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Limayem A, Martin EM, Shankar S. Study on the citrus greening disease: Current challenges and novel therapies. Microb Pathog 2024; 192:106688. [PMID: 38750772 DOI: 10.1016/j.micpath.2024.106688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 05/06/2024] [Accepted: 05/12/2024] [Indexed: 05/25/2024]
Abstract
The unprecedented worldwide spread of the Citrus greening disorder, called Huanglongbing (HLB), has urged researchers for rapid interventions. HLB poses a considerable threat to global citriculture owing to its devastating impact on citrus species. This disease is caused by Candidatus Liberibacter species (CLs), primarily transferred through psyllid insects, such as Trioza erytreae and Diaphorina citri. It results in phloem malfunction, root decline, and altered plant source-sink relationships, leading to a deficient plant with minimal yield before it dies. Thus, many various techniques have been employed to eliminate HLB and control vector populations through the application of insecticides and antimicrobials. The latter have evidenced short-term efficiency. While nucleic acid-based analyses and symptom-based identification of the disease have been used for detection, they suffer from limitations such as false negatives, complex sample preparation, and high costs. To address these challenges, secreted protein-based biomarkers offer a promising solution for accurate, rapid, and cost-effective disease detection. This paper presents an overview of HLB symptoms in citrus plants, including leaf and fruit symptoms, as well as whole tree symptoms. The differentiation between HLB symptoms and those of nutrient deficiencies is discussed, emphasizing the importance of precise identification for effective disease management. The elusive nature of CLs and the challenges in culturing them in axenic cultures have hindered the understanding of their pathogenic mechanisms. However, genome sequencing has provided insights into CLs strains' metabolic traits and potential virulence factors. Efforts to identify potential host target genes for resistance are discussed, and a high-throughput antimicrobial testing method using Citrus hairy roots is introduced as a promising tool for rapid assessment of potential treatments. This review summarizes current challenges and novel therapies for HLB disease. It highlights the urgency of developing accurate and efficient detection methods and identifying the complex relations between CLs and their host plants. Transgenic citrus in conjunction with secreted protein-based biomarkers and innovative testing methodologies could revolutionize HLB management strategies toward achieving a sustainable citrus cultivation. It offers more reliable and practical solutions to combat this devastating disease and safeguard the global citriculture industry.
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Affiliation(s)
- Alya Limayem
- Department of Biology, College of Arts & Sciences, University of North Florida, Jacksonville, FL, USA
| | - Elizabeth M Martin
- Food Science, Department of Biological and Agricultural Engineering, University of Arkansas, AR, USA
| | - Shiv Shankar
- Research Laboratories in Science, Applied to Food, INRS-Armand-Frappier Health and Biotechnology Centre, Laval, Quebec, Canada; School of Food Science and Environmental Health, Grangegorman, Technological University Dublin, Dublin, Ireland.
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2
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Sun Q, Hao Y, Liu Y, Cui M, Zhang G, Yu W, Luo L. Identification and Characterization of Polyamine Metabolism in Citrus in Response to ' Candidatus Liberibacter asiaticus' Infection. PHYTOPATHOLOGY 2024; 114:1380-1392. [PMID: 38349804 DOI: 10.1094/phyto-04-23-0114-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
Citrus Huanglongbing, one of the most devastating citrus diseases, is caused by 'Candidatus Liberibacter asiaticus' (CLas). Polyamines are aliphatic nitrogen-containing compounds that play important roles in disease resistance and are synthesized primarily by two pathways: an arginine decarboxylation pathway and an ornithine decarboxylation pathway. However, it is unclear whether polyamines play a role in the tolerance of citrus to infection by CLas and, if so, whether one or both of the core polyamine metabolic pathways are important. We used high-performance liquid chromatography and ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry to detect the contents of nine polyamine metabolism-related compounds in six citrus cultivars with varying levels of tolerance to CLas. We also systematically detected the changes in polyamine metabolism-related compounds and H2O2 contents and compared the gene expression levels and the activities of enzymes involved in the polyamine metabolic pathway among healthy, asymptomatic, and symptomatic leaves of Newhall navel oranges infected with CLas. The tolerant and moderately tolerant varieties showed higher polyamine metabolism-related compound levels than those of susceptible varieties. Compared with the healthy group, the symptomatic group showed significantly increased contents of arginine, ornithine, γ-aminobutyric acid, and putrescine by approximately 180, 19, 1.5, and 0.2 times, respectively, and upregulated expression of biosynthetic genes. Arginase and ornithine decarboxylase enzyme activities were the highest in the symptomatic group, whereas arginine decarboxylase and agmatine deiminase enzyme activities were the highest in the asymptomatic group. The two polyamine biosynthetic pathways showed different trends with the increase of the CLas titer, indicating that polyamines were mainly synthesized through the arginine decarboxylase pathway in the asymptomatic leaves and were synthesized via the ornithine decarboxylase pathway in symptomatic leaves. These findings provide new insight into the changes in polyamine metabolism in citrus infected with CLas.
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Affiliation(s)
- Qifang Sun
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | - Yingbin Hao
- School of Life Sciences, Nanchang University, Nanchang 330031, China
| | - Yongquan Liu
- College of Life Sciences, Gannan Normal University, Ganzhou 341000, China
| | - Meng Cui
- School of Life Sciences, Nanchang University, Nanchang 330031, China
| | - Gaowei Zhang
- School of Life Sciences, Nanchang University, Nanchang 330031, China
| | - Wenjie Yu
- School of Life Sciences, Nanchang University, Nanchang 330031, China
| | - Liping Luo
- School of Food and Health, Beijing Technology and Business University, Beijing 100048, China
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3
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Du P, Hu J, Du M, Gao X, Yang W, Zhang C, Zou X, Wang X, Li W. Interaction of a bacterial non-classically secreted RNase HⅠ with a citrus B-Box zinc finger protein delays flowering in Arabidopsis thaliana and suppresses the expression of FLOWERING LOCUS T. Microbiol Res 2024; 278:127541. [PMID: 37972521 DOI: 10.1016/j.micres.2023.127541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/21/2023] [Accepted: 10/31/2023] [Indexed: 11/19/2023]
Abstract
Ribonuclease HI (RNase HI) is well conserved across prokaryotes and eukaryotes, and has long been known to localize in the nucleic acid-containing cellular compartments for acting as an R-loop eraser but has never been determined to be a secreted protein. "Candidatus Liberibacter asiaticus" (CLas) is a fastidious α-proteobacterium that causes Huanglongbing (HLB), a devastating citrus disease often associated with flowering out of season. In this study, using the SecretomeP program coupled with an Escherichia coli-based alkaline phosphatase assay, we demonstrated that the CLas RNase HI (LasRNHⅠ) was a non-classically secreted protein. Further experiments identified that LasRNHⅠ could interact with a citrus B-box zinc finger protein CsBBX28 in the plant nucleolus. The in vitro assays indicated that CsBBX28 dramatically enhanced the R-loop-degrading activity of LasRNHⅠ. Remarkably, co-expression of CsBBX28 and LasRNHⅠ in Arabidopsis thaliana led to a much later flowering time than that of wild-type Arabidopsis, as well as that of the transgenic A. thaliana expressing only CsBBX28 or LasRNHⅠ, and lastingly and significantly repressed transcription of FLOWERING LOCUS T (FT), a floral pathway integrator. Similarly, ectopic expression of LasRNHⅠ in citrus greatly reduced the transcription level of FT. The data together disclosed the extracellular secretion of LasRNHⅠ, and that LasRNHⅠ physically interacted with CsBBX28 and served as a flowering repressor through suppressing the FT expression, suggesting a novel role of RNase HI in the bacteria interacting with the host plants.
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Affiliation(s)
- Peixiu Du
- Key Laboratory for Northern Urban Agriculture of Ministry of Agriculture and Rural Affairs, Beijing University of Agriculture, Beijing 102206, PR China; Innovative Institute of Chinese Medicine and Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, PR China; Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China
| | - Junxia Hu
- Department of Plant Protection, Beijing University of Agriculture, Beijing 102206, PR China
| | - Meixia Du
- Citrus Research Institute, Southwest University, Chongqing 400716, PR China
| | - Xiaoyu Gao
- Department of Plant Protection, Beijing University of Agriculture, Beijing 102206, PR China
| | - Wendi Yang
- Department of Plant Protection, Beijing University of Agriculture, Beijing 102206, PR China
| | - Chao Zhang
- College of Life Science, Hebei Agricultural University, Baoding 071001, PR China
| | - Xiuping Zou
- Citrus Research Institute, Southwest University, Chongqing 400716, PR China
| | - Xuefeng Wang
- Citrus Research Institute, Southwest University, Chongqing 400716, PR China
| | - Weimin Li
- Key Laboratory for Northern Urban Agriculture of Ministry of Agriculture and Rural Affairs, Beijing University of Agriculture, Beijing 102206, PR China; Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China; Department of Plant Protection, Beijing University of Agriculture, Beijing 102206, PR China.
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Wang M, Qin YY, Wei NN, Xue HY, Dai WS. Highly efficient Agrobacterium rhizogenes-mediated hairy root transformation in citrus seeds and its application in gene functional analysis. FRONTIERS IN PLANT SCIENCE 2023; 14:1293374. [PMID: 38023879 PMCID: PMC10644275 DOI: 10.3389/fpls.2023.1293374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 10/19/2023] [Indexed: 12/01/2023]
Abstract
Highly efficient genetic transformation technology is beneficial for plant gene functional research and molecular improvement breeding. However, the most commonly used Agrobacterium tumefaciens-mediated genetic transformation technology is time-consuming and recalcitrant for some woody plants such as citrus, hampering the high-throughput functional analysis of citrus genes. Thus, we dedicated to develop a rapid, simple, and highly efficient hairy root transformation system induced by Agrobacterium rhizogenes to analyze citrus gene function. In this report, a rapid, universal, and highly efficient hairy root transformation system in citrus seeds was described. Only 15 days were required for the entire workflow and the system was applicable for various citrus genotypes, with a maximum transformation frequency of 96.1%. After optimization, the transformation frequency of Citrus sinensis, which shows the lowest transformation frequency of 52.3% among four citrus genotypes initially, was increased to 71.4% successfully. To test the applicability of the hairy roots transformation system for gene functional analysis of citrus genes, we evaluated the subcellular localization, gene overexpression and gene editing in transformed hairy roots. Compared with the traditional transient transformation system performed in tobacco leaves, the transgenic citrus hairy roots displayed a more clear and specific subcellular fluorescence localization. Transcript levels of genes were significantly increased in overexpressing transgenic citrus hairy roots as compared with wild-type (WT). Additionally, hairy root transformation system in citrus seeds was successful in obtaining transformants with knocked out targets, indicating that the Agrobacterium rhizogenes-mediated transformation enables the CRISPR/Cas9-mediated gene editing. In summary, we established a highly efficient genetic transformation technology with non-tissue-culture in citrus that can be used for functional analysis such as protein subcellular localization, gene overexpression and gene editing. Since the material used for genetic transformation are roots protruding out of citrus seeds, the process of planting seedlings prior to transformation of conventional tissue culture or non-tissue-culture was eliminated, and the experimental time was greatly reduced. We anticipate that this genetic transformation technology will be a valuable tool for routine research of citrus genes in the future.
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Affiliation(s)
| | | | | | | | - Wen-Shan Dai
- China-USA Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, College of Life Sciences, Gannan Normal University, Ganzhou, Jiangxi, China
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Xu L, Mo K, Ran D, Ma J, Zhang L, Sun Y, Long Q, Jiang G, Zhao X, Zou X. An endolysin gene from Candidatus Liberibacter asiaticus confers dual resistance to huanglongbing and citrus canker. HORTICULTURE RESEARCH 2023; 10:uhad159. [PMID: 37719271 PMCID: PMC10500150 DOI: 10.1093/hr/uhad159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 07/27/2023] [Indexed: 09/19/2023]
Abstract
The most damaging citrus diseases are Huanglongbing (HLB) and citrus canker, which are caused by Candidatus Liberibacter asiaticus (CaLas) and Xanthomonas citri pv. citri (Xcc), respectively. Endolysins from bacteriophages are a possible option for disease resistance in plant breeding. Here, we report improvement of citrus resistance to HLB and citrus canker using the LasLYS1 and LasLYS2 endolysins from CaLas. LasLYS2 demonstrated bactericidal efficacy against several Rhizobiaceae bacteria and Xcc, according to inhibition zone analyses. The two genes, driven by a strong promoter from Cauliflower mosaic virus, 35S, were integrated into Carrizo citrange via Agrobacterium-mediated transformation. More than 2 years of greenhouse testing indicated that LasLYS2 provided substantial and long-lasting resistance to HLB, allowing transgenic plants to retain low CaLas titers and no obvious symptoms while also clearing CaLas from infected plants in the long term. LasLYS2 transgenic plants with improved HLB resistance also showed resistance to Xcc, indicating that LasLYS2 had dual resistance to HLB and citrus canker. A microbiome study of transgenic plants revealed that the endolysins repressed Xanthomonadaceae and Rhizobiaceae populations in roots while increasing Burkholderiaceae and Rhodanobacteraceae populations, which might boost the citrus defense response, according to transcriptome analysis. We also found that Lyz domain 2 is the key bactericidal motif of LasLYS1 and LasLYS2. Four endolysins with potential resistance to HLB and citrus canker were found based on the structures of LasLYS1 and LasLYS2. Overall, the work shed light on the mechanisms of resistance of CaLas-derived endolysins, providing insights for designing endolysins to develop broad-spectrum disease resistance in citrus.
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Affiliation(s)
- Lanzhen Xu
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing 400712, China
| | - Kaiqing Mo
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing 400712, China
| | - Danlu Ran
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing 400712, China
| | - Juanjuan Ma
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing 400712, China
| | - Lehuan Zhang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing 400712, China
| | - Yijia Sun
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing 400712, China
| | - Qin Long
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing 400712, China
| | - Guojin Jiang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing 400712, China
| | - Xiaochun Zhao
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing 400712, China
| | - Xiuping Zou
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing 400712, China
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Zeng T, Liao P, Zheng C, Gao H, Ye X, Zhou C, Zhou Y. The interaction between the lemon ribosomal protein ClRPS9-2 and citrus yellow vein clearing virus coat protein affects viral infection and gene silencing suppressor activity. MOLECULAR PLANT PATHOLOGY 2023; 24:1047-1062. [PMID: 37148475 PMCID: PMC10423326 DOI: 10.1111/mpp.13347] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 04/12/2023] [Accepted: 04/13/2023] [Indexed: 05/08/2023]
Abstract
Citrus yellow vein clearing virus (CYVCV) is an emerging virus that causes serious economic damage to the lemon industry worldwide. The coat protein (CP) of CYVCV is a strong RNA silencing suppressor and is associated with the severity of symptoms in citrus, yet the interaction between CP and host factors remains unknown. In this study, the 40S ribosomal subunit protein S9-2 (ClRPS9-2) was identified as a CP-binding partner using the yeast two-hybrid system from a lemon (cv. Eureka) cDNA library, and the interaction between CP and ClRPS9-2 was demonstrated by in vivo methods. The results suggest that the N-terminal 8-108 amino acid sequence of ClRPS9-2 is crucial for its interaction with CP and may be associated with the nuclear localization of ClRPS9-2. The accumulation and silencing suppressor activity of CP were reduced by transient expression of ClRPS9-2 in Nicotiana benthamiana. Reverse transcription-quantitative PCR analysis showed that the content of CYVCV in ClRPS9-2 transgenic Eureka lemon plants was approximately 50% of that in CYVCV-infected wild-type plants 1 month after inoculation, and mild yellowing and vein clearing symptoms were observed in the transgenic plants. These findings demonstrate that ClRPS9-2 plays a role in host defensive reactions, and the enhanced resistance of transgenic plants to CYVCV may be associated with the up-regulation of salicylic acid-related and R genes.
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Affiliation(s)
- Ting Zeng
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
| | - Ping Liao
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
| | - Cairong Zheng
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
| | - Haixing Gao
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
| | - Xiao Ye
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
| | - Changyong Zhou
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
| | - Yan Zhou
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
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Su Y, Dai S, Li N, Gentile A, He C, Xu J, Duan K, Wang X, Wang B, Li D. Unleashing the Potential of EIL Transcription Factors in Enhancing Sweet Orange Resistance to Bacterial Pathologies: Genome-Wide Identification and Expression Profiling. Int J Mol Sci 2023; 24:12644. [PMID: 37628825 PMCID: PMC10454048 DOI: 10.3390/ijms241612644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 08/02/2023] [Accepted: 08/05/2023] [Indexed: 08/27/2023] Open
Abstract
The ETHYLENE INSENSITIVE3-LIKE (EIL) family is one of the most important transcription factor (TF) families in plants and is involved in diverse plant physiological and biochemical processes. In this study, ten EIL transcription factors (CsEILs) in sweet orange were systematically characterized via whole-genome analysis. The CsEIL genes were unevenly distributed across the four sweet orange chromosomes. Putative cis-acting regulatory elements (CREs) associated with CsEIL were found to be involved in plant development, as well as responses to biotic and abiotic stress. Notably, quantitative reverse transcription polymerase chain reaction (qRT-PCR) revealed that CsEIL genes were widely expressed in different organs of sweet orange and responded to both high and low temperature, NaCl treatment, and to ethylene-dependent induction of transcription, while eight additionally responded to Xanthomonas citri pv. Citri (Xcc) infection, which causes citrus canker. Among these, CsEIL2, CsEIL5 and CsEIL10 showed pronounced upregulation. Moreover, nine genes exhibited differential expression in response to Candidatus Liberibacter asiaticus (CLas) infection, which causes Citrus Huanglongbing (HLB). The genome-wide characterization and expression profile analysis of CsEIL genes provide insights into the potential functions of the CsEIL family in disease resistance.
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Affiliation(s)
- Yajun Su
- National Citrus Improvement Center, Hunan Agricultural University (Changsha Branch), Changsha 410128, China
- College of Horticulture, Hunan Agricultural University, Changsha 410128, China
- College of Plant Protection, Hunan Agricultural University, Changsha 410128, China (X.W.)
| | - Suming Dai
- National Citrus Improvement Center, Hunan Agricultural University (Changsha Branch), Changsha 410128, China
- College of Horticulture, Hunan Agricultural University, Changsha 410128, China
| | - Na Li
- National Citrus Improvement Center, Hunan Agricultural University (Changsha Branch), Changsha 410128, China
- College of Horticulture, Hunan Agricultural University, Changsha 410128, China
| | - Alessandra Gentile
- Department of Agriculture and Food Science, University of Catania, 95123 Catania, Italy;
| | - Cong He
- National Citrus Improvement Center, Hunan Agricultural University (Changsha Branch), Changsha 410128, China
- College of Horticulture, Hunan Agricultural University, Changsha 410128, China
| | - Jing Xu
- College of Plant Protection, Hunan Agricultural University, Changsha 410128, China (X.W.)
| | - Kangle Duan
- College of Plant Protection, Hunan Agricultural University, Changsha 410128, China (X.W.)
| | - Xue Wang
- College of Plant Protection, Hunan Agricultural University, Changsha 410128, China (X.W.)
| | - Bing Wang
- College of Plant Protection, Hunan Agricultural University, Changsha 410128, China (X.W.)
| | - Dazhi Li
- National Citrus Improvement Center, Hunan Agricultural University (Changsha Branch), Changsha 410128, China
- College of Horticulture, Hunan Agricultural University, Changsha 410128, China
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Wang S, Du M, Dong L, Qu R, Ran D, Ma J, Wang X, Xu L, Li W, He Y, Zou X. Function and molecular mechanism analysis of CaLasSDE460 effector involved in the pathogenesis of "Candidatus Liberibacter asiaticus" in citrus. MOLECULAR HORTICULTURE 2023; 3:14. [PMID: 37789492 PMCID: PMC10514941 DOI: 10.1186/s43897-023-00062-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 07/10/2023] [Indexed: 10/05/2023]
Abstract
Citrus Huanglongbing (HLB), caused by Candidatus Liberibacter asiaticus (CaLas), is the most serious disease worldwide. CaLasSDE460 was previously characterized as a potential virulence factor of CaLas. However, the function and mechanism of CaLasSDE460 involved in CaLas against citrus is still elusive. Here, we showed that transgenic expression of CaLasSDE460 in Wanjincheng oranges (C. sinensis Osbeck) contributed to the early growth of CaLas and the development of symptoms. When the temperature increased from 25 °C to 32 °C, CaLas growth and symptom development in transgenic plants were slower than those in WT controls. RNA-seq analysis of transgenic plants showed that CaLasSDE460 affected multiple biological processes. At 25 °C, transcription activities of the "Protein processing in endoplasmic reticulum" and "Cyanoamino acid metabolism" pathways increased while transcription activities of many pathways decreased at 32 °C. 124 and 53 genes, separately annotated to plant-pathogen interaction and MAPK signaling pathways, showed decreased expression at 32 °C, compared with these (38 for plant-pathogen interaction and 17 for MAPK signaling) at 25 °C. Several important genes (MAPKKK14, HSP70b, NCED3 and WRKY33), remarkably affected by CaLasSDE460, were identified. Totally, our data suggested that CaLasSDE460 participated in the pathogenesis of CaLas through interfering transcription activities of citrus defense response and this interfering was temperature-dependent.
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Affiliation(s)
- Shuai Wang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Meixia Du
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Liting Dong
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Rongrong Qu
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Danlu Ran
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Juanjuan Ma
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Xuefeng Wang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Lanzhen Xu
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Weimin Li
- Key Laboratory for Northern Urban, Agriculture of Ministry of Agriculture and Rural Affairs, Beijing University of Agriculture, Beijing, People's Republic of China
| | - Yongrui He
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Xiuping Zou
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China.
- Key Laboratory for Northern Urban, Agriculture of Ministry of Agriculture and Rural Affairs, Beijing University of Agriculture, Beijing, People's Republic of China.
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de Oliveira Dorta S, Attílio LB, Zanardi OZ, Lopes JRS, Machado MA, Freitas-Astúa J. Genetic transformation of 'Hamlin' and 'Valencia' sweet orange plants expressing the cry11A gene of Bacillus thuringiensis as another tool to the management of Diaphorina citri (Hemiptera: Liviidae). J Biotechnol 2023; 368:60-70. [PMID: 37088156 DOI: 10.1016/j.jbiotec.2023.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 03/29/2023] [Accepted: 04/20/2023] [Indexed: 04/25/2023]
Abstract
The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama (Hemiptera: Liviidae) is the vector of Candidatus Liberibacter spp., the bacteria associated with huanglongbing (HLB), the most devastating disease of citrus worldwide. HLB management has heavily counted on insecticide applications to control the ACP, although there are efforts towards more sustainable alternatives. In previous work, our group assessed the potential bioactivity of different strains of Bacillus thuringiensis (Eubacteriales: Bacillaceae) (Bt) containing cry/cyt genes as feasible tools to control ACP nymphs. Here, we report an attempt to use the cry11A gene from Bt to produce transgenic sweet orange plants using two promoters. For the genetic transformation, 'Hamlin' and 'Valencia' sweet orange seedlings were used as sources of explants. Transgenic plants were detected by polymerase chain reaction (PCR) with specific primers, and the transgene copy number was confirmed by Southern blot analyses. Transcript expression levels were determined by qPCR. Mortality assays of D. citri nymphs were carried out in a greenhouse, and the effect of the events tested ranged from 22 to 43% at the end of the five-day exposure period. To our knowledge, this is the first manuscript reporting the production of citrus plants expressing the Bt cry11A gene for the management of D. citri nymphs.
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Affiliation(s)
- Sílvia de Oliveira Dorta
- Programa de Pós-Graduação em Microbiologia Agrícola, Escola Superior de Agricultura Luiz de Queiroz/Universidade de São Paulo (ESALQ/USP), 13.418-900, Piracicaba, São Paulo, Brazil; Laboratório de Biotecnologia, Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas (IAC), 13.490-970, Cordeirópolis, São Paulo, Brazil.
| | - Lísia Borges Attílio
- Laboratório de Biotecnologia, Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas (IAC), 13.490-970, Cordeirópolis, São Paulo, Brazil; Laboratório de Insetos Vetores de Fitopatógenos, Escola Superior de Agricultura Luiz de Queiroz/Universidade de São Paulo (ESALQ/USP), 13.418-900, Piracicaba, São Paulo, Brazil
| | - Odimar Zanuzo Zanardi
- Departamento de Ensino, Pesquisa e Extensão, Instituto Federal de Santa Catarina (IFSC), 89.900-000, São Miguel do Oeste, Santa Catarina, Brasil
| | - João Roberto Spotti Lopes
- Laboratório de Insetos Vetores de Fitopatógenos, Escola Superior de Agricultura Luiz de Queiroz/Universidade de São Paulo (ESALQ/USP), 13.418-900, Piracicaba, São Paulo, Brazil
| | - Marcos Antonio Machado
- Laboratório de Biotecnologia, Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas (IAC), 13.490-970, Cordeirópolis, São Paulo, Brazil
| | - Juliana Freitas-Astúa
- Embrapa Mandioca e Fruticultura, 44.380-000, Cruz das Almas, Bahia, Brazil; Unidade Laboratorial de Referência em Biologia Molecular Aplicada/Instituto Biológico (ULRBMA/IB), 04.014-900, São Paulo, São Paulo, Brazil.
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10
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Dai WS, Peng T, Wang M, Liu JH. Genome-wide identification and comparative expression profiling of the WRKY transcription factor family in two Citrus species with different Candidatus Liberibacter asiaticus susceptibility. BMC PLANT BIOLOGY 2023; 23:159. [PMID: 36959536 PMCID: PMC10037894 DOI: 10.1186/s12870-023-04156-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND Salicylic Acid (SA) is a pivotal phytohormone in plant innate immunity enhancement of triggered by various pathogens, such as Candidatus Liberibacter asiaticus (CLas), the causal agent of Huanglongbing (HLB). WRKY is a plant specific transcription factor (TF) family, which plays crucial roles in plant response to biotic stresses. So far, the evolutionary history, functions, and expression patterns under SA treatment and CLas infection of WRKY family are poorly understood in Citrus, despite the release of the genome of several Citrus species. A comprehensive genomic and expressional analysis is worth to conduct for this family. RESULTS Here, a genome-wide identification of WRKY TFs was performed in two Citrus species: Citrus sinensis (HLB-sensitive) and Poncirus trifoliata (HLB-tolerant). In total, 52 CsWRKYs and 51 PtrWRKYs were identified, whose physical and chemical properties, chromosome locations, phylogenetic relationships and structural characteristics were comparatively analyzed. Especially, expression patterns of these WRKY genes before and after SA treatment and CLas infection were compared. Based on this result, seven pairs of orthologous WRKY genes showing opposite expression patterns in two Citrus species were screened out. Moreover, two pairs of orthologous WRKY genes with significant differences in the number or type of stress-responsive cis-elements in the promoter regions were discovered. Subcellular localization and transcriptional activation activity assays revealed that these two pairs of orthologous genes are classic WRKY TFs localize in the nucleus and could function as transcriptional activators. CONCLUSION In this study, we systematically analyzed the genomic characterization of WRKY family in two Citrus species, together with the analyses of expression patterns under SA signaling and CLas infection. Our study laid a foundation for further study on the function of WRKY TFs in HLB response and SA signaling of Citrus.
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Affiliation(s)
- Wen-Shan Dai
- College of Life Sciences, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, 341000, China
| | - Ting Peng
- College of Life Sciences, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, 341000, China
| | - Min Wang
- College of Life Sciences, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, 341000, China.
| | - Ji-Hong Liu
- College of Horticulture and Forestry Sciences, National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
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11
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Ghosh D, Kokane S, Savita BK, Kumar P, Sharma AK, Ozcan A, Kokane A, Santra S. Huanglongbing Pandemic: Current Challenges and Emerging Management Strategies. PLANTS (BASEL, SWITZERLAND) 2022; 12:plants12010160. [PMID: 36616289 PMCID: PMC9824665 DOI: 10.3390/plants12010160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 12/06/2022] [Accepted: 12/07/2022] [Indexed: 05/09/2023]
Abstract
Huanglongbing (HLB, aka citrus greening), one of the most devastating diseases of citrus, has wreaked havoc on the global citrus industry in recent decades. The culprit behind such a gloomy scenario is the phloem-limited bacteria "Candidatus Liberibacter asiaticus" (CLas), which are transmitted via psyllid. To date, there are no effective long-termcommercialized control measures for HLB, making it increasingly difficult to prevent the disease spread. To combat HLB effectively, introduction of multipronged management strategies towards controlling CLas population within the phloem system is deemed necessary. This article presents a comprehensive review of up-to-date scientific information about HLB, including currently available management practices and unprecedented challenges associated with the disease control. Additionally, a triangular disease management approach has been introduced targeting pathogen, host, and vector. Pathogen-targeting approaches include (i) inhibition of important proteins of CLas, (ii) use of the most efficient antimicrobial or immunity-inducing compounds to suppress the growth of CLas, and (iii) use of tools to suppress or kill the CLas. Approaches for targeting the host include (i) improvement of the host immune system, (ii) effective use of transgenic variety to build the host's resistance against CLas, and (iii) induction of systemic acquired resistance. Strategies for targeting the vector include (i) chemical and biological control and (ii) eradication of HLB-affected trees. Finally, a hypothetical model for integrated disease management has been discussed to mitigate the HLB pandemic.
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Affiliation(s)
- Dilip Ghosh
- Plant Virology Laboratory, ICAR-Central Citrus Research Institute, Nagpur 440033, India
- Correspondence: (D.G.); (A.K.S.); (S.S.)
| | - Sunil Kokane
- Plant Virology Laboratory, ICAR-Central Citrus Research Institute, Nagpur 440033, India
| | - Brajesh Kumar Savita
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee 247667, India
| | - Pranav Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee 247667, India
| | - Ashwani Kumar Sharma
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee 247667, India
- Correspondence: (D.G.); (A.K.S.); (S.S.)
| | - Ali Ozcan
- Vocational School of Technical Sciences, Karamanoglu Mehmetbey University, 70200 Karaman, Turkey
- Scientific and Technological Studies Application and Research Center, Karamanoglu Mehmetbey University, 70200 Karaman, Turkey
| | - Amol Kokane
- Plant Virology Laboratory, ICAR-Central Citrus Research Institute, Nagpur 440033, India
| | - Swadeshmukul Santra
- Departments of Chemistry, Nano Science Technology Center, and Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL 32816, USA
- Correspondence: (D.G.); (A.K.S.); (S.S.)
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12
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Soares JM, Weber KC, Qiu W, Mahmoud LM, Grosser JW, Dutt M. Overexpression of the salicylic acid binding protein 2 (SABP2) from tobacco enhances tolerance against Huanglongbing in transgenic citrus. PLANT CELL REPORTS 2022; 41:2305-2320. [PMID: 36107199 DOI: 10.1007/s00299-022-02922-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023]
Abstract
Overexpression of the salicylic acid binding protein 2 (SABP2) gene from Tobacco results in enhanced tolerance to Huanglongbing (HLB; citrus greening disease) in transgenic sweet oranges. Huanglongbing (HLB), the most destructive citrus disease, is caused by Candidatus Liberibacter asiaticus (CaLas). Currently, no cure for this disease exists, and all commercially planted cultivars are highly susceptible. Salicylic Acid Binding Protein 2 (SABP2) is a well-characterized protein essential for establishing systemic acquired resistance (SAR) in tobacco. The constitutive over expression of SABP2 from tobacco (NtSABP2) in 'Hamlin' sweet orange resulted in the production of several transgenic lines with variable transcript levels. Transient expression of the NtSABP2-EGFP fusion protein in Nicotiana benthamiana plants demonstrated that NtSABP2 was cytosolic in its subcellular localization. In a long-term field study, we identified a SABP2 transgenic line with significantly reduced HLB symptoms that maintained a consistently low CaLas titer. Transcriptome analysis of this selected transgenic line demonstrated upregulation of several genes related to plant defense and SAR pathways. Genes, such as NPR family genes and those coding for monooxygenases and lipoxygenases, were upregulated in the 35S-NtSABP2 overexpressing line and might be candidates for incorporation into our citrus improvement program.
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Affiliation(s)
- Juliana M Soares
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, 33850, USA
| | - Kyle C Weber
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, 33850, USA
| | - Wenming Qiu
- Institute of Fruit and Tea, Hubei Academy of Agricultural Sciences, Wuhan, 430064, China
| | - Lamiaa M Mahmoud
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, 33850, USA
- Pomology Department, Faculty of Agriculture, Mansoura University, Mansoura, 35516, Egypt
| | - Jude W Grosser
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, 33850, USA
| | - Manjul Dutt
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, 33850, USA.
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13
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Bowen JK, Brummell DA, Gapper NE. Biotechnological approaches for reducing fruit losses caused by pathogenic infection. Curr Opin Biotechnol 2022; 78:102795. [PMID: 36116332 DOI: 10.1016/j.copbio.2022.102795] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/09/2022] [Accepted: 08/12/2022] [Indexed: 12/14/2022]
Abstract
Fruit loss due to disease occurs in both the field and postharvest. Knowledge of host immune responses and pathogen virulence is enabling the formulation of increasingly sophisticated strategies for disease control. Traditional genetic modification, typically involving overexpression of genes involved in pathogen perception and defence responses, is beginning to be superseded by CRISPR-Cas9 manipulation of host susceptibility targets. Moreover, the refinement of RNA interference (RNAi) strategies, including spray-induced gene silencing (SIGS), is allowing more nuanced control options. These latter approaches have the advantage over earlier technologies in that either they do not result in the generation of genetically modified organisms (RNAi-based SIGS), or the genetic manipulation used leaves no trace of introduced genetic material (gene editing). Thus, these strategies may be more widely acceptable for deployment for future disease control.
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Affiliation(s)
- Joanna K Bowen
- The New Zealand Institute for Plant and Food Research Limited, Mount Albert Research Centre, Private Bag 92169, Auckland 1142, New Zealand
| | - David A Brummell
- The New Zealand Institute for Plant and Food Research Limited, Food Industry Science Centre, Private Bag 11600, Palmerston North 4442, New Zealand
| | - Nigel E Gapper
- The New Zealand Institute for Plant and Food Research Limited, Mount Albert Research Centre, Private Bag 92169, Auckland 1142, New Zealand.
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14
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Shen P, Li X, Fu S, Zhou C, Wang X. A " Candidatus Liberibacter asiaticus"-secreted polypeptide suppresses plant immune responses in Nicotiana benthamiana and Citrus sinensis. FRONTIERS IN PLANT SCIENCE 2022; 13:997825. [PMID: 36352861 PMCID: PMC9638108 DOI: 10.3389/fpls.2022.997825] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/23/2022] [Indexed: 05/22/2023]
Abstract
Citrus Huanglongbing (HLB), known as the most economically devastating disease in citrus industry, is mainly caused by phloem-restricted Gram-negative bacterium "Candidatus Liberibacter asiaticus" (CLas). To date, CLas is still unculturable in vitro, which has been dramatically delaying the research on its pathogenesis, and only few Sec-dependent effectors (SDEs) have been identified to elucidate the pathogenesis of CLas. Here, we confirmed that a CLas-secreted Sec-dependent polypeptide, namely SECP8 (CLIBASIA_05330), localized in nucleus, cytoplasm and cytoplasmic membrane, and showed remarkably higher transcript abundance in citrus than in psyllids. Potato virus X (PVX)-mediated transient expression assays indicated that mSECP8 (the mature form of SECP8) suppressed pro-apoptotic mouse protein BAX and Phytophthora infestans elicitin INF1-triggered hypersensitive response (HR) associated phenotypes, including cell death, H2O2 accumulation and callose deposition. Intriguingly, mSECP8 also inhibited SDE1 (CLIBASIA_05315)-induced water-soaked and dwarfing symptoms in Nicotiana benthamiana. In addition, mSECP8 can promote the susceptibility of transgenic Wanjincheng orange (Citrus sinensis) to CLas invasion and further HLB symptom development, and it contributes to the proliferation of Xanthomonas citri subsp. citri (Xcc). Moreover, the expression of ten immunity-related genes were significantly down-regulated in mSECP8 transgenic citrus than those in wide-type (WT) plants. Overall, we propose that mSECP8 may serve as a novel broad-spectrum suppressor of plant immunity, and provide the first evidence counteractive effect among CLas effectors. This study will enrich and provide new evidences for elucidating the pathogenic mechanisms of CLas in citrus host.
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Affiliation(s)
| | | | | | - Changyong Zhou
- National Citrus Engineering Research Center, Citrus Research Institute, Southwest University, Chongqing, China
| | - Xuefeng Wang
- National Citrus Engineering Research Center, Citrus Research Institute, Southwest University, Chongqing, China
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15
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Sharma A, Abrahamian P, Carvalho R, Choudhary M, Paret ML, Vallad GE, Jones JB. Future of Bacterial Disease Management in Crop Production. ANNUAL REVIEW OF PHYTOPATHOLOGY 2022; 60:259-282. [PMID: 35790244 DOI: 10.1146/annurev-phyto-021621-121806] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Bacterial diseases are a constant threat to crop production globally. Current management strategies rely on an array of tactics, including improved cultural practices; application of bactericides, plant activators, and biocontrol agents; and use of resistant varieties when available. However, effective management remains a challenge, as the longevity of deployed tactics is threatened by constantly changing bacterial populations. Increased scrutiny of the impact of pesticides on human and environmental health underscores the need for alternative solutions that are durable, sustainable, accessible to farmers, and environmentally friendly. In this review, we discuss the strengths and shortcomings of existing practices and dissect recent advances that may shape the future of bacterial disease management. We conclude that disease resistance through genome modification may be the most effective arsenal against bacterial diseases. Nonetheless, more research is necessary for developing novel bacterial disease management tactics to meet the food demand of a growing global population.
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Affiliation(s)
- Anuj Sharma
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA;
| | - Peter Abrahamian
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA;
- Gulf Coast Research and Education Center, University of Florida, Wimauma, Florida, USA
- Plant Pathogen Confirmatory Diagnostic Laboratory, USDA-APHIS, Beltsville, Maryland, USA
| | - Renato Carvalho
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA;
| | - Manoj Choudhary
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA;
| | - Mathews L Paret
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA;
- North Florida Research and Education Center, University of Florida, Quincy, Florida, USA
| | - Gary E Vallad
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA;
- Gulf Coast Research and Education Center, University of Florida, Wimauma, Florida, USA
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA;
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16
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Longhi TV, de Carvalho DU, Duin IM, da Cruz MA, Leite Junior RP. Transgenic Sweet Orange Expressing the Sarcotoxin IA Gene Produces High-Quality Fruit and Shows Tolerance to ‘Candidatus Liberibacter asiaticus’. Int J Mol Sci 2022; 23:ijms23169300. [PMID: 36012564 PMCID: PMC9409437 DOI: 10.3390/ijms23169300] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 08/14/2022] [Accepted: 08/15/2022] [Indexed: 12/02/2022] Open
Abstract
Huanglongbing (otherwise known as HLB or greening) is currently the most devastating citrus disease worldwide. HLB is primarily associated with the phloem-inhabiting bacterium ‘Candidatus Liberibacter asiaticus’ (CLas). Currently, there are no citrus species resistant to CLas. Genetic transformation is one of the most effective approaches used to induce resistance against plant diseases. Antimicrobial peptides (AMPs) have shown potential breakthroughs to improve resistance to bacterial diseases in plants. In this paper, we confirm the Agrobacterium-mediated transformation of Pera sweet orange expressing the AMP sarcotoxin IA (stx IA) gene isolated from the flesh fly Sarcophaga peregrina and its reaction to CLas, involving plant performance and fruit quality assessments. Four independent transgenic lines, STX-5, STX-11, STX-12, and STX-13, and a non-transgenic control, were graft-inoculated with CLas. Based on our findings, none of the transgenic plants were immune to CLas. However, the STX-5 and STX-11 lines showed reduced susceptibility to HLB with mild disease symptoms and low incidence of plants with the presence of CLas. Fruit and juice quality were not affected by the genetic transformation. Further, no residues of the sarcotoxin IA protein were found in the juice of the STX-11 and STX-12 fruits, though detected in the juice of the STX-5 and STX-13 lines, as revealed by the immunoblotting test. However, juices from all transgenic lines showed low traces of sarcotoxin IA peptide in its composition. The accumulation of this peptide did not cause any deleterious effects on plants or in fruit/juice. Our findings reinforce the challenges of identifying novel approaches to managing HLB.
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Affiliation(s)
- Talita Vigo Longhi
- Área de Proteção de Plantas, Instituto de Desenvolvimento Rural do Paraná—IAPAR/Emater (IDR-Paraná), Celso Garcia Cid Road, km 375, Londrina 86047-902, PR, Brazil
- Centro de Ciências Agrárias, Universidade Estadual de Londrina (UEL), Celso Garcia Cid Road, km 380, Londrina 86057-970, PR, Brazil
| | - Deived Uilian de Carvalho
- Área de Proteção de Plantas, Instituto de Desenvolvimento Rural do Paraná—IAPAR/Emater (IDR-Paraná), Celso Garcia Cid Road, km 375, Londrina 86047-902, PR, Brazil
- Centro de Ciências Agrárias, Universidade Estadual de Londrina (UEL), Celso Garcia Cid Road, km 380, Londrina 86057-970, PR, Brazil
- Departamento de Pesquisa e Desenvolvimento, Fundo de Defesa da Citricultura (Fundecitrus), 201 Dr. Adhemar Pereira de Barros, Araraquara 14807-040, SP, Brazil
- Correspondence:
| | - Izabela Moura Duin
- Área de Proteção de Plantas, Instituto de Desenvolvimento Rural do Paraná—IAPAR/Emater (IDR-Paraná), Celso Garcia Cid Road, km 375, Londrina 86047-902, PR, Brazil
- Centro de Ciências Agrárias, Universidade Estadual de Londrina (UEL), Celso Garcia Cid Road, km 380, Londrina 86057-970, PR, Brazil
| | - Maria Aparecida da Cruz
- Área de Proteção de Plantas, Instituto de Desenvolvimento Rural do Paraná—IAPAR/Emater (IDR-Paraná), Celso Garcia Cid Road, km 375, Londrina 86047-902, PR, Brazil
- Centro de Ciências Agrárias, Universidade Estadual de Londrina (UEL), Celso Garcia Cid Road, km 380, Londrina 86057-970, PR, Brazil
| | - Rui Pereira Leite Junior
- Área de Proteção de Plantas, Instituto de Desenvolvimento Rural do Paraná—IAPAR/Emater (IDR-Paraná), Celso Garcia Cid Road, km 375, Londrina 86047-902, PR, Brazil
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17
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Du M, Wang S, Dong L, Qu R, Zheng L, He Y, Chen S, Zou X. Overexpression of a " Candidatus Liberibacter Asiaticus" Effector Gene CaLasSDE115 Contributes to Early Colonization in Citrus sinensis. Front Microbiol 2022; 12:797841. [PMID: 35265048 PMCID: PMC8899593 DOI: 10.3389/fmicb.2021.797841] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 12/20/2021] [Indexed: 11/29/2022] Open
Abstract
Huanglongbing (HLB), caused by "Candidatus liberibacter asiaticus" (CaLas), is one of the most devastating diseases in citrus but its pathogenesis remains poorly understood. Here, we reported the role of the CaLasSDE115 (CLIBASIA_05115) effector, encoded by CaLas, during pathogen-host interactions. Bioinformatics analyses showed that CaLasSDE115 was 100% conserved in all reported CaLas strains but had sequence differences compared with orthologs from other "Candidatus liberibacter." Prediction of protein structures suggested that the crystal structure of CaLasSDE115 was very close to that of the invasion-related protein B (IalB), a virulence factor from Bartonella henselae. Alkaline phosphatase (PhoA) assay in E. coli further confirmed that CaLasSDE115 was a Sec-dependent secretory protein while subcellular localization analyses in tobacco showed that the mature protein of SDE115 (mSDE115), without its putative Sec-dependent signal peptide, was distributed in the cytoplasm and the nucleus. Expression levels of CaLasSDE115 in CaLas-infected Asian citrus psyllid (ACP) were much higher (∼45-fold) than those in CaLas-infected Wanjincheng oranges, with the expression in symptomatic leaves being significantly higher than that in asymptomatic ones. Additionally, the overexpression of mSDE115 favored CaLas proliferation during the early stages (2 months) of infection while promoting the development of symptoms. Hormone content and gene expression analysis of transgenic plants also suggested that overexpressing mSDE115 modulated the transcriptional regulation of genes involved in systemic acquired resistance (SAR) response. Overall, our data indicated that CaLasSDE115 effector contributed to the early colonization of citrus by the pathogen and worsened the occurrence of Huanglongbing symptoms, thereby providing a theoretical basis for further exploring the pathogenic mechanisms of Huanglongbing disease in citrus.
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Affiliation(s)
| | | | | | | | | | | | | | - Xiuping Zou
- National Citrus Engineering Research Center, Citrus Research Institute, Southwest University, Chongqing, China
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18
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Tian T, Xie W, Liu L, Fan S, Zhang H, Qin Z, Yang C. Industrial application of antimicrobial peptides based on their biological activity and structure-activity relationship. Crit Rev Food Sci Nutr 2021:1-16. [PMID: 34955061 DOI: 10.1080/10408398.2021.2019673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Last several years, a rapid increase in drug resistance to traditional antibiotics has driven the emergence and development of antimicrobial peptides (AMPs). AMPs have also gained considerable attention from scientists due to their high potency in combatting infectious pathogens. A subset of analogues and their derivatives with specific targets have been successfully designed based on natural peptide patterns. In this review, scientific knowledge on the mechanisms of action related to biological activity and structure-activity relationship (SAR) of AMPs are summarized, and the biological applications in several important fields are critically discussed. SAR shows that the positive charge, secondary structure, special amino acid residues, hydrophobicity, and helicity of AMPs are closely related to their biological activities. The combination of nanotechnology, bioinformatics, and genetic engineering can accelerate to achieve the application of AMPs as effective, safe, economical, and nonresistant antimicrobial agents in medicine, the food and feed industries, and agriculture in coming years. Given the intense interest in AMPs, further investigations are needed in the future to evaluate the specific structure and function that make their use favorable in several industries. This review may provide a comprehensive reference for future studies on chemical modifications, mechanistic exploration, and applications of AMPs.
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Affiliation(s)
- Tiantian Tian
- Center for Biological Science and Technology, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Wansheng Xie
- Hainan Center for Drug and Medical Device Evaluation and Service, Hainan Provincial Drug Administration, Haikou, Hainan, China
| | - Luxuan Liu
- Center for Biological Science and Technology, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Siting Fan
- Center for Biological Science and Technology, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Heqian Zhang
- Center for Biological Science and Technology, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Zhiwei Qin
- Center for Biological Science and Technology, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Chao Yang
- Center for Biological Science and Technology, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China.,State Key Laboratory of Quality Research in Chinese Medicine/Macau Institute for Applied research in Medicine and Health, University of Science and Technology, Taipa, Macao, China
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19
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Xue A, Liu Y, Li H, Cui M, Huang X, Wang W, Wu D, Guo X, Hao Y, Luo L. Early detection of Huanglongbing with EESI-MS indicates a role of phenylpropanoid pathway in citrus. Anal Biochem 2021; 639:114511. [PMID: 34883070 DOI: 10.1016/j.ab.2021.114511] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/15/2021] [Accepted: 12/01/2021] [Indexed: 12/22/2022]
Abstract
Huanglongbing (HLB), a devastating disease for citrus worldwide, is caused by Candidatus Liberibacter asiaticus (CLas). In this study, we employed a novel extractive electrospray ionization-mass spectrometry (EESI-MS) method to analyze the metabolites in leaves of uninfected and HLB-infected Newhall navel orange. The results showed that uninfected and HLB-infected leaves could be readily distinguished based on EESI-MS combined by multivariable analysis. Nine phenolic compounds involved in phenylpropanoid pathway, such as p-coumaric acid, naringin, and apigenin, were principal components to distinguish the leaves of uninfected and HLB-infected Newhall navel orange. Gene expression was also conducted to further explore the molecular mechanism of phenylpropanoid branch pathway in HLB. The expression of genes (4CL, HCT, CHI, CHS, CYP, and C12R) involved in phenylpropanoid branch pathway was increased in asymptomatic and early period of HLB-infected leaves, while decreased in later period of HLB-infected leaves. This study provides a novel method for early detection of citrus HLB and suggests the regulation mechanism of phenylpropanoid pathway in the interaction between citrus and CLas.
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Affiliation(s)
- Ahui Xue
- School of Life Sciences, Nanchang University, Nanchang, 330031, China
| | - Yongquan Liu
- School of Life Sciences, Nanchang University, Nanchang, 330031, China
| | - Haoxing Li
- School of Life Sciences, Nanchang University, Nanchang, 330031, China
| | - Meng Cui
- School of Life Sciences, Nanchang University, Nanchang, 330031, China
| | - Xueyong Huang
- School of Life Sciences, Nanchang University, Nanchang, 330031, China
| | - Wenjing Wang
- School of Life Sciences, Nanchang University, Nanchang, 330031, China
| | - Dong Wu
- School of Life Sciences, Nanchang University, Nanchang, 330031, China
| | - Xiali Guo
- School of Life Sciences, Nanchang University, Nanchang, 330031, China
| | - Yingbin Hao
- School of Life Sciences, Nanchang University, Nanchang, 330031, China
| | - Liping Luo
- School of Life Sciences, Nanchang University, Nanchang, 330031, China; State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, 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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21
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Merritt BA, Zhang X, Triplett EW, Mou Z, Orbović V. Selection of transgenic citrus plants based on glyphosate tolerance conferred by a citrus 5-enolpyruvylshikimate-3-phosphate synthase variant. PLANT CELL REPORTS 2021; 40:1947-1956. [PMID: 34313832 DOI: 10.1007/s00299-021-02760-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 07/19/2021] [Indexed: 05/21/2023]
Abstract
KEY MESSAGE We have defined the conditions for citrus transformations using glyphosate as selection agent. This protocol results in high transformation rate and low incidence of chimeric shoots. Glyphosate, the most widely used herbicide in the world, specifically inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), an essential enzyme of the shikimate pathway. Various laboratory-generated or naturally evolved glyphosate-resistant EPSPS variants have been used to produce glyphosate-tolerant transgenic crops, enabling highly effective weed control in agriculture. In this study, we explored the potential of using a citrus EPSPS variant that mimics the previously reported Eleusine indica glyphosate-resistant TIPS (T102I + P106S) mutant for selection of transgenic citrus plants in the presence of glyphosate. We found that glyphosate did not suppress bud formation on 'Duncan' grapefruit seedling explants, but inhibited non-transgenic bud outgrowth to produce shoots in a concentration-dependent manner. At certain concentrations, glyphosate had dramatic effect on the transformation rate and the percentage of non-chimeric transgenic shoots in this newly developed selection system. Specifically, at 0, 10, 20, and 50 μM of glyphosate, the citrus TIPS EPSPS-based selection resulted in transformation rates of 4.02, 5.04, 14.46, and 40.78%, respectively, and 6.41, 23.96, 42.94, and 40.17% of non-chimeric transgenic shoots, respectively. These results indicate that the citrus TIPS EPSPS-glyphosate selection system is highly efficient and can be used as an alternative to antibiotic-based selection methods in citrus genetic transformation. Furthermore, the selection conditions defined in this study are expected to greatly facilitate the production of genetically modified, market-friendly citrus plants, such as cisgenic and intragenic plants.
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Affiliation(s)
- Benjamin A Merritt
- Citrus Research and Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred, FL, 33850, USA
| | - Xudong Zhang
- Department of Microbiology and Cell Science, University of Florida, P.O. Box 110700, Gainesville, FL, 32611, USA
| | - Eric W Triplett
- Department of Microbiology and Cell Science, University of Florida, P.O. Box 110700, Gainesville, FL, 32611, USA
| | - Zhonglin Mou
- Department of Microbiology and Cell Science, University of Florida, P.O. Box 110700, Gainesville, FL, 32611, USA.
| | - Vladimir Orbović
- Citrus Research and Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred, FL, 33850, USA.
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22
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Lobato-Gómez M, Hewitt S, Capell T, Christou P, Dhingra A, Girón-Calva PS. Transgenic and genome-edited fruits: background, constraints, benefits, and commercial opportunities. HORTICULTURE RESEARCH 2021; 8:166. [PMID: 34274949 PMCID: PMC8286259 DOI: 10.1038/s41438-021-00601-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/14/2021] [Accepted: 05/20/2021] [Indexed: 05/14/2023]
Abstract
Breeding has been used successfully for many years in the fruit industry, giving rise to most of today's commercial fruit cultivars. More recently, new molecular breeding techniques have addressed some of the constraints of conventional breeding. However, the development and commercial introduction of such novel fruits has been slow and limited with only five genetically engineered fruits currently produced as commercial varieties-virus-resistant papaya and squash were commercialized 25 years ago, whereas insect-resistant eggplant, non-browning apple, and pink-fleshed pineapple have been approved for commercialization within the last 6 years and production continues to increase every year. Advances in molecular genetics, particularly the new wave of genome editing technologies, provide opportunities to develop new fruit cultivars more rapidly. Our review, emphasizes the socioeconomic impact of current commercial fruit cultivars developed by genetic engineering and the potential impact of genome editing on the development of improved cultivars at an accelerated rate.
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Affiliation(s)
- Maria Lobato-Gómez
- Department of Crop and Forest Sciences, University of Lleida-Agrotecnio CERCA Center, Lleida, 25198, Spain
| | - Seanna Hewitt
- Department of Horticulture, Washington State University, PO Box, 646414, Pullman, WA, USA
| | - Teresa Capell
- Department of Crop and Forest Sciences, University of Lleida-Agrotecnio CERCA Center, Lleida, 25198, Spain
| | - Paul Christou
- Department of Crop and Forest Sciences, University of Lleida-Agrotecnio CERCA Center, Lleida, 25198, Spain
- ICREA, Catalan Institute for Research and Advanced Studies, 08010, Barcelona, Spain
| | - Amit Dhingra
- Department of Horticulture, Washington State University, PO Box, 646414, Pullman, WA, USA
| | - Patricia Sarai Girón-Calva
- Department of Crop and Forest Sciences, University of Lleida-Agrotecnio CERCA Center, Lleida, 25198, Spain.
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23
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Alquézar B, Carmona L, Bennici S, Peña L. Engineering of citrus to obtain huanglongbing resistance. Curr Opin Biotechnol 2021; 70:196-203. [PMID: 34198205 DOI: 10.1016/j.copbio.2021.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 06/04/2021] [Accepted: 06/07/2021] [Indexed: 12/23/2022]
Abstract
Huanglongbing (HLB) disease is threatening the sustainability of citriculture in affected regions because of its rapid spread and the severity of the symptoms it induces. Herein, we summarise the main research findings that can be exploited to develop HLB-resistant cultivars. A major bottleneck has been the lack of a system for the ex vivo cultivation of HLB-associated bacteria (CLs) in true plant hosts, which precludes the evaluation of target genes/metabolites in reliable plant/pathogen/vector environments. With regard to HLB vectors, several biotechnologies which have been proven in laboratory settings to be effective for insect control are presented. Finally, new genotypes that are resistant to CLs or their insect vectors are described, and the most relevant strategies for fighting HLB are highlighted.
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Affiliation(s)
- Berta Alquézar
- Laboratório de Biotecnologia Vegetal, Pesquisa & Desenvolvimento, Fundo de Defesa da Citricultura (Fundecitrus), Vila Melhado, 14807-040 Araraquara, São Paulo, Brazil; Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Politécnica de Valencia (UPV), 46022 Valencia, Spain
| | - Lourdes Carmona
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Politécnica de Valencia (UPV), 46022 Valencia, Spain
| | - Stefania Bennici
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Politécnica de Valencia (UPV), 46022 Valencia, Spain
| | - Leandro Peña
- Laboratório de Biotecnologia Vegetal, Pesquisa & Desenvolvimento, Fundo de Defesa da Citricultura (Fundecitrus), Vila Melhado, 14807-040 Araraquara, São Paulo, Brazil; Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Politécnica de Valencia (UPV), 46022 Valencia, Spain.
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24
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Pyramiding the antimicrobial PR1aCB and AATCB genes in 'Tarocco' blood orange (Citrus sinensis Osbeck) to enhance citrus canker resistance. Transgenic Res 2021; 30:635-647. [PMID: 34076822 DOI: 10.1007/s11248-021-00245-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 03/17/2021] [Indexed: 01/14/2023]
Abstract
Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc), is a major bacterial disease responsible for substantial economic losses in citrus-producing areas. To breed transgenic citrus plants with enhanced resistance to citrus canker, two antimicrobial peptide genes, PR1aCB and AATCB, were incorporated into 'Tarocco' blood orange (Citrus sinensis Osbeck) plants via co-transformation and sequential re-transformation. The presence of PR1aCB and AATCB in double transgenic plants was confirmed by PCR. The expression of PR1aCB and AATCB in double transformants was demonstrated by quantitative real-time PCR. An in vivo disease resistance assay involving the injection of Xcc revealed that the double transformants were more resistant to citrus canker than the single gene transformants and wild-type plants. An analysis of the bacterial population indicated that the enhanced citrus canker resistance of the double transformants was due to inhibited Xcc growth. These results proved that the pyramiding of multiple genes is a more effective strategy for increasing the disease resistance of transgenic citrus plants than single gene transformations.
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25
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Park AR, Kim SW, Kim SY, Kwon KC. Expression of Antimicrobial Peptide (AMP), Cecropin B, in a Fused Form to SUMO Tag With or Without Three-Glycine Linker in Escherichia coli and Evaluation of Bacteriolytic Activity of the Purified AMP. Probiotics Antimicrob Proteins 2021; 13:1780-1789. [PMID: 34018140 PMCID: PMC8578067 DOI: 10.1007/s12602-021-09797-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/06/2021] [Indexed: 01/10/2023]
Abstract
Current antibiotics have limited action mode, which makes it difficult for the antibiotics dealing with the emergence of bacteria resisting the existing antibiotics. As a need for new bacteriolytic agents alternative to the antibiotics, AMPs have long been considered substitutes for the antibiotics. Cecropin B was expressed in a fusion form to six-histidine and SUMO tags in Escherichia coli. Six-histidine tag attached to SUMO was for purification of SUMO-cecropin B fusion proteins and removal of the SUMO tag from cecropin B. Chimeric gene was constructed into pKSEC1 vector that was designed to be functional in both Escherichia coli and chloroplast. To maximize translation of the fusion protein, sequences were codon-optimized. Four different constructs were tested for the level of expression and solubility, and the construct with a linker, 6xHisSUMO3xGly-cecropin B, showed the highest expression. In addition, cleavage of the SUMO tag by SUMOase in the three fusion constructs which have no linker sequence (3xGly, three glycines) was not as efficient as the construct with the linker between SUMO and cecropin B. The cleaved cecropin B showed bacteriolytic activity against Bacillus subtilis at a concentration of 0.0625 μg/μL, while cecropin B fused to SUMO had no activity at a higher concentration, 0.125 μg/μL. As an expression system for AMPs in prokaryotic hosts, the use of tag proteins and appropriate codon-optimization strategy can be employed and further genetic modification of the fusion construct should help the complete removal of the tag proteins from the AMP in the final step of purification.
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Affiliation(s)
- A Rom Park
- Department of Biological Sciences, Andong National University, Andong, Korea
| | - Seon Woong Kim
- Department of Biological Sciences, Andong National University, Andong, Korea
| | - Soon Young Kim
- Department of Biological Sciences, Andong National University, Andong, Korea.
| | - Kwang-Chul Kwon
- MicroSynbiotiX Ltd, 11011 N Torrey Pines Rd Ste #135, La Jolla, CA, 92037, USA.
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26
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" Candidatus Liberibacter asiaticus" Secretes Nonclassically Secreted Proteins That Suppress Host Hypersensitive Cell Death and Induce Expression of Plant Pathogenesis-Related Proteins. Appl Environ Microbiol 2021; 87:AEM.00019-21. [PMID: 33579681 PMCID: PMC8091116 DOI: 10.1128/aem.00019-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although emerging evidence indicates that bacteria extracellularly export many cytoplasmic proteins referred to as non-classically secreted proteins (ncSecPs) for their own benefit, the mechanisms and functional significance of the ncSecPs in extracellular milieu remain elusive. "Candidatus Liberibacter asiaticus" (CLas) is a fastidious Gram-negative bacterium that causes Huanglongbing (HLB), the most globally devastating citrus disease. In this study, using the SecretomeP program coupled with an Escherichia coli alkaline phosphatase assay, we identified 27 ncSecPs from the CLas genome. Further, we demonstrated that 10 of these exhibited significantly higher levels of gene expression in citrus than in psyllid hosts, and particularly suppressed hypersensitive response (HR)-based cell death and H2O2 overaccumulation in Nicotiana benthamiana, indicating their opposing effects on early plant defenses. However, these proteins also dramatically enhanced the gene expression of pathogenesis-related 1 protein (PR-1), PR-2, and PR-5, essential components of plant defense mechanisms. Additional experiments disclosed that the increased expression of these PR genes, in particular PR-1 and PR-5, could negatively regulate HR-based cell death development and H2O2 accumulation. Remarkably, CLas infection clearly induced gene expression of PR-1, PR-2, and PR-5 in both HLB-tolerant and HLB-susceptible species of citrus plants. Taken together, we hypothesized that CLas has evolved an arsenal of ncSecPs that function cooperatively to overwhelm the early plant defenses by inducing host PR genes.IMPORTANCE In this study, we present a combined computational and experimental methodology that allows a rapid and efficient identification of the ncSecPs from bacteria, in particular the unculturable bacteria like CLas. Meanwhile, the study determined that a number of CLas ncSecPs suppressed HR-based cell death, and thus indicated a novel role for the bacterial ncSecPs in extracellular milieu. More importantly, these ncSecPs were found to suppress cell death presumably by utilizing host PR proteins. The data overall provide a novel clue to understand the CLas pathogenesis and also suggest a new way by which phytopathogens manipulate host cellular machinery to establish infection.
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27
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Zou X, Zhao K, Liu Y, Du M, Zheng L, Wang S, Xu L, Peng A, He Y, Long Q, Chen S. Overexpression of Salicylic Acid Carboxyl Methyltransferase ( CsSAMT1) Enhances Tolerance to Huanglongbing Disease in Wanjincheng Orange ( Citrus sinensis (L.) Osbeck). Int J Mol Sci 2021; 22:ijms22062803. [PMID: 33802058 PMCID: PMC7999837 DOI: 10.3390/ijms22062803] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/05/2021] [Accepted: 03/08/2021] [Indexed: 11/30/2022] Open
Abstract
Citrus Huanglongbing (HLB) disease or citrus greening is caused by Candidatus Liberibacter asiaticus (Las) and is the most devastating disease in the global citrus industry. Salicylic acid (SA) plays a central role in regulating plant defenses against pathogenic attack. SA methyltransferase (SAMT) modulates SA homeostasis by converting SA to methyl salicylate (MeSA). Here, we report on the functions of the citrus SAMT (CsSAMT1) gene from HLB-susceptible Wanjincheng orange (Citrus sinensis (L.) Osbeck) in plant defenses against Las infection. The CsSAMT1 cDNA was expressed in yeast. Using in vitro enzyme assays, yeast expressing CsSAMT1 was confirmed to specifically catalyze the formation of MeSA using SA as a substrate. Transgenic Wanjincheng orange plants overexpressing CsSAMT1 had significantly increased levels of SA and MeSA compared to wild-type controls. HLB resistance was evaluated for two years and showed that transgenic plants displayed significantly alleviated symptoms including a lack of chlorosis, low bacterial counts, reduced hyperplasia of the phloem cells, and lower levels of starch and callose compared to wild-type plants. These data confirmed that CsSAMT1 overexpression confers an enhanced tolerance to Las in citrus fruits. RNA-seq analysis revealed that CsSAMT1 overexpression significantly upregulated the citrus defense response by enhancing the transcription of disease resistance genes. This study provides insight for improving host resistance to HLB by manipulation of SA signaling in citrus fruits.
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28
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Peng A, Zou X, He Y, Chen S, Liu X, Zhang J, Zhang Q, Xie Z, Long J, Zhao X. Overexpressing a NPR1-like gene from Citrus paradisi enhanced Huanglongbing resistance in C. sinensis. PLANT CELL REPORTS 2021; 40:529-541. [PMID: 33386424 DOI: 10.1007/s00299-020-02648-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 12/01/2020] [Indexed: 05/21/2023]
Abstract
Overexpression of CiNPR4 enhanced resistance of transgenic citrus plants to Huanglongbing by perceiving the salicylic acid and jasmonic acid signals and up-regulating the transcriptional activities of plant-pathogen interaction genes. Developing transgenic citrus plants with enhanced immunity is an efficient strategy to control citrus Huanglongbing (HLB). Here, a nonexpressor of pathogenesis-related gene 1 (NPR1) like gene from HLB-tolerant 'Jackson' grapefruit (Citrus paradisi Macf.), CiNPR4, was introduced into 'Wanjincheng' orange (Citrus sinensis Obseck). CiNPR4 expression was determined in transgenic citrus plants using quantitative real-time PCR analyses. The Candidatus Liberibacter asiaticus (CLas) pathogen of HLB was successfully transmitted to transgenic citrus plants by grafting infected buds. HLB symptoms developed in transgenic and wild-type (WT) plants by 9 months after inoculation. A CLas population analysis showed that 26.9% of transgenic lines exhibited significantly lower CLas titer levels compared with the CLas-infected WT plants at 21 months after inoculation. Lower starch contents and anatomical aberration levels in the phloem were observed in transgenic lines having enhanced resistance compared with CLas-infected WT plants. CiNPR4 overexpression changed the jasmonic acid, but not salicylic acid, level. Additionally, the jasmonic acid and salicylic acid levels increased after CLas infection. Transcriptome analyses revealed that the enhanced resistance of transgenic plants to HLB resulted from the up-regulated transcriptional activities of plant-pathogen interaction-related genes.
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Affiliation(s)
- Aihong Peng
- Citrus Research Institute, Southwest University, National Citrus Engineering Research Center, Chongqing, 400712, People's Republic of China
| | - Xiuping Zou
- Citrus Research Institute, Southwest University, National Citrus Engineering Research Center, Chongqing, 400712, People's Republic of China.
| | - Yongrui He
- Citrus Research Institute, Southwest University, National Citrus Engineering Research Center, Chongqing, 400712, People's Republic of China
| | - Shanchun Chen
- Citrus Research Institute, Southwest University, National Citrus Engineering Research Center, Chongqing, 400712, People's Republic of China
| | - Xiaofeng Liu
- Citrus Research Institute, Southwest University, National Citrus Engineering Research Center, Chongqing, 400712, People's Republic of China
| | - Jingyun Zhang
- Citrus Research Institute, Southwest University, National Citrus Engineering Research Center, Chongqing, 400712, People's Republic of China
| | - Qingwen Zhang
- Citrus Research Institute, Southwest University, National Citrus Engineering Research Center, Chongqing, 400712, People's Republic of China
| | - Zhu Xie
- Citrus Research Institute, Southwest University, National Citrus Engineering Research Center, Chongqing, 400712, People's Republic of China
| | - Junhong Long
- Citrus Research Institute, Southwest University, National Citrus Engineering Research Center, Chongqing, 400712, People's Republic of China
| | - Xiaochun Zhao
- Citrus Research Institute, Southwest University, National Citrus Engineering Research Center, Chongqing, 400712, People's Republic of China
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29
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Wang Y, Bao Y, Zheng Y, Guo P, Peng D, Wang B. Promoter P PSP1-5- BnPSP-1 From Ramie ( Boehmeria nivea L. Gaud.) Can Drive Phloem-Specific GUS Expression in Arabidopsis thaliana. Front Genet 2021; 11:553265. [PMID: 33391335 PMCID: PMC7772962 DOI: 10.3389/fgene.2020.553265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 11/26/2020] [Indexed: 11/21/2022] Open
Abstract
Isolation of phloem-specific promoters is one of the basic conditions for improving the fiber development and resistance of ramie phloem using genetic engineering. In this study, we isolated a ramie endogenous promoter (named PPSP1-BnPSP-1) and analyzed the function of its truncated fragments in Arabidopsis. The results show that PPSP1-BnPSP-1 can drive the GUS reporter gene to be specifically expressed in the veins of Arabidopsis. After hormone and simulated drought treatment of the independent Arabidopsis lines carrying PPSP1-BnPSP-1 and its truncated fragments, only PPSP1–5-BnPSP-1 (−600 to −1 bp region of PPSP1-BnPSP-1) is stably expressed and exhibits phloem specificity. Our findings suggest that PPSP1–5-BnPSP-1 can be used as a phloem specific promoter for further research.
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Affiliation(s)
- Yunhe Wang
- MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Yaning Bao
- MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China.,College of Tobacco Science, University of Guizhou, Guiyang, China
| | - Yancheng Zheng
- MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Ping'an Guo
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, University of Hubei Normal, Huangshi, China
| | - Dingxiang Peng
- MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Bo Wang
- MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
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30
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Munir S, Li Y, He P, He P, He P, Cui W, Wu Y, Li X, Li Q, Zhang S, Xiong Y, Lu Z, Wang W, Zong K, Yang Y, Yang S, Mu C, Wen H, Wang Y, Guo J, Karunarathna SC, He Y. Defeating Huanglongbing Pathogen Candidatus Liberibacter asiaticus With Indigenous Citrus Endophyte Bacillus subtilis L1-21. FRONTIERS IN PLANT SCIENCE 2021; 12:789065. [PMID: 35126416 PMCID: PMC8813962 DOI: 10.3389/fpls.2021.789065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 11/26/2021] [Indexed: 05/11/2023]
Abstract
Huanglongbing (HLB) has turned into a devastating botanical pandemic of citrus crops, caused by Candidatus Liberibacter asiaticus (CLas). However, until now the disease has remained incurable with very limited control strategies available. Restoration of the affected microbiomes in the diseased host through the introduction of an indigenous endophyte Bacillus subtilis L1-21 isolated from healthy citrus may provide an innovative approach for disease management. A novel half-leaf method was developed in vitro to test the efficacy of the endophyte L1-21 against CLas. Application of B. subtilis L1-21 at 104 colony forming unit (cfu ml-1) resulted in a 1,000-fold reduction in the CLas copies per gram of leaf midrib (107 to 104) in 4 days. In HLB-affected citrus orchards over a period of 2 years, the CLas incidence was reduced to < 3%, and CLas copies declined from 109 to 104 g-1 of diseased leaf midribs in the endophyte L1-21 treated trees. Reduction in disease incidence may corroborate a direct or an indirect biocontrol effect of the endophytes as red fluorescent protein-labeled B. subtilis L1-21 colonized and shared niche (phloem) with CLas. This is the first large-scale study for establishing a sustainable HLB control strategy through citrus endophytic microbiome restructuring using an indigenous endophyte.
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Affiliation(s)
- Shahzad Munir
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Yongmei Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Pengbo He
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Pengfei He
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Pengjie He
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Wenyan Cui
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Yixin Wu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Xingyu Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Qi Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Sixiang Zhang
- Binchuan Institute for Food and Medicine Inspection and Testing, Binchuan, China
| | - Yangsu Xiong
- Binchuan Institute for Food and Medicine Inspection and Testing, Binchuan, China
| | - Zhanjun Lu
- College of Life Sciences, Gannan Normal University, Ganzhou, China
| | - Wenbiao Wang
- Binchuan Institute for Food and Medicine Inspection and Testing, Binchuan, China
| | - Kexian Zong
- Binchuan Institute for Food and Medicine Inspection and Testing, Binchuan, China
| | - Yongchao Yang
- Institute of Upland Crops, Wenshan Academy of Agricultural Sciences, Wenshan, China
| | - Shaocong Yang
- Institute of Crop Fertilization, Yuxi Academy of Agricultural Sciences, Yuxi, China
| | - Chan Mu
- Institute of Crop Fertilization, Yuxi Academy of Agricultural Sciences, Yuxi, China
| | - Heming Wen
- Institute of Upland Crops, Wenshan Academy of Agricultural Sciences, Wenshan, China
| | - Yuehu Wang
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences (CAS), Kunming, China
| | - Jun Guo
- Institute of Tropical and Subtropical Cash Crops, Yunnan Academy of Agricultural Sciences, Baoshan, China
| | - Samantha C. Karunarathna
- Center for Mountain Futures (CMF), Kunming Institute of Botany, Chinese Academy of Sciences (CAS), Kunming, China
| | - Yueqiu He
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
- *Correspondence: Yueqiu He
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Dasgupta K, Hotton S, Belknap W, Syed Y, Dardick C, Thilmony R, Thomson JG. Isolation of novel citrus and plum fruit promoters and their functional characterization for fruit biotechnology. BMC Biotechnol 2020; 20:43. [PMID: 32819338 PMCID: PMC7439555 DOI: 10.1186/s12896-020-00635-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 08/02/2020] [Indexed: 01/22/2023] Open
Abstract
Background Promoters that confer expression in fruit tissues are important tools for genetic engineering of fruit quality traits, yet few fruit-specific promoters have been identified, particularly for citrus fruit development. Results In this study, we report five citrus fruit-specific/preferential promoters for genetic engineering. Additionally, we have characterized a novel fruit-preferential promoter from plum. Genes specifically expressed in fruit tissues were selected and their isolated promoter regions were fused with the GUSPlus reporter gene for evaluation in transgenic plants. Stable transformation in Micro-Tom tomato demonstrated that the candidate promoter regions exhibit differing levels of expression and with varying degrees of fruit specificity. Conclusions Among the five candidate citrus promoters characterized in this study, the CitSEP promoter showed a fruit-specific expression pattern, while the CitWAX and CitJuSac promoters exhibited high fruit-preferential expression with strong activity in the fruit, weak activity in floral tissues and low or undetectable activity in other tissues. The CitVO1, CitUNK and PamMybA promoters, while exhibiting strong fruit-preferential expression, also showed consistent weak but detectable activity in leaves and other vegetative tissues. Use of these fruit specific/preferential promoters for genetic engineering can help with precise expression of beneficial genes and help with accurate prediction of the activity of new genes in host fruit plants.
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Affiliation(s)
- Kasturi Dasgupta
- Citrus Research Board, Visalia, CA, USA.,Crop Improvement and Genetics, Western Regional Research Center, USDA-ARS, Albany, CA, USA.,Present address: Impossible Foods, Redwood City, CA, 94063, USA
| | - Sara Hotton
- Crop Improvement and Genetics, Western Regional Research Center, USDA-ARS, Albany, CA, USA
| | - William Belknap
- Crop Improvement and Genetics, Western Regional Research Center, USDA-ARS, Albany, CA, USA
| | - Yasra Syed
- Crop Improvement and Genetics, Western Regional Research Center, USDA-ARS, Albany, CA, USA
| | - Christopher Dardick
- Genetic Improvement of Fruit Crops using advanced Genomics and Breeding Technologies, Kearneysville, WV, USA
| | - Roger Thilmony
- Crop Improvement and Genetics, Western Regional Research Center, USDA-ARS, Albany, CA, USA.
| | - James G Thomson
- Crop Improvement and Genetics, Western Regional Research Center, USDA-ARS, Albany, CA, USA.
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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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Heterologous Expression of the Constitutive Disease Resistance 2 and 8 Genes from Poncirus trifoliata Restored the Hypersensitive Response and Resistance of Arabidopsis cdr1 Mutant to Bacterial Pathogen Pseudomonas syringae. PLANTS 2020; 9:plants9070821. [PMID: 32629813 PMCID: PMC7412121 DOI: 10.3390/plants9070821] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/19/2020] [Accepted: 06/29/2020] [Indexed: 01/23/2023]
Abstract
Huanglongbing (HLB), also known as citrus greening, is the most destructive disease of citrus worldwide. In the United States, this disease is associated with a phloem-restricted bacterium, Candidatus Liberibacter asiaticus. Commercial citrus cultivars are susceptible to HLB, but Poncirus trifoliata, a close relative of Citrus, is highly tolerant of HLB. Isolating P. trifoliata gene(s) controlling its HLB tolerance followed by expressing the gene(s) in citrus is considered a potential cisgenic approach to engineering citrus for tolerance to HLB. Previous gene expression studies indicated that the constitutive disease resistance (CDR) genes in P. trifoliata (PtCDRs) may play a vital role in its HLB tolerance. This study was designed to use Arabidopsis mutants as a model system to confirm the function of PtCDRs in plant disease resistance. PtCDR2 and PtCDR8 were amplified from P. trifoliata cDNA and transferred into the Arabidopsis cdr1 mutant, whose resident CDR1 gene was disrupted by T-DNA insertion. The PtCDR2 and PtCDR8 transgenic Arabidopsis cdr1 mutant restored its hypersensitive response to the bacterial pathogen Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000) expressing avrRpt2. The defense marker gene PATHOGENESIS RELATED 1 (PR1) expressed at much higher levels in the PtCDR2 or PtCDR8 transgenic cdr1 mutant than in the non-transgenic cdr1 mutant with or without pathogen infection. Multiplication of Pst DC3000 bacteria in Arabidopsis was inhibited by the expression of PtCDR2 and PtCDR8. Our results showed that PtCDR2 and PtCDR8 were functional in Arabidopsis and played a positive role in disease resistance and demonstrated that Arabidopsis mutants can be a useful alternate system for screening Poncirus genes before making the time-consuming effort to transfer them into citrus, a perennial woody plant that is highly recalcitrant for Agrobacterium or biolistic-mediated transformation.
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Direct identification and metabolomic analysis of Huanglongbing associated with Candidatus Liberibacter spp. in navel orange by MALDI-TOF-MS. Anal Bioanal Chem 2020; 412:3091-3101. [DOI: 10.1007/s00216-020-02555-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/23/2020] [Accepted: 02/27/2020] [Indexed: 01/09/2023]
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Li H, Ying X, Shang L, Redfern B, Kypraios N, Xie X, Xu F, Wang S, Zhang J, Jian H, Yu H, Lv D. Heterologous Expression of CLIBASIA_03915/CLIBASIA_04250 by Tobacco Mosaic Virus Resulted in Phloem Necrosis in the Senescent Leaves of Nicotiana benthamiana. Int J Mol Sci 2020; 21:E1414. [PMID: 32093101 PMCID: PMC7073121 DOI: 10.3390/ijms21041414] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 02/15/2020] [Accepted: 02/17/2020] [Indexed: 12/02/2022] Open
Abstract
Huanglongbing (HLB), also known as citrus greening, is the most notorious citrus disease worldwide. Candidatus Liberibacter asiaticus (CaLas) is a phloem-restricted bacterium associated with HLB. Because there is no mutant library available, the pathogenesis of CaLas is obscure. In this study, we employed tobacco mosaic virus (TMV) to express two mature secretion proteins CLIBASIA_03915 (m03915) and CLIBASIA_04250 (m04250) in Nicotiana benthamiana (N. benthamiana). Phloem necrosis was observed in the senescent leaves of N. benthamiana that expressed the two low molecular weight proteins, while no phloem necrosis was observed in the plants that expressed the control, green fluorescent protein (GFP). Additionally, no phloem necrosis was observed in the senescent leaves of N. benthamiana that expressed the null mutation of m03915 and frameshifting m04250. The subcellular localizations of m03915 and m04250 were determined by fusion with GFP using confocal microscopy. The subcellular localization of m03915 was found to be as free GFP without a nuclear localization sequence (NLS). However, m04250 did have an NLS. Yeast two-hybrid (Y2H) was carried out to probe the citrus proteins interacting with m03915 and m04250. Six citrus proteins were found to interact with m03915. The identified proteins were involved in the metabolism of compounds, transcription, response to abiotic stress, ubiquitin-mediated protein degradation, etc. The prey of m04250 was involved in the processing of specific pre-mRNAs. Identification of new virulence factors of CaLas will give insight into the pathogenesis of CaLas, and therefore, it will eventually help develop the HLB-resistant citrus.
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Affiliation(s)
- Hui Li
- College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China; (H.L.); (L.S.); (H.J.)
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Chongqing 400715, China
| | - Xiaobao Ying
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598, USA; (X.Y.); (B.R.); (N.K.)
| | - Lina Shang
- College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China; (H.L.); (L.S.); (H.J.)
| | - Bryce Redfern
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598, USA; (X.Y.); (B.R.); (N.K.)
| | - Nicholas Kypraios
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598, USA; (X.Y.); (B.R.); (N.K.)
| | - Xuejun Xie
- Changzhou Institute of Technology, Changzhou 213032, China;
| | - FeiFei Xu
- Heilongjiang Academy of Agricultural Sciences, Harbin 10086, China (S.W.); (J.Z.); (H.Y.)
| | - Shaopeng Wang
- Heilongjiang Academy of Agricultural Sciences, Harbin 10086, China (S.W.); (J.Z.); (H.Y.)
| | - Jinghua Zhang
- Heilongjiang Academy of Agricultural Sciences, Harbin 10086, China (S.W.); (J.Z.); (H.Y.)
| | - Hongju Jian
- College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China; (H.L.); (L.S.); (H.J.)
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Chongqing 400715, China
| | - Hongtao Yu
- Heilongjiang Academy of Agricultural Sciences, Harbin 10086, China (S.W.); (J.Z.); (H.Y.)
| | - Dianqiu Lv
- College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China; (H.L.); (L.S.); (H.J.)
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Chongqing 400715, China
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Munir S, Li Y, He P, He P, Ahmed A, Wu Y, He Y. Unraveling the metabolite signature of citrus showing defense response towards Candidatus Liberibacter asiaticus after application of endophyte Bacillus subtilis L1-21. Microbiol Res 2020; 234:126425. [PMID: 32035248 DOI: 10.1016/j.micres.2020.126425] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/17/2020] [Accepted: 01/30/2020] [Indexed: 10/25/2022]
Abstract
Huanglongbing (HLB) is one of the most serious citrus diseases, caused by phloem limited endophytic bacteria Candidatus Liberibacter asiaticus (Clas), affecting worldwide citrus production. Metabolomics approaches were employed to gain insight into mechanisms involved in defense against Clas in endophyte Bacillus subtilis L1-21 treated diseased and healthy citrus plants. Using LC-ESI-MS/MS, we compared the metabolic profile of citrus plants before and after treatment with endophyte L1-21. Our analysis indicated large differences in citrus metabolites after endophyte L1-21 application. In total, seven hundred and fourty two metabolites were detected with highest percentage recorded for organic acids, flavone, amino acid derivatives, flavone C-glycosides, nucleotide derivatives, and flavonol. Interestingly, differentially expressed metabolites (DEMs) analysis revealed the amino acids, such as lysine and tyrosine which are involved in plant defense agianst pathogen attack were regulated in diseased citrus plants after endophyte application (padj<0.05). In addition, other important metabolites up-regulated were xanthine, leucic acid, and α-Linolenic acid implicated in different plant defense pathways against Clas. Furhter, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed important pathways related to purine metabolism, biotin metabolism, and betalain biosynthesis, terpenoid-quinone biosynthesis, phenylalanine, tyrosine and lysine biosynthesis, isoflavonoid biosynthesis (padj<0.05). Taken together, this is the first study using native endophytes in diseased and healthy state of citrus which has proven to be useful in disease management by strengthening the defense of citrus to Clas pathogen.
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Affiliation(s)
- Shahzad Munir
- State Key Laboratory for Conservation and Utilization of Bio-resources in Yunnan, Yunnan Agricultural University, Kunming 650201, Yunnan, China
| | - Yongmei Li
- State Key Laboratory for Conservation and Utilization of Bio-resources in Yunnan, Yunnan Agricultural University, Kunming 650201, Yunnan, China
| | - Pengfei He
- State Key Laboratory for Conservation and Utilization of Bio-resources in Yunnan, Yunnan Agricultural University, Kunming 650201, Yunnan, China
| | - Pengbo He
- State Key Laboratory for Conservation and Utilization of Bio-resources in Yunnan, Yunnan Agricultural University, Kunming 650201, Yunnan, China
| | - Ayesha Ahmed
- State Key Laboratory for Conservation and Utilization of Bio-resources in Yunnan, Yunnan Agricultural University, Kunming 650201, Yunnan, China
| | - Yixin Wu
- National and Local Joint Engineering Research Center for Screening and Application of Microbial Strains, Kunming 650217, Yunnan, China; College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming 650201, Yunnan, China
| | - Yueqiu He
- State Key Laboratory for Conservation and Utilization of Bio-resources in Yunnan, Yunnan Agricultural University, Kunming 650201, Yunnan, China; National and Local Joint Engineering Research Center for Screening and Application of Microbial Strains, Kunming 650217, Yunnan, China; College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming 650201, Yunnan, China.
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Overexpressing GH3.1 and GH3.1L reduces susceptibility to Xanthomonas citri subsp. citri by repressing auxin signaling in citrus (Citrus sinensis Osbeck). PLoS One 2019; 14:e0220017. [PMID: 31830052 PMCID: PMC6907806 DOI: 10.1371/journal.pone.0220017] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 11/16/2019] [Indexed: 12/11/2022] Open
Abstract
The auxin early response gene Gretchen Hagen3 (GH3) plays dual roles in plant development and responses to biotic or abiotic stress. It functions in regulating hormone homeostasis through the conjugation of free auxin to amino acids. In citrus, GH3.1 and GH3.1L play important roles in responding to Xanthomonas citri subsp. citri (Xcc). Here, in Wanjingcheng orange (Citrus sinensis Osbeck), the overexpression of CsGH3.1 and CsGH3.1L caused increased branching and drooping dwarfism, as well as smaller, thinner and upward curling leaves compared with wild-type. Hormone determinations showed that overexpressing CsGH3.1 and CsGH3.1L decreased the free auxin contents and accelerated the Xcc-induced decline of free auxin levels in transgenic plants. A resistance analysis showed that transgenic plants had reduced susceptibility to citrus canker, and a transcriptomic analysis revealed that hormone signal transduction-related pathways were significantly affected by the overexpression of CsGH3.1 and CsGH3.1L. A MapMan analysis further showed that overexpressing either of these two genes significantly downregulated the expression levels of the annotated auxin/indole-3-acetic acid family genes and significantly upregulated biotic stress-related functions and pathways. Salicylic acid, jasmonic acid, abscisic acid, ethylene and zeatin levels in transgenic plants displayed obvious changes compared with wild-type. In particular, the salicylic acid and ethylene levels involved in plant resistance responses markedly increased in transgenic plants. Thus, the overexpression of CsGH3.1 and CsGH3.1L reduces plant susceptibility to citrus canker by repressing auxin signaling and enhancing defense responses. Our study demonstrates auxin homeostasis' potential in engineering disease resistance in citrus.
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Li J, Pang Z, Duan S, Lee D, Kolbasov VG, Wang N. The in Planta Effective Concentration of Oxytetracycline Against ' Candidatus Liberibacter asiaticus' for Suppression of Citrus Huanglongbing. PHYTOPATHOLOGY 2019; 109:2046-2054. [PMID: 31369360 DOI: 10.1094/phyto-06-19-0198-r] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Huanglongbing (HLB) or greening currently is the most devastating citrus disease worldwide. The fastidious phloem-colonizing bacterium 'Candidatus Liberibacter asiaticus' (CLas) is the causal agent of citrus HLB in Florida. Bactericides containing the active ingredient oxytetracycline (OTC) have been used in foliar spray to control citrus HLB in Florida since 2016. However, the minimum concentration of OTC required to suppress CLas in planta remains unknown. We developed a new method for evaluating the effects of OTC treatment on CLas titers in infected plants and determined the relationship between OTC residue levels and control levels achieved for CLas using mathematical modeling in greenhouse and field experiments. In both greenhouse and field, OTC spray did not reduce the titers of CLas, and it produced undetectable or mild levels of OTC residue in leaves within 7 days post-application (DPA). In greenhouse, OTC injection at 0.05 g per tree decreased CLas titers to an undetectable level (cycle threshold value ≥ 36.0) from 7 to 30 DPA and produced a residue level of OTC at 0.68 to 0.73 µg/g of fresh tissue over this period. In the field, OTC injection at 0.50 g per tree resulted in the decline of CLas titers by 1.52 log reduction from 14 to 60 DPA, with residue levels of OTC at 0.27 to 0.33 µg/g of fresh tissue. In both trials, a first-order compart model of OTC residue dynamics in leaves of trunk-injected trees was specified for estimating the retention of effective concentrations. Furthermore, nonlinear modeling revealed significant positive correlations between OTC residue levels in leaves and the control levels for CLas achieved. The results suggested that the minimum concentrations of OTC required to suppress CLas populations in planta to below the detection limit are 0.68 and 0.86 µg/g and that the minimum concentrations of OTC required for initial inhibition of CLas growth in planta are ∼0.17 and ∼0.215 µg/g in leaf tissues under greenhouse and field conditions, respectively. This finding highlights that a minimum concentration of OTC should be guaranteed to be delivered to target CLas in infected plants for effective control of citrus HLB.
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Affiliation(s)
- Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Zhiqian Pang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Shuo Duan
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Donghwan Lee
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Vladimir G Kolbasov
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
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Abstract
Approaches to manipulating disease resistance in plants is expanding exponentially due to advances in our understanding of plant defense mechanisms and new tools for manipulating the plant genome. The application of effective strategies is only limited now by adoption of rapid classical genetic techniques and the acceptance of genetically engineered traits for some problems. The use of genome editing and cis-genetics, where possible, may facilitate applications that otherwise require considerable time or genetic engineering, depending on settling legal definitions of the products. Nonetheless, the variety of approaches to developing disease resistance has never been greater.
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Affiliation(s)
- Anuj Sharma
- Department of Plant Pathology, University of Florida, Gainesville, FL, USA
| | - Jeffrey B. Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL, USA
| | - Frank F. White
- Department of Plant Pathology, University of Florida, Gainesville, FL, USA
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Sun L, Ke F, Nie Z, Wang P, Xu J. Citrus Genetic Engineering for Disease Resistance: Past, Present and Future. Int J Mol Sci 2019; 20:E5256. [PMID: 31652763 PMCID: PMC6862092 DOI: 10.3390/ijms20215256] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/20/2019] [Accepted: 10/21/2019] [Indexed: 11/16/2022] Open
Abstract
Worldwide, citrus is one of the most important fruit crops and is grown in more than 130 countries, predominantly in tropical and subtropical areas. The healthy progress of the citrus industry has been seriously affected by biotic and abiotic stresses. Several diseases, such as canker and huanglongbing, etc., rigorously affect citrus plant growth, fruit quality, and yield. Genetic engineering technologies, such as genetic transformation and genome editing, represent successful and attractive approaches for developing disease-resistant crops. These genetic engineering technologies have been widely used to develop citrus disease-resistant varieties against canker, huanglongbing, and many other fungal and viral diseases. Recently, clustered regularly interspaced short palindromic repeats (CRISPR)-based systems have made genome editing an indispensable genetic manipulation tool that has been applied to many crops, including citrus. The improved CRISPR systems, such as CRISPR/CRISPR-associated protein (Cas)9 and CRISPR/Cpf1 systems, can provide a promising new corridor for generating citrus varieties that are resistant to different pathogens. The advances in biotechnological tools and the complete genome sequence of several citrus species will undoubtedly improve the breeding for citrus disease resistance with a much greater degree of precision. Here, we attempt to summarize the recent successful progress that has been achieved in the effective application of genetic engineering and genome editing technologies to obtain citrus disease-resistant (bacterial, fungal, and virus) crops. Furthermore, we also discuss the opportunities and challenges of genetic engineering and genome editing technologies for citrus disease resistance.
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Affiliation(s)
- Lifang Sun
- Institute of Citrus Research, Zhejiang Academy of Agricultural Sciences, Taizhou 318026, China.
- National Center for Citrus Variety Improvement, Zhejiang Branch, Taizhou 318026, China.
| | - Fuzhi Ke
- Institute of Citrus Research, Zhejiang Academy of Agricultural Sciences, Taizhou 318026, China.
- National Center for Citrus Variety Improvement, Zhejiang Branch, Taizhou 318026, China.
| | - Zhenpeng Nie
- Institute of Citrus Research, Zhejiang Academy of Agricultural Sciences, Taizhou 318026, China.
- National Center for Citrus Variety Improvement, Zhejiang Branch, Taizhou 318026, China.
| | - Ping Wang
- Institute of Citrus Research, Zhejiang Academy of Agricultural Sciences, Taizhou 318026, China.
- National Center for Citrus Variety Improvement, Zhejiang Branch, Taizhou 318026, China.
| | - Jianguo Xu
- Institute of Citrus Research, Zhejiang Academy of Agricultural Sciences, Taizhou 318026, China.
- National Center for Citrus Variety Improvement, Zhejiang Branch, Taizhou 318026, China.
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Tang J, Ding Y, Nan J, Yang X, Sun L, Zhao X, Jiang L. Transcriptome sequencing and ITRAQ reveal the detoxification mechanism of Bacillus GJ1, a potential biocontrol agent for Huanglongbing. PLoS One 2018; 13:e0200427. [PMID: 30091977 PMCID: PMC6084860 DOI: 10.1371/journal.pone.0200427] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 06/26/2018] [Indexed: 11/18/2022] Open
Abstract
Huanglongbing (HLB) is the most serious disease affecting citrus production worldwide. No HLB-resistant citrus varieties exist. The HLB pathogen Candidatus Liberibacter asiaticus is nonculturable, increasing the difficulty of preventing and curing the disease. We successfully screened the biocontrol agent Bacillus GJ1 for the control of HLB in nursery-grown citrus plants. RNA sequencing (RNA-seq) of the transcriptome and isobaric tags for relative and absolute quantification of the proteome revealed differences in the detoxification responses of Bacillus GJ1-treated and -untreated Ca. L. asiaticus-infected citrus. Phylogenetic tree alignment showed that GJ1 was classified as B. amyloliquefaciens. The effect of eliminating the HLB pathogen was measured using real-time quantitative polymerase chain reaction (qPCR) and PCR. The results indicate that the rate of detoxification reached 50% after seven irrigations, of plants with an OD600nm≈1 Bacillus GJ1 suspension. Most importantly, photosynthesis-antenna proteins, photosynthesis, plant-pathogen interactions, and protein processing in the endoplasmic reticulum were significantly upregulated (padj < 0.05), as shown by the KEGG enrichment analysis of the transcriptomes; nine of the upregulated genes were validated by qPCR. Transcription factor analysis of the transcriptomes was performed, and 10 TFs were validated by qPCR. Cyanoamino acid metabolism, regulation of autophagy, isoflavonoid biosynthesis, starch and sucrose metabolism, protein export, porphyrin and chlorophyll metabolism, and carotenoid biosynthesis were investigated by KEGG enrichment analysis of the proteome, and significant differences were found in the expression of the genes involved in those pathways. Correlation analysis of the proteome and transcriptome showed common entries for the significantly different expression of proteins and the significantly different expression of genes in the GO and KEGG pathways, respectively. The above results reveal important information about the detoxification pathways.
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Affiliation(s)
- Jizhou Tang
- College of Horticulture and Forestry, Key Laboratory of Horticultural Plant Biology of Ministry of Education, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yuanxi Ding
- College of Horticulture and Forestry, Key Laboratory of Horticultural Plant Biology of Ministry of Education, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Jing Nan
- College of Horticulture and Forestry, Key Laboratory of Horticultural Plant Biology of Ministry of Education, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Xiangyu Yang
- College of Horticulture and Forestry, Key Laboratory of Horticultural Plant Biology of Ministry of Education, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Liang Sun
- College of Horticulture and Forestry, Key Laboratory of Horticultural Plant Biology of Ministry of Education, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Xiuyun Zhao
- College of life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China.,State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Ling Jiang
- College of Horticulture and Forestry, Key Laboratory of Horticultural Plant Biology of Ministry of Education, Huazhong Agricultural University, Wuhan, Hubei, China.,National Indoor Conservation Center of Virus-free Germplasm of Fruit Crops, Huazhong Agricultural University, Wuhan, Hubei, China
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Hao G, Zhang S, Stover E. Transgenic expression of antimicrobial peptide D2A21 confers resistance to diseases incited by Pseudomonas syringae pv. tabaci and Xanthomonas citri, but not Candidatus Liberibacter asiaticus. PLoS One 2017; 12:e0186810. [PMID: 29049366 PMCID: PMC5648250 DOI: 10.1371/journal.pone.0186810] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 10/06/2017] [Indexed: 11/18/2022] Open
Abstract
Citrus Huanglongbing (HLB) associated with 'Candidatus Liberibacter asiaticus' (Las) and citrus canker disease incited by Xanthomonas citri are the most devastating citrus diseases worldwide. To control citrus HLB and canker disease, we previously screened over forty antimicrobial peptides (AMPs) in vitro for their potential application in genetic engineering. D2A21 was one of the most active AMPs against X. citri, Agrobacterium tumefaciens and Sinorhizobium meliloti with low hemolysis activity. Therefore, we conducted this work to assess transgenic expression of D2A21 peptide to achieve citrus resistant to canker and HLB. We generated a construct expressing D2A21 and initially transformed tobacco as a model plant. Transgenic tobacco expressing D2A21 was obtained by Agrobacterium-mediated transformation. Successful transformation and D2A21 expression was confirmed by molecular analysis. We evaluated disease development incited by Pseudomonas syringae pv. tabaci in transgenic tobacco. Transgenic tobacco plants expressing D2A21 showed remarkable disease resistance compared to control plants. Therefore, we performed citrus transformations with the same construct and obtained transgenic Carrizo citrange. Gene integration and gene expression in transgenic plants were determined by PCR and RT-qPCR. Transgenic Carrizo expressing D2A21 showed significant canker resistance while the control plants showed clear canker symptoms following both leaf infiltration and spray inoculation with X. citri 3213. Transgenic Carrizo plants were challenged for HLB evaluation by grafting with Las infected rough lemon buds. Las titer was determined by qPCR in the leaves and roots of transgenic and control plants. However, our results showed that transgenic plants expressing D2A21 did not significantly reduce Las titer compared to control plants. We demonstrated that transgenic expression of D2A21 conferred resistance to diseases incited by P. syringae pv. tabaci and X. citri but not Las. Our results underscore the difficulty in controlling HLB compared to other bacterial diseases.
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Affiliation(s)
- Guixia Hao
- U. S. Horticultural Research Laboratory, USDA-ARS, Fort Pierce, FL, United States of America
| | - Shujian Zhang
- U. S. Horticultural Research Laboratory, USDA-ARS, Fort Pierce, FL, United States of America
| | - Ed Stover
- U. S. Horticultural Research Laboratory, USDA-ARS, Fort Pierce, FL, United States of America
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