Therefore, SaCas9/sgRNA can be used as an alternative tool to SpCas9/sgRNA for citrus genome editing.
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Affiliation(s)
- Hongge Jia
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
| | - Jin Xu
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
| | - Vladimir Orbović
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
| | - Yunzeng Zhang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
- *Correspondence: Nian Wang,
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Huang R, Hui S, Zhang M, Li P, Xiao J, Li X, Yuan M, Wang S. A Conserved Basal Transcription Factor Is Required for the Function of Diverse TAL Effectors in Multiple Plant Hosts. FRONTIERS IN PLANT SCIENCE 2017; 8:1919. [PMID: 29163628 PMCID: PMC5681966 DOI: 10.3389/fpls.2017.01919] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 10/23/2017] [Indexed: 05/17/2023]
Abstract
Many Xanthomonas bacteria use transcription activator-like effector (TALE) proteins to activate plant disease susceptibility (S) genes, and this activation contributes to disease. We recently reported that rice basal transcription factor IIA gamma subunit, OsTFIIAγ5, is hijacked by TALE-carrying Xanthomonas oryzae infecting the plants. However, whether TFIIAγs are also involved in TALE-carrying Xanthomonas-caused diseases in other plants is unknown. Here, molecular and genetic approaches were used to investigate the role of TFIIAγs in other plants. We found that TFIIAγs are also used by TALE-carrying Xanthomonas to cause disease in other plants. The TALEs of Xanthomonas citri pv. citri (Xcc) causing canker in citrus and Xanthomonas campestris pv. vesicatoria (Xcv) causing bacterial spot in pepper and tomato interacted with corresponding host TFIIAγs as in rice. Transcriptionally suppressing TFIIAγ led to resistance to Xcc in citrus and Xcv in pepper and tomato. The 39th residue of OsTFIIAγ5 and citrus CsTFIIAγ is vital for TALE-dependent induction of plant S genes. As mutated OsTFIIAγ5V 39E, CsTFIIAγV 39E, pepper CaTFIIAγV 39E, and tomato SlTFIIAγV 39E also did not interact with TALEs to prevent disease. These results suggest that TALE-carrying bacteria share a common mechanism for infecting plants. Using TFIIAγV 39E-type mutation could be a general strategy for improving resistance to TALE-carrying pathogens in crops.
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Affiliation(s)
| | | | | | | | | | | | - Meng Yuan
- *Correspondence: Meng Yuan, Shiping Wang,
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Wu H, Acanda Y, Jia H, Wang N, Zale J. Biolistic transformation of Carrizo citrange (Citrus sinensis Osb. × Poncirus trifoliata L. Raf.). PLANT CELL REPORTS 2016; 35:1955-62. [PMID: 27277128 DOI: 10.1007/s00299-016-2010-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/01/2016] [Indexed: 05/21/2023]
Abstract
The development of transgenic citrus plants by the biolistic method. A protocol for the biolistic transformation of epicotyl explants and transgenic shoot regeneration of immature citrange rootstock, cv. Carrizo (Citrus sinensis Osb. × Poncirus trifoliata L. Raf.) and plant regeneration is described. Immature epicotyl explants were bombarded with a vector containing the nptII selectable marker and the gfp reporter. The number of independent, stably transformed tissues/total number of explants, recorded by monitoring GFP fluorescence 4 weeks after bombardment was substantial at 18.4 %, and some fluorescing tissues regenerated into shoots. Fluorescing GFP, putative transgenic shoots were micro-grafted onto immature Carrizo rootstocks in vitro, confirmed by PCR amplification of nptII and gfp coding regions, followed by secondary grafting onto older rootstocks grown in soil. Southern blot analysis indicated that all the fluorescing shoots were transgenic. Multiple and single copies of nptII integrations were confirmed in five regenerated transgenic lines. There is potential to develop a higher throughput biolistics transformation system by optimizing the tissue culture medium to improve shoot regeneration and narrowing the window for plant sampling. This system will be appropriate for transformation with minimal cassettes.
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Affiliation(s)
- Hao Wu
- Plant Pathology Department, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, University of Florida, Lake Alfred, FL, 33850, USA.
| | - Yosvanis Acanda
- Plant Pathology Department, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, University of Florida, Lake Alfred, FL, 33850, USA
| | - Hongge Jia
- Plant Pathology Department, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, University of Florida, Lake Alfred, FL, 33850, USA
| | - Nian Wang
- Plant Pathology Department, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, University of Florida, Lake Alfred, FL, 33850, USA
| | - Janice Zale
- Plant Pathology Department, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, University of Florida, Lake Alfred, FL, 33850, USA.
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Schaeffer SM, Nakata PA. The expanding footprint of CRISPR/Cas9 in the plant sciences. PLANT CELL REPORTS 2016; 35:1451-68. [PMID: 27137209 DOI: 10.1007/s00299-016-1987-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 04/19/2016] [Indexed: 05/18/2023]
Abstract
CRISPR/Cas9 has evolved and transformed the field of biology at an unprecedented pace. From the initial purpose of introducing a site specific mutation within a genome of choice, this technology has morphed into enabling a wide array of molecular applications, including site-specific transgene insertion and multiplexing for the simultaneous induction of multiple cleavage events. Efficiency, specificity, and flexibility are key attributes that have solidified CRISPR/Cas9 as the genome-editing tool of choice by scientists from all areas of biology. Within the field of plant biology, several CRISPR/Cas9 technologies, developed in other biological systems, have been successfully implemented to probe plant gene function and to modify specific crop traits. It is anticipated that this trend will persist and lead to the development of new applications and modifications of the CRISPR technology, adding to an ever-expanding collection of genome-editing tools. We envision that these tools will bestow plant researchers with new utilities to alter genome complexity, engineer site-specific integration events, control gene expression, generate transgene-free edited crops, and prevent or cure plant viral disease. The successful implementation of such utilities will represent a new frontier in plant biotechnology.
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Affiliation(s)
- Scott M Schaeffer
- Department of Pediatrics, Baylor College of Medicine, USDA/ARS Children's Nutrition Research Center, 1100 Bates St., Houston, TX, 77030-2600, USA
| | - Paul A Nakata
- Department of Pediatrics, Baylor College of Medicine, USDA/ARS Children's Nutrition Research Center, 1100 Bates St., Houston, TX, 77030-2600, USA.
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Jia H, Orbovic V, Jones JB, Wang N. Modification of the PthA4 effector binding elements in Type I CsLOB1 promoter using Cas9/sgRNA to produce transgenic Duncan grapefruit alleviating XccΔpthA4:dCsLOB1.3 infection. PLANT BIOTECHNOLOGY JOURNAL 2016; 14:1291-301. [PMID: 27071672 DOI: 10.1111/pbi.12495] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 08/04/2015] [Accepted: 08/25/2015] [Indexed: 05/19/2023]
Abstract
Citrus canker caused by Xanthomonas citri subspecies citri (Xcc) is a severe disease for most commercial citrus cultivars and responsible for significant economic losses worldwide. Generating canker-resistant citrus varieties will provide an efficient and sustainable solution to control citrus canker. Here, we report our progress in generating canker-resistant grapefruit by modifying the PthA4 effector binding elements (EBEs) in the CsLOB1 Promoter (EBEPthA4 -CsLOBP) of the CsLOB1 (Citrus sinensis Lateral Organ Boundaries) gene. CsLOB1 is a susceptibility gene for citrus canker and is induced by the pathogenicity factor PthA4, which binds to the EBEPthA4 -CsLOBP to induce CsLOB1 gene expression. There are two alleles, Type I and Type II, of CsLOB1 in Duncan grapefruit. Here, a binary vector was designed to disrupt the PthA4 EBEs in Type I CsLOB1 Promoter (TI CsLOBP) via epicotyl transformation of Duncan grapefruit. Four transgenic Duncan plants with targeted modification of EBEPthA4 -T1 CsLOBP were successfully created. As for Type I CsLOB1 promoter, the mutation rate was 15.63% (#D13), 14.29% (#D17), 54.54% (#D18) and 81.25% (#D22). In the presence of wild-type Xcc, transgenic Duncan grapefruit developed canker symptoms similarly as wild type. An artificially designed dTALE dCsLOB1.3, which specifically recognizes Type I CsLOBP, but not the mutated Type I CsLOBP or Type II CsLOBP, was developed to infect Duncan transformants. Consequently, #D18 had weakened canker symptoms and #D22 had no visible canker symptoms in the presence of XccΔpthA4:dCsLOB1.3. Our data suggest that activation of a single allele of susceptibility gene CsLOB1 by PthA4 is sufficient to induce citrus canker disease, and mutation in the promoters of both alleles of CsLOB1 is probably required to generate citrus canker-resistant plants. This work lays the groundwork to generate canker-resistant citrus varieties via Cas9/sgRNA in the future.
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Affiliation(s)
- Hongge Jia
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, USA
| | - Vladimir Orbovic
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, USA
| | - Jeffrey B Jones
- Department of Plant Pathology, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Gainesville, FL, USA
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, USA
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