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Núñez-Muñoz LA, Sánchez-García ME, Calderón-Pérez B, De la Torre-Almaraz R, Ruiz-Medrano R, Xoconostle-Cázares B. Metagenomic Analysis of Rhizospheric Bacterial Community of Citrus Trees Expressing Phloem-Directed Antimicrobials. MICROBIAL ECOLOGY 2024; 87:93. [PMID: 39008123 PMCID: PMC11249458 DOI: 10.1007/s00248-024-02408-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2024] [Accepted: 07/05/2024] [Indexed: 07/16/2024]
Abstract
Huanglongbing, also known as citrus greening, is currently the most devastating citrus disease with limited success in prevention and mitigation. A promising strategy for Huanglongbing control is the use of antimicrobials fused to a carrier protein (phloem protein of 16 kDa or PP16) that targets vascular tissues. This study investigated the effects of genetically modified citrus trees expressing Citrus sinensis PP16 (CsPP16) fused to human lysozyme and β-defensin-2 on the soil microbiome diversity using 16S amplicon analysis. The results indicated that there were no significant alterations in alpha diversity, beta diversity, phylogenetic diversity, differential abundance, or functional prediction between the antimicrobial phloem-overexpressing plants and the control group, suggesting minimal impact on microbial community structure. However, microbiota diversity analysis revealed distinct bacterial assemblages between the rhizosphere soil and root environments. This study helps to understand the ecological implications of crops expressing phloem-targeted antimicrobials for vascular disease management, with minimal impact on soil microbiota.
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Affiliation(s)
- Leandro Alberto Núñez-Muñoz
- Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Mexico City, Mexico
| | - Martín Eduardo Sánchez-García
- Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Mexico City, Mexico
| | - Berenice Calderón-Pérez
- Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Mexico City, Mexico
| | - Rodolfo De la Torre-Almaraz
- Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, 54090, Mexico City, Estado de México, Mexico
| | - Roberto Ruiz-Medrano
- Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Mexico City, Mexico
- Centro de Investigación y de Estudios Avanzados, Programa de Doctorado Transdisciplinario en Desarrollo Científico y Tecnológico Para La Sociedad, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Mexico City, Mexico
| | - Beatriz Xoconostle-Cázares
- Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Mexico City, Mexico.
- Centro de Investigación y de Estudios Avanzados, Programa de Doctorado Transdisciplinario en Desarrollo Científico y Tecnológico Para La Sociedad, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Mexico City, Mexico.
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Pandey SS, Li J, Oswalt C, Wang N. Dynamics of ' Candidatus Liberibacter asiaticus' Growth, Concentrations of Reactive Oxygen Species, and Ion Leakage in Huanglongbing-Positive Sweet Orange. PHYTOPATHOLOGY 2024; 114:961-970. [PMID: 38478730 DOI: 10.1094/phyto-08-23-0294-kc] [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: 05/08/2024]
Abstract
Citrus Huanglongbing (HLB) caused by 'Candidatus Liberibacter asiaticus' (CLas) is the most devastating citrus disease worldwide. CLas induces systemic and chronic reactive oxygen species (ROS) production, which has been suggested to be a primary cause of cell death in phloem tissues and subsequent HLB symptoms. Mitigating oxidative stress caused by CLas using horticultural approaches has been suggested as a useful strategy to reduce HLB damages. To provide information regarding the application timing to mitigate ROS, we investigated monthly dynamics of CLas concentration, CLas-triggered ROS, and phloem cell death in the bark tissues of asymptomatic and symptomatic branches of HLB-positive Hamlin and Valencia sweet orange trees in the field. Healthy branches in the screenhouse were used as controls. CLas concentration exhibited significant variations over the course of the year, with two distinct peaks observed in Florida citrus groves-late spring/early summer and late fall. Within both Hamlin and Valencia asymptomatic tissues, CLas concentration demonstrated a negative correlation with the deviation between the monthly average mean temperature and the optimal temperature for CLas colonization in plants (25.7°C). However, such a correlation was not evident in symptomatic tissues of Hamlin or Valencia sweet oranges. ROS levels were consistently higher in symptomatic or asymptomatic branches than in healthy branches in most months. ROS concentrations were higher in symptomatic branches than in asymptomatic branches in most months. CLas triggered significant increases in ion leakage in most months for asymptomatic and symptomatic branches compared with healthy controls. In asymptomatic branches of Hamlin, a positive correlation was observed between CLas concentration and ROS concentrations, CLas concentration and ion leakage levels, as well as ROS and ion leakage. Intriguingly, such a relationship was not observed in Valencia asymptomatic branches or in the symptomatic branches of Hamlin and Valencia. This study sheds light on the pathogenicity of CLas by providing useful information on the temporal dynamics of ROS production, phloem cell death, and CLas growth, as well as provides useful information in determining the timing for application of antioxidants and antimicrobial agents to control HLB.
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Affiliation(s)
- Sheo Shankar Pandey
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850, U.S.A
- Current affiliation: Life Sciences Division, Institute of Advanced Study in Science and Technology (IASST), Guwahati 781035, India
| | - Jinyun Li
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850, U.S.A
| | - Chris Oswalt
- Institute of Food and Agricultural Sciences, University of Florida, Bartow, FL 33830, U.S.A
| | - Nian Wang
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850, U.S.A
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Guerrero-Santos R, Cabrales-Orona G, Délano-Frier JP, Cabello-Romero J, Torres-Lubián JR, Valenzuela-Soto JH. Trunk Injection of Citrus Trees with a Polymeric Nanobactericide Reduces Huanglongbing Severity Caused by Candidatus Liberibacter asiaticus. THE PLANT PATHOLOGY JOURNAL 2024; 40:139-150. [PMID: 38606444 PMCID: PMC11016554 DOI: 10.5423/ppj.oa.12.2023.0165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 02/06/2024] [Accepted: 02/18/2024] [Indexed: 04/13/2024]
Abstract
Huanglongbing (HLB) is a disease caused by the phloem- limited Candidatus Liberibacter asiaticus (CLas) that affects the citrus industry worldwide. To date, only indirect strategies have been implemented to eradicate HLB. Included among these is the population control of the psyllid vector (Diaphorina citri), which usually provides inconsistent results. Even though strategies for direct CLas suppression seem a priori more promising, only a handful of reports have been focused on a confrontation of the pathogen. Recent developments in polymer chemistry have allowed the design of polycationic self-assembled block copolymers with outstanding antibacterial capabilities. Here, we report the use of polymeric nano-sized bactericide particles (PNB) to control CLas directly in the phloem vasculature. The field experiments were performed in Rioverde, San Luis Potosí, and is one of the most important citrusproducing regions in Mexico. An average 52% reduction in the bacterial population was produced when PNB was injected directly into the trunk of 20 infected trees, although, in some cases, reduction levels reached 97%. These results position PNB as a novel and promising nanotechnological tool for citrus crop protection against CLas and other related pathogens.
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Affiliation(s)
- Ramiro Guerrero-Santos
- Centro de Investigación en Química Aplicada, Boulevard Enrique Reyna No. 140, 25294, Saltillo, México
| | - Gabriela Cabrales-Orona
- Centro de Investigación y de Estudios Avanzados del IPN, Unidad Irapuato, Irapuato, 36821, Guanajuato, México
| | - John Paul Délano-Frier
- Centro de Investigación y de Estudios Avanzados del IPN, Unidad Irapuato, Irapuato, 36821, Guanajuato, México
| | - Judith Cabello-Romero
- Centro de Investigación en Química Aplicada, Boulevard Enrique Reyna No. 140, 25294, Saltillo, México
| | - José Román Torres-Lubián
- Centro de Investigación en Química Aplicada, Boulevard Enrique Reyna No. 140, 25294, Saltillo, México
| | - José Humberto Valenzuela-Soto
- Centro de Investigación en Química Aplicada, Boulevard Enrique Reyna No. 140, 25294, Saltillo, México
- CONAHCyT-Centro de Investigación en Química Aplicada, Boulevard Enrique Reyna Hermosillo 140, Saltillo, 25294, Coahuila, México
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Zhu F, Cao MY, Zhang QP, Mohan R, Schar J, Mitchell M, Chen H, Liu F, Wang D, Fu ZQ. Join the green team: Inducers of plant immunity in the plant disease sustainable control toolbox. J Adv Res 2024; 57:15-42. [PMID: 37142184 PMCID: PMC10918366 DOI: 10.1016/j.jare.2023.04.016] [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: 02/20/2023] [Revised: 04/13/2023] [Accepted: 04/25/2023] [Indexed: 05/06/2023] Open
Abstract
BACKGROUND Crops are constantly attacked by various pathogens. These pathogenic microorganisms, such as fungi, oomycetes, bacteria, viruses, and nematodes, threaten global food security by causing detrimental crop diseases that generate tremendous quality and yield losses worldwide. Chemical pesticides have undoubtedly reduced crop damage; however, in addition to increasing the cost of agricultural production, the extensive use of chemical pesticides comes with environmental and social costs. Therefore, it is necessary to vigorously develop sustainable disease prevention and control strategies to promote the transition from traditional chemical control to modern green technologies. Plants possess sophisticated and efficient defense mechanisms against a wide range of pathogens naturally. Immune induction technology based on plant immunity inducers can prime plant defense mechanisms and greatly decrease the occurrence and severity of plant diseases. Reducing the use of agrochemicals is an effective way to minimize environmental pollution and promote agricultural safety. AIM OF REVIEW The purpose of this workis to offer valuable insights into the current understanding and future research perspectives of plant immunity inducers and their uses in plant disease control, ecological and environmental protection, and sustainable development of agriculture. KEY SCIENTIFIC CONCEPTS OF REVIEW In this work, we have introduced the concepts of sustainable and environment-friendly concepts of green disease prevention and control technologies based on plant immunity inducers. This article comprehensively summarizes these recent advances, emphasizes the importance of sustainable disease prevention and control technologies for food security, and highlights the diverse functions of plant immunity inducers-mediated disease resistance. The challenges encountered in the potential applications of plant immunity inducers and future research orientation are also discussed.
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Affiliation(s)
- Feng Zhu
- College of Plant Protection, Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu 225009, China.
| | - Meng-Yao Cao
- College of Plant Protection, Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Qi-Ping Zhang
- College of Plant Protection, Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | | | - Jacob Schar
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | | | - Huan Chen
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA; Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, Jiangsu 210014, China
| | - Fengquan Liu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, Jiangsu 210014, China
| | - Daowen Wang
- State Key Laboratory of Wheat and Maize Crop Science, College of Agronomy, and Center for Crop Genome Engineering, Henan Agricultural University, Zhengzhou 450002, China
| | - Zheng Qing Fu
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA.
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Widyawan A, Al-Saleh MA, El Komy MH, Al Dhafer HM, Ibrahim YE. Potential of resistance inducers for citrus huanglongbing management via soil application and assessment of induction of pathogenesis-related protein genes. Heliyon 2023; 9:e19715. [PMID: 37809984 PMCID: PMC10558989 DOI: 10.1016/j.heliyon.2023.e19715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 08/30/2023] [Accepted: 08/30/2023] [Indexed: 10/10/2023] Open
Abstract
Huanglongbing (HLB) or citrus greening currently is the most devastating citrus disease worldwide. Unfortunately, no practical cure has been available up to now. This makes the control of HLB as early as possible very important to be conducted. The objective of this study was to investigate the efficacy of the application of salicylic acid (SA) and Phenylacetic acid (PAA) on one-year-old seedlings of different citrus species (Citrus reticulata, C. sinensis, C. aurantifolii) growing on C. volkameriana and C. aurantium by soil drench methods. Factorial analysis of variance showed the percent change in "Candidatus Liberibacter asiaticus" titer and disease severity on a different combination of citrus species growing on the two rootstocks treated with inducers and Oxytetracycline (OTC) were significantly different compared to the untreated plants. SA alone or in combination with OTC provided excellent (P-value < 0.05) control of HLB based on all parameters. The interaction between both factors (Rootstocks x Citrus species) significantly influenced the Ct value (P-value = 0.0001). "Candidatus Liberibacter asiaticus" titer in plants treated with OTC was reduced significantly with a range of -18.75 up to -78.42. Overall, the highest reduction was observed in the application of OTC on sweet orange growing on C. volkameriana (-78.42), while the lowest reduction was observed in the same cultivar which was treated with a combination of SA and OTC (-3.36). Induction of pathogenesis-related (PR) genes, i.e., PR1, PR2, and PR15, biosynthesis of Jasmonic acid and ethylene which are also important pathways to defense activity were also significantly increased in treated plants compared to untreated plants. This study suggests that the application of inducer alone is acceptable for HLB management. We proposed the application of SA and PAA as a soil drench on the citrus seedlings as promising, easy, and environmentally safe for HLB disease control on citrus seedlings.
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Affiliation(s)
- Arya Widyawan
- Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, Saudi Arabia
| | - Mohammed A. Al-Saleh
- Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, Saudi Arabia
| | - Mahmoud H. El Komy
- Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, Saudi Arabia
| | - Hathal M. Al Dhafer
- Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, Saudi Arabia
| | - Yasser E. Ibrahim
- Plant Protection Department, College of Food and Agriculture Sciences, King Saud University, Saudi Arabia
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Luo X, Zhang Y, Liu X, Zou Y, Song H, Wang S, Chen J. Screening Method and Antibacterial Activity of 1,3,4-Oxadiazole Sulfone Compounds against Citrus Huanglongbing. Int J Mol Sci 2023; 24:10515. [PMID: 37445692 DOI: 10.3390/ijms241310515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 06/10/2023] [Accepted: 06/16/2023] [Indexed: 07/15/2023] Open
Abstract
Citrus Huanglongbing (HLB) is one of the most destructive diseases in the citrus industry. At present, Candidatus Liberibacter asiaticus (CLas) cannot be cultured in vitro, and there is a lack of rapid methods to test antibacterial activity, which greatly hinders the discovery of new antibacterial agents against HLB. To establish a rapid screening method for antibacterial agents against HLB with simple operation, a short cycle, and a large number of tests, the CLas contents in leaves from different citrus branches, different leaves from the same citrus branch, and two halves of the same citrus leaf were detected. Compared with the leaves on different branches and different leaves on the same branch, the difference in CLas content of the left and right halves of the same leaf was small; the difference was basically between 0.7 and 1.3. A rapid and efficient method for primary screening agents against HLB termed the "half-leaf method" was established through our long-term optimization and improvement. To verify the stability and reliability of the activity data measured using this method, 6-chloropurine riboside, which is highly soluble in water, was used as the test agent, and its antibacterial activity against HLB was tested 45 times. The results of the antibacterial activity test showed little difference in the mean values of each data group, indicating that this method could be used as a rapid method for screening agents against HLB. We used this method to test the antibacterial activity of compounds synthesized by our research group against HLB and found that some of the compounds showed good activity.
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Affiliation(s)
- Xin Luo
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Yong Zhang
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Xing Liu
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Yue Zou
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Hongyi Song
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Sheng Wang
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Jixiang Chen
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
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Gao J, Tao T, Arthurs SP, Ye F, An X, Hussain M, Mao R. Plant jasmonic acid mediated contrasting effects of two citrus aphid species on Diaphorina citri Kuwayama. PEST MANAGEMENT SCIENCE 2023; 79:811-820. [PMID: 36264110 DOI: 10.1002/ps.7249] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 10/14/2022] [Accepted: 10/18/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Herbivores may influence each other directly and through plant mediated inter-specific interactions. The Asian citrus psyllid (Diaphorina citri Kuwayama) and citrus aphids are key pests that can co-exist on citrus, but their plant-mediated interaction between them is unknown. Here we investigated plant-mediated effect of two citrus aphid species, the polyphagous Aphis spiraecola Patch and the oligophagous Aphis (Toxoptera) citricidus (Kirkaldy) on the feeding behavior and reproduction of Diaphorina citri, and explored the underlying mechanisms. RESULTS In comparison with those on aphid free plants, Diaphorina citri had decreased reproduction and reduced phloem feeding on Aphis spiraecola pre-infested plants, while the reproduction and feeding efficiency were increased on Aphis citricidus pre-infested plants. Jasmonic acid (JA) dependent defense was significantly activated by Diaphorina citri feeding on Aphis spiraecola pre-infested plants, but was suppressed by Diaphorina citri feeding on Aphis citricidus pre-infested plants compared with that on aphid free plant. By contrast, only one tested marker gene in salicylic acid (SA) signaling was activated by Diaphorina citri feeding on Aphis spiraecola pre-infested plants. Furthermore, exogenous application of methyl jasmonate, but not SA, conferred resistance against Diaphorina citri in our citrus trials. CONCLUSION Our results indicate that pre-infestation by two citrus aphid species differentially altered Diaphorina citri induced citrus JA dependent defense, which resulted in different effect on subsequent Diaphorina citri performance. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Jing Gao
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Engineering Research Center for Mineral Oil Pesticides, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, China
| | - TongLai Tao
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Engineering Research Center for Mineral Oil Pesticides, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, China
- School of Life Sciences, South China Normal University, Guangzhou, China
| | | | - Fengxian Ye
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Engineering Research Center for Mineral Oil Pesticides, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, China
| | - Xincheng An
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Engineering Research Center for Mineral Oil Pesticides, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, China
| | - Mubasher Hussain
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Engineering Research Center for Mineral Oil Pesticides, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, China
| | - Runqian Mao
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong Engineering Research Center for Mineral Oil Pesticides, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, China
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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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Chavan SN, De Kesel J, Desmedt W, Degroote E, Singh RR, Nguyen GT, Demeestere K, De Meyer T, Kyndt T. Dehydroascorbate induces plant resistance in rice against root-knot nematode Meloidogyne graminicola. MOLECULAR PLANT PATHOLOGY 2022; 23:1303-1319. [PMID: 35587614 PMCID: PMC9366072 DOI: 10.1111/mpp.13230] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/27/2022] [Accepted: 04/27/2022] [Indexed: 06/01/2023]
Abstract
Ascorbic acid (AsA) is an important antioxidant in plants and regulates various physiological processes. In this study, we show that exogenous treatments with the oxidized form of AsA, that is, dehydroascorbate (DHA), activates induced systemic resistance in rice against the root-knot nematode Meloidogyne graminicola, and investigate the molecular and biochemical mechanisms underlying this phenotype. Detailed transcriptome analysis on roots of rice plants showed an early and robust transcriptional response on foliar DHA treatment, with induction of several genes related to plant stress responses, immunity, antioxidant activity, and secondary metabolism already at 1 day after treatment. Quantitative and qualitative evaluation of H2 O2 levels confirmed the appearance of a reactive oxygen species (ROS) burst on DHA treatment, both at the site of treatment and systemically. Experiments using chemical ROS inhibitors or scavengers confirmed that H2 O2 accumulation contributes to DHA-based induced resistance. Furthermore, hormone measurements in DHA-treated plants showed a significant systemic accumulation of the defence hormone salicylic acid (SA). The role of the SA pathway in DHA-based induced resistance was confirmed by nematode infection experiments using an SA-signalling deficient WRKY45-RNAi line and reverse transcription-quantitative PCR on SA marker genes. Our results collectively reveal that DHA activates induced systemic resistance in rice against the root-knot nematode M. graminicola, mediated through the production of ROS and activation of the SA pathway.
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Affiliation(s)
- Satish Namdeo Chavan
- Department of Biotechnology, Faculty of Bioscience EngineeringGhent UniversityGhentBelgium
- ICAR – Indian Institute of Rice ResearchHyderabadIndia
| | - Jonas De Kesel
- Department of Biotechnology, Faculty of Bioscience EngineeringGhent UniversityGhentBelgium
| | - Willem Desmedt
- Department of Biotechnology, Faculty of Bioscience EngineeringGhent UniversityGhentBelgium
| | - Eva Degroote
- Department of Biotechnology, Faculty of Bioscience EngineeringGhent UniversityGhentBelgium
| | - Richard Raj Singh
- Department of Biotechnology, Faculty of Bioscience EngineeringGhent UniversityGhentBelgium
- Department Plants and Crops, Faculty of Bioscience EngineeringGhent UniversityGhentBelgium
| | - Giang Thu Nguyen
- Department of Biotechnology, Faculty of Bioscience EngineeringGhent UniversityGhentBelgium
| | - Kristof Demeestere
- Department of Green Chemistry and Technology, Faculty of Bioscience EngineeringGhent UniversityGhentBelgium
| | - Tim De Meyer
- Department of Data Analysis and Mathematical ModellingGhent UniversityGhentBelgium
| | - Tina Kyndt
- Department of Biotechnology, Faculty of Bioscience EngineeringGhent UniversityGhentBelgium
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10
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Zhang F, Qiu Z, Huang A, Cheng Y, Fan G. Global dynamics and bifurcation analysis of an insect-borne plant disease model with two transmission routes. INT J BIOMATH 2022. [DOI: 10.1142/s1793524522500553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Huanglongbing (HLB) is a plant disease mainly spread by the insect-borne citrus psyllid. It is the most destructive citrus pathosystem worldwide. To understand the impact of sexual transmission on HLB dynamics, we propose a host–vector–HLB compartment model incorporating two transmission routes. The basic reproduction number [Formula: see text] is derived. Various interventions of the disease are assessed. We also investigate the effect of different incidence functions to simulate sexual transmission. For the case of sublinear incidence functions, the disease-free equilibrium is globally asymptotically stable (GAS) provided [Formula: see text]. For mass action incidence of sexual transmission, the endemic equilibrium is GAS provided [Formula: see text]. However, under nonlinear incidence, it is proved that the model may exhibit backward bifurcation. Theoretical and numerical studies reveal that (i) different forces of infection between heterosexual psyllids in the model may have a distinct impact on disease dynamics; (ii) sensitivity analysis shows that for [Formula: see text], the transmission rate between host and vector is more sensitive parameter than that between heterosexual psyllids; (iii) if the sexual transmission is ignored, the disease burden is likely to be underestimated in comparison with realistic scenarios; (iv) in the absence of chemical insecticides, the combined use of yellow sticky traps and injection of nutrient solutions can be more effective in suppressing the spread of HLB. These findings provide valuable insights for public policymakers to determine the long-term viability of implemented HLB management strategies and highlight the urgency of finding sustainable HLB solutions.
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Affiliation(s)
- Fumin Zhang
- School of Mathematics and Statistics, Nanjing University of Science and Technology, Nanjing, P. R. China
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou, P. R. China
| | - Zhipeng Qiu
- Interdisciplinary Center for Fundamental and Frontier Sciences, Nanjing University of Science and Technology, Jiangyin, P. R. China
| | - Aijun Huang
- National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, P. R. China
| | - Yan Cheng
- College of Mathematics, Taiyuan University of Technology, Taiyuan, P. R. China
| | - Guihong Fan
- Department of Mathematics, Columbus State University, Columbus, GA, USA
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11
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Yang C, Ancona V. An Overview of the Mechanisms Against " Candidatus Liberibacter asiaticus": Virulence Targets, Citrus Defenses, and Microbiome. Front Microbiol 2022; 13:850588. [PMID: 35391740 PMCID: PMC8982080 DOI: 10.3389/fmicb.2022.850588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 02/18/2022] [Indexed: 12/01/2022] Open
Abstract
Citrus Huanglongbing (HLB) or citrus greening, is the most destructive disease for citrus worldwide. It is caused by the psyllid-transmitted, phloem-limited bacteria "Candidatus Liberibacter asiaticus" (CLas). To date, there are still no effective practical strategies for curing citrus HLB. Understanding the mechanisms against CLas can contribute to the development of effective approaches for combatting HLB. However, the unculturable nature of CLas has hindered elucidating mechanisms against CLas. In this review, we summarize the main aspects that contribute to the understanding about the mechanisms against CLas, including (1) CLas virulence targets, focusing on inhibition of virulence genes; (2) activation of citrus host defense genes and metabolites of HLB-tolerant citrus triggered by CLas, and by agents; and (3) we also review the role of citrus microbiome in combatting CLas. Finally, we discuss novel strategies to continue studying mechanisms against CLas and the relationship of above aspects.
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Affiliation(s)
- Chuanyu Yang
- Department of Agriculture, Agribusiness, and Environmental Sciences, Citrus Center, Texas A&M University-Kingsville, Weslaco, TX, United States
| | - Veronica Ancona
- Department of Agriculture, Agribusiness, and Environmental Sciences, Citrus Center, Texas A&M University-Kingsville, Weslaco, TX, United States
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12
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Lally RD, Donaleshen K, Chirwa U, Eastridge K, Saintilnord W, Dickinson E, Murphy R, Borst S, Horgan K, Dawson K. Transcriptomic Response of Huanglongbing-Infected Citrus sinensis Following Field Application of a Microbial Fermentation Product. FRONTIERS IN PLANT SCIENCE 2021; 12:754391. [PMID: 34917102 PMCID: PMC8669595 DOI: 10.3389/fpls.2021.754391] [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: 08/06/2021] [Accepted: 11/05/2021] [Indexed: 06/14/2023]
Abstract
Huanglongbing (HLB) is considered the most destructive disease in Citrus production and threatens the future of the industry. Microbial-derived defense elicitors have gained recognition for their role in plant defense priming. This work assessed a 5% (V/V) microbial fermentation application (MFA) and its role in the elicitation of defense responses in HLB-infected Citrus sinensis trees following a foliar application with a pump sprayer. Using a PCR detection method, HLB infection levels were monitored in healthy and infected trees for 20months. Nutrient analysis assessed N, P, K, Ca, Mg, Mn, Zn, Fe, B, and Cu concentrations in the trees. MFA significantly increased Cu concentrations in treated trees and resulted in the stabilization of disease index (DI) in infected trees. Initial real-time qPCR analysis of defense-associated genes showed a significant increase in pathogenesis-related protein 2 (PR2) and phenylalanine ammonia lyase (PAL) gene expression in healthy and HLB-infected trees in response to MFA. Gene expression of PR2 and PAL peaked 6h post-microbial fermentation application during an 8-h sampling period. A transcriptomic assessment using GeneChip microarray of the hour 6 samples revealed differential expression of 565 genes when MFA was applied to healthy trees and 909 genes when applied infected citrus trees when compared to their respective controls. There were 403 uniquely differentially expressed genes in response to MFA following an intersectional analysis of both healthy and infected citrus trees. The transcriptomic analysis revealed that several genes associated with plant development, growth, and defense were upregulated in response to MFA, including multiple PR genes, lignin formation genes, ROS-related genes, hormone synthases, and hormone regulators. This study provides further evidence that MFA may play an important role as a plant elicitor in an integrated pest management strategy in citrus and other agronomically important crops.
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Affiliation(s)
| | | | | | | | - Wesley Saintilnord
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, United States
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13
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Li X, Ruan H, Zhou C, Meng X, Chen W. Controlling Citrus Huanglongbing: Green Sustainable Development Route Is the Future. FRONTIERS IN PLANT SCIENCE 2021; 12:760481. [PMID: 34868155 PMCID: PMC8636133 DOI: 10.3389/fpls.2021.760481] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/06/2021] [Indexed: 05/12/2023]
Abstract
Huanglongbing (HLB) is the most severe bacterial disease of citrus crops caused by Candidatus Liberibacter spp. It causes a reduction in fruit yield, poor fruit quality, and even plants death. Due to the lack of effective medicine, HLB is also called citrus "AIDS." Currently, it is essential for the prevention and control of HLB to use antibiotics and pesticides while reducing the spread of HLB by cultivating pathogen-free seedlings, removing disease trees, and killing Asian citrus psyllid (ACP). New compounds [e.g., antimicrobial peptides (AMPs) and nanoemulsions] with higher effectiveness and less toxicity were also found and they have made significant achievements. However, further evaluation is required before these new antimicrobial agents can be used commercially. In this review, we mainly introduced the current strategies from the aspects of physical, chemical, and biological and discussed their environmental impacts. We also proposed a green and ecological strategy for controlling HLB basing on the existing methods and previous research results.
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Affiliation(s)
- Xue Li
- MOE Key Laboratory of Laser Life Science, Institute of Laser Life Science, Guangzhou, China
- Guangdong Provincial Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Huaqin Ruan
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Chengqian Zhou
- Neuroscience Laboratory, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, MD, United States
| | - Xiangchun Meng
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (MOA), Guangzhou, China
- Key Laboratory of Tropical and Subtropical Fruit Tree Research, Guangzhou, China
- Institute of Fruit Tree Research, Guangdong Academy of Agricultural Science, Guangzhou, China
| | - Wenli Chen
- MOE Key Laboratory of Laser Life Science, Institute of Laser Life Science, Guangzhou, China
- Guangdong Provincial Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
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14
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Hopkins DL, Ager KL. Biological Control of Citrus Huanglongbing with EB92-1, a Benign Strain of Xylella fastidiosa. PLANT DISEASE 2021; 105:2914-2918. [PMID: 33822659 DOI: 10.1094/pdis-02-21-0362-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Huanglongbing (HLB), caused by Candidatus Liberibacter asiaticus, is currently the most destructive disease of citrus and threatens production in all affected areas. There is no cure. Benign Xylella fastidiosa strain EB92-1 provided good control of Pierce's disease of grapevine by inducing host resistance; therefore, we evaluated the strain for the biological control of HLB in citrus. Treatment was by injection into the trunk of the trees. Strain EB92-1 was shown to colonize citrus and provided control of HLB by reducing both the incidence of symptomatic trees and the percentage of trees with severe symptoms in three separate trials. All trees were positive by quantitative PCR (qPCR) for Candidatus Liberibacter asiaticus at the start of the trials, and treatment did not eliminate the bacterium. In a trial of asymptomatic mature trees, a single treatment with EB92-1 reduced the incidence of trees with symptoms through 18 months after treatment and reduced the incidence of trees with severe symptoms through 3 years. In mature trees that had 60% incidence of mild HLB symptoms at trial initiation, percentage of trees with symptoms and trees with severe symptoms continued to develop in both the untreated and in the EB92-1-treated trees for 12 months. However, retreatment at 9 and 20 months prevented the development of additional severe symptoms in the EB92-1-treated trees throughout the remainder of the 5-year trial. In 2-year-old trees, incidence of trees with HLB symptoms was higher in the untreated trees than in the treated trees throughout the 6 years of the trial, reaching 90% in the untreated versus 50% in the treated. After 6 years, severity of symptoms was much lower in the EB92-1-treated trees, only 3% of the treated trees had become unproductive compared with 18% of the untreated. In 2020, the reduction in HLB severity resulted in approximately twice as much yield in the treated trees as in these untreated 8-year-old trees. X. fastidiosa strain EB92-1 proved to be efficacious for the control of HLB symptoms in both mature trees and newly planted young trees, but trees may need to be retreated yearly for at least the first 2 to 3 years.
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Affiliation(s)
- D L Hopkins
- Mid-Florida Research and Education Center, University of Florida, Apopka, FL 32703
| | - K L Ager
- Mid-Florida Research and Education Center, University of Florida, Apopka, FL 32703
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15
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Yuan X, Chen C, Bassanezi RB, Wu F, Feng Z, Shi D, Li J, Du Y, Zhong L, Zhong B, Lu Z, Song X, Hu Y, Ouyang Z, Liu X, Xie J, Rao X, Wang X, Wu DO, Guan Z, Wang N. Region-Wide Comprehensive Implementation of Roguing Infected Trees, Tree Replacement, and Insecticide Applications Successfully Controls Citrus Huanglongbing. PHYTOPATHOLOGY 2021; 111:1361-1368. [PMID: 33356429 DOI: 10.1094/phyto-09-20-0436-r] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Huanglongbing (HLB) is a devastating citrus disease worldwide. A three-pronged approach to controlling HLB has been suggested, namely, removal of HLB-symptomatic trees, psyllid control, and replacement with HLB-free trees. However, such a strategy did not lead to successful HLB control in many citrus-producing regions, such as Florida. We hypothesize that this is because of the small-scale or incomprehensive implementation of the program; conversely, a comprehensive implementation of such a strategy at the regional level can successfully control HLB. To test our hypothesis, we investigated the effects of region-wide comprehensive implementation of this scheme to control HLB in Gannan region, China, with a total planted citrus acreage of over 110,000 ha from 2013 to 2019. With the region-wide implementation of comprehensive HLB management, the overall HLB incidence in Gannan decreased from 19.71% in 2014 to 3.86% in 2019. A partial implementation of such a program (without a comprehensive inoculum removal) at the regional level in Brazil resulted in HLB incidence increasing from 1.89% in 2010 to 19.02% in 2019. Using dynamic regression model analyses with data from both Brazil and China, we constructed a model to predict HLB incidence when all three components were applied at 100%. It was predicated that in a region-wide comprehensive implementation of such a program, HLB incidence would be controlled to a level of less than 1%. We conducted economic feasibility analyses and showed that average net profits were positive for groves that implemented the comprehensive strategy, but groves that did not implement it had negative net profits over a 10-year period. Overall, the key for the three-pronged program to successfully control HLB is the large scale (region-wide) and comprehensiveness in implementation. This study provides valuable information to control HLB and other economically important endemic diseases worldwide.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Xiaoyong Yuan
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Cixiang Chen
- Ganzhou Plant Protection Department of Fruit Industry/Jiangxi Navel Orange Engineering Research Center, Ganzhou, Jiangxi, China
| | | | - Feng Wu
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, U.S.A
| | - Zheng Feng
- Department of Electrical & Computer Engineering, University of Florida, Gainesville, FL, U.S.A
| | - Damin Shi
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, U.S.A
| | - Yimin Du
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Ling Zhong
- Plant Protection Bureau, Department of Agriculture, Nanchang, Jiangxi, China
| | - Balian Zhong
- National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Zhanjun Lu
- National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Xiang Song
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Yan Hu
- Ganzhou Plant Protection Department of Fruit Industry/Jiangxi Navel Orange Engineering Research Center, Ganzhou, Jiangxi, China
| | - Zhigang Ouyang
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Xinjun Liu
- Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
| | - Jinzhao Xie
- Ganzhou Plant Protection Department of Fruit Industry/Jiangxi Navel Orange Engineering Research Center, Ganzhou, Jiangxi, China
| | - Xi Rao
- Plant Protection Bureau, Department of Agriculture, Nanchang, Jiangxi, China
| | - Xi Wang
- Plant Protection Bureau, Department of Agriculture, Nanchang, Jiangxi, China
| | - Dapeng Oliver Wu
- Department of Electrical & Computer Engineering, University of Florida, Gainesville, FL, U.S.A
| | - Zhengfei Guan
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, U.S.A
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, U.S.A
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16
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Gur L, Reuveni M, Cohen Y. β-Aminobutyric Acid Induced Resistance against Alternaria Fruit Rot in Apple Fruits. J Fungi (Basel) 2021; 7:jof7070564. [PMID: 34356943 PMCID: PMC8305653 DOI: 10.3390/jof7070564] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/06/2021] [Accepted: 07/12/2021] [Indexed: 11/21/2022] Open
Abstract
Fruit body rot and calyx rot caused by Alternaria alternata f. sp. mali is an important disease of apple worldwide. The disease has recently become severe in cv. Pink Lady apple in Israel to an extent that has never been reported elsewhere in the world. No alternative control measures of the disease except fungicides are known. Here, we show for the first time that dl-β-aminobutyric acid (BABA) induces resistance against Alternaria fruit rot (AFR) in apple fruits in the laboratory and in the orchard. AFR was inhibited in fruits treated with BABA of 1000 μg/mL. BABA did not inhibit spore germination or mycelial growth of the pathogen in vitro (up to 2000 μg/mL). It was most inhibitory when applied 4 days prior to inoculation of detached fruits. BABA inhibited AFR also curatively when applied at 24 h post inoculation. Five other isomers of aminobutyric acid failed to protect the fruits from rot formation. Three field trials in commercial apple orchards proved that BABA was as protective against AFR as the commercial standard fungicidal mixture of azoxystrobin and difenoconazole. This research suggests that BABA may serve as a resistance inducer in apple against AFR. It can be used as an adequate alternative to the currently used fungicides or integrated in disease management programs to reduce fungicide load and buildup of fungicide resistance.
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Affiliation(s)
- Lior Gur
- Shamir Research Institute, University of Haifa, Katzrin 1290000, Israel;
- Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 5290002, Israel;
| | - Moshe Reuveni
- Shamir Research Institute, University of Haifa, Katzrin 1290000, Israel;
- Correspondence: ; Tel.: +972-54-777-2447
| | - Yigal Cohen
- Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 5290002, Israel;
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17
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Li J, Kolbasov VG, Lee D, Pang Z, Huang Y, Collins N, Wang N. Residue Dynamics of Streptomycin in Citrus Delivered by Foliar Spray and Trunk Injection and Effect on ' Candidatus Liberibacter asiaticus' Titer. PHYTOPATHOLOGY 2021; 111:1095-1103. [PMID: 33267628 DOI: 10.1094/phyto-09-20-0427-r] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Streptomycin (STR) has been used to control citrus huanglongbing (HLB) caused by 'Candidatus Liberibacter asiaticus' (CLas) via foliar spray. Here, we studied the residue dynamics of STR and its effect on CLas titers in planta applied by foliar spray and trunk injection of 3-year-old citrus trees that were naturally infected by CLas in the field. After foliar spray, STR levels in leaves peaked at 2 to 7 days postapplication (dpa) and gradually declined thereafter. The STR spray did not significantly affect CLas titers in leaves of treated plants as determined by quantitative PCR. After trunk injection, peak levels of STR were observed 7 to 14 dpa in the leaf and root tissues, and near-peak levels were sustained for another 14 days before significantly declining. At 12 months after injection, moderate to low or undetectable levels of STR were observed in the leaf, root, and fruit, depending on the doses of STR injected, with a residue level of 0.28 µg/g in harvested fruit at the highest injection concentration of 2.0 µg/tree. CLas titers in leaves were significantly reduced by trunk injection of STR at 1.0 or 2.0 g/tree, starting from 7 dpa and throughout the experimental period. The reduction of CLas titers was positively correlated with STR residue levels in leaves. The in planta minimum effective concentration of STR needed to suppress the CLas titer to an undetectable level (cycle threshold ≥36.0) was 1.92 µg/g fresh weight. Determination of the in planta minimum effective concentration of STR against CLas and its spatiotemporal residue levels in planta provides the guidance to use STR for HLB management.
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Affiliation(s)
- Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Vladimir G Kolbasov
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Donghwan Lee
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Zhiqian Pang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Yixiao Huang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Nicole Collins
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850
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18
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Nan J, Zhang S, Zhan P, Jiang L. Discovery of Novel GMPS Inhibitors of Candidatus Liberibacter Asiaticus by Structure Based Design and Enzyme Kinetic. BIOLOGY 2021; 10:biology10070594. [PMID: 34203217 PMCID: PMC8301025 DOI: 10.3390/biology10070594] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 12/12/2022]
Abstract
Simple Summary The spread of citrus Huanglongbing caused significant damage to the world’s citrus industry. Thermotherapy and chemical agents were used to control this disease; however, the effectiveness of these treatments is frequently inconsistent. In addition, CLas cannot be cultured in vitro. Therefore, structure-based virtual screening is a novel method to find compounds that work against CLas. This study used CLas GMPS as a target for high-throughput screening and selected some compounds which have a higher binding affinity to test their inhibition of CLas GMPS. Finally, two molecules were identified as the lead compound to control citrus HLB. Abstract Citrus production is facing an unprecedented problem because of huanglongbing (HLB) disease. Presently, no effective HLB-easing method is available when citrus becomes infected. Guanosine 5′-monophosphate synthetase (GMPS) is a key protein in the de novo synthesis of guanine nucleotides. GMPS is used as an attractive target for developing agents that are effective against the patogen infection. In this research, homology modeling, structure-based virtual screening, and molecular docking were used to discover the new inhibitors against CLas GMPS. Enzyme assay showed that folic acid and AZD1152 showed high inhibition at micromole concentrations, with AZD1152 being the most potent molecule. The inhibition constant (Ki) value of folic acid and AZD1152 was 51.98 µM and 4.05 µM, respectively. These results suggested that folic acid and AZD1152 could be considered as promising candidates for the development of CLas agents.
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Affiliation(s)
- Jing Nan
- Ministry of Education Key Laboratory of Plant Biology, Huazhong Agricultural University, Wuhan 430070, China; (J.N.); (P.Z.)
| | - Shaoran Zhang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China;
| | - Ping Zhan
- Ministry of Education Key Laboratory of Plant Biology, Huazhong Agricultural University, Wuhan 430070, China; (J.N.); (P.Z.)
| | - Ling Jiang
- Ministry of Education Key Laboratory of Plant Biology, Huazhong Agricultural University, Wuhan 430070, China; (J.N.); (P.Z.)
- Correspondence:
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19
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Luo Y, Zhang F, Liu Y, Gao S. Analysis and optimal control of a Huanglongbing mathematical model with resistant vector. Infect Dis Model 2021; 6:782-804. [PMID: 34189362 PMCID: PMC8214098 DOI: 10.1016/j.idm.2021.05.004] [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: 04/21/2021] [Revised: 05/24/2021] [Accepted: 05/28/2021] [Indexed: 11/03/2022] Open
Abstract
Huanglongbing (HLB) is an incurable disease that affects citrus trees. To better understand the transmission of HLB, the mathematical model is developed to investigate the transmission dynamics of the disease between Asian citrus psyllid (ACP) and citrus trees. Through rigorous mathematical derivations, we derive the expression of the basic reproduction number (R0) of HLB. The findings show that the disease-free equilibrium is locally asymptotically stable if R0 < 1, and if R0 > 1 the system is uniformly persistent. By applying the global sensitivity analysis of R0, we can obtain some parameters that have the greatest influence on the HLB transmission dynamics. Additionally, the optimal control theory is used to explore the corresponding optimal control problem of the HLB model. Numerical simulations are conducted to reinforce the analytical results. These theoretical and numerical results provide useful insights for understanding the transmission dynamics of HLB and may help policy makers to develop intervention strategies for the disease.
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Affiliation(s)
- Youquan Luo
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou, 341000, PR China
| | - Fumin Zhang
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou, 341000, PR China
| | - Yujiang Liu
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou, 341000, PR China
| | - Shujing Gao
- Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou, 341000, PR China.,National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, 341000, PR China
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20
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Pandey SS, Nogales da Costa Vasconcelos F, Wang N. Spatiotemporal Dynamics of ' Candidatus Liberibacter asiaticus' Colonization Inside Citrus Plant and Huanglongbing Disease Development. PHYTOPATHOLOGY 2021; 111:921-928. [PMID: 33174821 DOI: 10.1094/phyto-09-20-0407-r] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
'Candidatus Liberibacter asiaticus' (CLas), the causal agent of citrus huanglongbing (HLB), colonizes inside the phloem and is naturally transmitted by the Asian citrus psyllid (ACP). Here, we investigated spatiotemporal CLas colonization in different tissues after ACP transmission. Of the nine plants successfully infected via ACP transmission, CLas was detected in the roots of all trees at 75 days postremoval of ACPs (DPR) but in the mature leaf of only one tree; this finding is consistent with the model that CLas moves passively from source to sink tissues. At 75 and 365 DPR, CLas was detected in 11.1 and 43.1% of mature leaves not fed on by ACPs during transmission, respectively, unveiling active movement to the source tissue. The difference in colonization timing of sink and source tissues indicates that CLas is capable of both passive and active movement, with passive movement being dominant. At 225 DPR, leaves fed on by ACPs during the young stage showed the highest ratio of HLB symptomatic leaves and the highest CLas titer, followed by leaves that emerged after ACP removal and mature leaves not fed on by ACPs. Importantly, our data showed that ACPs were unable to transmit CLas via feeding on mature leaves. It is estimated that it takes 3 years at most for CLas to infect the whole tree. Overall, spatiotemporal detection of CLas in different tissues after ACP transmission helps visualize the infection process of CLas in planta and subsequent HLB symptom development and provides evidence showing that young leaves should be the focus of HLB management.
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Affiliation(s)
- Sheo Shankar Pandey
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850
| | | | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850
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21
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Sun X, Yang H, Zhao W, Bourcier E, Baldwin EA, Plotto A, Irey M, Bai J. Huanglongbing and Foliar Spray Programs Affect the Chemical Profile of "Valencia" Orange Peel Oil. FRONTIERS IN PLANT SCIENCE 2021; 12:611449. [PMID: 33995429 PMCID: PMC8118161 DOI: 10.3389/fpls.2021.611449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 02/16/2021] [Indexed: 05/03/2023]
Abstract
Florida orange trees have been affected by huanglongbing (HLB) for more than a decade. To alleviate disease-caused tree decline, maintain fruit productivity, and reduce disease transmission, enhanced foliar spray programs combining vector control and nutritional supplementation have been applied to healthy and diseased trees. The aim of this research was to discover if the various foliar sprays affect fruit peel oil chemical components. In this study, "Valencia" orange trees, with or without HLB (HLB±), were treated with the grower standard program (control, C) or one of four proprietary enhanced foliar spray programs (N1, N2, N3, and N4) over 16 months. Compared with HLB-, HLB+ samples had lower concentrations of typical peel oil components, including valencene, octanal, and decanal, and were abundant in oxidative/dehydrogenated terpenes, such as carvone and limonene oxide. However, limonene, the dominant component, was not affected by any treatment. Control and three out of four enhanced foliar spray programs, N2, N3, and N4, had very little influence on the chemical profiles of both HLB- and HLB+ samples, while N1 treatment greatly altered the chemical profile of HLB+ samples, resulting in peel oil similar to that of HLB- samples.
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Affiliation(s)
- Xiuxiu Sun
- USDA/ARS Horticultural Research Laboratory, Fort Pierce, FL, United States
| | - Huqing Yang
- USDA/ARS Horticultural Research Laboratory, Fort Pierce, FL, United States
- Zhejiang A & F University, Hangzhou, China
| | - Wei Zhao
- USDA/ARS Horticultural Research Laboratory, Fort Pierce, FL, United States
| | - Elise Bourcier
- USDA/ARS Horticultural Research Laboratory, Fort Pierce, FL, United States
| | | | - Anne Plotto
- USDA/ARS Horticultural Research Laboratory, Fort Pierce, FL, United States
| | - Mike Irey
- Southern Gardens Citrus Nursery, Clewiston, FL, United States
| | - Jinhe Bai
- USDA/ARS Horticultural Research Laboratory, Fort Pierce, FL, United States
- *Correspondence: Jinhe Bai,
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22
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Irigoyen S, Ramasamy M, Pant S, Niraula P, Bedre R, Gurung M, Rossi D, Laughlin C, Gorman Z, Achor D, Levy A, Kolomiets MV, Sétamou M, Badillo-Vargas IE, Avila CA, Irey MS, Mandadi KK. Plant hairy roots enable high throughput identification of antimicrobials against Candidatus Liberibacter spp. Nat Commun 2020; 11:5802. [PMID: 33199718 PMCID: PMC7669877 DOI: 10.1038/s41467-020-19631-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 10/26/2020] [Indexed: 12/20/2022] Open
Abstract
A major bottleneck in identifying therapies to control citrus greening and other devastating plant diseases caused by fastidious pathogens is our inability to culture the pathogens in defined media or axenic cultures. As such, conventional approaches for antimicrobial evaluation (genetic or chemical) rely on time-consuming, low-throughput and inherently variable whole-plant assays. Here, we report that plant hairy roots support the growth of fastidious pathogens like Candidatus Liberibacter spp., the presumptive causal agents of citrus greening, potato zebra chip and tomato vein greening diseases. Importantly, we leverage the microbial hairy roots for rapid, reproducible efficacy screening of multiple therapies. We identify six antimicrobial peptides, two plant immune regulators and eight chemicals which inhibit Candidatus Liberibacter spp. in plant tissues. The antimicrobials, either singly or in combination, can be used as near- and long-term therapies to control citrus greening, potato zebra chip and tomato vein greening diseases.
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Affiliation(s)
- Sonia Irigoyen
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
| | | | - Shankar Pant
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
- Agricultural Research Service, US Department of Agriculture, Stillwater, OK, USA
| | - Prakash Niraula
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
| | - Renesh Bedre
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
| | - Meena Gurung
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
| | - Denise Rossi
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
| | - Corinne Laughlin
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
| | - Zachary Gorman
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, USA
| | - Diann Achor
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA
| | - Amit Levy
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA
- Department of Plant Pathology, University of Florida, Gainesville, FL, USA
| | - Michael V Kolomiets
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, USA
| | - Mamoudou Sétamou
- Texas A&M University-Kingsville, Citrus Center, Weslaco, TX, USA
| | - Ismael E Badillo-Vargas
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Carlos A Avila
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
- Department of Horticultural Sciences, Texas A&M University, College Station, TX, USA
| | | | - Kranthi K Mandadi
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA.
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, USA.
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23
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Salah SB, Necibi F, Goumont R, Boubaker T. Electrophilicities of 4‐Nitrobenzochalcogenadiazoles. ChemistrySelect 2020. [DOI: 10.1002/slct.202001928] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Saida Ben Salah
- Laboratoire C.H.P.N.R Faculté des Sciences de Monastir Université de Monastir Avenue de l'Environnement 5019 Monastir Tunisia
| | - Feriel Necibi
- Laboratoire C.H.P.N.R Faculté des Sciences de Monastir Université de Monastir Avenue de l'Environnement 5019 Monastir Tunisia
| | - Régis Goumont
- Institut Lavoisier de Versailles UMR 8180 Université de Versailles 45, Avenue des Etats-Unis 78035 Versailles Cedex France
| | - Taoufik Boubaker
- Laboratoire C.H.P.N.R Faculté des Sciences de Monastir Université de Monastir Avenue de l'Environnement 5019 Monastir Tunisia
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Qiu W, Soares J, Pang Z, Huang Y, Sun Z, Wang N, Grosser J, Dutt M. Potential Mechanisms of AtNPR1 Mediated Resistance against Huanglongbing (HLB) in Citrus. Int J Mol Sci 2020; 21:ijms21062009. [PMID: 32187998 PMCID: PMC7139736 DOI: 10.3390/ijms21062009] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/12/2020] [Accepted: 03/12/2020] [Indexed: 02/03/2023] Open
Abstract
Huanglongbing (HLB), a bacterial disease caused by Candidatus Liberibacter asiaticus (CLas), is a major threat to the citrus industry. In a previous study conducted by our laboratory, several citrus transgenic trees expressing the Arabidopsis thaliana NPR1 (AtNPR1) gene remained HLB-free when grown in a field site under high HLB disease pressure. To determine the molecular mechanisms behind AtNPR1-mediated tolerance to HLB, a transcriptome analysis was performed using AtNPR1 overexpressing transgenic trees and non-transgenic trees as control, from which we identified 57 differentially expressed genes (DEGs). Data mining revealed the enhanced transcription of genes encoding pathogen-associated molecular patterns (PAMPs), transcription factors, leucine-rich repeat receptor kinases (LRR-RKs), and putative ankyrin repeat-containing proteins. These proteins were highly upregulated in the AtNPR1 transgenic line compared to the control plant. Furthermore, analysis of protein–protein interactions indicated that AtNPR1 interacts with CsNPR3 and CsTGA5 in the nucleus. Our results suggest that AtNPR1 positively regulates the innate defense mechanisms in citrus thereby boosting resistance and effectively protecting the plant against HLB.
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Affiliation(s)
- Wenming Qiu
- Institute of Fruit and Tea, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (W.Q.); (Z.S.)
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, USA; (J.S.); (Z.P.); (Y.H.); (N.W.); (J.G.)
| | - Juliana Soares
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, USA; (J.S.); (Z.P.); (Y.H.); (N.W.); (J.G.)
| | - Zhiqian Pang
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, USA; (J.S.); (Z.P.); (Y.H.); (N.W.); (J.G.)
| | - Yixiao Huang
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, USA; (J.S.); (Z.P.); (Y.H.); (N.W.); (J.G.)
| | - Zhonghai Sun
- Institute of Fruit and Tea, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (W.Q.); (Z.S.)
| | - Nian Wang
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, USA; (J.S.); (Z.P.); (Y.H.); (N.W.); (J.G.)
| | - Jude Grosser
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, USA; (J.S.); (Z.P.); (Y.H.); (N.W.); (J.G.)
| | - Manjul Dutt
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, USA; (J.S.); (Z.P.); (Y.H.); (N.W.); (J.G.)
- Correspondence:
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25
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Chen Y, Bendix C, Lewis JD. Comparative Genomics Screen Identifies Microbe-Associated Molecular Patterns from ' Candidatus Liberibacter' spp. That Elicit Immune Responses in Plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:539-552. [PMID: 31790346 DOI: 10.1094/mpmi-11-19-0309-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Citrus huanglongbing (HLB), caused by phloem-limited 'Candidatus Liberibacter' bacteria, is a destructive disease threatening the worldwide citrus industry. The mechanisms of pathogenesis are poorly understood and no efficient strategy is available to control HLB. Here, we used a comparative genomics screen to identify candidate microbe-associated molecular patterns (MAMPs) from 'Ca. Liberibacter' spp. We identified the core genome from multiple 'Ca. Liberibacter' pathogens, and searched for core genes with signatures of positive selection. We hypothesized that genes encoding putative MAMPs would evolve to reduce recognition by the plant immune system, while retaining their essential functions. To efficiently screen candidate MAMP peptides, we established a high-throughput microtiter plate-based screening assay, particularly for citrus, that measured reactive oxygen species (ROS) production, which is a common immune response in plants. We found that two peptides could elicit ROS production in Arabidopsis and Nicotiana benthamiana. One of these peptides elicited ROS production and defense gene expression in HLB-tolerant citrus genotypes, and induced MAMP-triggered immunity against the bacterial pathogen Pseudomonas syringae. Our findings identify MAMPs that boost immunity in citrus and could help prevent or reduce HLB infection.
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Affiliation(s)
- Yuan Chen
- Plant Gene Expression Center, United States Department of Agriculture-Agricultural Research Service and Department of Plant and Microbial Biology, University of California-Berkeley, 800 Buchanan Street, Albany, CA 94710, U.S.A
| | - Claire Bendix
- Plant Gene Expression Center, United States Department of Agriculture-Agricultural Research Service and Department of Plant and Microbial Biology, University of California-Berkeley, 800 Buchanan Street, Albany, CA 94710, U.S.A
| | - Jennifer D Lewis
- Plant Gene Expression Center, United States Department of Agriculture-Agricultural Research Service and Department of Plant and Microbial Biology, University of California-Berkeley, 800 Buchanan Street, Albany, CA 94710, U.S.A
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26
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Britt K, Gebben S, Levy A, Al Rwahnih M, Batuman O. The Detection and Surveillance of Asian Citrus Psyllid ( Diaphorina citri)-Associated Viruses in Florida Citrus Groves. FRONTIERS IN PLANT SCIENCE 2020; 10:1687. [PMID: 32010169 PMCID: PMC6978739 DOI: 10.3389/fpls.2019.01687] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Accepted: 11/29/2019] [Indexed: 05/26/2023]
Abstract
The plant pathogenic bacterium Candidatus Liberibacter asiaticus (CLas), the causal agent of the citrus disease Huanglongbing (HLB), and its insect vector, the Asian citrus psyllid (ACP; Diaphorina citri), have been devastating the Florida citrus industry. To restore the competitive production presence of Florida in the worldwide citrus market, effective and sustainable control of HLB and the ACP needs to be identified. As alternatives for resistance-inducing insecticides, viruses are currently being considered for biological control of the ACP. To identify possible biological control candidates, we conducted one of the most comprehensive surveys of natural ACP populations in major citrus production regions spanning 21 counties in Florida. By optimizing PCRs and RT-PCRs, we were able to successfully detect and monitor the prevalence of five previously identified ACP-associated RNA and DNA viruses throughout Florida citrus groves, which include: Diaphorina citri-associated C virus (DcACV), Diaphorina citri flavi-like virus (DcFLV), Diaphorina citri densovirus (DcDNV), Diaphorina citri reovirus (DcRV), and Diaphorina citri picorna-like virus (DcPLV). Adult and nymph ACP populations from 21 of Florida's major citrus-producing counties were collected each month during approximately 18 consecutive months. RNA extracts used for these viral screens were also regionally combined and subjected to High Throughput Sequencing (HTS) to reveal a more comprehensive picture of known and unknown viruses in Florida ACP populations. We discovered that DcACV was the most prevalent ACP-associated virus throughout nymph and adult ACP populations in Florida, detected in more than 60% of all samples tested, followed by DcPLV and DcFLV. HTS allowed us to identify a novel ACP-associated reo-like virus and a picorna-like virus. The putative reo-like virus, tentatively named Diaphorina citri cimodo-like virus, was later surveyed and detected back in seasonal adult and nymph ACP samples collected in Florida during this study. HTS generated data also revealed that the most abundant virus in Florida ACP populations was Citrus tristeza virus (CTV), which is not an ACP-associated virus, suggesting persistent presence of CTV infection in citrus throughout Florida groves. Collectively, information obtained from our study may be able to help guide the direction of biotechnological pest control efforts involving a number of viruses that were detected for the first time in Florida ACP populations, including two newly identified ACP-associated viruses.
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Affiliation(s)
- Kellee Britt
- Department of Plant Pathology, Southwest Florida Research and Education Center, University of Florida, Immokalee, FL, United States
| | - Samantha Gebben
- Department of Plant Pathology, Southwest Florida Research and Education Center, University of Florida, Immokalee, FL, United States
| | - Amit Levy
- Department of Plant Pathology, Citrus Research and Education Center, University of Florida, Lake Alfred, FL, United States
| | - Maher Al Rwahnih
- Department of Plant Pathology, University of California-Davis, Davis, CA, United States
| | - Ozgur Batuman
- Department of Plant Pathology, Southwest Florida Research and Education Center, University of Florida, Immokalee, FL, United States
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27
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Andrade MO, Pang Z, Achor DS, Wang H, Yao T, Singer BH, Wang N. The flagella of 'Candidatus Liberibacter asiaticus' and its movement in planta. MOLECULAR PLANT PATHOLOGY 2020; 21:109-123. [PMID: 31721403 PMCID: PMC6913195 DOI: 10.1111/mpp.12884] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Citrus huanglongbing (HLB) is the most devastating citrus disease worldwide. 'Candidatus Liberibacter asiaticus' (Las) is the most prevalent HLB causal agent that is yet to be cultured. Here, we analysed the flagellar genes of Las and Rhizobiaceae and observed two characteristics unique to the flagellar proteins of Las: (i) a shorter primary structure of the rod capping protein FlgJ than other Rhizobiaceae bacteria and (ii) Las contains only one flagellin-encoding gene flaA (CLIBASIA_02090), whereas other Rhizobiaceae species carry at least three flagellin-encoding genes. Only flgJAtu but not flgJLas restored the swimming motility of Agrobacterium tumefaciens flgJ mutant. Pull-down assays demonstrated that FlgJLas interacts with FlgB but not with FliE. Ectopic expression of flaALas in A. tumefaciens mutants restored the swimming motility of ∆flaA mutant and ∆flaAD mutant, but not that of the null mutant ∆flaABCD. No flagellum was observed for Las in citrus and dodder. The expression of flagellar genes was higher in psyllids than in planta. In addition, western blotting using flagellin-specific antibody indicates that Las expresses flagellin protein in psyllids, but not in planta. The flagellar features of Las in planta suggest that Las movement in the phloem is not mediated by flagella. We also characterized the movement of Las after psyllid transmission into young flush. Our data support a model that Las remains inside young flush after psyllid transmission and before the flush matures. The delayed movement of Las out of young flush after psyllid transmission provides opportunities for targeted treatment of young flush for HLB control.
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Affiliation(s)
- Maxuel O. Andrade
- Citrus Research and Education CenterDepartment of Microbiology and Cell ScienceUniversity of Florida/Institute of Food and Agricultural SciencesLake AlfredFLUSA
| | - Zhiqian Pang
- Citrus Research and Education CenterDepartment of Microbiology and Cell ScienceUniversity of Florida/Institute of Food and Agricultural SciencesLake AlfredFLUSA
| | - Diann S. Achor
- Citrus Research and Education CenterDepartment of Microbiology and Cell ScienceUniversity of Florida/Institute of Food and Agricultural SciencesLake AlfredFLUSA
| | - Han Wang
- Citrus Research and Education CenterDepartment of Microbiology and Cell ScienceUniversity of Florida/Institute of Food and Agricultural SciencesLake AlfredFLUSA
| | - Tingshan Yao
- Citrus Research and Education CenterDepartment of Microbiology and Cell ScienceUniversity of Florida/Institute of Food and Agricultural SciencesLake AlfredFLUSA
- National Engineering Research Center for Citrus, Citrus Research Institute, Southwest UniversityChongqing400712People’s Republic of China
| | - Burton H. Singer
- Emerging Pathogens InstituteUniversity of FloridaGainesvilleFLUSA
| | - Nian Wang
- Citrus Research and Education CenterDepartment of Microbiology and Cell ScienceUniversity of Florida/Institute of Food and Agricultural SciencesLake AlfredFLUSA
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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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29
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Vitamin C in Plants: From Functions to Biofortification. Antioxidants (Basel) 2019; 8:antiox8110519. [PMID: 31671820 PMCID: PMC6912510 DOI: 10.3390/antiox8110519] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 10/25/2019] [Accepted: 10/26/2019] [Indexed: 12/18/2022] Open
Abstract
Vitamin C (l-ascorbic acid) is an excellent free radical scavenger, not only for its capability to donate reducing equivalents but also for the relative stability of the derived monodehydroascorbate radical. However, vitamin C is not only an antioxidant, since it is also a cofactor for numerous enzymes involved in plant and human metabolism. In humans, vitamin C takes part in various physiological processes, such as iron absorption, collagen synthesis, immune stimulation, and epigenetic regulation. Due to the functional loss of the gene coding for l-gulonolactone oxidase, humans cannot synthesize vitamin C; thus, they principally utilize plant-based foods for their needs. For this reason, increasing the vitamin C content of crops could have helpful effects on human health. To achieve this objective, exhaustive knowledge of the metabolism and functions of vitamin C in plants is needed. In this review, the multiple roles of vitamin C in plant physiology as well as the regulation of its content, through biosynthetic or recycling pathways, are analyzed. Finally, attention is paid to the strategies that have been used to increase the content of vitamin C in crops, emphasizing not only the improvement of nutritional value of the crops but also the acquisition of plant stress resistance.
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30
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Li J, Li L, Pang Z, Kolbasov VG, Ehsani R, Carter EW, Wang N. Developing Citrus Huanglongbing (HLB) Management Strategies Based on the Severity of Symptoms in HLB-Endemic Citrus-Producing Regions. PHYTOPATHOLOGY 2019; 109:582-592. [PMID: 30418089 DOI: 10.1094/phyto-08-18-0287-r] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Citrus Huanglongbing (HLB), also known as greening, is a destructive disease caused by the fastidious, phloem-colonizing bacteria Candidatus Liberibacter spp.; 'Ca. Liberibacter asiaticus' (Las) is the most prevalent of the species causing HLB. The Asian citrus psyllid (ACP, Diaphorina citri) transmits Las. HLB is threatening citrus production worldwide, and there is no cure for infected trees. Management strategies targeting diseased trees at different stages of colonization by Las are needed for sustainable citrus production in HLB-endemic regions. We evaluated the effect of the combinations of plant defense elicitors, nitrogen (N) fertilizer, and compost on mildly diseased trees. We tested thermotherapy on severely diseased trees and assessed tree protectors to prevent feeding by ACP, thus preventing Las from being transmitted to new plantings that replaced HLB-moribund trees. After four applications over two consecutive growing seasons we found that the combination of compost, urea, and plant defense elicitors β-aminobutyric acid, plus ascorbic acid and potassium phosphite with or without salicylic acid, slowed down the progression of HLB and reduced disease severity by approximately 18%, compared with the untreated control. Our data showed no decline in fruit yield, indeed treatment resulted in a higher yield compared with the untreated control. Thermotherapy treatment (55°C for 2 min) exhibited a suppressive effect on growth of Las and progress of HLB in severely diseased trees for 2 to 3 months after treatment. The tree protectors prevented feeding by ACP, and therefore young replant trees remained healthy and free from infection by Las over the 2-year duration of the experiment. Taken together, these results may contribute to a basis for developing a targeted approach to control HLB based on stage of host colonization, application of plant defense elicitors, N fertilizer, compost, thermotherapy, and tree protectors. There is potential to implement these strategies in conjunction with other disease control measures to contribute to sustainable citrus production in HLB-endemic regions.
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Affiliation(s)
- Jinyun Li
- 1 Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred 33850, U.S.A
| | - Lei Li
- 1 Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred 33850, U.S.A
- 3 Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Zhiqian Pang
- 1 Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred 33850, U.S.A
| | - Vladimir G Kolbasov
- 1 Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred 33850, U.S.A
| | - Reza Ehsani
- 4 Department of Mechanical Engineering, University of California, Merced, 5200 N. Lake Road, SE2-282, Merced 95343, U.S.A.; and
| | - Erica W Carter
- 5 Citrus Research and Education Center, Department of Plant Pathology, University of Florida, 700 Experiment Station Road, Lake Alfred 33850, U.S.A
| | - Nian Wang
- 1 Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred 33850, U.S.A
- 2 China-USA Citrus Huanglongbing Joint Laboratory (A joint laboratory of The University of Florida's Institute of Food and Agricultural Sciences and Gannan Normal University), National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China
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Sun YD, Folimonova SY. The p33 protein of Citrus tristeza virus affects viral pathogenicity by modulating a host immune response. THE NEW PHYTOLOGIST 2019; 221:2039-2053. [PMID: 30220089 DOI: 10.1111/nph.15482] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 09/10/2018] [Indexed: 06/08/2023]
Abstract
Accumulation of reactive oxygen species (ROS) is a general plant basal defense strategy against viruses. In this study, we show that infection by Citrus tristeza virus (CTV) triggered ROS burst in Nicotiana benthamiana and in the natural citrus host, the extent of which was virus-dose dependent. Using Agrobacterium-mediated expression of CTV-encoded proteins in N. benthamiana, we found that p33, a unique viral protein, contributed to the induction of ROS accumulation and programmed cell death. The role of p33 in CTV pathogenicity was assessed based on gene knockout and complementation in N. benthamiana. In the citrus-CTV pathosystem, deletion of the p33 open reading frame in a CTV variant resulted in a significant decrease in ROS production, compared to that of the wild type CTV, which correlated with invasion of the mutant virus into the immature xylem tracheid cells and abnormal differentiation of the vascular system. By contrast, the wild type CTV exhibited phloem-limited distribution with a minor effect on the vasculature. We conclude that the p33 protein is a CTV effector that negatively affects virus pathogenicity and suggest that N. benthamiana recognizes p33 to activate the host immune response to restrict CTV into the phloem tissue and minimize the disease syndrome.
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Affiliation(s)
- Yong-Duo Sun
- Plant Pathology Department, University of Florida, Gainesville, FL, 32611, USA
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL, 32611, USA
| | - Svetlana Y Folimonova
- Plant Pathology Department, University of Florida, Gainesville, FL, 32611, USA
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL, 32611, USA
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Yang C, Zhong Y, Powell CA, Doud MS, Duan Y, Huang Y, Zhang M. Antimicrobial Compounds Effective against Candidatus Liberibacter asiaticus Discovered via Graft-based Assay in Citrus. Sci Rep 2018; 8:17288. [PMID: 30470774 PMCID: PMC6251869 DOI: 10.1038/s41598-018-35461-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 11/01/2018] [Indexed: 01/08/2023] Open
Abstract
Huanglongbing (HLB), the most destructive citrus disease, is caused by three species of phloem-limited Candidatus Liberibacter. Chemical control is a critical short-term strategy against Candidatus Liberibacter asiaticus (Las). Currently, application of antibiotics in agricultural practices is limited due to public concerns regarding emergence of antibiotic-resistant bacteria and potential side effects in humans. The present study screened 39 antimicrobials (non-antibiotics) for effectiveness against Las using an optimized graft-based screening system. Results of principal component, hierarchical clustering and membership function analyses demonstrated that 39 antimicrobials were clustered into three groups: "effective" (Group I), "partly effective" (Group II), and "ineffective" (Group III). Despite different modes of action, 8 antimicrobials (aluminum hydroxide, D,L-buthionine sulfoximine, nicotine, surfactin from Bacillus subtilis, SilverDYNE, colloidal silver, EBI-601, and EBI-602), were all as highly effective at eliminating or suppressing Las, showing both the lowest Las infection rates and titers in treated scions and inoculated rootstock. The ineffective group, which included 21 antimicrobials, did not eliminate or suppress Las, resulting in plants with increased titers of Candidatus Liberibacter. The other 10 antimicrobials partly eliminated/suppressed Las in treated and graft-inoculated plants. These effective antimicrobials are potential candidates for HLB control either via rescuing infected citrus germplasms or restricted field application.
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Affiliation(s)
- Chuanyu Yang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Biological Resources, Guangxi University, Nanning, Guangxi, 530005, China
- Indian River Research and Education Center-Institute of Food and Agricultural Sciences, University of Florida, 2199 South Rock Rd, Fort Pierce, FL, 34945, USA
- Fruit research institute, Fujian Academy of Agricultural Sciences, Fuzhou, Fujian, 350003, China
| | - Yun Zhong
- Indian River Research and Education Center-Institute of Food and Agricultural Sciences, University of Florida, 2199 South Rock Rd, Fort Pierce, FL, 34945, USA
- Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, Guangdong, China
| | - Charles A Powell
- Indian River Research and Education Center-Institute of Food and Agricultural Sciences, University of Florida, 2199 South Rock Rd, Fort Pierce, FL, 34945, USA
| | - Melissa S Doud
- US Department of Agriculture-Agricultural Research Service-US Horticultural Research Laboratory, 2001 South Rock Rd, Fort Pierce, FL, 34945, USA
| | - Yongping Duan
- US Department of Agriculture-Agricultural Research Service-US Horticultural Research Laboratory, 2001 South Rock Rd, Fort Pierce, FL, 34945, USA
| | - Youzong Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Biological Resources, Guangxi University, Nanning, Guangxi, 530005, China
- Indian River Research and Education Center-Institute of Food and Agricultural Sciences, University of Florida, 2199 South Rock Rd, Fort Pierce, FL, 34945, USA
| | - Muqing Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Biological Resources, Guangxi University, Nanning, Guangxi, 530005, China.
- Indian River Research and Education Center-Institute of Food and Agricultural Sciences, University of Florida, 2199 South Rock Rd, Fort Pierce, FL, 34945, USA.
- US Department of Agriculture-Agricultural Research Service-US Horticultural Research Laboratory, 2001 South Rock Rd, Fort Pierce, FL, 34945, USA.
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Localized expression of antimicrobial proteins mitigates huanglongbing symptoms in Mexican lime. J Biotechnol 2018; 285:74-83. [DOI: 10.1016/j.jbiotec.2018.08.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 07/16/2018] [Accepted: 08/24/2018] [Indexed: 11/19/2022]
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Riera N, Wang H, Li Y, Li J, Pelz-Stelinski K, Wang N. Induced Systemic Resistance Against Citrus Canker Disease by Rhizobacteria. PHYTOPATHOLOGY 2018; 108:1038-1045. [PMID: 29648949 DOI: 10.1094/phyto-07-17-0244-r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Citrus canker, caused by Xanthomonas citri subsp. citri, is an important citrus disease that causes significant economic losses worldwide. All commercial citrus varieties are susceptible to citrus canker. Currently, chemical control with copper based products is the main approach to control X. citri subsp. citri dispersal and plant colonization. However, extensive use of copper compounds can result in copper-resistant strains and cause adverse effects on the environment. Alternatives to chemical control involve the activation of citrus immunity to control the disease. Here, we investigated the ability of multiple rhizobacteria to induce a systemic defense response in cultivar Duncan grapefruit. Burkholderia territorii strain A63, Burkholderia metallica strain A53, and Pseudomonas geniculata strain 95 were found to effectively activate plant defense and significantly reduce symptom development in leaves challenged with X. citri subsp. citri. In the priming phase, root application of P. geniculata induced the expression of salicylic acid (SA)-signaling pathway marker genes (PR1, PR2, PR5, and salicylic acid carboxyl methyltransferase [SAM-SACM]). Gene expression analyses after X. citri subsp. citri challenge showed that root inoculation with P. geniculata strain 95 increased the relative levels of phenylalanine ammonia lyase 1 and SAM-SACM, two genes involved in the phenylpropanoid pathway as well as the biosynthesis of SA and methyl salicylate (MeSA), respectively. However, hormone analyses by UPLC-MS/MS showed no significant difference between SA in P. geniculata-treated plants and control plants at 8 days post-beneficial bacteria root inoculation. Moreover, P. geniculata root-treated plants contained higher reactive oxygen species levels in aerial tissues than control plants 8 days post-treatment application. This study demonstrates that rhizobacteria can modulate citrus immunity resulting in a systemic defense response against X. citri subsp. citri under greenhouse conditions.
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Affiliation(s)
- Nadia Riera
- First, second, third, and fourth authors: Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred; fifth author: Citrus Research and Education Center, Department of Entomology and Nematology, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred; and sixth author: China-USA Citrus Huanglongbing Joint Laboratory (A joint laboratory of The University of Florida's Institute of Food and Agricultural Sciences and Gannan Normal University), National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China; Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred
| | - Han Wang
- First, second, third, and fourth authors: Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred; fifth author: Citrus Research and Education Center, Department of Entomology and Nematology, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred; and sixth author: China-USA Citrus Huanglongbing Joint Laboratory (A joint laboratory of The University of Florida's Institute of Food and Agricultural Sciences and Gannan Normal University), National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China; Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred
| | - Yong Li
- First, second, third, and fourth authors: Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred; fifth author: Citrus Research and Education Center, Department of Entomology and Nematology, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred; and sixth author: China-USA Citrus Huanglongbing Joint Laboratory (A joint laboratory of The University of Florida's Institute of Food and Agricultural Sciences and Gannan Normal University), National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China; Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred
| | - Jinyun Li
- First, second, third, and fourth authors: Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred; fifth author: Citrus Research and Education Center, Department of Entomology and Nematology, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred; and sixth author: China-USA Citrus Huanglongbing Joint Laboratory (A joint laboratory of The University of Florida's Institute of Food and Agricultural Sciences and Gannan Normal University), National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China; Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred
| | - Kirsten Pelz-Stelinski
- First, second, third, and fourth authors: Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred; fifth author: Citrus Research and Education Center, Department of Entomology and Nematology, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred; and sixth author: China-USA Citrus Huanglongbing Joint Laboratory (A joint laboratory of The University of Florida's Institute of Food and Agricultural Sciences and Gannan Normal University), National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China; Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred
| | - Nian Wang
- First, second, third, and fourth authors: Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred; fifth author: Citrus Research and Education Center, Department of Entomology and Nematology, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred; and sixth author: China-USA Citrus Huanglongbing Joint Laboratory (A joint laboratory of The University of Florida's Institute of Food and Agricultural Sciences and Gannan Normal University), National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China; Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida/Institute of Food and Agricultural Sciences, Lake Alfred
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Ding F, Allen V, Luo W, Zhang S, Duan Y. Molecular mechanisms underlying heat or tetracycline treatments for citrus HLB control. HORTICULTURE RESEARCH 2018; 5:30. [PMID: 29872535 PMCID: PMC5981314 DOI: 10.1038/s41438-018-0038-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 03/06/2018] [Accepted: 03/27/2018] [Indexed: 05/05/2023]
Abstract
Huanglongbing (HLB), a destructive plant bacterial disease, severely impedes worldwide citrus production. In our previous reports, we revealed the molecular mechanisms of host plant responses that underlie thermotherapy against HLB. In this study, we investigated the molecular mechanism underlying heat or tetracycline treatments on the HLB bacterium, 'Candidatus Liberibacter asiaticus' (Las) by focusing on Las prophage/phage conversion under stress conditions. By comparing the prophage FP1 and FP2 copy number to the copy number of 16S rDNA in HLB-affected plants, we found that the relative copy number of both FP1 and FP2 increased significantly, ranging from 3.4- to 6.7-fold change when Las-infected samples underwent a temperature shift from 23 to 37, 42 or 45 °C. When treated with tetracycline at 50-150 and 200-250 µg/ml, respectively, the relative copy number of both FP1 and FP2 increased by 3.4- to 6.0-fold. In addition, analyses of Las prophage structural gene and antirepressor gene copy numbers showed similar trends for all treatments. Furthermore, transmission electron microscopy provided direct evidence of lysogenic to lytic conversion upon temperature increase. These results not only provide new insight into the molecular mechanisms underlying heat or tetracycline treatment but also suggest a novel HLB control strategy by enhancing the endogenous conversion from Las prophages to phages.
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Affiliation(s)
- Fang Ding
- Hubei Key Laboratory of PLant Pathology, Huazhong Agricultural University, 430070 Wuhan, Hubei P.R. China
- USDA-ARS-USHRL, Fort Pierce, FL 34945 USA
| | | | - Weiqi Luo
- USDA-ARS-USHRL, Fort Pierce, FL 34945 USA
- Center for Integrated Pest Management, North Carolina State University, Raleigh, NC 27606 USA
| | - Shouan Zhang
- IFAS-TREC, University of Florida, Homestead, FL 33031 USA
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Blaustein RA, Lorca GL, Teplitski M. Challenges for Managing Candidatus Liberibacter spp. (Huanglongbing Disease Pathogen): Current Control Measures and Future Directions. PHYTOPATHOLOGY 2018; 108:424-435. [PMID: 28990481 DOI: 10.1094/phyto-07-17-0260-rvw] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Huanglongbing (HLB; "citrus greening" disease) has caused significant damages to the global citrus industry as it has become well established in leading citrus-producing regions and continues to spread worldwide. Insecticidal control has been a critical component of HLB disease management, as there is a direct relationship between vector control and Candidatus Liberibacter spp. (i.e., the HLB pathogen) titer in HLB-infected citrus trees. In recent years, there have been substantial efforts to develop practical strategies for specifically managing Ca. Liberibacter spp.; however, a literature review on the outcomes of such attempts is still lacking. This work summarizes the greenhouse and field studies that have documented the effects and implications of chemical-based treatments (i.e., applications of broad-spectrum antibiotics, small molecule compounds) and nonchemical measures (i.e., applications of plant-beneficial compounds, applications of inorganic fertilizers, biological control, thermotherapy) for phytopathogen control. The ongoing challenges associated with mitigating Ca. Liberibacter spp. populations at the field-scale, such as the seasonality of the phytopathogen and associated HLB disease symptoms, limitations for therapeutics to contact the phytopathogen in planta, adverse impacts of broad-spectrum treatments on plant-beneficial microbiota, and potential implications on public and ecosystem health, are also discussed.
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Affiliation(s)
- Ryan A Blaustein
- First and third authors: Department of Soil and Water Sciences, Genetics Institute, University of Florida, Gainesville; and second author: Department of Microbiology and Cell Science, Genetics Institute, University of Florida, Gainesville
| | - Graciela L Lorca
- First and third authors: Department of Soil and Water Sciences, Genetics Institute, University of Florida, Gainesville; and second author: Department of Microbiology and Cell Science, Genetics Institute, University of Florida, Gainesville
| | - Max Teplitski
- First and third authors: Department of Soil and Water Sciences, Genetics Institute, University of Florida, Gainesville; and second author: Department of Microbiology and Cell Science, Genetics Institute, University of Florida, Gainesville
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Patt JM, Robbins PS, Niedz R, McCollum G, Alessandro R. Exogenous application of the plant signalers methyl jasmonate and salicylic acid induces changes in volatile emissions from citrus foliage and influences the aggregation behavior of Asian citrus psyllid (Diaphorina citri), vector of Huanglongbing. PLoS One 2018; 13:e0193724. [PMID: 29596451 PMCID: PMC5875780 DOI: 10.1371/journal.pone.0193724] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 02/18/2018] [Indexed: 11/18/2022] Open
Abstract
Huanglongbing, also known as citrus greening, is a destructive disease that threatens citrus production worldwide. It is putatively caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (Las). Currently, the disease is untreatable and efforts focus on intensive insecticide use to control the vector, Asian citrus psyllid (Diaphorina citri). Emerging psyllid resistance to multiple insecticides has generated investigations into the use of exogenously applied signaling compounds to enhance citrus resistance to D. citri and Las. In the present study, we examined whether foliar applications of methyl jasmonate (MJ), a volatile signaling compound associated with the induced systemic resistance pathway, and salicylic acid, a constituent of the systemic acquired resistance pathway, would elicit the emission of defense-related volatiles in citrus foliage, and what effect this might have on the host-plant searching behavior of D. citri. Comparisons were made of volatiles emitted from growing shoots of uninfected and Las-infected 'Valencia' sweet orange (Citrus sinensis) trees over two consecutive sampling days. A settling behavioral assay was used to compare psyllid attraction to MJ-treated vs. Tween-treated citrus sprigs. All three main effects, Las infection status, plant signaler application, and sampling day, influenced the proportions of individual volatile compounds emitted in different treatment groups. MJ- and SA-treated trees had higher emission rates than Tween-treated trees. Methyl salicylate (MeSA) and β-caryophyllene were present in higher proportions in the volatiles collected from Las-infected + trees. On the other hand, Las-infected + MJ-treated trees emitted lower proportions of MeSA than did Las-infected + Tween-treated trees. Because MeSA is a key D. citri attractant, this result suggests that MJ application could suppress MeSA emission from Las-infected trees, an approach that could be used to discourage psyllid colonization during shoot growth. MJ application enhanced emission of E-β-ocimene, indole, volatiles attractive to many of the psyllid's natural enemies, indicating that MJ application could be used in an 'attract and reward' conservation biological control strategy. Volatile emissions in SA-treated trees were dominated by MeSA. MJ application elicited aggregation behavior in D. citri. Similar numbers of psyllids settled on MJ-treated versus Tween-treated sprigs, but a significantly greater percentage of the MJ-treated sprigs had aggregations of nine or more psyllids on them. Taken together, the results of this study indicate that exogenous applications of MJ or SA could be used to influence Asian citrus psyllid settling behavior and attract its natural enemies.
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Affiliation(s)
- Joseph M. Patt
- United States Department of Agriculture, Agricultural Research Service, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
- * E-mail:
| | - Paul S. Robbins
- United States Department of Agriculture, Agricultural Research Service, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
| | - Randy Niedz
- United States Department of Agriculture, Agricultural Research Service, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
| | - Greg McCollum
- United States Department of Agriculture, Agricultural Research Service, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
| | - Rocco Alessandro
- United States Department of Agriculture, Agricultural Research Service, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
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Hu J, Jiang J, Wang N. Control of Citrus Huanglongbing via Trunk Injection of Plant Defense Activators and Antibiotics. PHYTOPATHOLOGY 2018; 108:186-195. [PMID: 28945516 DOI: 10.1094/phyto-05-17-0175-r] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Citrus huanglongbing (HLB) or greening is a devastating disease of citrus worldwide and no effective control measure is currently available. Plant defense activators environmentally friendly compounds capable of inducing resistance against many plant pathogens. Earlier studies showed that foliar spray of plant defense inducers could slow down HLB disease progress. In this study, eight plant defense activators and three antibiotics were evaluated in three field trials for their effect to control HLB by trunk injection of young and mature sweet orange trees. Results showed that four trunk injections of several activators, including salicylic acid, oxalic acid, acibenzolar-S-methyl, and potassium phosphate, provided significant control of HLB by suppressing 'Candidatus Liberibacter asiaticus' titer and disease progress. Trunk injection of penicillin, streptomycin, and oxytetracycline hydrochloride resulted in excellent control of HLB. In general, antibiotics were more effective in reduction of 'Ca. L. asiaticus' titer and HLB symptom expressions than plant defense activators. These treatments also resulted in increased yield and better fruit quality. Injection of both salicylic acid and acibenzolar-S-methyl led to significant induction of pathogenesis-related (PR) genes PR-1 and PR-2 genes. Meanwhile, injection of either potassium phosphate or oxalic acid resulted in significant induction of PR-2 or PR-15 gene expression, respectively. These results suggested that HLB diseased trees remained inducible for systemic acquired resistance under field conditions. In summary, this study presents information regarding controlling HLB via trunk injection of plant defense activators and antibiotics, which helps citrus growers in decision making regarding developing an effective HLB management program.
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Affiliation(s)
- J Hu
- First author: Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred 33850; second author: College of Agronomy, Jiangxi Agricultural University, Nanchang 330045, China; and third author: China-USA Citrus Huanglongbing Joint Laboratory (A joint laboratory of The University of Florida's Institute of Food and Agricultural Sciences and Gannan Normal University), National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China; Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred, FL
| | - J Jiang
- First author: Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred 33850; second author: College of Agronomy, Jiangxi Agricultural University, Nanchang 330045, China; and third author: China-USA Citrus Huanglongbing Joint Laboratory (A joint laboratory of The University of Florida's Institute of Food and Agricultural Sciences and Gannan Normal University), National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China; Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred, FL
| | - N Wang
- First author: Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred 33850; second author: College of Agronomy, Jiangxi Agricultural University, Nanchang 330045, China; and third author: China-USA Citrus Huanglongbing Joint Laboratory (A joint laboratory of The University of Florida's Institute of Food and Agricultural Sciences and Gannan Normal University), National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, Jiangxi, China; Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred, FL
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Wang N, Pierson EA, Setubal JC, Xu J, Levy JG, Zhang Y, Li J, Rangel LT, Martins J. The Candidatus Liberibacter-Host Interface: Insights into Pathogenesis Mechanisms and Disease Control. ANNUAL REVIEW OF PHYTOPATHOLOGY 2017. [PMID: 28637377 DOI: 10.1146/annurev-phyto-080516-035513] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
"Candidatus Liberibacter" species are associated with economically devastating diseases of citrus, potato, and many other crops. The importance of these diseases as well as the proliferation of new diseases on a wider host range is likely to increase as the insects vectoring the "Ca. Liberibacter" species expand their territories worldwide. Here, we review the progress on understanding pathogenesis mechanisms of "Ca. Liberibacter" species and the control approaches for diseases they cause. We discuss the Liberibacter virulence traits, including secretion systems, putative effectors, and lipopolysaccharides (LPSs), as well as other important traits likely to contribute to disease development, e.g., flagella, prophages, and salicylic acid hydroxylase. The pathogenesis mechanisms of Liberibacters are discussed. Liberibacters secrete Sec-dependent effectors (SDEs) or other virulence factors into the phloem elements or companion cells to interfere with host targets (e.g., proteins or genes), which cause cell death, necrosis, or other phenotypes of phloem elements or companion cells, leading to localized cell responses and systemic malfunction of phloem. Receptors on the remaining organelles in the phloem, such as plastid, vacuole, mitochondrion, or endoplasmic reticulum, interact with secreted SDEs and/or other virulence factors secreted or located on the Liberibacter outer membrane to trigger cell responses. Some of the host genes or proteins targeted by SDEs or other virulence factors of Liberibacters serve as susceptibility genes that facilitate compatibility (e.g., promoting pathogen growth or suppressing immune responses) or disease development. In addition, Liberibacters trigger plant immunity response via pathogen-associated molecular patterns (PAMPs, such as lipopolysaccharides), which leads to premature cell death, callose deposition, or phloem protein accumulation, causing a localized response and/or systemic effect on phloem transportation. Physical presence of Liberibacters and their metabolic activities may disturb the function of phloem, via disrupting osmotic gradients, or the integrity of phloem conductivity. We also review disease management strategies, including promising new technologies. Citrus production in the presence of Huanglongbing is possible if the most promising management approaches are integrated. HLB management is discussed in the context of local, area-wide, and regional Huanglongbing/Asian Citrus Psyllid epidemiological zones. For zebra chip disease control, aggressive psyllid management enables potato production, although insecticide resistance is becoming an issue. Meanwhile, new technologies such as clustered regularly interspaced short palindromic repeat (CRISPR)-derived genome editing provide an unprecedented opportunity to provide long-term solutions.
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Affiliation(s)
- Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850;
| | - Elizabeth A Pierson
- Department of Horticultural Sciences, Texas A&M University, College Station, Texas 77843
| | - João Carlos Setubal
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, 05508-000, Brazil
| | - Jin Xu
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850;
| | - Julien G Levy
- Department of Horticultural Sciences, Texas A&M University, College Station, Texas 77843
| | - Yunzeng Zhang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850;
| | - Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850;
| | - Luiz Thiberio Rangel
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, 05508-000, Brazil
| | - Joaquim Martins
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, 05508-000, Brazil
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Li J, Pang Z, Trivedi P, Zhou X, Ying X, Jia H, Wang N. 'Candidatus Liberibacter asiaticus' Encodes a Functional Salicylic Acid (SA) Hydroxylase That Degrades SA to Suppress Plant Defenses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:620-630. [PMID: 28488467 DOI: 10.1094/mpmi-12-16-0257-r] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Pathogens from the fastidious, phloem-restricted 'Candidatus Liberibacter' species cause the devastating Huanglongbing (HLB) disease in citrus worldwide and cause diseases on many solanaceous crops and plants in the Apiaceae family. However, little is known about the pathogenic mechanisms due to the difficulty in culturing the corresponding 'Ca. Liberibacter' species. Here, we report that the citrus HLB pathogen 'Ca. L. asiaticus' uses an active salicylate hydroxylase SahA to degrade salicylic acid (SA) and suppress plant defenses. Purified SahA protein displays strong enzymatic activity to degrade SA and its derivatives. Overexpression of SahA in transgenic tobacco plants abolishes SA accumulation and hypersensitive response (HR) induced by nonhost pathogen infection. By degrading SA, 'Ca. L. asiaticus' not only enhances the susceptibility of citrus plants to both nonpathogenic and pathogenic Xanthomonas citri but also attenuates the responses of citrus plants to exogenous SA. In addition, foliar spraying of 2,1,3-benzothiadiazole and 2,6-dichloroisonicotinic acid, SA functional analogs not degradable by SahA, displays comparable (and even better) effectiveness with SA in suppressing 'Ca. L. asiaticus' population growth and HLB disease progression in infected citrus trees under field conditions. This study demonstrates one or more pathogens suppress plant defenses by degrading SA and establish clues for developing novel SA derivatives-based management approaches to control the associated plant diseases.
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Affiliation(s)
- Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
| | - Zhiqian Pang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
| | - Pankaj Trivedi
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
| | - Xiaofeng Zhou
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
| | - Xiaobao Ying
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
| | - Hongge Jia
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A
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Sundin GW, Castiblanco LF, Yuan X, Zeng Q, Yang C. Bacterial disease management: challenges, experience, innovation and future prospects: Challenges in Bacterial Molecular Plant Pathology. MOLECULAR PLANT PATHOLOGY 2016; 17:1506-1518. [PMID: 27238249 PMCID: PMC6638406 DOI: 10.1111/mpp.12436] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Plant diseases caused by bacterial pathogens place major constraints on crop production and cause significant annual losses on a global scale. The attainment of consistent effective management of these diseases can be extremely difficult, and management potential is often affected by grower reliance on highly disease-susceptible cultivars because of consumer preferences, and by environmental conditions favouring pathogen development. New and emerging bacterial disease problems (e.g. zebra chip of potato) and established problems in new geographical regions (e.g. bacterial canker of kiwifruit in New Zealand) grab the headlines, but the list of bacterial disease problems with few effective management options is long. The ever-increasing global human population requires the continued stable production of a safe food supply with greater yields because of the shrinking areas of arable land. One major facet in the maintenance of the sustainability of crop production systems with predictable yields involves the identification and deployment of sustainable disease management solutions for bacterial diseases. In addition, the identification of novel management tactics has also come to the fore because of the increasing evolution of resistance to existing bactericides. A number of central research foci, involving basic research to identify critical pathogen targets for control, novel methodologies and methods of delivery, are emerging that will provide a strong basis for bacterial disease management into the future. Near-term solutions are desperately needed. Are there replacement materials for existing bactericides that can provide effective disease management under field conditions? Experience should inform the future. With prior knowledge of bactericide resistance issues evolving in pathogens, how will this affect the deployment of newer compounds and biological controls? Knowledge is critical. A comprehensive understanding of bacterial pathosystems is required to not only identify optimal targets in the pathogens, but also optimal seasonal timings for deployment. Host resistance to effectors must be exploited, carefully and correctly. Are there other candidate genes that could be targeted in transgenic approaches? How can new technologies (CRISPR, TALEN, etc.) be most effectively used to add sustainable disease resistance to existing commercially desirable plant cultivars? We need an insider's perspective on the management of systemic pathogens. In addition to host resistance or reduced sensitivity, are there other methods that can be used to target these pathogen groups? Biological systems are variable. Can biological control strategies be improved for bacterial disease management and be made more predictable in function? The answers to the research foci outlined above are not all available, as will become apparent in this article, but we are heading in the right direction. In this article, we summarize the contributions from past experiences in bacterial disease management, and also describe how advances in bacterial genetics, genomics and host-pathogen interactions are informing novel strategies in virulence inhibition and in host resistance. We also outline potential innovations that could be exploited as the pressures to maximize a safe and productive food supply continue to become more numerous and more complex.
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Affiliation(s)
- George W. Sundin
- Department of Plant, Soil, and Microbial SciencesMichigan State UniversityEast LansingMI48824USA
| | - Luisa F. Castiblanco
- Department of Plant, Soil, and Microbial SciencesMichigan State UniversityEast LansingMI48824USA
| | - Xiaochen Yuan
- Department of Biological SciencesUniversity of Wisconsin‐MilwaukeeMilwaukeeWI53211USA
| | - Quan Zeng
- Department of Plant Pathology and Ecology, Connecticut Agricultural Experiment StationNew HavenCT06504USA
| | - Ching‐Hong Yang
- Department of Biological SciencesUniversity of Wisconsin‐MilwaukeeMilwaukeeWI53211USA
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Li HX, Stevenson KL, Brewer MT. Differences in Sensitivity to a Triazole Fungicide Among Stagonosporopsis Species Causing Gummy Stem Blight of Cucurbits. PLANT DISEASE 2016; 100:2106-2112. [PMID: 30683001 DOI: 10.1094/pdis-03-16-0341-re] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Gummy stem blight (GSB) is a destructive disease of cucurbits caused by three closely related Stagonosporopsis species. In the southeastern United States, GSB management relies heavily on triazole fungicides. Our objectives were to determine if resistance to triazoles has developed in populations of GSB fungi in the southeastern United States, and if so, to investigate the molecular basis of resistance. A tebuconazole sensitivity assay was conducted on 303 Stagonosporopsis citrulli and 19 S. caricae isolates collected from the southeastern United States in 2013 and 2014, as well as three S. citrulli, three S. cucurbitacearum, and six S. caricae isolates from other regions or years. Tebuconazole resistance was detected for all 19 S. caricae isolates from the southeastern United States and one S. caricae isolate from Brazil. All S. citrulli and S. cucurbitacearum isolates were sensitive to tebuconazole. For resistant and sensitive isolates of S. caricae, coding and promoter regions of the target gene Cyp51 were sequenced and expression levels of Cyp51 and ScAtrG (an ATP-binding cassette transporter) were measured. Tebuconazole resistance was not associated with mutations within Cyp51, multiple copies of Cyp51, changes in the promoter region, or increased expression of Cyp51 or ScAtrG. Tebuconazole resistance may explain the increase in frequency of S. caricae isolates recovered from GSB-infected cucurbits in Georgia.
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Affiliation(s)
- Hao-Xi Li
- Department of Plant Pathology, University of Georgia, Athens, GA 30602
| | | | - Marin T Brewer
- Department of Plant Pathology, University of Georgia, Athens, GA 30602
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