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Sagouti T, Rhallabi N, Polizzi G, Tahiri A, Belabess Z, Barka EA, Lahlali R. Comparison of Serological and Molecular Methods for Detection of Spiroplasma citri in Moroccan Citrus-Growing Areas. PLANTS (BASEL, SWITZERLAND) 2023; 12:667. [PMID: 36771751 PMCID: PMC9918891 DOI: 10.3390/plants12030667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 01/24/2023] [Accepted: 01/28/2023] [Indexed: 06/18/2023]
Abstract
Spiroplasma citri, a helical motile, wall-less, and cultivable microorganism of the class Mollicutes, is the agent of the citrus stubborn disease. There is currently a lack of data about the presence of this pathogen in Moroccan citrus orchards. This study aims to validate serological and molecular methods for routine S. citri diagnosis in Moroccan citrus groves. To provide an update on the present status of the outbreak of the pathogen in Moroccan citrus orchards, a survey of S. citri was conducted in the main citrus-growing regions of Morocco. A total of 575 leaf samples were collected from citrus trees with symptoms attributable to S. citri infection. Samples were collected during 2020 and 2021 from 23 citrus orchards. The presence of S. citri was tested in all samples using the double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Using this method, 57 samples were found to be infected with S. citri, 41 samples had doubtful results, and the remaining samples were negative. To corroborate the results of the DAS-ELISA test, 148 samples were chosen for additional molecular testing using conventional polymerase chain reaction (PCR) and real-time PCR (qPCR) based on specific primer pairs targeting three different genes (putative adhesion-like gene P58, putative adhesion gene P89, and spiralin gene). Using primers that target the putative adhesion-like gene P58, S. citri was detected by conventional and real-time PCR amplification from plant tissue with differing degrees of specificity. The results allowed us to determine the incidence of S. citri in all Moroccan citrus orchards, with a wide range of positive samples varying from 6.5% to 78%, and to show that molecular tests, particularly real-time PCR assays that target the putative adhesion-like gene P58, are the most sensitive for making an accurate diagnosis of S. citri. Indeed, the real-time PCR with P58-targeting primers yielded positive results from all positive and doubtful ELISA samples as well as some negative samples, with an OD value close to 1.5× times healthy samples, thus demonstrating a high sensibility of this technique.
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Affiliation(s)
- Tourya Sagouti
- Laboratoire de Virologie, Microbiologie et Qualité/Ecotoxicologie et Biodiversité, Faculté des Sciences et Techniques de Mohammedia, Mohammedia 20650, Morocco
| | - Naima Rhallabi
- Laboratoire de Virologie, Microbiologie et Qualité/Ecotoxicologie et Biodiversité, Faculté des Sciences et Techniques de Mohammedia, Mohammedia 20650, Morocco
| | - Giancarlo Polizzi
- Dipartimento di Agricoltura, Alimentazione e Ambiente, sez. Patologia Vegetale, University of Catania, Via S. Sofia 100, 95123 Catania, Italy
| | - Abdessalem Tahiri
- Phytopathology Unit, Department of Plant Protection, Ecole Nationale d’Agriculture de Meknès, Km 10, Rte Haj Kaddour, BP S/40, Meknes 50001, Morocco
| | - Zineb Belabess
- Plant Protection Laboratory, Regional Center of Agricultural Research of Meknes, National Institute of Agricultural Research, Km 13, Route Haj Kaddour, BP. 578, Meknes 50000, Morocco
| | - Essaid Ait Barka
- Unité de Recherche Résistance Induite et Bio-Protection des Plantes-EA 4707, Université de Reims Champagne-Ardenne, 51100 Reims, France
| | - Rachid Lahlali
- Phytopathology Unit, Department of Plant Protection, Ecole Nationale d’Agriculture de Meknès, Km 10, Rte Haj Kaddour, BP S/40, Meknes 50001, Morocco
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McNeil CJ, Araujo K, Godfrey K, Slupsky CM. Metabolite Signature and Differential Expression of Genes in Washington Navel Oranges ( Citrus sinensis) Infected by Spiroplasma citri. PHYTOPATHOLOGY 2023; 113:299-308. [PMID: 35984373 DOI: 10.1094/phyto-05-22-0177-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Spiroplasma citri is the pathogen that causes citrus stubborn disease (CSD). Infection of citrus with S. citri has been shown to cause leaf mottling, reduce fruit yield, and stunt tree growth. Fruit from trees exhibiting symptoms of CSD are misshapen and discolored. The symptoms of CSD are easily confused with nutrient deficiencies or symptoms of citrus greening disease. In this study, young Washington navel oranges (Citrus sinensis) were graft-inoculated with budwood originating from trees confirmed to be infected with S. citri. Leaf samples were collected monthly for 10 months for metabolomics and differential gene expression analyses. Significant differences in the concentration of metabolites and expressed genes were observed between control and S. citri-infected trees throughout the experiment. Metabolites and genes associated with important defense and stress pathways, including jasmonic acid signaling, cell wall modification, amino acid biosynthesis, and the production of antioxidant and antimicrobial secondary metabolites, were impacted by S. citri throughout the study, and even prior to symptom development. This work fills a current gap in knowledge surrounding the pathogenicity of S. citri and provides an updated mechanistic explanation for the development of CSD symptoms in S. citri-infected plants.
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Affiliation(s)
- Christopher J McNeil
- Department of Food Science & Technology, University of California-Davis, Davis, CA 95616
| | - Karla Araujo
- Contained Research Facility, University of California-Davis, Davis, CA 95616
| | - Kristine Godfrey
- Contained Research Facility, University of California-Davis, Davis, CA 95616
| | - Carolyn M Slupsky
- Department of Food Science & Technology, University of California-Davis, Davis, CA 95616
- Department of Nutrition, University of California-Davis, Davis, CA 95616
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Yokomi R, Chen J, Rattner R, Selvaraj V, Maheshwari Y, Osman F, Pagliaccia D, Vidalakis G. Genome Sequence Resource for Spiroplasma citri, Strain CC-2, Associated with Citrus Stubborn Disease in California. PHYTOPATHOLOGY 2020; 110:254-256. [PMID: 31502518 DOI: 10.1094/phyto-08-19-0304-a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Spiroplasma citri is a bacterium that causes stubborn disease of citrus and infects other crops, ornamentals, and weeds. It is transmitted by leafhoppers in a circulative manner. Due to limited sequence data on S. citri, the bacterium was isolated from naturally infected Chinese cabbage grown on a farm in Fresno County, CA. DNA from S. citri CC-2 was extracted from a pure culture in LD8 and subjected to PacBio sequencing. Four contigs were obtained with a single circular chromosome of 1,709,192 bp and three plasmids of 40,210, 39,313, and 2,921 bp in size. The genome developed herein extends the sequence database of S. citri and is the first whole-genome sequence record of S. citri from California.
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Affiliation(s)
- Raymond Yokomi
- United States Department of Agriculture-Agricultural Research Service, San Joaquin Valley Agricultural Sciences Center, Parlier, CA 93648
| | - Jianchi Chen
- United States Department of Agriculture-Agricultural Research Service, San Joaquin Valley Agricultural Sciences Center, Parlier, CA 93648
| | - Rachel Rattner
- United States Department of Agriculture-Agricultural Research Service, San Joaquin Valley Agricultural Sciences Center, Parlier, CA 93648
| | - Vijayanandraj Selvaraj
- United States Department of Agriculture-Agricultural Research Service, San Joaquin Valley Agricultural Sciences Center, Parlier, CA 93648
| | - Yogita Maheshwari
- United States Department of Agriculture-Agricultural Research Service, San Joaquin Valley Agricultural Sciences Center, Parlier, CA 93648
| | - Fatima Osman
- Department of Plant Pathology, University of California, Davis, CA 95616
| | - Deborah Pagliaccia
- Department of Botany & Plant Sciences, University of California, Riverside, CA 92521
| | - Georgios Vidalakis
- Department of Microbiology and Plant Pathology, University of California, Riverside
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