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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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Galvañ A, Bassanezi RB, Luo W, Vanaclocha P, Vicent A, Lázaro E. Risk-based regionalization approach for area-wide management of HLB vectors in the Mediterranean Basin. FRONTIERS IN PLANT SCIENCE 2023; 14:1256935. [PMID: 38111874 PMCID: PMC10725980 DOI: 10.3389/fpls.2023.1256935] [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: 07/11/2023] [Accepted: 10/23/2023] [Indexed: 12/20/2023]
Abstract
Huanglongbing (HLB) is one of the most devastating citrus diseases worldwide. It is associated with the non-culture bacteria Candidatus Liberibacter spp., which can be transmitted by grafting and/or the psyllid vectors Diaphorina citri (ACP) and Trioza erytreae (AfCP). Although HLB has not been reported in the Mediterranean Basin to date, both vectors are present, and thus represent a serious threat to the citrus industry in this region. Resistant citrus cultivars or effective therapeutic treatments are not currently available for HLB. Nevertheless, area-wide pest management via coordinated management efforts over large areas has been implemented in Brazil, China and the USA for HLB control. This study proposes an open access flexible methodology to address area-wide management of both HLB vectors in the Mediterranean Basin. Based on a risk-based approach which considers climatic information and other variables that may influence vector introduction and spread, such as conventional, organic, abandoned and residential citrus areas as well as transportation corridors, an area-wide management division in pest management areas (PMAs) is proposed. The size and location of these PMAs were estimated by means of a hierarchical clustering algorithm with spatial constraints whose performance was assessed under different configuration scenarios. This proposal may assist policymakers and the citrus industry of the citrus-growing areas of the Mediterranean Basin in risk management planning in the case of the spread of HLB vectors or a possible introduction of the disease. Additionally, it may be a valuable resource to inform opinion dynamic models, enabling the identification of pivotal factors for the success of control measures.
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Affiliation(s)
- Anaïs Galvañ
- Centre de Protecció Vegetal i Biotecnologia, Institut Valencià d’Investigacions Agràries (IVIA), Moncada, Spain
| | - Renato Beozzo Bassanezi
- Departamento de Pesquisa e Desenvolvimento, Fundo de Defesa da Citricultura, Araraquara, SP, Brazil
| | - Weiqi Luo
- Agricultural Research Service, U.S. Department of Agriculture, Fort Pierce, FL, United States
- Center for Integrated Pest Management, North Carolina State University, Raleigh, NC, United States
| | - Pilar Vanaclocha
- Centre de Protecció Vegetal i Biotecnologia, Institut Valencià d’Investigacions Agràries (IVIA), Moncada, Spain
| | - Antonio Vicent
- Centre de Protecció Vegetal i Biotecnologia, Institut Valencià d’Investigacions Agràries (IVIA), Moncada, Spain
| | - Elena Lázaro
- Centre de Protecció Vegetal i Biotecnologia, Institut Valencià d’Investigacions Agràries (IVIA), Moncada, Spain
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Xu J, Zhang Y, Li J, Teper D, Sun X, Jones D, Wang Y, Tao J, Goss EM, Jones JB, Wang N. Phylogenomic analysis of 343 Xanthomonas citri pv. citri strains unravels introduction history and dispersal paths. PLoS Pathog 2023; 19:e1011876. [PMID: 38100539 PMCID: PMC10756548 DOI: 10.1371/journal.ppat.1011876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 12/29/2023] [Accepted: 11/30/2023] [Indexed: 12/17/2023] Open
Abstract
Xanthomonas citri pv. citri (Xcc) causes the devastating citrus canker disease. Xcc is known to have been introduced into Florida, USA in at least three different events in 1915, 1986 and 1995 with the first two claimed to be eradicated. It was questioned whether the Xcc introduction in 1986 has been successfully eradicated. Furthermore, it is unknown how Xcc has spread throughout the citrus groves in Florida. In this study, we investigated the population structure of Xcc to address these questions. We sequenced the whole genome of 343 Xcc strains collected from Florida groves between 1997 and 2016. Our analysis revealed two distinct clusters of Xcc. Our data strongly indicate that the claimed eradication of the 1986 Xcc introduction was not successful and Xcc strains from 1986 introduction were present in samples from at least 8 counties collected after 1994. Importantly, our data revealed that the Cluster 2 strains, which are present in all 20 citrus-producing counties sampled in Florida, originated from the Xcc introduction event in the Miami area in 1995. Our data suggest that Polk County is the epicenter of the dispersal of Cluster 2 Xcc strains, which is consistent with the fact that three major hurricanes passed through Polk County in 2004. As copper-based products have been extensively used to control citrus canker, we also investigated whether Xcc strains have developed resistance to copper. Notably, none of the 343 strains contained known copper resistance genes. Twenty randomly selected Xcc strains displayed sensitivity to copper. Overall, this study provides valuable insights into the introduction, eradication, spread, and copper resistance of Xcc in Florida.
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Affiliation(s)
- Jin Xu
- Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred, Florida, United States of America
| | - Yanan Zhang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred, Florida, United States of America
| | - Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred, Florida, United States of America
| | - Doron Teper
- Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred, Florida, United States of America
| | - Xiaoan Sun
- Florida Department of Agriculture and Consumer Services, Gainesville, Florida, United States of America
| | - Debra Jones
- Florida Department of Agriculture and Consumer Services, Gainesville, Florida, United States of America
| | - Yayu Wang
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, China
| | - Jin Tao
- Guangdong Magigene Biotechnology Co., Ltd., Guangzhou, China
| | - Erica M. Goss
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
| | - Jeffrey B. Jones
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, Florida, United States of America
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, IFAS, University of Florida, Lake Alfred, Florida, United States of America
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Hao J, Ma J, Shi H, Wang Y. A tug-of-war to control plant emission of an airborne alarm signal. STRESS BIOLOGY 2023; 3:48. [PMID: 37975927 PMCID: PMC10656406 DOI: 10.1007/s44154-023-00135-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 11/02/2023] [Indexed: 11/19/2023]
Abstract
Aphids represent a major threat to crops. Hundreds of different viruses are aphid-borne. Upon aphid attack, plants release volatile organic compounds (VOCs) as airborne alarm signals to turn on the airborne defense (AD) of neighboring plants, thereby repelling aphids as well as reducing aphid fitness and virus transmission. This phenomenon provides a critical community-wide plant protection to fend off aphids, but the underlying molecular basis remains undetermined for a long time. In a recent article, Gong et al. established the NAC2-SAMT1 module as the core component regulating the emission of methyl-salicylate (MeSA), a major component of VOCs in aphid-attacked plants. Furthermore, they showed that SABP2 protein is critical for the perception of volatile MeSA signal by converting MeSA to Salicylic Acid (SA), which is the cue to elicit AD against aphids at the community level. Moreover, they showed that multiple viruses use a conserved glycine residue in the ATP-dependent helicase domain in viral proteins to shuttle NAC2 from the nucleus to the cytoplasm for degradation, leading to the attenuation of MeSA emission and AD. These findings illuminate the functional roles of key regulators in the complex MeSA-mediated airborne defense process and a counter-defense mechanism used by viruses, which has profound significance in advancing the knowledge of plant-pathogen interactions as well as providing potential targets for gene editing-based crop breeding.
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Affiliation(s)
- Jie Hao
- Plant Pathology Department, University of Florida, Gainesville, 32611, USA
| | - Junfei Ma
- Plant Pathology Department, University of Florida, Gainesville, 32611, USA
| | - Hua Shi
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, 650201, China.
| | - Ying Wang
- Plant Pathology Department, University of Florida, Gainesville, 32611, USA.
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Jeger MJ, Fereres A, Malmstrom CE, Mauck KE, Wintermantel WM. Epidemiology and Management of Plant Viruses Under a Changing Climate. PHYTOPATHOLOGY 2023; 113:1620-1621. [PMID: 37924846 DOI: 10.1094/phyto-07-23-0262-v] [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: 11/06/2023]
Abstract
Plant viruses are an ever-present threat to agricultural production and provide a wide array of symptoms resulting in economic losses throughout the world. Diseases can be transmitted by insect vectors, as well as through pollen, seed, and other means. With the increased globalization of agriculture, the introduction of new viruses from exotic locations and their establishment in new production regions and even new crops is a growing concern. Advancing knowledge of the epidemiology of plant viruses including development of new diagnostic methods, virus surveillance, and modeling, virus ecology and evolution, virus interactions with insect vectors, and other factors are important toward reducing the spread of plant viruses and managing virus diseases.
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Affiliation(s)
- Michael J Jeger
- Imperial College London, Division of Biology, Wye Campus, High Street, Wye, Ashford TN25 5AH, United Kingdom of Great Britain and Northern Ireland
| | - Alberto Fereres
- Institute of Agricultural Sciences, ICA, CSIC, Madrid, Spain
| | - Carolyn E Malmstrom
- Michigan State University, Plant Biology, 612 Wilson Road, East Lansing, MI 48824, U.S.A
| | - Kerry E Mauck
- University of California, Riverside, Entomology, 163 Entomology Bldg., Riverside, CA 92521, U.S.A
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