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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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Gong J, Tian Z, Qu X, Meng Q, Guan Y, Liu P, Chen C, Deng X, Guo W, Cheng Y, Wang P. Illuminating the cells: transient transformation of citrus to study gene functions and organelle activities related to fruit quality. HORTICULTURE RESEARCH 2021; 8:175. [PMID: 34333523 PMCID: PMC8325690 DOI: 10.1038/s41438-021-00611-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/14/2021] [Accepted: 05/04/2021] [Indexed: 05/16/2023]
Abstract
Although multiple microscopic techniques have been applied to horticultural research, few studies of individual organelles in living fruit cells have been reported to date. In this paper, we established an efficient system for the transient transformation of citrus fruits using an Agrobacterium-mediated method. Kumquat (Fortunella crassifolia Swingle) was used; it exhibits higher transformation efficiency than all citrus fruits that have been tested and a prolonged-expression window. Fruits were transformed with fluorescent reporters, and confocal microscopy and live-cell imaging were used to study their localization and dynamics. Moreover, various pH sensors targeting different subcellular compartments were expressed, and the local pH environments in cells from different plant tissues were compared. The results indicated that vacuoles are most likely the main organelles that contribute to the low pH of citrus fruits. In summary, our method is effective for studying various membrane trafficking events, protein localization, and cell physiology in fruit and can provide new insight into fruit biology research.
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Affiliation(s)
- Jinli Gong
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, 430070, Wuhan, China
- National R&D Centre for Citrus Preservation, Huazhong Agricultural University, 430070, Wuhan, China
- Interdisciplinary Sciences Research Institute, Huazhong Agricultural University, 430070, Wuhan, China
| | - Zhen Tian
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, 430070, Wuhan, China
- National R&D Centre for Citrus Preservation, Huazhong Agricultural University, 430070, Wuhan, China
- Interdisciplinary Sciences Research Institute, Huazhong Agricultural University, 430070, Wuhan, China
| | - Xiaolu Qu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, 430070, Wuhan, China
| | - Qiunan Meng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, 430070, Wuhan, China
- National R&D Centre for Citrus Preservation, Huazhong Agricultural University, 430070, Wuhan, China
- Interdisciplinary Sciences Research Institute, Huazhong Agricultural University, 430070, Wuhan, China
| | - Yajie Guan
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, 430070, Wuhan, China
- National R&D Centre for Citrus Preservation, Huazhong Agricultural University, 430070, Wuhan, China
- Interdisciplinary Sciences Research Institute, Huazhong Agricultural University, 430070, Wuhan, China
| | - Ping Liu
- Guangxi Academy of Specialty Crops/Guangxi Engineering Research Center of Citrus Breeding and Culture, 541004, Guilin, China
| | - Chuanwu Chen
- Guangxi Academy of Specialty Crops/Guangxi Engineering Research Center of Citrus Breeding and Culture, 541004, Guilin, China
| | - Xiuxin Deng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, 430070, Wuhan, China
| | - Wenwu Guo
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, 430070, Wuhan, China
| | - Yunjiang Cheng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, 430070, Wuhan, China
- National R&D Centre for Citrus Preservation, Huazhong Agricultural University, 430070, Wuhan, China
| | - Pengwei Wang
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, 430070, Wuhan, China.
- National R&D Centre for Citrus Preservation, Huazhong Agricultural University, 430070, Wuhan, China.
- Interdisciplinary Sciences Research Institute, Huazhong Agricultural University, 430070, Wuhan, China.
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Dutt M, Mou Z, Zhang X, Tanwir SE, Grosser JW. Efficient CRISPR/Cas9 genome editing with Citrus embryogenic cell cultures. BMC Biotechnol 2020; 20:58. [PMID: 33167938 PMCID: PMC7654154 DOI: 10.1186/s12896-020-00652-9] [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: 06/17/2020] [Accepted: 10/29/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Development of precise genome editing strategies is a prerequisite for producing edited plants that can aid in the study of gene function and help understand the genetic traits in a cultivar. Citrus embryogenic cell cultures can be used to rapidly produce a large population of genome edited transformed citrus lines. The ability to introduce specific mutations in the genome of these cells using two constructs (pC-PDS1 and pC-PDS2) was evaluated in this study. RESULTS Citrus sinensis 'EV2' embryogenic cell cultures are amenable to Agrobacterium-mediated CRISPR/Cas9-based genome editing. Guide RNAs (gRNAs) targeting two locations in the phytoene desaturase (PDS) gene were either driven by the Arabidopsis U6-26 promoter (pC-PDS1) or assembled as a Csy4 array under the control of the CmYLCV promoter (pC-PDS2). All transgenic embryos were completely albino and no variegated phenotype was observed. We evaluated 12 lines from each construct in this study and the majority contain either insertion (1-2 bp), substitution (1 bp), or deletion (1-3 bp) mutations that occurred close to the protospacer adjacent motif. CONCLUSIONS Both the pC-PDS1 and pC-PDS2 could successfully edit the citrus embryogenic cell cultures. However, the editing efficiency was dependent on the gRNA, confirming that the selection of a proper gRNA is essential for successful genome editing using the CRISPR/Cas9 technique. Also, utilization of embryogenic cell cultures offers another option for successful genome editing in citrus.
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Affiliation(s)
- Manjul Dutt
- Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, USA.
| | - Zhonglin Mou
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA
| | - Xudong Zhang
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA
| | - Sameena E Tanwir
- Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, USA
| | - Jude W Grosser
- Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, USA
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Singh B, Virk GS, Nagpal AK. An efficient plant regeneration protocol from callus cultures of Citrus jambhiri Lush. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2011; 17:161-9. [PMID: 23573006 PMCID: PMC3550540 DOI: 10.1007/s12298-011-0055-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Citrus jambhiri Lush. (family Rutaceae), commonly known as 'rough lemon', is one of the favourite rootstocks for lemons, oranges, mandarins, grape fruits and kinnows in Punjab. The present investigation deals with development of an efficient miropropagation protocol for Citrus jambhiri Lush. using cotyledons as explant. Maximum callus induction (91.66 %) was observed on MS medium supplemented with 2,4-D (2 mg/L) in combination with ME (500 mg/L). Green healthy calli were cut into small pieces and cultured on MS medium for regeneration. Maximum shoot regeneration (87.50 %) was observed with BA (3 mg/L). Effect of increasing age of callus was also studied which showed that callus retained regeneration capacity (58.33 %) even after 420 days of culture. Regenerated shoots were separated out and cultured on rooting medium. Maximum rooting response (91.67 %) was observed on half strength MS medium supplemented with NAA (0.5 mg/L). After hardening and acclimatization the plantlet were transferred to the field and showed 67 % survival.
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Affiliation(s)
- Balwinder Singh
- />Department of Biotechnology, Khalsa College, Amritsar, India
| | - Gurdeep Singh Virk
- />Department of Botanical and Environmental Sciences, Guru Nanak Dev University, Amritsar, 143005 India
| | - Avinash Kaur Nagpal
- />Department of Botanical and Environmental Sciences, Guru Nanak Dev University, Amritsar, 143005 India
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Fagoaga C, López C, Moreno P, Navarro L, Flores R, Peña L. Viral-like symptoms induced by the ectopic expression of the p23 gene of Citrus tristeza virus are citrus specific and do not correlate with the pathogenicity of the virus strain. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2005; 18:435-45. [PMID: 15915642 DOI: 10.1094/mpmi-18-0435] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Ectopic expression of the p23 gene from a severe (T36) strain of Citrus tristeza virus (CTV) induces viral-like symptoms in Mexican lime. Here, we report that expressing the same gene from a mild strain induced similar symptoms that correlated with accumulation of p23 protein irrespective of the source strain. CTV inoculation of transgenic limes showing CTV-like leaf symptoms and high p23 accumulation did not modify symptoms initially, with the virus titer being as in inoculated nontransgenic controls; however, at later stages, symptoms became attenuated. Transformation with p23-T36 of CTV-susceptible sweet and sour orange and CTV-resistant trifoliate orange also led to CTV-like leaf symptoms that did not develop when plants were transformed with a truncated p23 version. In transgenic citrus species and relatives other than Mexican lime, p23 was barely detectable, although symptom intensity correlated with levels of p23 transcripts. The lower accumulation of p23 in sweet and sour orange compared with Mexican lime also was observed in nontransgenic plants inoculated with CTV, suggesting that minimal p23 levels cause deleterious effects in the first two species. Conversely, transgenic expression of p23 in CTV nonhost Nicotiana spp. led to accumulation of p23 without phenotypic aberrations, indicating that p23 interferes with plant development only in citrus species and relatives.
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Affiliation(s)
- Carmen Fagoaga
- Instituto Valenciano de Investigaciones Agrarias, Apdo. Oficial, Moncada 46113, Valencia, Spain
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Ghorbel R, López C, Fagoaga C, Moreno P, Navarro L, Flores R, Peña L. Transgenic citrus plants expressing the citrus tristeza virus p23 protein exhibit viral-like symptoms. MOLECULAR PLANT PATHOLOGY 2001; 2:27-36. [PMID: 20572989 DOI: 10.1046/j.1364-3703.2001.00047.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Summary The 23 kDa protein (p23) coded by the 3'-terminal gene of Citrus tristeza virus (CTV), a member of the genus Closterovirus with the largest genome among plant RNA viruses, is an RNA-binding protein that contains a motif rich in cysteine and histidine residues in the core of a putative zinc-finger domain. On this basis, a regulatory role for CTV replication or gene expression has been suggested for p23. To explore whether over-expression of this protein in transgenic plants could affect the normal CTV infection process, transgenic Mexican lime plants were generated carrying the p23 transgene, or a truncated version thereof, under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Constitutive expression of p23 induced phenotypic aberrations that resembled symptoms incited by CTV in non-transgenic lime plants, whereas transgenic plants expressing the p23 truncated version were normal. The onset of CTV-like symptoms in p23-transgenic plants was associated with the expression of p23, and its accumulation level paralleled the intensity of the symptoms. This demonstrates that p23 is involved in symptom development and that it most likely plays a key role in CTV pathogenesis. This is the first case in which a protein encoded by a woody plant-infecting RNA virus has been identified as being directly involved in pathogenesis in its natural host. This finding also delimits a small region of the large CTV genome for the future mapping of specific pathogenic determinants.
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Affiliation(s)
- R Ghorbel
- Instituto Valenciano de Investigaciones Agrarias (IVIA), Apdo. Oficial, Moncada 46113, Valencia, Spain
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