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Sun X, Hu C, Yi G, Zhang X. Identification and characterization of two P450 enzymes from Citrus sinensis involved in TMTT and DMNT biosyntheses and Asian citrus psyllid defense. HORTICULTURE RESEARCH 2024; 11:uhae037. [PMID: 38617747 PMCID: PMC11009467 DOI: 10.1093/hr/uhae037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 01/26/2024] [Indexed: 04/16/2024]
Abstract
The homoterpenes (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene (TMTT) are the major herbivore-induced plant volatiles that help in defense directly by acting as repellants and indirectly by recruiting insects' natural enemies. In this study, DMNT and TMTT were confirmed to be emitted from citrus (Citrus sinensis) leaves infested with Asian citrus psyllid (Diaphorina citri Kuwayama; ACP), and two cytochrome P450 (CYP) genes (CsCYP82L1 and CsCYP82L2) were newly identified and characterized. Understanding the functions of these genes in citrus defense will help plan strategies to manage huanglongbing caused by Candidatus Liberibacter asiaticus (CLas) and spread by ACP. Quantitative real-time PCR (qPCR) analysis showed that CsCYP82L1 and CsCYP82L2 were significantly upregulated in citrus leaves after ACP infestation. Yeast recombinant expression and enzyme assays indicated that CsCYP82L1 and CsCYP82L2 convert (E)-nerolidol to DMNT and (E,E)-geranyllinalool to TMTT. However, citrus calluses stably overexpressing CsCYP82L1 generated only DMNT, whereas those overexpressing CsCYP82L2 produced DMNT and TMTT. Furthermore, ACPs preferred wild-type lemon (Citrus limon) over the CsCYP82L1-overexpressing line in dual-choice feeding assays and mineral oil over TMTT or DMNT in behavioral bioassays. Finally, yeast one-hybrid, electrophoretic mobility shift, and dual luciferase assays demonstrated that CsERF017, an AP2/ERF transcription factor, directly bound to the CCGAC motif and activated CsCYP82L1. Moreover, the transient overexpression of CsERF017 in lemon leaves upregulated CsCYP82L1 in the absence and presence of ACP infestation. These results provide novel insights into homoterpene biosynthesis in C. sinensis and demonstrate the effect of homoterpenes on ACP behavior, laying a foundation to genetically manipulate homoterpene biosynthesis for application in huanglongbing and ACP control.
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Affiliation(s)
- Xueli Sun
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture and Rural Affairs; Guangdong Provincial Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
- College of Life Sciences, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China
| | - Chunhua Hu
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture and Rural Affairs; Guangdong Provincial Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
| | - Ganjun Yi
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture and Rural Affairs; Guangdong Provincial Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
| | - Xinxin Zhang
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture and Rural Affairs; Guangdong Provincial Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
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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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Liao J, Xie L, Shi H, Cui S, Lan F, Luo Z, Ma X. Development of an efficient transient expression system for Siraitia grosvenorii fruit and functional characterization of two NADPH-cytochrome P450 reductases. PHYTOCHEMISTRY 2021; 189:112824. [PMID: 34102591 DOI: 10.1016/j.phytochem.2021.112824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 05/24/2021] [Accepted: 05/24/2021] [Indexed: 06/12/2023]
Abstract
Siraitia grosvenorii (Luo hanguo or monk fruit) is a valuable medicinal herb for which the market demand has increased dramatically worldwide. As promising natural sweeteners, mogrosides have received much attention from researchers because of their extremely high sweetness and lack of calories. Nevertheless, owing to the absence of genetic transformation methods, the molecular mechanisms underlying the regulation of mogroside biosynthesis have not yet been fully elucidated. Therefore, an effective method for gene function analysis needs to be developed for S. grosvenorii fruit. As a powerful approach, transient expression has become a versatile method to elucidate the biological functions of genes and proteins in various plant species. In this study, PBI121 with a β-glucuronidase (GUS) marker and tobacco rattle virus (TRV) were used as vectors for overexpression and silencing, respectively, of the SgCPR1 and SgCPR2 genes in S. grosvenorii fruit. The effectiveness of transient expression was validated by GUS staining in S. grosvenorii fruit, and the expression levels of SgCPR1 and SgCPR2 increased significantly after infiltration for 36 h. In addition, TRV-induced gene silencing suppressed the expression of SgCPR1 and SgCPR2 in S. grosvenorii fruit. More importantly, the production of the major secondary metabolites mogrol, mogroside IIE (MIIE) and mogroside III (MIII) was activated by the overexpression of SgCPR1 and SgCPR2 in S. grosvenorii fruit, with levels 1-2 times those in the control group. Moreover, the accumulation of mogrol, MIIE and MIII was decreased in the SgCPR1 and SgCPR2 gene silencing assays. Therefore, this transient expression approach was available for S. grosvenorii fruit, providing insight into the expression of the SgCPR1 and SgCPR2 genes involved in the mogroside biosynthesis pathway. Our study also suggests that this method has potential applications in the exploration of the molecular mechanisms, biochemical hypotheses and functional characteristics of S. grosvenorii genes.
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Affiliation(s)
- Jingjing Liao
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100193, China
| | - Lei Xie
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100193, China
| | - Hongwu Shi
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100193, China
| | - Shengrong Cui
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100193, China
| | - Fusheng Lan
- Guilin GFS Monk Fruit Corp, Guilin, 541006, China
| | - Zuliang Luo
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100193, China.
| | - Xiaojun Ma
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100193, China.
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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: 13] [Impact Index Per Article: 4.3] [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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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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6
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Long Q, Du M, Long J, Xie Y, Zhang J, Xu L, He Y, Li Q, Chen S, Zou X. Transcription factor WRKY22 regulates canker susceptibility in sweet orange (Citrus sinensis Osbeck) by enhancing cell enlargement and CsLOB1 expression. HORTICULTURE RESEARCH 2021; 8:50. [PMID: 33642585 PMCID: PMC7917094 DOI: 10.1038/s41438-021-00486-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 11/30/2020] [Accepted: 12/13/2020] [Indexed: 05/27/2023]
Abstract
Pathological hypertrophy (cell enlargement) plays an important role in the development of citrus canker, but its regulators are largely unknown. Although WRKY22 is known to be involved in pathogen-triggered immunity and positively regulates resistance to bacterial pathogens in Arabidopsis, rice and pepper, the CRISPR/Cas9-mediated partial knockout of CsWRKY22 improves resistance to Xanthomonas citri subsp. citri (Xcc) in Wanjincheng orange (Citrus sinensis Osbeck). Here, we demonstrate that CsWRKY22 is a nucleus-localized transcriptional activator. CsWRKY22-overexpressing plants exhibited dwarf phenotypes that had wrinkled and thickened leaves and were more sensitive to Xcc, whereas CsWRKY22-silenced plants showed no visible phenotype changes and were more resistant to Xcc. Microscopic observations revealed that the overexpression of CsWRKY22 increased cell size in the spongy mesophyll. Transcriptome analysis showed that cell growth-related pathways, such as the auxin and brassinosteroid hormonal signaling and cell wall organization and biogenesis pathways, were significantly upregulated upon CsWRKY22 overexpression. Interestingly, CsWRKY22 activated the expression of CsLOB1, which is a key gene regulating susceptibility to citrus canker. We further confirmed that CsWRKY22 bound directly to the W-boxes just upstream of the transcription start site of CsLOB1 in vivo and in vitro. We conclude that CsWRKY22 enhances susceptibility to citrus canker by promoting host hypertrophy and CsLOB1 expression. Thus, our study provides new insights into the mechanism regulating pathological hypertrophy and the function of WRKY22 in citrus.
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Affiliation(s)
- Qin Long
- Citrus Research Institute, Southwest University/Chinese Academy of Agricultural Sciences, Chongqing, People's Republic of China
| | - Meixia Du
- Citrus Research Institute, Southwest University/Chinese Academy of Agricultural Sciences, Chongqing, People's Republic of China
| | - Junhong Long
- Citrus Research Institute, Southwest University/Chinese Academy of Agricultural Sciences, Chongqing, People's Republic of China
| | - Yu Xie
- Citrus Research Institute, Southwest University/Chinese Academy of Agricultural Sciences, Chongqing, People's Republic of China
| | - Jingyun Zhang
- Citrus Research Institute, Southwest University/Chinese Academy of Agricultural Sciences, Chongqing, People's Republic of China
| | - Lanzhen Xu
- Citrus Research Institute, Southwest University/Chinese Academy of Agricultural Sciences, Chongqing, People's Republic of China
| | - Yongrui He
- Citrus Research Institute, Southwest University/Chinese Academy of Agricultural Sciences, Chongqing, People's Republic of China
| | - Qiang Li
- Citrus Research Institute, Southwest University/Chinese Academy of Agricultural Sciences, Chongqing, People's Republic of China
| | - Shanchun Chen
- Citrus Research Institute, Southwest University/Chinese Academy of Agricultural Sciences, Chongqing, People's Republic of China.
| | - Xiuping Zou
- Citrus Research Institute, Southwest University/Chinese Academy of Agricultural Sciences, Chongqing, People's Republic of China.
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Buscaill P, Sanguankiattichai N, Lee YJ, Kourelis J, Preston G, van der Hoorn RAL. Agromonas: a rapid disease assay for Pseudomonas syringae growth in agroinfiltrated leaves. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:831-840. [PMID: 33124734 PMCID: PMC7898395 DOI: 10.1111/tpj.15056] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 10/05/2020] [Accepted: 10/21/2020] [Indexed: 05/04/2023]
Abstract
The lengthy process to generate transformed plants is a limitation in current research on the interactions of the model plant pathogen Pseudomonas syringae with plant hosts. Here we present an easy method called agromonas, where we quantify P. syringae growth in agroinfiltrated leaves of Nicotiana benthamiana using a cocktail of antibiotics to select P. syringae on plates. As a proof of concept, we demonstrate that transient expression of PAMP receptors reduces bacterial growth, and that transient depletion of a host immune gene and transient expression of a type-III effector increase P. syringae growth in agromonas assays. We show that we can rapidly achieve structure-function analysis of immune components and test the function of immune hydrolases. The agromonas method is easy, fast and robust for routine disease assays with various Pseudomonas strains without transforming plants or bacteria. The agromonas assay offers a reliable approach for further comprehensive analysis of plant immunity.
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Affiliation(s)
- Pierre Buscaill
- Plant Chemetics LabDepartment of Plant SciencesUniversity of OxfordOxfordOX1 3RBUK
| | - Nattapong Sanguankiattichai
- Plant Chemetics LabDepartment of Plant SciencesUniversity of OxfordOxfordOX1 3RBUK
- Department of Plant SciencesUniversity of OxfordOxfordOX1 3RBUK
| | - Yoon Joo Lee
- Plant Chemetics LabDepartment of Plant SciencesUniversity of OxfordOxfordOX1 3RBUK
| | - Jiorgos Kourelis
- Plant Chemetics LabDepartment of Plant SciencesUniversity of OxfordOxfordOX1 3RBUK
| | - Gail Preston
- Department of Plant SciencesUniversity of OxfordOxfordOX1 3RBUK
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8
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Buscaill P, Sanguankiattichai N, Lee YJ, Kourelis J, Preston G, van der Hoorn RAL. Agromonas: a rapid disease assay for Pseudomonas syringae growth in agroinfiltrated leaves. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:831-840. [PMID: 33124734 DOI: 10.1101/2020.08.10.243808] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 10/05/2020] [Accepted: 10/21/2020] [Indexed: 05/27/2023]
Abstract
The lengthy process to generate transformed plants is a limitation in current research on the interactions of the model plant pathogen Pseudomonas syringae with plant hosts. Here we present an easy method called agromonas, where we quantify P. syringae growth in agroinfiltrated leaves of Nicotiana benthamiana using a cocktail of antibiotics to select P. syringae on plates. As a proof of concept, we demonstrate that transient expression of PAMP receptors reduces bacterial growth, and that transient depletion of a host immune gene and transient expression of a type-III effector increase P. syringae growth in agromonas assays. We show that we can rapidly achieve structure-function analysis of immune components and test the function of immune hydrolases. The agromonas method is easy, fast and robust for routine disease assays with various Pseudomonas strains without transforming plants or bacteria. The agromonas assay offers a reliable approach for further comprehensive analysis of plant immunity.
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Affiliation(s)
- Pierre Buscaill
- Plant Chemetics Lab, Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
| | - Nattapong Sanguankiattichai
- Plant Chemetics Lab, Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
- Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
| | - Yoon Joo Lee
- Plant Chemetics Lab, Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
| | - Jiorgos Kourelis
- Plant Chemetics Lab, Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
| | - Gail Preston
- Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
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Zheng L, Yang J, Chen Y, Ding L, Wei J, Wang H. An improved and efficient method of Agrobacterium syringe infiltration for transient transformation and its application in the elucidation of gene function in poplar. BMC PLANT BIOLOGY 2021; 21:54. [PMID: 33478390 PMCID: PMC7818742 DOI: 10.1186/s12870-021-02833-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 01/11/2021] [Indexed: 05/23/2023]
Abstract
BACKGROUND Forest trees have important economic and ecological value. As a model tree, poplar has played a significant role in elucidating the molecular mechanisms underlying tree biology. However, a lack of mutant libraries and time-consuming stable genetic transformation processes severely limit progress into the functional characterization of poplar genes. A convenient and fast transient transformation method is therefore needed to enhance progress on functional genomics in poplar. METHODS A total of 11 poplar clones were screened for amenability to syringe infiltration. Syringe infiltration was performed on the lower side of the leaves of young soil-grown plants. Transient expression was evaluated by visualizing the reporters β-glucuronidase (GUS) and green fluorescent protein (GFP). The experimental parameters of the syringe agroinfiltration were optimized based on the expression levels of the reporter luciferase (LUC). Stably transformed plants were regenerated from transiently transformed leaf explants through callus-induced organogenesis. The functions of Populus genes in secondary cell wall-thickening were characterized by visualizing lignin deposition therein after staining with basic fuchsin. RESULTS We greatly improved the transient transformation efficiency of syringe Agrobacterium infiltration in poplar through screening for a suitable poplar clone from a variety of clones and optimizing the syringe infiltration procedure. The selected poplar clone, Populus davidiana × P. bolleana, is amenable to Agrobacterium syringe infiltration, as indicated by the easy diffusion of the bacterial suspension inside the leaf tissues. Using this technique, we localized a variety of poplar proteins in specific intracellular organelles and illustrated the protein-protein and protein-DNA interactions. The transiently transformed leaves could be used to generate stably transformed plants with high efficiency through callus induction and differentiation processes. Furthermore, transdifferentiation of the protoxylem-like vessel element and ectopic secondary wall thickening were induced in the agroinfiltrated leaves via the transient overexpression of genes associated with secondary wall formation. CONCLUSIONS The application of P. davidiana × P. bolleana in Agrobacterium syringe infiltration provides a foundation for the rapid and high-throughput functional characterization of Populus genes in intact poplar plants, including those involved in wood formation, and provides an effective alternative to Populus stable genetic transformation.
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Affiliation(s)
- Lin Zheng
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agricultural and Forestry Sciences, No. 9, Shuguang Huayuan Middle Road, Haidian District, Beijing, 100097, People's Republic of China
| | - Jixiu Yang
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agricultural and Forestry Sciences, No. 9, Shuguang Huayuan Middle Road, Haidian District, Beijing, 100097, People's Republic of China
- College of Bioscience and Resources Environment, Beijing University of Agriculture, No. 7, Beinong Road, Huilongguan, Changping District, Beijing, 102206, People's Republic of China
| | - Yajuan Chen
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agricultural and Forestry Sciences, No. 9, Shuguang Huayuan Middle Road, Haidian District, Beijing, 100097, People's Republic of China
| | - Liping Ding
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agricultural and Forestry Sciences, No. 9, Shuguang Huayuan Middle Road, Haidian District, Beijing, 100097, People's Republic of China
| | - Jianhua Wei
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agricultural and Forestry Sciences, No. 9, Shuguang Huayuan Middle Road, Haidian District, Beijing, 100097, People's Republic of China.
| | - Hongzhi Wang
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agricultural and Forestry Sciences, No. 9, Shuguang Huayuan Middle Road, Haidian District, Beijing, 100097, People's Republic of China.
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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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Sharma R, Liang Y, Lee MY, Pidatala VR, Mortimer JC, Scheller HV. Agrobacterium-mediated transient transformation of sorghum leaves for accelerating functional genomics and genome editing studies. BMC Res Notes 2020; 13:116. [PMID: 32103777 PMCID: PMC7045639 DOI: 10.1186/s13104-020-04968-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 02/20/2020] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVES Sorghum is one of the most recalcitrant species for transformation. Considering the time and effort required for stable transformation in sorghum, establishing a transient system to screen the efficiency and full functionality of vector constructs is highly desirable. RESULTS Here, we report an Agrobacterium-mediated transient transformation assay with intact sorghum leaves using green fluorescent protein as marker. It also provides a good monocot alternative to tobacco and protoplast assays with a direct, native and more reliable system for testing single guide RNA (sgRNA) expression construct efficiency. Given the simplicity and ease of transformation, high reproducibility, and ability to test large constructs, this method can be widely adopted to speed up functional genomic and genome editing studies.
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Affiliation(s)
- Rita Sharma
- Joint BioEnergy Institute, Emeryville, CA 94608 USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
- Crop Genetics and Informatics Group, School of Computational & Integrative Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
| | - Yan Liang
- Joint BioEnergy Institute, Emeryville, CA 94608 USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Mi Yeon Lee
- Joint BioEnergy Institute, Emeryville, CA 94608 USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Venkataramana R. Pidatala
- Joint BioEnergy Institute, Emeryville, CA 94608 USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Jenny C. Mortimer
- Joint BioEnergy Institute, Emeryville, CA 94608 USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Henrik V. Scheller
- Joint BioEnergy Institute, Emeryville, CA 94608 USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA 94720 USA
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12
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Salonia F, Ciacciulli A, Poles L, Pappalardo HD, La Malfa S, Licciardello C. New Plant Breeding Techniques in Citrus for the Improvement of Important Agronomic Traits. A Review. FRONTIERS IN PLANT SCIENCE 2020; 11:1234. [PMID: 32922420 PMCID: PMC7456868 DOI: 10.3389/fpls.2020.01234] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 07/28/2020] [Indexed: 05/18/2023]
Abstract
New plant breeding techniques (NPBTs) aim to overcome traditional breeding limits for fruit tree species, in order to obtain new varieties with improved organoleptic traits and resistance to biotic and abiotic stress, and to maintain fruit quality achieved over centuries by (clonal) selection. Knowledge on the gene(s) controlling a specific trait is essential for the use of NPBTs, such as genome editing and cisgenesis. In the framework of the international scientific community working on fruit tree species, including citrus, NPBTs have mainly been applied to address pathogen threats. Citrus could take advantage of NPBTs because of its complex species biology (seedlessness, apomixis, high heterozygosity, and long juvenility phase) and aptitude for in vitro manipulation. To our knowledge, genome editing in citrus via transgenesis has successful for induced resistance to Citrus bacterial canker in sweet orange and grapefruit using the resistance gene CsLOB1. In the future, NPBTs will also be used to improve fruit traits, making them healthier. The regeneration of plants following the application of NPBTs is a bottleneck, making it necessary to optimize the efficiency of current protocols. The strengths and weaknesses of using explants from young in vitro plantlets, and from mature plants, will be discussed. Other major issues addressed in this review are related to the requirement for marker-free systems and shortening the long juvenility phase. This review aims to summarize methods and approaches available in the literature that are suitable to citrus, focusing on the principles observed before the use of NPBTs.
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Affiliation(s)
- Fabrizio Salonia
- CREA - Research Centre for Olive, Fruit and Citrus Crops, Acireale, Italy
- Department of Agriculture, Food and Environment (Di3A), University of Catania, Catania, Italy
| | - Angelo Ciacciulli
- CREA - Research Centre for Olive, Fruit and Citrus Crops, Acireale, Italy
| | - Lara Poles
- CREA - Research Centre for Olive, Fruit and Citrus Crops, Acireale, Italy
- Department of Agriculture, Food and Environment (Di3A), University of Catania, Catania, Italy
| | | | - Stefano La Malfa
- Department of Agriculture, Food and Environment (Di3A), University of Catania, Catania, Italy
- *Correspondence: Stefano La Malfa, ; Concetta Licciardello,
| | - Concetta Licciardello
- CREA - Research Centre for Olive, Fruit and Citrus Crops, Acireale, Italy
- *Correspondence: Stefano La Malfa, ; Concetta Licciardello,
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13
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Ference CM, Gochez AM, Behlau F, Wang N, Graham JH, Jones JB. Recent advances in the understanding of Xanthomonas citri ssp. citri pathogenesis and citrus canker disease management. MOLECULAR PLANT PATHOLOGY 2018; 19:1302-1318. [PMID: 29105297 PMCID: PMC6638175 DOI: 10.1111/mpp.12638] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 10/29/2017] [Accepted: 10/31/2017] [Indexed: 05/09/2023]
Abstract
Taxonomic status: Bacteria; Phylum Proteobacteria; Class Gammaproteobacteria; Order Xanthomonadales; Family Xanthomonadaceae; Genus Xanthomonas; Species Xanthomonas citri ssp. citri (Xcc). Host range: Compatible hosts vary in their susceptibility to citrus canker (CC), with grapefruit, lime and lemon being the most susceptible, sweet orange being moderately susceptible, and kumquat and calamondin being amongst the least susceptible. Microbiological properties: Xcc is a rod-shaped (1.5-2.0 × 0.5-0.75 µm), Gram-negative, aerobic bacterium with a single polar flagellum. The bacterium forms yellow colonies on culture media as a result of the production of xanthomonadin. Distribution: Present in South America, the British Virgin Islands, Africa, the Middle East, India, Asia and the South Pacific islands. Localized incidence in the USA, Argentina, Brazil, Bolivia, Uruguay, Senegal, Mali, Burkina Faso, Tanzania, Iran, Saudi Arabia, Yemen and Bangladesh. Widespread throughout Paraguay, Comoros, China, Japan, Malaysia and Vietnam. Eradicated from South Africa, Australia and New Zealand. Absent from Europe.
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Affiliation(s)
- Christopher M. Ference
- United States Department of Agriculture, Agricultural Research Service, US Horticultural Research LaboratoryFort PierceFL 34945USA
- Department of Plant PathologyUniversity of FloridaGainesvilleFL 32611USA
| | - Alberto M. Gochez
- Citrus Pathology, EEA INTA Bella VistaBella VistaCorrientes 3432Argentina
| | - Franklin Behlau
- Department of Research & DevelopmentFundo de Defesa da Citricultura (Fundecitrus)AraraquaraSão Paulo 14.807‐040Brazil
| | - Nian Wang
- Department of Microbiology and Cell Science, Citrus Research and Education Center, University of FloridaLake AlfredFL 33850USA
| | - James H. Graham
- Department of Soil and Water Science, Citrus Research and Education Center, University of FloridaLake AlfredFL 33850USA
| | - Jeffrey B. Jones
- Department of Plant PathologyUniversity of FloridaGainesvilleFL 32611USA
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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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Shantharaj D, Römer P, Figueiredo JFL, Minsavage GV, Krönauer C, Stall RE, Moore GA, Fisher LC, Hu Y, Horvath DM, Lahaye T, Jones JB. An engineered promoter driving expression of a microbial avirulence gene confers recognition of TAL effectors and reduces growth of diverse Xanthomonas strains in citrus. MOLECULAR PLANT PATHOLOGY 2017; 18:976-989. [PMID: 27362693 PMCID: PMC6638256 DOI: 10.1111/mpp.12454] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/13/2016] [Accepted: 06/27/2016] [Indexed: 05/19/2023]
Abstract
Xanthomonas citri ssp. citri (X. citri), causal agent of citrus canker, uses transcription activator-like effectors (TALEs) as major pathogenicity factors. TALEs, which are delivered into plant cells through the type III secretion system (T3SS), interact with effector binding elements (EBEs) in host genomes to activate the expression of downstream susceptibility genes to promote disease. Predictably, TALEs bind EBEs in host promoters via known combinations of TALE amino acids to DNA bases, known as the TALE code. We introduced 14 EBEs, matching distinct X. citri TALEs, into the promoter of the pepper Bs3 gene (ProBs31EBE ), and fused this engineered promoter with multiple EBEs (ProBs314EBE ) to either the β-glucuronidase (GUS) reporter gene or the coding sequence (cds) of the pepper gene, Bs3. TALE-induced expression of the Bs3 cds in citrus leaves resulted in no visible hypersensitive response (HR). Therefore, we utilized a different approach in which ProBs31EBE and ProBs314EBE were fused to the Xanthomonas gene, avrGf1, which encodes a bacterial effector that elicits an HR in grapefruit and sweet orange. We demonstrated, in transient assays, that activation of ProBs314EBE by X. citri TALEs is T3SS dependent, and that the expression of AvrGf1 triggers HR and correlates with reduced bacterial growth. We further demonstrated that all tested virulent X. citri strains from diverse geographical locations activate ProBs314EBE . TALEs are essential for the virulence of X. citri strains and, because the engineered promoter traps are activated by multiple TALEs, this concept has the potential to confer broad-spectrum, durable resistance to citrus canker in stably transformed plants.
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Affiliation(s)
- Deepak Shantharaj
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFL 32611USA
| | - Patrick Römer
- Genetics, Department of Biology, Ludwig‐Maximilians‐University MunichMartinsriedD‐82152Germany
- Present address:
Nomad Bioscience GmbH, Biozentrum Halle Weinbergweg 22 D‐06120 Halle (Saale)
| | | | | | - Christina Krönauer
- Zentrum für Molekularbiologie der Pflanzen (ZMBP)Eberhard‐Karls‐Universität TübingenAuf der Morgenstelle 32TübingenD‐72076Germany
| | - Robert E. Stall
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFL 32611USA
| | - Gloria A. Moore
- Department of Horticultural SciencesUniversity of FloridaGainesvilleFL 32611USA
| | - Latanya C. Fisher
- Department of Horticultural SciencesUniversity of FloridaGainesvilleFL 32611USA
| | - Yang Hu
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFL 32611USA
| | - Diana M. Horvath
- 2Blades Foundation, Suite 19011630 Chicago AvenueEvanstonIL60201USA
| | - Thomas Lahaye
- Genetics, Department of Biology, Ludwig‐Maximilians‐University MunichMartinsriedD‐82152Germany
- Zentrum für Molekularbiologie der Pflanzen (ZMBP)Eberhard‐Karls‐Universität TübingenAuf der Morgenstelle 32TübingenD‐72076Germany
| | - Jeffrey B. Jones
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFL 32611USA
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16
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Gochez AM, Shantharaj D, Potnis N, Zhou X, Minsavage GV, White FF, Wang N, Hurlbert JC, Jones JB. Molecular characterization of XopAG effector AvrGf2 from Xanthomonas fuscans ssp. aurantifolii in grapefruit. MOLECULAR PLANT PATHOLOGY 2017; 18:405-419. [PMID: 27030294 PMCID: PMC6638233 DOI: 10.1111/mpp.12408] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 03/17/2016] [Accepted: 03/29/2016] [Indexed: 05/20/2023]
Abstract
Xanthomonas fuscans ssp. aurantifolii group C strains exhibit host specificity on different citrus species. The strains possess a type III effector, AvrGf2, belonging to the XopAG effector gene family, which restricts host range on citrus. We dissected the modular nature and mode of action of AvrGf2 in grapefruit resistance. XopAG effectors possess characteristic features, such as a chloroplast localization signal, a cyclophilin-binding domain characteristic amino acid sequence motif (GPLL) and a C-terminal domain-containing CLNAxYD. Mutation of GPLL to AASL in AvrGf2 abolished the elicitation of the hypersensitive response (HR), whereas mutation of only the first amino acid to SPLL delayed the HR in grapefruit. Yeast two-hybrid experiments showed strong interaction of AvrGf2 with grapefruit cyclophilin (GfCyp), whereas AvrGf2-SPLL and AvrGf2-AASL mutants showed weak and no interaction, respectively. Molecular modelling and in silico docking studies for the cyclophilin-AvrGf2 interaction predicted the binding of citrus cyclophilins (CsCyp, GfCyp) to hexameric peptides spanning the cyclophilin-binding domain of AvrGf2 and AvrGf2 mutants (VAGPLL, VASPLL and VAAASL) with affinities equivalent to or better than a positive control peptide (YSPSA) previously demonstrated to bind CsCyp. In addition, the C-terminal domain of XopAG family effectors contains a highly conserved motif, CLNAxYD, which was identified to be crucial for the induction of HR based on site-directed mutagenesis (CLNAxYD to CASAxYD). Our results suggest a model in which grapefruit cyclophilin promotes a conformational change in AvrGf2, thereby triggering the resistance response.
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Affiliation(s)
- Alberto M. Gochez
- Citrus Pathology, EEA INTA Bella VistaCC5 Bella VistaCorrientesArgentina 3432
- Department of Plant PathologyUniversity of FloridaGainesvilleFLUSA 32611
| | - Deepak Shantharaj
- Department of Plant PathologyUniversity of FloridaGainesvilleFLUSA 32611
| | - Neha Potnis
- Department of Plant PathologyUniversity of FloridaGainesvilleFLUSA 32611
| | - Xiaofeng Zhou
- Department of Microbiology and Cell ScienceUniversity of FloridaLake AlfredFLUSA 33850
| | | | - Frank F. White
- Department of Plant PathologyUniversity of FloridaGainesvilleFLUSA 32611
| | - Nian Wang
- Department of Microbiology and Cell ScienceUniversity of FloridaLake AlfredFLUSA 33850
| | - Jason C. Hurlbert
- Department of Chemistry, Physics and GeologyCitrus Research and Education Center, Winthrop UniversityRock HillSCUSA 29733
| | - Jeffrey B. Jones
- Department of Plant PathologyUniversity of FloridaGainesvilleFLUSA 32611
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17
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Bond DM, Albert NW, Lee RH, Gillard GB, Brown CM, Hellens RP, Macknight RC. Infiltration-RNAseq: transcriptome profiling of Agrobacterium-mediated infiltration of transcription factors to discover gene function and expression networks in plants. PLANT METHODS 2016; 12:41. [PMID: 27777610 PMCID: PMC5069895 DOI: 10.1186/s13007-016-0141-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 10/04/2016] [Indexed: 05/20/2023]
Abstract
BACKGROUND Transcription factors (TFs) coordinate precise gene expression patterns that give rise to distinct phenotypic outputs. The identification of genes and transcriptional networks regulated by a TF often requires stable transformation and expression changes in plant cells. However, the production of stable transformants can be slow and laborious with no guarantee of success. Furthermore, transgenic plants overexpressing a TF of interest can present pleiotropic phenotypes and/or result in a high number of indirect gene expression changes. Therefore, fast, efficient, high-throughput methods for assaying TF function are needed. RESULTS Agroinfiltration is a simple plant biology method that allows transient gene expression. It is a rapid and powerful tool for the functional characterisation of TF genes in planta. High throughput RNA sequencing is now a widely used method for analysing gene expression profiles (transcriptomes). By coupling TF agroinfiltration with RNA sequencing (named here as Infiltration-RNAseq), gene expression networks and gene function can be identified within a few weeks rather than many months. As a proof of concept, we agroinfiltrated Medicago truncatula leaves with M. truncatula LEGUME ANTHOCYANIN PRODUCITION 1 (MtLAP1), a MYB transcription factor involved in the regulation of the anthocyanin pathway, and assessed the resulting transcriptome. Leaves infiltrated with MtLAP1 turned red indicating the production of anthocyanin pigment. Consistent with this, genes encoding enzymes in the anthocyanin biosynthetic pathway, and known transcriptional activators and repressors of the anthocyanin biosynthetic pathway, were upregulated. A novel observation was the induction of a R3-MYB transcriptional repressor that likely provides transcriptional feedback inhibition to prevent the deleterious effects of excess anthocyanins on photosynthesis. CONCLUSIONS Infiltration-RNAseq is a fast and convenient method for profiling TF-mediated gene expression changes. We utilised this method to identify TF-mediated transcriptional changes and TF target genes in M. truncatula and Nicotiana benthamiana. This included the identification of target genes of a TF not normally expressed in leaves, and targets of TFs from other plant species. Infiltration-RNAseq can be easily adapted to other plant species where agroinfiltration protocols have been optimised. The ability to identify downstream genes, including positive and negative transcriptional regulators, will result in a greater understanding of TF function.
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Affiliation(s)
- Donna M. Bond
- Department of Biochemistry, University of Otago, PO Box 56, Dunedin, 9054 New Zealand
| | - Nick W. Albert
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11-600, Palmerston North, New Zealand
| | - Robyn H. Lee
- Department of Biochemistry, University of Otago, PO Box 56, Dunedin, 9054 New Zealand
| | - Gareth B. Gillard
- Department of Biochemistry, University of Otago, PO Box 56, Dunedin, 9054 New Zealand
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1432 Ås, Norway
| | - Chris M. Brown
- Department of Biochemistry, University of Otago, PO Box 56, Dunedin, 9054 New Zealand
| | - Roger P. Hellens
- Centre for Tropical Crops and Biocommodities, Institute for Future Environments, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 Australia
| | - Richard C. Macknight
- Department of Biochemistry, University of Otago, PO Box 56, Dunedin, 9054 New Zealand
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11-600, Palmerston North, New Zealand
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18
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de Torres Zabala M, Littlejohn G, Jayaraman S, Studholme D, Bailey T, Lawson T, Tillich M, Licht D, Bölter B, Delfino L, Truman W, Mansfield J, Smirnoff N, Grant M. Chloroplasts play a central role in plant defence and are targeted by pathogen effectors. NATURE PLANTS 2015; 1:15074. [PMID: 27250009 DOI: 10.1038/nplants.2015.74] [Citation(s) in RCA: 178] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 04/24/2015] [Indexed: 05/19/2023]
Abstract
Microbe associated molecular pattern (MAMP) receptors in plants recognize MAMPs and activate basal defences; however a complete understanding of the molecular and physiological mechanisms conferring immunity remains elusive. Pathogens suppress active defence in plants through the combined action of effector proteins. Here we show that the chloroplast is a key component of early immune responses. MAMP perception triggers the rapid, large-scale suppression of nuclear encoded chloroplast-targeted genes (NECGs). Virulent Pseudomonas syringae effectors reprogramme NECG expression in Arabidopsis, target the chloroplast and inhibit photosynthetic CO2 assimilation through disruption of photosystem II. This activity prevents a chloroplastic reactive oxygen burst. These physiological changes precede bacterial multiplication and coincide with pathogen-induced abscisic acid (ABA) accumulation. MAMP pretreatment protects chloroplasts from effector manipulation, whereas application of ABA or the inhibitor of photosynthetic electron transport, DCMU, abolishes the MAMP-induced chloroplastic reactive oxygen burst, and enhances growth of a P. syringae hrpA mutant that fails to secrete effectors.
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Affiliation(s)
- Marta de Torres Zabala
- Biosciences, College of Life and Environment Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - George Littlejohn
- Biosciences, College of Life and Environment Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Siddharth Jayaraman
- Biosciences, College of Life and Environment Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - David Studholme
- Biosciences, College of Life and Environment Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Trevor Bailey
- Biosciences, College of Life and Environment Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Tracy Lawson
- School of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK
| | - Michael Tillich
- Max Planck Institute of Molecular Plant Physiology, Am Müehlenberg 1, Potsdam-Golm D-14476, Germany
| | - Dirk Licht
- Max Planck Institute of Molecular Plant Physiology, Am Müehlenberg 1, Potsdam-Golm D-14476, Germany
| | - Bettina Bölter
- Department of Biology I, Botany, Ludwig-Maximilians-Universität München, Groβhaderner Strase 2-4, Planegg-Martinsried D-82152, Germany
| | - Laura Delfino
- Department of Biology I, Botany, Ludwig-Maximilians-Universität München, Groβhaderner Strase 2-4, Planegg-Martinsried D-82152, Germany
| | - William Truman
- Department of Plant Biology, University of Minnesota, USA
| | - John Mansfield
- Department of Life Sciences, Imperial College, London SW7 2AZ, UK
| | - Nicholas Smirnoff
- Biosciences, College of Life and Environment Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Murray Grant
- Biosciences, College of Life and Environment Sciences, University of Exeter, Exeter EX4 4QD, UK
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19
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Jia H, Wang N. Xcc-facilitated agroinfiltration of citrus leaves: a tool for rapid functional analysis of transgenes in citrus leaves. PLANT CELL REPORTS 2014; 33:1993-2001. [PMID: 25146436 DOI: 10.1007/s00299-014-1673-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 07/14/2014] [Accepted: 08/04/2014] [Indexed: 05/21/2023]
Abstract
Xanthomonas citri subsp. citri pretreatment before agroinfiltration could significantly promote transient expression in citrus leaves which were previously recalcitrant to agroinfiltration. Transient expression via agroinfiltration is widely used in biotechnology but remains problematic in many economically important plants. Xanthomonas citri subsp. citri (Xcc)-facilitated agroinfiltration was employed to promote transient protein expression in Valencia sweet orange leaves, which are recalcitrant to agroinfiltration. However, it is unclear whether Xcc-facilitated agroinfiltration has broad application, i.e., whether Xcc-facilitated agroinfiltration could be used on other citrus varieties. In addition, we intended to investigate whether Xcc-facilitated agroinfiltration could be used to hasten transgene function assays, e.g., Cre/lox system and Cas9/sgRNA system. In this report, Xcc-facilitated agroinfiltration was further exploited to enhance β-glucuronidase (GUS) expression in five citrus varieties. Xcc-facilitated agroinfiltration also significantly increased GFP expression in six citrus varieties tested. Both GUS and GFP assays indicated that Xcc-facilitated agroinfiltration had the best performance in grapefruit. After Xcc-facilitated agroinfiltration was carried out in grapefruit, protoplast analysis of the transformed cells indicated that there were more than 20 % leaf cells expressing GFP. In grapefruit, usefulness of Xcc-facilitated agroinfiltration was assayed in three case studies: (1) fast functional analysis of Cre/lox system, (2) the heat shock regulation of HSP70B promoter derived from Arabidopsis, and (3) Cas9/sgRNA-mediated genome modification.
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Affiliation(s)
- Hongge Jia
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, Lake Alfred, Fl, USA
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Agrobacterium-mediated genetic transformation and regeneration of transgenic plants using leaf midribs as explants in ramie [Boehmeria nivea (L.) Gaud]. Mol Biol Rep 2014; 41:3257-69. [PMID: 24488319 DOI: 10.1007/s11033-014-3188-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2013] [Accepted: 01/21/2014] [Indexed: 12/21/2022]
Abstract
In this study, leaf midribs, the elite explants, were used for the first time to develop an efficient regeneration and transformation protocol for ramie [Boehmeria nivea (L.) Gaud.] via Agrobacterium-mediated genetic transformation. Sensitivity of leaf midribs regeneration to kanamycin was evaluated, which showed that 40 mg l(-1) was the optimal concentration needed to create the necessary selection pressure. Factors affecting the ramie transformation efficiency were evaluated, including leaf age, Agrobacterium concentration, length of infection time for the Agrobacterium solution, acetosyringone concentration in the co-cultivation medium, and the co-cultivation period. The midrib explants from 40-day-old in vitro shoots, an Agrobacterium concentration at OD600 of 0.6, 10-min immersion in the bacteria solution, an acetosyringone concentration of 50 mg l(-1) in the co-cultivation medium and a 3-day co-cultivation period produced the highest efficiencies of regeneration and transformation. In this study, the average transformation rate was 23.25%. Polymerase chain reactions using GUS and NPTII gene-specific primers, Southern blot and histochemical GUS staining analyses further confirmed that the transgene was integrated into the ramie genome and expressed in the transgenic ramie. The establishment of this system of Agrobacterium-mediated genetic transformation and regeneration of transgenic plants will be used not only to introduce genes of interest into the ramie genome for the purpose of trait improvement, but also as a common means of testing gene function by enhancing or inhibiting the expression of target genes.
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Picard K, Lee R, Hellens R, Macknight R. Transient gene expression in Medicago truncatula leaves via Agroinfiltration. Methods Mol Biol 2013; 1069:215-26. [PMID: 23996318 DOI: 10.1007/978-1-62703-613-9_15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Transient expression is a powerful method for the functional characterization of genes. In this chapter, we outline a protocol for the transient expression of constructs in Medicago truncatula leaves using Agrobacterium tumefaciens infiltration. Using quantitative real-time PCR we demonstrate that the infiltration of a construct containing the LEGUME ANTHOCYANIN PRODUCTION 1 (LAP1) transcription factor results in the strong upregulation of key biosynthetic genes and the accumulation of anthocyanin pigment in the leaves after just 3 days. Thus, this method provides a rapid and powerful way to the discovery of downstream targets of M. truncatula transcription factors.
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Affiliation(s)
- Kelsey Picard
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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Dunger G, Garofalo CG, Gottig N, Garavaglia BS, Rosa MCP, Farah CS, Orellano EG, Ottado J. Analysis of three Xanthomonas axonopodis pv. citri effector proteins in pathogenicity and their interactions with host plant proteins. MOLECULAR PLANT PATHOLOGY 2012; 13:865-76. [PMID: 22435635 PMCID: PMC6638619 DOI: 10.1111/j.1364-3703.2012.00797.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Xanthomonas axonopodis pv. citri, the bacterium responsible for citrus canker, uses effector proteins secreted by a type III protein secretion system to colonize its hosts. Among the putative effector proteins identified for this bacterium, we focused on the analysis of the roles of AvrXacE1, AvrXacE2 and Xac3090 in pathogenicity and their interactions with host plant proteins. Bacterial deletion mutants in avrXacE1, avrXacE2 and xac3090 were constructed and evaluated in pathogenicity assays. The avrXacE1 and avrXacE2 mutants presented lesions with larger necrotic areas relative to the wild-type strain when infiltrated in citrus leaves. Yeast two-hybrid studies were used to identify several plant proteins likely to interact with AvrXacE1, AvrXacE2 and Xac3090. We also assessed the localization of these effector proteins fused to green fluorescent protein in the plant cell, and observed that they co-localized to the subcellular spaces in which the plant proteins with which they interacted were predicted to be confined. Our results suggest that, although AvrXacE1 localizes to the plant cell nucleus, where it interacts with transcription factors and DNA-binding proteins, AvrXacE2 appears to be involved in lesion-stimulating disease 1-mediated cell death, and Xac3090 is directed to the chloroplast where its function remains to be clarified.
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Affiliation(s)
- Germán Dunger
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Rosario, Suipacha 531 (S2002LRK) Rosario, Argentina
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Faizal A, Geelen D. Agroinfiltration of intact leaves as a method for the transient and stable transformation of saponin producing Maesa lanceolata. PLANT CELL REPORTS 2012; 31:1517-1526. [PMID: 22534683 DOI: 10.1007/s00299-012-1266-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 04/05/2012] [Accepted: 04/10/2012] [Indexed: 05/31/2023]
Abstract
UNLABELLED A method has been developed to genetically transform the medicinal plant Maesa lanceolata. Initially, we tested conditions for transient expression of GFP-bearing constructs in agroinfiltrated leaves. Leaf tissues of M. lanceolata were infiltrated with Agrobacterium tumefaciens carrying a nuclear-targeted GFP construct to allow the quantification of the transformation efficiency. The number of transfected cells was depended on the bacterial density, bacterial strains, the co-cultivation time, and presence of acetosyringone. The transient transformation assay generated the highest ratio of transfected cells over non-transfected cells upon 5 days post-infiltration using A. tumefaciens strain LBA4404 at an OD₆₀₀ = 1.0 in the presence of 100 μM acetosyringone and in the absence of a viral suppressor construct. In a second series of experiments we set up a stable transformation protocol that resulted in the regeneration of kanamycin-resistant plants expressing nuclear GFP. This transformation protocol will be used to introduce overexpression and RNAi constructs into M. lanceolata plants that may interfere with triterpenoid saponin biosynthesis. KEY MESSAGE We have developed a transformation protocol for saponin producing Maesa lanceolata. Using the protocol reported here, now we are able to generate the tools for the modification of saponin production.
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Affiliation(s)
- Ahmad Faizal
- Department of Plant Production, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
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Liu W, Mazarei M, Rudis MR, Fethe MH, Stewart CN. Rapid in vivo analysis of synthetic promoters for plant pathogen phytosensing. BMC Biotechnol 2011; 11:108. [PMID: 22093754 PMCID: PMC3247077 DOI: 10.1186/1472-6750-11-108] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 11/17/2011] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND We aimed to engineer transgenic plants for the purpose of early detection of plant pathogen infection, which was accomplished by employing synthetic pathogen inducible promoters fused to reporter genes for altered phenotypes in response to the pathogen infection. Toward this end, a number of synthetic promoters consisting of inducible regulatory elements fused to a red fluorescent protein (RFP) reporter were constructed for use in phytosensing. RESULTS For rapid analysis, an Agrobacterium-mediated transient expression assay was evaluated, then utilized to assess the inducibility of each synthetic promoter construct in vivo. Tobacco (Nicotiana tabacum cv. Xanthi) leaves were infiltrated with Agrobacterium harboring the individual synthetic promoter-reporter constructs. The infiltrated tobacco leaves were re-infiltrated with biotic (bacterial pathogens) or abiotic (plant defense signal molecules salicylic acid, ethylene and methyl jasmonate) agents 24 and 48 hours after initial agroinfiltration, followed by RFP measurements at relevant time points after treatment. These analyses indicated that the synthetic promoter constructs were capable of conferring the inducibility of the RFP reporter in response to appropriate phytohormones and bacterial pathogens, accordingly. CONCLUSIONS These observations demonstrate that the Agrobacterium-mediated transient expression is an efficient method for in vivo assays of promoter constructs in less than one week. Our results provide the opportunity to gain further insights into the versatility of the expression system as a potential tool for high-throughput in planta expression screening prior to generating stably transgenic plants for pathogen phytosensing. This system could also be utilized for temporary phytosensing; e.g., not requiring stably transgenic plants.
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Affiliation(s)
- Wusheng Liu
- Department of Plant Sciences, The University of Tennessee, 252 Ellington Plant Sciences, 2431 Joe Johnson Dr., Knoxville, TN 37996, USA
| | - Mitra Mazarei
- Department of Plant Sciences, The University of Tennessee, 252 Ellington Plant Sciences, 2431 Joe Johnson Dr., Knoxville, TN 37996, USA
| | - Mary R Rudis
- Department of Plant Sciences, The University of Tennessee, 252 Ellington Plant Sciences, 2431 Joe Johnson Dr., Knoxville, TN 37996, USA
| | - Michael H Fethe
- Department of Plant Sciences, The University of Tennessee, 252 Ellington Plant Sciences, 2431 Joe Johnson Dr., Knoxville, TN 37996, USA
| | - C Neal Stewart
- Department of Plant Sciences, The University of Tennessee, 252 Ellington Plant Sciences, 2431 Joe Johnson Dr., Knoxville, TN 37996, USA
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