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Tettey E, Aidoo OF, Ativor IN, Yankey EN. Relative contribution of biotic and abiotic factors to population fluctuations of Auchenorrhyncha community that could play a role in the Cape Saint Paul Wilt Disease (CSPWD) (lethal yellowing) pathosystem in Ghana. JOURNAL OF ECONOMIC ENTOMOLOGY 2024; 117:2186-2193. [PMID: 39158062 DOI: 10.1093/jee/toae188] [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: 11/29/2023] [Revised: 07/23/2024] [Accepted: 08/02/2024] [Indexed: 08/20/2024]
Abstract
As a major setback to the global coconut industry, lethal yellowing disease (LYD), caused by phytoplasmas, continues to threaten coconut palms in the Americas, the Caribbean, Africa, and Oceania. Despite its economic impacts, limited information exists on LYD vectors, which impedes the prevention and management of the disease. Using double-sided yellow sticky traps, we investigate the factors that influence the seasonal abundance and population dynamics of three sap-sucking insects of LYD, i.e., Diostrombus (Hemiptera: Derbidae) sp. and Patara sp. (Hemiptera: Derbidae), and Nedoptepa curta Dmitriev (Hemiptera: Cicadellidae), on five coconut genotypes (Sri Lanka Green Dwarf (SGD), Vanuatu Tall (VTT), SGD × VTT, Malayan Yellow Dwarf (MYD) × VTT, and West African Tall (WAT)) in the Western Region, and one (SGD) in the Central Region of Ghana from April 2019 to May 2021. The results showed that N. curta and Patara sp. were the most abundant species in the Western and Central Regions, respectively. There was a significant difference between the coconut cultivars and sap-sucking insects. The peak population development of the sap-sucking insects was recorded during the dry season on all the coconut genotypes at all sampling locations. A significant positive correlation was detected between temperature and the population of N. curta and Patara sp. In the Agona Nkwanta, VTT had the highest population of N. curta, whereas WAT had the highest population of Patara sp. and Diostrombus sp. These findings provide useful information for assessing the role of factors that could affect the Cape Saint Paul Wilt disease pathosystem.
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Affiliation(s)
- Elizabeth Tettey
- Coconut Research Program, Council for Scientific and Industrial Research (CSIR), P.O. Box 245, Sekondi, Ghana
- African Regional Postgraduate Program in Insect Science (ARPPIS), School of Agriculture, College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Owusu F Aidoo
- Department of Biological Sciences, School of Natural and Environmental Sciences, University of Environment and Sustainable Development, Somanya, Ghana
- Department of Entomology, Washington State University, Pullman, WA 99164, USA
| | - Isaac N Ativor
- Coconut Research Program, Council for Scientific and Industrial Research (CSIR), P.O. Box 245, Sekondi, Ghana
- Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH 03824, USA
| | - Egya N Yankey
- Coconut Research Program, Council for Scientific and Industrial Research (CSIR), P.O. Box 245, Sekondi, Ghana
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Zhang Y, Li X, Zhang S, Ma T, Mao C, Zhang C. Quantitative Loop-Mediated Isothermal Amplification Detection of Ustilaginoidea virens Causing Rice False Smut. Int J Mol Sci 2023; 24:10388. [PMID: 37373534 DOI: 10.3390/ijms241210388] [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: 04/28/2023] [Revised: 06/14/2023] [Accepted: 06/19/2023] [Indexed: 06/29/2023] Open
Abstract
Rice false smut caused by Ustilaginoidea virens is one of the most devastating diseases in rice worldwide, which results in serious reductions in rice quality and yield. As an airborne fungal disease, early diagnosis of rice false smut and monitoring its epidemics and distribution of its pathogens is particularly important to manage the infection. In this study, a quantitative loop-mediated isothermal amplification (q-LAMP) method for U. virens detection and quantification was developed. This method has higher sensitivity and efficiency compared to the quantitative real-time PCR (q-PCR) method. The species-specific primer that the UV-2 set used was designed based on the unique sequence of the U. virens ustiloxins biosynthetic gene (NCBI accession number: BR001221.1). The q-LAMP assay was able to detect a concentration of 6.4 spores/mL at an optimal reaction temperature of 63.4 °C within 60 min. Moreover, the q-LAMP assay could even achieve accurate quantitative detection when there were only nine spores on the tape. A linearized equation for the standard curve, y = -0.2866x + 13.829 (x is the amplification time, the spore number = 100.65y), was established for the detection and quantification of U. virens. In field detection applications, this q-LAMP method is more accurate and sensitive than traditional observation methods. Collectively, this study has established a powerful and simple monitoring tool for U. virens, which provides valuable technical support for the forecast and management of rice false smut, and a theoretical basis for precise fungicide application.
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Affiliation(s)
- Yu Zhang
- Department of Plant Pathology, Zhejiang Agriculture and Forest University, Hangzhou 311300, China
| | - Xinyue Li
- Department of Plant Pathology, Zhejiang Agriculture and Forest University, Hangzhou 311300, China
| | - Shuya Zhang
- Department of Plant Pathology, Zhejiang Agriculture and Forest University, Hangzhou 311300, China
| | - Tianling Ma
- Department of Plant Pathology, Zhejiang Agriculture and Forest University, Hangzhou 311300, China
| | - Chengxin Mao
- Department of Plant Pathology, Zhejiang Agriculture and Forest University, Hangzhou 311300, China
| | - Chuanqing Zhang
- Department of Plant Pathology, Zhejiang Agriculture and Forest University, Hangzhou 311300, China
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Wang G, Wu W, Tan S, Liang Y, He C, Chen H, Huang X, Yi K. Development of a Specific Nested PCR Assay for the Detection of 16SrI Group Phytoplasmas Associated with Sisal Purple Leafroll Disease in Sisal Plants and Mealybugs. PLANTS (BASEL, SWITZERLAND) 2022; 11:2817. [PMID: 36365270 PMCID: PMC9658197 DOI: 10.3390/plants11212817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/12/2022] [Accepted: 10/20/2022] [Indexed: 06/16/2023]
Abstract
Sisal purple leafroll disease (SPLD) is currently the most destructive disease affecting sisal in China, yet its aetiology remains unclear. In our previous research, it was verified to be associated with phytoplasmas, and nested PCR based on the 16S rRNA gene using universal primers R16mF2/R16mR1 followed by R16F2n/R16R2 was confirmed as the most effective molecular method for the detection of phytoplasmas associated with SPLD (SPLDaP). However, the method has a shortcoming of inaccuracy, for it could produce false positive results. To further manage the disease, accurate detection is needed. In this study, we developed a specific nested PCR assay using universal primers R16F2n/R16R2, followed by a set of primers designed on 16Sr gene sequences amplified from SPLDaP, nontarget bacteria from sisal plants, and other phytoplasma subgroups or groups. This established method is accurate, specific, and effective for detection of 16SrI group phytoplasma in sisal, and its sensitivity is up to 10 fg/μL of total DNA. It also minimized the false positive problem of nested PCR using universal primers R16mF2/R16mR1 followed by R16F2n/R16R2. This method was further used to verify the presence of phytoplasma in Dysmicoccusneobrevipes, and the results showed that D. neobrevipes could be infected by SPLDaP and thus could be a candidate for vector transmission assays.
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Affiliation(s)
- Guihua Wang
- College of Ecology and Environment, Hainan University, Haikou 570228, China
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- College of Forestry, Hainan University, Haikou 570228, China
| | - Weihuai Wu
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture and Rural Affairs, Haikou 571101, China
| | - Shibei Tan
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Yanqiong Liang
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Chunping He
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Helong Chen
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Xing Huang
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Kexian Yi
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture and Rural Affairs, Haikou 571101, China
- Sanya Research Institute, Chinese Academy of Tropical Agricultural Sciences, Sanya 572025, China
- Hainan Key Laboratory for Monitoring and Control of Tropical Agricultural Pests, Haikou 571101, China
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Mou DF, Di Lella B, Halbert SE, Bextine B, Helmick EE, Bahder BW. Acquisition and Transmission of the Lethal Bronzing Phytoplasma by Haplaxius crudus Using Infected Palm Spear Leaves and Artificial Feeding Media. PHYTOPATHOLOGY 2022; 112:2052-2061. [PMID: 35439034 DOI: 10.1094/phyto-03-22-0079-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Lethal bronzing (LB) is a fatal palm disease caused by the phytoplasma 'Candidatus Phytoplasma aculeata'. This disease causes significant economic losses in palm industries and landscapes. The American palm cixiid, Haplaxius crudus, recently was identified as the vector of the phytoplasma. However, knowledge about LB phytoplasma transmission is limited due to the lack of a method to generate phytoplasma-infected insects in the laboratory. In this study, the acquisition and transmission of the LB phytoplasma by H. crudus were investigated. Successful acquisitions of the phytoplasma by H. crudus were observed at 2 days acquisition access period on LB-infected palm spear leaves. Analyses revealed increased phytoplasma infection rates of H. crudus with longer acquisition access periods and latent periods. A significantly higher phytoplasma infection rate was shown after various acquisition access periods and latent periods than the infection rate of the field-collected H. crudus population. Transmission of the phytoplasma from LB-infected spear leaves to sucrose media by H. crudus also was observed using digital PCR assays. These results further support the vector status of H. crudus and offer valuable information to understand LB phytoplasma transmission. Additionally, these results generate a critical baseline for future LB phytoplasma-vector research by providing a way to generate vectors with high phytoplasma infection rates in the laboratory setting.
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Affiliation(s)
- De-Fen Mou
- Department of Entomology and Nematology-Fort Lauderdale Research and Education Center, University of Florida, Davie, FL 33314-7719
| | - Brandon Di Lella
- Department of Entomology and Nematology-Fort Lauderdale Research and Education Center, University of Florida, Davie, FL 33314-7719
| | - Susan E Halbert
- Division of Plant Industry, Florida Department of Agriculture and Consumer Services, Gainesville, FL 32608
| | - Blake Bextine
- Department of Biology, University Texas at Tyler, Tyler, TX 75799
| | - Ericka E Helmick
- Department of Entomology and Nematology-Fort Lauderdale Research and Education Center, University of Florida, Davie, FL 33314-7719
| | - Brian W Bahder
- Department of Entomology and Nematology-Fort Lauderdale Research and Education Center, University of Florida, Davie, FL 33314-7719
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Ahmed EA, Shoala T, Abdelkhalik A, El-Garhy HAS, Ismail IA, Farrag AA. Nanoinhibitory Impacts of Salicylic Acid, Glycyrrhizic Acid Ammonium Salt, and Boric Acid Nanoparticles against Phytoplasma Associated with Faba Bean. Molecules 2022; 27:1467. [PMID: 35268567 PMCID: PMC8911656 DOI: 10.3390/molecules27051467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/13/2022] [Accepted: 02/16/2022] [Indexed: 11/17/2022] Open
Abstract
Phytoplasmas are economically important plant pathogenic bacterial diseases, causing severe yield losses worldwide. In this study, we tested nanoformulations such as glycyrrhizic acid ammonium salt (GAS), salicylic acid (SA), and boric acid (BA) as novel antimicrobial agents inducing the resistance against the phytoplasma disease in faba bean. The nanoparticles (NP) were foliar-applied to naturally phytoplasma-infected faba bean with three concentrations from each of SA, GAS, and BA, under field conditions. Nested PCR (using universal primer pairs P1/P7 and R16F2n/R16R2) were reacted positively with all symptomatic samples and gave a product size of approximately 1200 bp, while the healthy plant gave no results. Transmission electron microscopy examinations of phytoplasma-infected faba bean plants treated with different nanoparticles revealed that severe damage occurred in phytoplasma particle's structure, degradation, malformation, lysis in the cell membrane, and the cytoplasmic leakage followed by complete lysis of phytoplasma cells. Exogenous application of GAS-NP (1.68 µM), SA-NP (0.28 µM), and BA-NP (0.124 µM) suppressed the infection percentage of phytoplasma by 75%, 50%, and 20%, and the disease severity by 84%, 64%, and 54%, respectively. Foliar application of nanoparticles improved Fv/Fm (maximum quantum efficiency of PSII Photochemistry), PI (the performance index), SPAD chlorophyll (the relative chlorophyll content), shoots height, and leaves number, thus inducing recovery of the plant biomass and green pods yield. The most effective treatment was GAS-NP at 1.68 µM that mediated substantial increases in the shoots' fresh weight, shoots' dry weight, number of pods per plant, and green pods yield by 230%, 244%, 202% and 178%, respectively, compared to those of infected plants not sprayed with nanoparticles. This study demonstrated the utility of using nanoparticles, particularly GAS-NP at 1.68 µM to suppress the phytoplasma infection.
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Affiliation(s)
- Eman A. Ahmed
- Virus and Phytoplasma Research Department, Plant Pathology Research Institute, Agricultural Research Center (ARC), Giza 12619, Egypt;
| | - Tahsin Shoala
- Environmental Biotechnology Department, College of Biotechnology, Misr University for Science and Technology, Giza 12563, Egypt
| | | | - Hoda A. S. El-Garhy
- Genetics and Genetic Engineering Department, Faculty of Agriculture, Benha University, Qalyubia 13736, Egypt;
| | - Ismail A. Ismail
- Department of Biology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia;
| | - Amro A. Farrag
- Virus and Phytoplasma Research Department, Plant Pathology Research Institute, Agricultural Research Center (ARC), Giza 12619, Egypt;
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In vitro transmission of 16SrIV phytoplasmas to coconut plants by Haplaxius crudus in Yucatan, Mexico. 3 Biotech 2022; 12:5. [PMID: 34926118 PMCID: PMC8643390 DOI: 10.1007/s13205-021-03069-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 11/19/2021] [Indexed: 01/03/2023] Open
Abstract
The coconut palm is an important crop worldwide. In America, it is affected by lethal yellowing (LY) disease, associated with the presence of 16SrIV ribosomal group phytoplasmas. Studies in Florida using insect-proof cages indicate Haplaxius crudus as a vector of LY phytoplasmas to palm species, including coconut. Here, an in vitro transmission system was used to verify that H. crudus collected in Yucatan, Mexico, transmit 16SrIV phytoplasmas to coconut. Three transmission trials were carried out using micropropagated coconut plants. In each trial, at least one plant was positive to 16SrIV phytoplasmas. In total, there were 4 positive plants out of 34 exposed to insects, and the phytoplasma presence was detected in root, stem, and leaf tissues. The phytoplasmas identified were 16SrIV-A and 16SrIV-D, both found in both plants and insects. In each assay where a plant was positive for either 16SrIV-A or 16SrIV-D, the same phytoplasma was present in the insect or insects used in this assay. This is the first demonstration of transmission of LY phytoplasmas to coconut plants by H. crudus in Mexico and with an in vitro system. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s13205-021-03069-z.
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7
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Soto N, Helmick EE, Harrison NA, Bahder BW. Genetic Variability of Palm Lethal Decline Phytoplasmas in the Caribbean Basin and Florida, U.S.A., Based on a Multilocus Analysis. PHYTOPATHOLOGY 2021; 111:2203-2212. [PMID: 34844420 DOI: 10.1094/phyto-04-21-0130-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Palm lethal decline phytoplasmas are an important group of plant pathogens that cause death in a variety of palm species throughout the Caribbean basin and the southeastern United States. The 16SrIV-D phytoplasma was introduced to the state of Florida, United States; it has since caused severe economic losses to the green industries of Florida and is threating natural ecosystems because of its ability to infect the native palm Sabal palmetto. In this study, the genetic variability of the 16SrIV-D phytoplasma was assessed over a 10-year period to determine if multiple introductions had occurred or if natural mutations were occurring. Furthermore, the genetic variability of the palm lethal decline phytoplasma group (16SrIV) was assessed with a multiple locus analysis using the 16S ribosomal RNA gene, the 16S-23S intergenic spacer region, and secA and groEL genes. Overall, no variability of the 16SrIV-D phytoplasma was documented in Florida over a 10-year period. The multilocus analysis showed support for three distinct species of the phytoplasma in the Caribbean basin that infect palms and further support that the 16SrIV-C from Tanzania is not closely related. Furthermore, 16SrIV-B and 16SrIV-D were found to be the same phytoplasma based on 100% identity between the two based on intergenic spacer region, secA, and groEL analysis. This study represents the first robust, multilocus analysis of palm-infecting phytoplasmas from the Caribbean and sheds light on the phylogeny and evolution of the group.
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Affiliation(s)
- Noemi Soto
- Department of Entomology and Nematology, University of Florida Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Ericka E Helmick
- Department of Entomology and Nematology, University of Florida Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Nigel A Harrison
- Department of Plant Pathology, University of Florida Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Brian W Bahder
- Department of Entomology and Nematology, University of Florida Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
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Jones LM, Pease B, Perkins SL, Constable FE, Kinoti WM, Warmington D, Allgood B, Powell S, Taylor P, Pearce C, Davis RI. 'Candidatus Phytoplasma dypsidis', a novel taxon associated with a lethal wilt disease of palms in Australia. Int J Syst Evol Microbiol 2021; 71. [PMID: 34003739 DOI: 10.1099/ijsem.0.004818] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A phytoplasma was initially detected in Dypsis poivriana by nested and real-time PCR from the botanical gardens in Cairns, Queensland, Australia in 2017. Further surveys in the Cairns region identified phytoplasma infections in eight additional dying ornamental palm species (Euterpe precatoria, Cocos nucifera, Verschaffeltia splendida, Brassiophoenix drymophloeodes, Burretiokentia hapala, Cyrtostachys renda, Reinhardtia gracilis, Carpoxylon macrospermum), a Phoenix species, a Euterpe species and two native palms (Archontophoenix alexandrae). Analysis of 16S rRNA gene sequences showed that this phytoplasma is distinct as it shared less than 97.5 % similarity with all other 'Candidatus Phytoplasma' species. At 96.3 % similarity, the most closely related formally described member of the provisional 'Ca. Phytoplasma' genus was 'Ca. Phytoplasma noviguineense', a novel taxon from the island of New Guinea found in monocotyledonous plants. It was slightly more closely related (96.6-96.8 %) to four palm-infecting strains from the Americas, which belong to strain group 16SrIV and which have not been assigned to a formal 'Candidatus Phytoplasma' species taxon. Phylogenetic analysis of the 16S rRNA gene and ribosomal protein genes of the phytoplasma isolate from a dying coconut palm revealed that the phytoplasma represented a distinct lineage within the phytoplasma clade. As the nucleotide identity with other phytoplasmas is less than 97.5 % and the phylogenetic analyses show that it is distinct, a novel taxon 'Candidatus Phytoplasma dypsidis' is proposed for the phytoplasma found in Australia. Strain RID7692 (GenBank accession no. MT536195) is the reference strain. The impact and preliminary aspects of the epidemiology of the disease outbreak associated with this novel taxon are described.
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Affiliation(s)
- Lynne M Jones
- Northern Australia Quarantine Strategy, Department of Agriculture Water and Environment, 114 Catalina Crescent, Cairns International Airport, Qld 4870, Australia
| | - Bradley Pease
- Northern Australia Quarantine Strategy, Department of Agriculture Water and Environment, 114 Catalina Crescent, Cairns International Airport, Qld 4870, Australia
| | - Sandy L Perkins
- Northern Australia Quarantine Strategy, Department of Agriculture Water and Environment, 114 Catalina Crescent, Cairns International Airport, Qld 4870, Australia
| | - Fiona E Constable
- Department of Jobs, Precincts and Regions, AgriBio, Centre for AgriBioscience, Bundoora, Victoria 3083, Australia
| | - Wycliff M Kinoti
- Department of Jobs, Precincts and Regions, AgriBio, Centre for AgriBioscience, Bundoora, Victoria 3083, Australia
| | - David Warmington
- Botanic Reserves Parks and Leisure, Cairns Regional Council, Cairns Queensland 4870, Australia
| | - Ben Allgood
- Botanic Reserves Parks and Leisure, Cairns Regional Council, Cairns Queensland 4870, Australia
| | - Sonya Powell
- Botanic Reserves Parks and Leisure, Cairns Regional Council, Cairns Queensland 4870, Australia
| | - Pieter Taylor
- Infrastructure Services, Cairns Regional Council, Cairns Queensland 4870, Australia
| | - Ceri Pearce
- Biosecurity Queensland, Queensland Department of Agriculture and Fisheries, Centre for Wet Tropics Agriculture, South Johnstone QLD 4859, Australia
| | - Richard I Davis
- Northern Australia Quarantine Strategy, Department of Agriculture Water and Environment, 114 Catalina Crescent, Cairns International Airport, Qld 4870, Australia
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Dzido JL, Sánchez R, Dollet M, Julia JF, Narvaez M, Fabre S, Oropeza C. Haplaxius crudus (Hemiptera: Cixiidae) Transmits the Lethal Yellowing Phytoplasmas, 16SrIV, to Pritchardia pacifica Seem. & H.Wendl (Arecaceae) in Yucatan, Mexico. NEOTROPICAL ENTOMOLOGY 2020; 49:795-805. [PMID: 32813216 DOI: 10.1007/s13744-020-00799-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 06/22/2020] [Indexed: 06/11/2023]
Abstract
Lethal yellowing (LY) affects several palm species in the Americas. It is caused by 16SrIV group phytoplasmas. In Florida (USA), LY was shown to be transmitted by the planthopper Haplaxius crudus ( Van Duzee ) (Hemiptera, Cixiidae) to different palm species, including Pritchardia pacifica Seem . & H. Wendl . (Arecaceae) in insect-proof cage experiments in the 1980s, a result that had never been reproduced later. LY has destroyed many coconut plantations as well as other palm species in the Caribbean and Mexico. In order to evaluate if H. crudus is a vector of LY phytoplasmas in Mexico, experiments were carried out in Yucatan (Mexico). Several H. crudus from palms infected by LY in the field were introduced into cages containing young P. pacifica palms. These insects were able to transmit 16SrIV group phytoplasmas to P. pacifica palms. According to DNA sequences comparative analysis, virtual restriction fragment length polymorphism, and phylogenetic analysis, the phytoplasmas detected in these infected P. pacifica were of subgroups A and D. All of ten P. pacifica palms infected with the subgroup D phytoplasmas developed symptoms of LY and died, whereas only one of two palms infected with subgroup A developed LY symptoms and died. This is the first time, more than 30 years later, that the role of H. crudus as a vector of LY is confirmed.
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Affiliation(s)
- J-L Dzido
- Cirad, UMR IPME, Montpellier, France
| | - R Sánchez
- Centro de Investigación Científica de Yucatán (CICY), Mérida, Mexico
| | - M Dollet
- Cirad, UMR IPME, Montpellier, France.
- Embrapa CENARGEN, Brasília DF, Brasil.
| | - J-F Julia
- Cirad, UMR IPME, Montpellier, France
| | - M Narvaez
- Centro de Investigación Científica de Yucatán (CICY), Mérida, Mexico
| | - S Fabre
- Cirad, UMR IPME, Montpellier, France
| | - C Oropeza
- Centro de Investigación Científica de Yucatán (CICY), Mérida, Mexico
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Ramos Hernández E, Lesher Gordillo JM, Oropeza Salín C, Ortiz García CF, Magaña Alejandro MA, Sánchez Soto S, García Estrada Y. Detection and Identification of Phytoplasmas in the 16SrIV-A, -B, and -D Subgroups in Palms in Tabasco, Mexico. PLANT DISEASE 2020; 104:2606-2612. [PMID: 32813613 DOI: 10.1094/pdis-09-18-1488-re] [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: 06/11/2023]
Abstract
The 16SrIV-A phytoplasmas are associated with the devastating disease lethal yellowing (LY) of palms. In Tabasco (Mexico), the death of Cocos nucifera, Adonidia merrillii, and Attalea butyracea palms have been suspected to be associated with LY based on symptomatology. Samples from the trunk of both symptomatic and nonsymptomatic palms were collected in three different environments: two species of palms within a rural zone and the other within an urban zone. DNA was extracted to perform a nested PCR with phytoplasma primers P1/P7-LY16SF/R16R2. A 1,345-bp fragment was amplified from the DNA extracted from each of the 29 LY-symptomatic palms sampled. Phytoplasma identification was achieved by amplicon sequencing and virtual restriction fragment length polymorphism analyses. Three 16SrIV phytoplasma subgroups were detected: 16SrIV-A in C. nucifera, 16SrIV-B in A. merrillii, and 16SrIV-D in C. nucifera, A. merrillii, and A. butyracea. Phylogenetic analysis showed also that the three phytoplasma strains found in the palm species clustered with phytoplasmas reported in the literature in the three subgroups identified. This is the first report of phytoplasmas associated with these palm species in Tabasco.
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Affiliation(s)
- Eder Ramos Hernández
- Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Campo Experimental Huimanguillo, 86400, Huimanguillo, Tabasco, México
| | - Julia M Lesher Gordillo
- Universidad Juárez Autónoma de Tabasco, División Académica de Ciencias Biológicas, 86150, Villahermosa, Tabasco, México
| | - Carlos Oropeza Salín
- Centro de Investigación Científica de Yucatán A.C., 97205, Chuburná de Hidalgo, Mérida, Yucatán, México
| | | | - Miguel A Magaña Alejandro
- Universidad Juárez Autónoma de Tabasco, División Académica de Ciencias Biológicas, 86150, Villahermosa, Tabasco, México
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Soto N, Humphries AR, Mou DF, Helmick EE, Glover JP, Bahder BW. Effect of Oxytetracycline-Hydrochloride on Phytoplasma Titer and Symptom Progression of the 16SrIV-D Phytoplasma in Cabbage Palms from Florida. PLANT DISEASE 2020; 104:2330-2337. [PMID: 32687435 DOI: 10.1094/pdis-01-20-0029-re] [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: 06/11/2023]
Abstract
Lethal bronzing (LB) is a phytoplasma disease of palms in Florida, U.S.A. Historically, the use of the antibiotic oxytetracycline-hydrochloride (OTC-HCl) was optimized to treat for LY, and currently label rates for OTC-HCl developed for LY are being used to treat palms preventatively against LB. Because of the economic impact of LB, assessing OTC-HCl against LB is essential for developing and optimizing management options for this disease. In this study, Sabal palmetto palms declining from LB were injected with OTC-HCl to assess efficacy on LB. Four groups of palms were selected that represented healthy palms, early symptomatic palms, palms with moderate symptoms, and palms with late-stage symptoms. Within each group, treatment palms injected with OTC-HCl and a control group with no antibiotics were tested weekly by quantitative PCR for 1 year. For asymptomatic palms, treated palms never developed symptoms or tested positive, whereas one of the control palms did. The early symptomatic palms that were treated had similar levels of phytoplasma to the control group but had much slower symptom development. Palms with moderate symptoms had no difference in titer between the treatment and the control group, but treated palms had much slower symptom development. Palms with late-stage symptoms showed no difference in phytoplasma titer or symptom progression between treated and control palms. These results suggest that label rates of OTC-HCl appear useful as a preventative against LB, but once symptoms develop, label rates cannot cure palms. In the meantime, removal of symptomatic palms is recommended.
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Affiliation(s)
- Noemi Soto
- Department of Entomology and Nematology, University of Florida - Fort Lauderdale Research and Education Center, Davie, FL 33314
| | - Alessandra R Humphries
- Department of Entomology and Nematology, University of Florida - Fort Lauderdale Research and Education Center, Davie, FL 33314
| | - De-Fen Mou
- Department of Entomology and Nematology, University of Florida - Fort Lauderdale Research and Education Center, Davie, FL 33314
| | - Ericka E Helmick
- Department of Entomology and Nematology, University of Florida - Fort Lauderdale Research and Education Center, Davie, FL 33314
| | - James P Glover
- Department of Entomology and Nematology, University of Florida - Fort Lauderdale Research and Education Center, Davie, FL 33314
| | - Brian W Bahder
- Department of Entomology and Nematology, University of Florida - Fort Lauderdale Research and Education Center, Davie, FL 33314
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12
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Bahder BW, Soto N, Mou DF, Humphries AR, Helmick EE. Quantification and Distribution of the 16SrIV-D Phytoplasma in the Wild Date Palm, Phoenix sylvestris, at Different Stages of Decline Using Quantitative PCR (qPCR) Analysis. PLANT DISEASE 2020; 104:1328-1334. [PMID: 32202466 DOI: 10.1094/pdis-10-19-2146-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Lethal bronzing disease (LBD) is a fatal infection in a variety of ornamental palms in Florida caused by the 16SrIV-D phytoplasma. The disease was first found in 2006 in Florida and has since spread to 31 different counties, reaching as far north as Jacksonville and as far south as Key Largo. Stakeholders (nursery personnel, landscaping personnel, and extension agents) from across the state take and send samples for analysis. To provide better sampling recommendations and reduce the time associated with the sampling process, the distribution of the 16SrIV-D phytoplasma was examined by quantitative PCR analysis in various Phoenix sylvestris that displayed different stages of decline, including early symptoms, moderate symptoms, and late symptoms. A declining Sabal palmetto was also available for analysis and examined as well. The findings of this study revealed that regardless of the stage of decline, the highest amount of phytoplasma detected was nearest to the base of the trunk and gradually decreased further up the trunk. Also, in P. sylvestris it was found that with symptoms present, the entire trunk has a systemic infection, resulting in positive reactions for every sample taken. These data are useful to stakeholders because they provide useful sampling recommendations in that only a single sample is needed when sampling a palm suspected to be infected with phytoplasma. Also, based on these results, sampling lower on the trunk is advised.
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Affiliation(s)
- Brian W Bahder
- Department of Entomology and Nematology, University of Florida-Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Noemi Soto
- Department of Entomology and Nematology, University of Florida-Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - De-Fen Mou
- Department of Entomology and Nematology, University of Florida-Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Alessandra R Humphries
- Department of Entomology and Nematology, University of Florida-Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Ericka E Helmick
- Department of Entomology and Nematology, University of Florida-Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
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13
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Wang Z, Zhu Y, Li Z, Yang X, Zhang T, Zhou G. Development of a Specific Polymerase Chain Reaction System for the Detection of Rice Orange Leaf Phytoplasma Detection. PLANT DISEASE 2020; 104:521-526. [PMID: 31801036 DOI: 10.1094/pdis-05-19-1047-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Rice orange leaf disease (ROLD), caused by rice orange leaf phytoplasma (ROLP), is transmitted by leafhopper vectors Recilia dorsalis and Nephotettix cinticeps. ROLD severely devastates rice production in Asia. Accurate detection of the pathogen is important for disease management. Current nested polymerase chain reaction (nested PCR) method using phytoplasma universal primers is widely used to detect phytoplasmas; however, it has shortcoming of inconvenience and inaccuracy, for it needs two round of PCR reactions and could produce false positive results due to nontarget amplification. In this study, we developed a PCR assay using a set of primers designed based on the ROLP genome sequence to amplify house-keeping gene FtsH-1 in rice and leafhopper vector samples. This method is simple and rapid, and its sensitivity up to 10 pg/μl of total ROLP DNA. It also minimizes the false positive problem produced by nested PCR. This method was used to survey the geographic distribution of ROLD in southern China from 2016 to 2018. The results showed that the distribution areas and vector carrying rate of ROLD had gradually increased.
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Affiliation(s)
- Zhiyi Wang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Agriculture, South China Agricultural University, Guangzhou, Guangdong 510642, China
| | - Yingzhi Zhu
- College of Marine and Biotechnology, Guangxi University for Nationalities, Nanning, Guangxi 530007, China
| | - Zhanbiao Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Agriculture, South China Agricultural University, Guangzhou, Guangdong 510642, China
| | - Xin Yang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Agriculture, South China Agricultural University, Guangzhou, Guangdong 510642, China
| | - Tong Zhang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Agriculture, South China Agricultural University, Guangzhou, Guangdong 510642, China
| | - Guohui Zhou
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Agriculture, South China Agricultural University, Guangzhou, Guangdong 510642, China
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14
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Bahder BW, Soto N, Helmick EE, Dey KK, Komondy L, Humphries AR, Mou DF, Bailey R, Ascunce MS, Goss EM. A Survey of Declining Palms (Arecaceae) With 16SrIV-D Phytoplasma to Evaluate the Distribution and Host Range in Florida. PLANT DISEASE 2019; 103:2512-2519. [PMID: 31432773 DOI: 10.1094/pdis-03-19-0633-re] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The 16SrIV-D phytoplasma was first identified in Florida in 2006. Since its discovery, it has spread throughout most of the state. It is most prevalent in the central part of Florida, from Hillsborough County on the west coast to St. Lucie County on the east coast. The 16SrIV-D phytoplasma is the causal agent of lethal bronzing disease (LBD), which is also known as Texas Phoenix palm decline (TPPD). It affects a variety of common and economically important ornamental palm species as well as the native and ecologically important species, Sabal palmetto. It has spread into the southern portions of Florida, where the palm species diversity is higher. The aims of this survey were to document the spread of disease in terms of geographic and host range one decade after its introduction into Florida, and to assess the risk that LBD poses to the nursery and landscaping industries. The survey included samples received from stakeholders throughout the state, covering 18 counties, as well as a systematic sampling of palms at the Fort Lauderdale Research and Education Center (FLREC), where the disease is spreading actively. The findings of this survey resulted in the detection of LBD in eight new counties, including Collier, Hernando, Jefferson, Martin, Miami-Dade, Monroe, Seminole, and St. Johns, and the expansion of LBD into four new host species, Cocos nucifera, Livistona chinensis, Butia capitata, and Carpentaria acuminata. These findings are crucial for stakeholders because they highlight new hosts of 16SrIV-D phytoplasma and the geographic expansion of the disease, indicating that vigilance is needed when surveying declining palms.
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Affiliation(s)
- Brian W Bahder
- University of Florida, Department of Entomology and Nematology - Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Noemi Soto
- University of Florida, Department of Entomology and Nematology - Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Ericka E Helmick
- University of Florida, Department of Entomology and Nematology - Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Kishore K Dey
- Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville 32614
| | - Lidia Komondy
- University of Florida, Department of Entomology and Nematology - Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Alessandra R Humphries
- University of Florida, Department of Entomology and Nematology - Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - De-Fen Mou
- University of Florida, Department of Entomology and Nematology - Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | | | - Marina S Ascunce
- University of Florida, Department of Plant Pathology and Emerging Pathogens Institute, Gainesville, FL 32611
| | - Erica M Goss
- University of Florida, Department of Plant Pathology and Emerging Pathogens Institute, Gainesville, FL 32611
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15
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Bahder BW, Soto N, Komondy L, Mou DF, Humphries AR, Helmick EE. Detection and Quantification of the 16SrIV-D Phytoplasma in Leaf Tissue of Common Ornamental Palm Species in Florida using qPCR and dPCR. PLANT DISEASE 2019; 103:1918-1922. [PMID: 31161934 DOI: 10.1094/pdis-01-19-0010-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Lethal bronzing disease (LBD) is a lethal decline of various palm species caused by the 16SrIV-D phytoplasma. The disease was described in Texas in 2002 but found in Florida in 2006. Since its introduction, the phytoplasma has spread throughout much of the state. Typically, sampling of infected palms involves taking trunk tissue; however, in some instances this is not possible so alternative protocols are needed. In this study, phytoplasma titers were measured in different leaf tissues of infected palm in order to provide stakeholders with more sampling options. In addition, understanding the phytoplasma distribution in the palm canopy can shed light on the pathogen's biology and aid in vector studies. Three species of palm, Phoenix roebelinii, Sabal palmetto, and Syagrus romanzoffiana, were identified and confirmed positive for infection by qPCR analysis. Leaf tissue from these species that represented different stages of decay were sampled and tested by qPCR and dPCR. For each species, phytoplasma was only detectable in the spear leaf tissue that was connected directly to the apical meristem by both qPCR and dPCR. These data are useful by demonstrating that the 16SrIV-D phytoplasma appears to be restricted to the spear leaf so stakeholders who wish to sample palms but cannot sample trunk tissue due to palm size or lack of permission to drill into the trunk have an alternative tissue type to reliably sample. In addition, this information will help improve vector research by knowing where to collect insects that have a higher probably of possessing the phytoplasma.
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Affiliation(s)
- Brian W Bahder
- Department of Entomology and Nematology, University of Florida-Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Noemi Soto
- Department of Entomology and Nematology, University of Florida-Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Lidia Komondy
- Department of Entomology and Nematology, University of Florida-Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - De-Fen Mou
- Department of Entomology and Nematology, University of Florida-Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Alessandra R Humphries
- Department of Entomology and Nematology, University of Florida-Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
| | - Ericka E Helmick
- Department of Entomology and Nematology, University of Florida-Fort Lauderdale Research and Education Center, Davie, FL 33314-7719
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16
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Abstract
Phytoplasma detection and identification is primarily based on PCR followed by restriction fragment length polymorphism analysis. This method detects and differentiates phytoplasmas including those not yet identified. The protocol describes the application of this method for identification of phytoplasmas at 16S rRNA (16Sr) group and 16Sr subgroup levels on amplicons and also in silico on the same sequences.
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17
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Ferguson MH, Singh R. First Report of Lethal Yellowing Associated with Phytoplasma Subgroup 16SrIV-A on Silver Date Palm and Chinese Windmill Palm in Louisiana. PLANT DISEASE 2018; 102:PDIS11171729PDN. [PMID: 30113258 DOI: 10.1094/pdis-11-17-1729-pdn] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Affiliation(s)
- M H Ferguson
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge 70803
| | - R Singh
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge 70803
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18
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Bahder BW, Helmick EE, Mou DF, Harrison NA, Davis R. Digital PCR Technology for Detection of Palm-Infecting Phytoplasmas Belonging to Group 16SrIV that Occur in Florida. PLANT DISEASE 2018; 102:1008-1014. [PMID: 30673395 DOI: 10.1094/pdis-06-17-0787-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Phytoplasmas are an economically important group of plant pathogens that negatively impact a wide variety of plants in agricultural and natural ecosystems. In Florida, palm trees are essential elements in the nursery and landscaping industries that suffer from diseases caused by phytoplasmas that are related to each other but are classified in two different subgroups, 16SrIV-A and 16SrIV-D. In this study, a TaqMan assay was developed for digital polymerase chain reaction (dPCR) to detect both palm-infecting phytoplasmas found in Florida. When compared with real-time PCR assays and nested PCR assays, dPCR was capable of detecting the phytoplasmas at much lower concentrations than was possible by using real-time PCR and nested PCR. Additionally, the assay was capable of detecting 16SrIV-B phytoplasma as well as isolates representing the 16SrI and 16SrIII phytoplasma groups. Due to sequence identity of primer annealing regions across diverse phytoplasmas, the assay is likely to be successful for detection of a wide variety of phytoplasmas. The increased sensitivity of this dPCR assay over real-time PCR will allow for earlier detection of phytoplasma infection in palm trees, as well as for screening of salivary glands of candidate insect vector species. These advantages should aid timely management decisions to reduce disease spread and rapid determination of phytoplasma transmission by vectors.
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Affiliation(s)
- Brian W Bahder
- Department of Entomology and Nematology, University of Florida, Fort Lauderdale Research and Education Center (FLREC), Davie 33314-7719
| | - Ericka E Helmick
- Department of Entomology and Nematology, University of Florida, Fort Lauderdale Research and Education Center (FLREC), Davie 33314-7719
| | - De-Fen Mou
- Department of Entomology and Nematology, University of Florida, Fort Lauderdale Research and Education Center (FLREC), Davie 33314-7719
| | | | - Robert Davis
- Molecular Plant Pathology Laboratory, United States Department of Agriculture-Agricultural Research Service, Beltsville, MD 20705
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19
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Narváez M, Vázquez-Euán R, Harrison NA, Nic-Matos G, Julia JF, Dzido JL, Fabre S, Dollet M, Oropeza C. Presence of 16SrIV phytoplasmas of subgroups A, D and E in planthopper Haplaxius crudus Van Duzee insects in Yucatán, Mexico. 3 Biotech 2018; 8:61. [PMID: 29354372 PMCID: PMC5762597 DOI: 10.1007/s13205-018-1094-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 01/04/2018] [Indexed: 10/18/2022] Open
Abstract
The present study was carried out to determine if group 16SrIV phytoplasmas, causing lethal yellowing (LY) disease, are present in Haplaxius crudus Van Duzee (Hemiptera: Cixiidae) insects associated with palms in Yucatán, Mexico. Haplaxius crudus feral insects were captured from palm foliage at two locations (Chicxulub Puerto and CICY, Mérida, where LY-type diseases are active) and evaluated individually for the presence of phytoplasma DNA by a group 16SrIV-specific nested PCR assay. The results showed positive detection in H. crudus insects in a proportion of 2.7% (of the total 2726 analyzed) during a 3-year period of study. The percentage of detection was different for each site, 5.9% positive of 799 insects from Mérida and 1.7% of 1927 from Chicxulub Puerto. Positive detections were also obtained in extracts from 5.3 to 1.2% of males and females, respectively. Sequencing and in silico RFLP and phylogenetic analyses of PCR-amplified rDNA products indicated that H. crudus insects from Chicxulub Puerto harbored phytoplasma strains of subgroups 16SrIV-A or 16SrIV-D, whereas in insects from Mérida the strains found were 16SrIV-A, 16SrIV-D or 16SrIV-E. The diversity of subgroup strains detected in H. crudus coincided with strains previously identified in palms showing LY-type disease syndromes in Yucatán thereby implicating H. crudus as a candidate vector of 16SrIV phytoplasmas in this region of Mexico.
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Affiliation(s)
- María Narváez
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán (CICY), A.C., Calle 43 No. 130 x 32 y 34, Chuburná de Hidalgo, 97205 Mérida, Yucatán Mexico
| | - Roberto Vázquez-Euán
- Departamento de Investigaciones Científicas y Tecnológicas, Universidad de Sonora, Hermosillo, Sonora Mexico
| | - Nigel A. Harrison
- University of Florida, Research and Education Center (UF-REC), Fort Lauderdale, FL 33314 USA
| | - Germán Nic-Matos
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán (CICY), A.C., Calle 43 No. 130 x 32 y 34, Chuburná de Hidalgo, 97205 Mérida, Yucatán Mexico
| | | | | | | | | | - Carlos Oropeza
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán (CICY), A.C., Calle 43 No. 130 x 32 y 34, Chuburná de Hidalgo, 97205 Mérida, Yucatán Mexico
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20
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Jeger M, Bragard C, Candresse T, Chatzivassiliou E, Dehnen-Schmutz K, Gilioli G, Gregoire JC, Jaques Miret JA, MacLeod A, Navajas Navarro M, Niere B, Parnell S, Potting R, Rafoss T, Rossi V, Urek G, Van Bruggen A, Van der Werf W, West J, Winter S, Dickinson M, Marzachi C, Hollo G, Caffier D. Pest categorisation of Palm lethal yellowing phytoplasmas. EFSA J 2017; 15:e05028. [PMID: 32625317 PMCID: PMC7009989 DOI: 10.2903/j.efsa.2017.5028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The EFSA Panel on Plant Health performed a pest categorisation of Palm lethal yellowing phytoplasmas for the EU territory. This name is used to describe diseases that share the same succession of symptoms in palms that are caused by a number of strains of phytoplasma, for which efficient molecular detection assays are available. The pest is not known to occur in the EU and therefore does not meet one of the criteria for being a Union regulated non-quarantine pest. For 'Candidatus Phytoplasma palmae', the planthopper Haplaxius crudus, which is not known to be present in the EU, is the confirmed vector, but for the other strains, the vectors are unknown. The host range of the pest is restricted to Arecaceae species, in particular coconut. The pest is regulated on all known hosts in Annex IIAI of Directive 2000/29/EC. It could potentially enter the EU via plants for planting or through infected vectors. The phytoplasmas could become established in the EU as host plants are present. It is unknown whether arthropods present in the EU could be vectors. The potential impact of the pest if introduced into the EU is difficult to assess given this uncertainty but is estimated to be limited. The main knowledge gaps concern the status of potential vector insects in the EU; the possibility for seed transmission of the phytoplasmas; the origin and volume of the trade in palm seeds and plants for planting; the host status and susceptibility of many palm species grown in the EU and the potential new assignments of phytoplasmas to this categorisation that might have associated alternate hosts. Palm lethal yellowing phytoplasmas meet the criteria assessed by EFSA for consideration as Union quarantine pest.
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21
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Bahder BW, Helmick EE, Harrison NA. Detecting and Differentiating Phytoplasmas Belonging to Subgroups 16SrIV-A and 16SrIV-D Associated With Lethal Declines of Palms in Florida Using qPCR and High-Resolution Melt Analysis (HRMA). PLANT DISEASE 2017; 101:1449-1454. [PMID: 30678590 DOI: 10.1094/pdis-01-17-0023-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Lethal yellowing (LY) and Texas Phoenix palm decline (TPPD) are two important phytoplasma diseases of palms in Florida. Both have been responsible for major economic losses historically and remain a constant threat to the sustainability of palm production in the landscaping and nursery industries in Florida. These two diseases cause rapid, lethal decline in afflicted palms, so rapid detection and identification is crucial to implement appropriate management strategies to reduce further spread and losses. In this study, a qPCR assay was developed to detect and identify the causal agents of LY and TPPD. Based on sequence data of the 16S gene for the 16SrIV-A phytoplasma (LY) and the 16SrIV-D phytoplasma (TPPD), two regions were identified in the gene that possessed sufficient variation to yield amplicons with measurable differences in melting temperature based on high resolution melt analysis (HRMA). One region was in the 5' region and the other was located in the 3' region of the gene. Products from both regions yielded amplicons with significantly different melting temperatures between the two phytoplasma strains. This research allows for the detection and identification of phytoplasmas in palms rapidly by eliminating many lengthy and post-PCR steps commonly used in phytoplasma identification.
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Affiliation(s)
- Brian W Bahder
- Department of Entomology and Nematology, University of Florida, Davie, 33314-7719
| | - Ericka E Helmick
- Department of Entomology and Nematology, University of Florida, Davie, 33314-7719
| | - Nigel A Harrison
- Department of Plant Pathology, University of Florida, Davie, 33314-7719
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22
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Demeuse KL, Grode AS, Szendrei Z. Comparing qPCR and Nested PCR Diagnostic Methods for Aster Yellows Phytoplasma in Aster Leafhoppers. PLANT DISEASE 2016; 100:2513-2519. [PMID: 30686179 DOI: 10.1094/pdis-12-15-1444-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The aster yellows phytoplasma (AYp) is a wall-less bacterium that causes damage in multiple crops. They are spread primarily by the aster leafhopper, Macrosteles quadrilineatus (Hemiptera: Cicadellidae). A total of 3,156 aster leafhoppers were collected during the 2014 and 2015 growing seasons in Michigan celery and carrot fields using sweep nets. The objective of this study was to test previously developed 16S rDNA phytoplasma gene primers to find the most reliable and least time-consuming method for AYp detection in leafhoppers. Nested polymerase chain reaction (PCR) was performed with universal primers P1/P7 and R16F2n/R16R2, and then, restriction enzymes AluI, MseI, and HhaI identified the phytoplasma to subgroup. Over the two years, 2.2% of samples were phytoplasma positive with nested PCR, classified in subgroups 16SrI-A or 16SrI-B. All samples were also tested with a TaqMan quantitative qPCR assay with universal phytoplasma primers and probe and 4.6% tested positive. A subset of samples were also tested with AYp-specific SYBR green qPCR, showing a >93% similarity between SYBR green and TaqMan qPCR assay results. The qPCR assays were more than two times faster than nested PCR. However, qPCR assays likely have specificity issues that need to be addressed before they can be used as a reliable method of detection for AYp in leafhoppers.
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Affiliation(s)
| | - Ari S Grode
- Department of Entomology, Michigan State University, East Lansing 48824
| | - Zsofia Szendrei
- Department of Entomology, Michigan State University, East Lansing 48824
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23
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Gurr GM, Johnson AC, Ash GJ, Wilson BAL, Ero MM, Pilotti CA, Dewhurst CF, You MS. Coconut Lethal Yellowing Diseases: A Phytoplasma Threat to Palms of Global Economic and Social Significance. FRONTIERS IN PLANT SCIENCE 2016; 7:1521. [PMID: 27833616 PMCID: PMC5080360 DOI: 10.3389/fpls.2016.01521] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 09/26/2016] [Indexed: 05/25/2023]
Abstract
The recent discovery of Bogia coconut syndrome in Papua New Guinea (PNG) is the first report of a lethal yellowing disease (LYD) in Oceania. Numerous outbreaks of LYDs of coconut have been recorded in the Caribbean and Africa since the late Nineteenth century and have caused the death of millions of palms across several continents during the Twentieth century. Despite the severity of economic losses, it was only in the 1970s that the causes of LYDs were identified as phytoplasmas, a group of insect-transmitted bacteria associated with diseases in many other economically important crop species. Since the development of polymerase chain reaction (PCR) technology, knowledge of LYDs epidemiology, ecology and vectors has grown rapidly. There is no economically viable treatment for LYDs and vector-based management is hampered by the fact that vectors have been positively identified in very few cases despite many attempted transmission trials. Some varieties and hybrids of coconut palm are known to be less susceptible to LYD but none are completely resistant. Optimal and current management of LYD is through strict quarantine, prompt detection and destruction of symptomatic palms, and replanting with less susceptible varieties or crop species. Advances in technology such as loop mediated isothermal amplification (LAMP) for detection and tracking of phytoplasma DNA in plants and insects, remote sensing for identifying symptomatic palms, and the advent of clustered regularly interspaced short palindromic repeats (CRISPR)-based tools for gene editing and plant breeding are likely to allow rapid progress in taxonomy as well as understanding and managing LYD phytoplasma pathosystems.
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Affiliation(s)
- Geoff M. Gurr
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujain Agriculture and Forestry UniversityFuzhou, China
- Institute of Applied Ecology, College of Plant Protection, Fujian Agriculture and Forestry UniversityFuzhou, China
- Graham Centre of Agricultural Innovation, Charles Sturt UniversityOrange, NSW, Australia
| | - Anne C. Johnson
- Graham Centre of Agricultural Innovation, Charles Sturt UniversityOrange, NSW, Australia
| | - Gavin J. Ash
- Research and Innovation Division, Centre for Crop Health, Institute for Agriculture and the Environment, University of Southern QueenslandToowoomba, QLD, Australia
| | - Bree A. L. Wilson
- Research and Innovation Division, Centre for Crop Health, Institute for Agriculture and the Environment, University of Southern QueenslandToowoomba, QLD, Australia
| | - Mark M. Ero
- PNG Oil Palm Research AssociationKimbe, Papua New Guinea
| | | | - Charles F. Dewhurst
- Formerly affiliated with the PNG Oil Palm Research AssociationKimbe, Papua New Guinea
| | - Minsheng S. You
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujain Agriculture and Forestry UniversityFuzhou, China
- Institute of Applied Ecology, College of Plant Protection, Fujian Agriculture and Forestry UniversityFuzhou, China
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24
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de Souza AN, da Silva FN, Bedendo IP, Carvalho CM. A Phytoplasma Belonging to a 16SrIII-A Subgroup and dsRNA Virus Associated with Cassava Frogskin Disease in Brazil. PLANT DISEASE 2014; 98:771-779. [PMID: 30708630 DOI: 10.1094/pdis-04-13-0440-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Cassava frogskin disease (CFSD) is a particular threat in cassava because symptoms remain hidden until harvest and losses can be total. The information related to the etiological agent of this disease is contradictory, because some authors believe it is caused by phytoplasmas while others believe that it is caused by a virus. In order to refine detection protocols and to characterize organisms associated with CFSD in Brazil, 32 symptomatic and 20 asymptomatic cassava plants were collected in Minas Gerais state. Total DNA was extracted and used for nested polymerase chain reaction (PCR) to detect phytoplasmas. Because endophytic Bacillus spp. led to false positives, primers were designed to facilitate the detection of phytoplasma in the presence of bacteria. In addition, double-stranded (ds)RNA was extracted from tubers and used in reverse-transcription PCR for the detection of the RNA-dependent RNA polymerase gene from Cassava frogskin virus segment 4. The detected phytoplasma was identified as belonging to the group 16SrIII-A by restriction fragment length polymorphism (RFLP), sequencing, and RFLP in silico. This is the first report of a phytoplasma belonging to the 16SrIII-A group associated with cassava plants, the first molecular characterization of a phytoplasma associated with CFSD in Brazil, and a first report of phytoplasma and a dsRNA virus (possible reovirus) co-infecting cassava plants with CFSD symptoms.
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Affiliation(s)
| | | | - Ivan P Bedendo
- Department of Plant Pathology and Nematology, ESALQ/USP, Piracicaba, Brazil
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25
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Bertaccini A, Duduk B, Paltrinieri S, Contaldo N. Phytoplasmas and Phytoplasma Diseases: A Severe Threat to Agriculture. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ajps.2014.512191] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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26
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Harrison NA, Davis RE, Helmick EE. DNA extraction from arborescent monocots and how to deal with other challenging hosts. Methods Mol Biol 2013; 938:147-58. [PMID: 22987413 DOI: 10.1007/978-1-62703-089-2_13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Detection of pathogen DNA by polymerase chain reaction (PCR) assays is the most widely used method for diagnosing phytoplasma diseases. Reliable and efficient detection of phytoplasmas, especially in woody perennial plants, is challenging due to the unusually low abundance and sporadic distribution of phytoplasmas within infected host tissues. Detection success depends largely upon the host species and sampling procedures and, to a lesser extent, on the protocol used for DNA extraction. Here we describe a simple, straightforward, nondestructive stem sampling protocol to confirm phytoplasma infection of palms and other arborescent monocots of large stature. The protocol requires minimal processing of excised tissues and yields phytoplasma DNA preparations in suitable quantity for reliable detection by nested PCR assays.
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Affiliation(s)
- Nigel A Harrison
- Plant Pathology Department, Research & Education Center, University of Florida, Fort Lauderdale, FL, USA.
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27
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Hodgetts J, Dickinson M. T-RFLP for detection and identification of phytoplasmas in plants. Methods Mol Biol 2013; 938:233-244. [PMID: 22987420 DOI: 10.1007/978-1-62703-089-2_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Conventionally, detection of phytoplasmas has been performed by PCR of the 16S rRNA gene, followed by either RFLP or DNA sequencing to determine the phytoplasma 16Sr group. This chapter demonstrates the technique of terminal restriction fragment length polymorphism (T-RFLP), a fingerprinting technique which combines both detection and identification in a single method, with the added benefit of inbuilt controls which removes the risk of false negative results and in addition highlights potential false positive results.
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28
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Dickinson M, Hodgetts J. PCR analysis of phytoplasmas based on the secA gene. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2012; 938:205-15. [PMID: 22987417 DOI: 10.1007/978-1-62703-089-2_17] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Conventionally, diagnostics and phylogenetics of phytoplasmas have been primarily based on the 16S rRNA gene, for which "universal" primers are available that amplify from most phytoplasma 16Sr groups. However, there has been a drive in recent years to develop "universal" primers for other genes that can be used to complement the use of the 16S rRNA gene. This chapter details the use of primers based on the phytoplasma secA gene and describes how these primers can be used in both a single or nested PCR approach for amplification. It also notes the use of appropriate controls that should be undertaken and provides a source for phytoplasma secA sequences that are available in databases that can be used for phylogenetic analyses.
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Affiliation(s)
- Matt Dickinson
- School of Biosciences, University of Nottingham, Sutton Bonington, Nottingham, UK.
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29
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Rao G, Mall S, Raj S, Snehi S. Review article: Phytoplasma diseases affecting various plant species in India. ACTA ACUST UNITED AC 2011. [DOI: 10.1556/aphyt.46.2011.1.7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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30
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Vázquez-Euán R, Harrison N, Narvaez M, Oropeza C. Occurrence of a 16SrIV Group Phytoplasma not Previously Associated with Palm Species in Yucatan, Mexico. PLANT DISEASE 2011; 95:256-262. [PMID: 30743539 DOI: 10.1094/pdis-02-10-0150] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The occurrence of 16SrIV group phytoplasmas in palm species Sabal mexicana and Pseudophoenix sargentii is reported here for the first time. Palm trees showed leaf decay and leaf yellowing syndromes, respectively. An amplification product (1.4 kb) was obtained in symptomatic S. mexicana (18 of 21) and symptomatic P. sargentii (1 of 1) palm trees sampled in different locations in Yucatan State, Mexico; five of the positive S. mexicana and the positive P. sargentii trees died. The identity of the phytoplasmas from these species was determined by restriction fragment length polymorphism profiling with restriction enzymes AluI and HinfI, showing there could be two phytoplasma strains of the 16SrIV group. In one S. mexicana palm, the profile was the same as observed with these enzymes for phytoplasmas of 16SrIV-A subgroup, previously associated with Cocos nucifera palm trees and, in the rest of the trees, including the P. sargentii palm, the profile was for phytoplasmas of the 16SrIV-D subgroup. These identities were supported by analyses of the amplicons obtained by nested polymerase chain reaction by nucleotide-nucleotide BLAST analysis. Geographical distribution of the association S. mexicana/16SrIV group phytoplasmas was found widely dispersed in Yucatan State. A potential role of S. mexicana palm trees as a permanent source of phytoplasma inoculum is suggested. In addition to P. sargentii, other palm species (Thrinax radiata and C. nucifera) coexisting with S. mexicana trees were also sampled and analyzed.
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Affiliation(s)
- Roberto Vázquez-Euán
- Centro de Investigación Científica de Yucatán, Mérida, Unidad de Biotecnología, Yucatán 97200, México
| | - Nigel Harrison
- University of Florida, Plant Pathology Department, Research and Education Center, Fort Lauderdale 33314
| | - María Narvaez
- Centro de Investigación Científica de Yucatán, México
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31
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Gitau CW, Gurr GM, Dewhurst CF, Fletcher MJ, Mitchell A. Insect pests and insect-vectored diseases of palms. ACTA ACUST UNITED AC 2009. [DOI: 10.1111/j.1440-6055.2009.00724.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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32
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Zhao Y, Sun Q, Wei W, Davis RE, Wu W, Liu Q. 'Candidatus Phytoplasma tamaricis', a novel taxon discovered in witches'-broom-diseased salt cedar (Tamarix chinensis Lour.). Int J Syst Evol Microbiol 2009; 59:2496-504. [DOI: 10.1099/ijs.0.010413-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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33
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Hodgetts J, Boonham N, Mumford R, Dickinson M. Panel of 23S rRNA gene-based real-time PCR assays for improved universal and group-specific detection of phytoplasmas. Appl Environ Microbiol 2009; 75:2945-50. [PMID: 19270148 PMCID: PMC2681720 DOI: 10.1128/aem.02610-08] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 02/25/2009] [Indexed: 11/20/2022] Open
Abstract
Primers and probes based on the 23S rRNA gene have been utilized to design a range of real-time PCR assays for routine phytoplasma diagnostics. These assays have been authenticated as phytoplasma specific and shown to be at least as sensitive as nested PCR. A universal assay to detect all phytoplasmas has been developed, along with a multiplex assay to discriminate 16SrI group phytoplasmas from members of all of the other 16Sr groups. Assays for the 16SrII, 16SrIV, and 16SrXII groups have also been developed to confirm that the 23S rRNA gene can be used to design group-specific assays.
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Affiliation(s)
- Jennifer Hodgetts
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom
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Schneider B, Torres E, Martín MP, Schröder M, Behnke HD, Seemüller E. 'Candidatus Phytoplasma pini', a novel taxon from Pinus silvestris and Pinus halepensis. Int J Syst Evol Microbiol 2005; 55:303-307. [PMID: 15653891 DOI: 10.1099/ijs.0.63285-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pinus silvestris and Pinus halepensis trees grown in Germany and Spain, respectively, showing abnormal shoot branching, dwarfed needles and other symptoms were examined for the presence of plant-pathogenic mollicutes (phytoplasmas). While phytoplasmas could not be detected unambiguously with microscopical methods, PCR amplification using universal phytoplasma primers yielded positive results. Samples collected from symptomatic and non-symptomatic plant parts of both symptomatic Pinus silvestris and Pinus halepensis trees tested positive. Also, surrounding non-symptomatic trees proved to be phytoplasma-infected. Comparisons revealed that the 16S rRNA gene sequences of the phytoplasmas identified in Pinus silvestris and Pinus halepensis were nearly identical. However, the pine phytoplasma is only distantly related to other phytoplasmas. The closest relatives are members of the palm lethal yellowing and rice yellow dwarf groups and 'Candidatus Phytoplasma castaneae', which share between 94.5 and 96.6 % 16S rRNA gene sequence similarity. From these data it can be concluded that the phytoplasmas identified in the two Pinus species represent a coherent but discrete taxon; it is proposed that this taxon be distinguished at putative species level under the name 'Candidatus Phytoplasma pini'.
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Affiliation(s)
- Bernd Schneider
- Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut für Pflanzenschutz im Obstbau, D-69211 Dossenheim, Germany
| | - Ester Torres
- Laboratori Sanitat Vegetal, Generalitat de Catalunya, Barcelona, Spain
| | | | | | - Heinz-Dietmar Behnke
- Universität Heidelberg, Heidelberger Institut für Pflanzenwissenschaften, D-69120 Heidelberg, Germany
| | - Erich Seemüller
- Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut für Pflanzenschutz im Obstbau, D-69211 Dossenheim, Germany
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35
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Cordova I, Jones P, Harrison NA, Oropeza C. In situ PCR detection of phytoplasma DNA in embryos from coconut palms with lethal yellowing disease. MOLECULAR PLANT PATHOLOGY 2003; 4:99-108. [PMID: 20569368 DOI: 10.1046/j.1364-3703.2003.00152.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
SUMMARY DNA of the lethal yellowing (LY) phytoplasma was detected in 13 of 72 embryos from fruits of four diseased Atlantic tall coconut palms by polymerase chain reaction (PCR) assays employing phytoplasma universal rRNA primer pair P1/P7, nested LY group-specific rRNA primer pair 503f/LY16Sr or LY phytoplasma-specific nonribosomal primer pair LYF1/R1. Phytoplasma distribution in sectioned tissues from six PCR positive embryos was determined by in situ PCR and digoxigenin-11-deoxy-UTP (Dig) labelling of amplification products. Dig-labeled DNA products detected by colourimetric assay were clearly evident on sections from the same three embryos investigated in detail by in situ PCRs employing primer pairs P1/P7 or LYF1/R1. Deposition of blue-green stain on sections as a result of each assay was restricted to areas of the embryos corresponding to the plumule and cells ensheathing it. By comparison, similarly treated embryo sections derived from fruits of a symptomless Atlantic tall coconut palm were consistently devoid of any stain. Presence of phytoplasma DNA in embryo tissues suggests the possible potential for seed transmission which remains to be demonstrated.
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Affiliation(s)
- Ivan Cordova
- Plant Pathogen Interactions Division, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, UK
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