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Tambong JT, Xu R, Fleitas MC, Wang L, Akuma M, Chi SI, Kutcher HR. TaqMan Real-Time PCR Assay for Specific Detection and Differentiation of Xanthomonas translucens pv. undulosa from Other Pathovars Targeting a Recombination Mediator Gene, recF. PLANT DISEASE 2024; 108:1869-1878. [PMID: 38345539 DOI: 10.1094/pdis-09-23-1827-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: 06/01/2024]
Abstract
Bacterial leaf streak and black chaff diseases of wheat caused by Xanthomonas translucens pv. undulosa is becoming a major constraint to growers and trade since it is seedborne. Molecular tools for specific detection/differentiation of pv. undulosa are lacking. We report the development of a TaqMan real-time PCR for specific detection/identification of pv. undulosa targeting the recombination mediator gene (recF). Analysis of the complete recF (1,117 bp) sequences identified the gene as a reliable phylogenetic marker for identification of pv. undulosa, differentiating it from the other pathovars; recF-based sequence homology values among the 11 pathovars correlated well with genome-based DNA-DNA hybridization values. The discriminatory power of recF to differentiate pv. undulosa from the other pathovars is due to nucleotide polymorphic positions. We used these nucleotide polymorphisms to develop a TaqMan PCR for specific detection of pv. undulosa. The specificity of the assay was validated using 67 bacterial and fungal/oomycete strains. The selected primers and the double-quenched FAM-labeled TaqMan probe were specific for the detection of 11 pv. undulosa/secalis strains. The 56 strains of other X. translucens pathovars (n = 39) and non-Xanthomonas spp. (n = 17) did not exhibit any detectable fluorescence. Also, greenhouse-inoculated and naturally infected wheat leaf samples showed positive reactions for the presence of pv. undulosa DNA but not healthy control plants. The TaqMan assay reliably detected as low as 1-pg DNA amount and 10 colony forming units of the target pathogen per reaction. This TaqMan assay could be useful to regulatory agencies with economic benefits to wheat growers.
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Affiliation(s)
- James T Tambong
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada
- Department of Plant Science, University of Manitoba, Winnipeg, MB, Canada
| | - Renlin Xu
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada
| | - Maria Constanza Fleitas
- Department of Plant Sciences and Crop Development Centre, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada
| | - Lipu Wang
- Department of Plant Sciences and Crop Development Centre, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada
| | - Mercy Akuma
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada
- University of Ottawa, Ottawa, ON, Canada
| | - Sylvia I Chi
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada
- Canadian Blood Services, Ottawa, ON, Canada
| | - Hadley R Kutcher
- Department of Plant Sciences and Crop Development Centre, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada
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Tambong JT, Xu R, Fleitas MC, Wang L, Hubbard K, Kutcher R. Phylogenomic Insights on the Xanthomonas translucens Complex, and Development of a TaqMan Real-Time Assay for Specific Detection of pv. translucens on Barley. PHYTOPATHOLOGY 2023; 113:2091-2102. [PMID: 37097305 DOI: 10.1094/phyto-01-23-0022-sa] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The reemergence and spread of Xanthomonas translucens, the causal agent of bacterial leaf streak in cereal crops and wilt in turfgrass and forage species, is a concern to growers in the United States and Canada. The pathogen is seedborne and listed as an A2 quarantine organism by EPPO, making it a major constraint to international trade and exchange of germplasm. The pathovar concept of the X. translucens group is confusing due to overlapping of plant host ranges and specificity. Here, comparative genomics, phylogenomics, and 81 up-to-date bacterial core gene set (ubcg2) were used to assign the pathovars of X. translucens into three genetically and taxonomically distinct clusters. The study also showed that whole genome-based digital DNA-DNA hybridization unambiguously can differentiate the pvs. translucens and undulosa. Orthologous gene and proteome matrix analyses suggest that the cluster consisting of graminis, poae, arrhenatheri, phlei, and phleipratensis is very divergent. Whole-genome data were exploited to develop the first pathovar-specific TaqMan real-time PCR tool for detection of pv. translucens on barley. Specificity of the TaqMan assay was validated using 62 Xanthomonas and non-Xanthomonas strains as well as growth chamber-inoculated and naturally infected barley leaves. Sensitivity levels of 0.1 pg (purified DNA) and 23 CFUs per reaction (direct culture) compared favorably with other previously reported real-time PCR assays. The phylogenomics data reported here suggest that the clusters could constitute novel taxonomic units or new species. Finally, the pathovar-specific diagnostic tool will have significant benefits to growers and facilitate international exchange of barley germplasm and trade.
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Affiliation(s)
- James T Tambong
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada
- Department of Plant Science, University of Manitoba, Winnipeg, MB, Canada
| | - Renlin Xu
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada
| | - Maria Constanza Fleitas
- Department of Plant Sciences & Crop Development Centre, University of Saskatchewan, Saskatoon, SK, Canada
| | - Lipu Wang
- Department of Plant Sciences & Crop Development Centre, University of Saskatchewan, Saskatoon, SK, Canada
| | - Keith Hubbard
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada
| | - Randy Kutcher
- Department of Plant Sciences & Crop Development Centre, University of Saskatchewan, Saskatoon, SK, Canada
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Zhang T, Zeng Q, Ji F, Wu H, Ledesma-Amaro R, Wei Q, Yang H, Xia X, Ren Y, Mu K, He Q, Kang Z, Deng R. Precise in-field molecular diagnostics of crop diseases by smartphone-based mutation-resolved pathogenic RNA analysis. Nat Commun 2023; 14:4327. [PMID: 37468480 PMCID: PMC10356797 DOI: 10.1038/s41467-023-39952-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 07/05/2023] [Indexed: 07/21/2023] Open
Abstract
Molecular diagnostics for crop diseases can guide the precise application of pesticides, thereby reducing pesticide usage while improving crop yield, but tools are lacking. Here, we report an in-field molecular diagnostic tool that uses a cheap colorimetric paper and a smartphone, allowing multiplexed, low-cost, rapid detection of crop pathogens. Rapid nucleic acid amplification-free detection of pathogenic RNA is achieved by combining toehold-mediated strand displacement with a metal ion-mediated urease catalysis reaction. We demonstrate multiplexed detection of six wheat pathogenic fungi and an early detection of wheat stripe rust. When coupled with a microneedle for rapid nucleic acid extraction and a smartphone app for results analysis, the sample-to-result test can be completed in ~10 min in the field. Importantly, by detecting fungal RNA and mutations, the approach allows to distinguish viable and dead pathogens and to sensitively identify mutation-carrying fungicide-resistant isolates, providing fundamental information for precision crop disease management.
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Affiliation(s)
- Ting Zhang
- College of Biomass Science and Engineering, Healthy Food Evaluation Research Center, Sichuan University, Chengdu, 610065, China
| | - Qingdong Zeng
- State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, 712100, China
| | - Fan Ji
- State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, 712100, China
| | - Honghong Wu
- MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Rodrigo Ledesma-Amaro
- Department of Bioengineering, Imperial College Centre for Synthetic Biology, Imperial College London, London, SW7 2AZ, UK
| | - Qingshan Wei
- Department of Chemical and Biomolecular Engineering, Emerging Plant Disease and Global Food Security Cluster, North Carolina State University, Raleigh, NC, 27696, USA
| | - Hao Yang
- College of Biomass Science and Engineering, Healthy Food Evaluation Research Center, Sichuan University, Chengdu, 610065, China
| | - Xuhan Xia
- College of Biomass Science and Engineering, Healthy Food Evaluation Research Center, Sichuan University, Chengdu, 610065, China
| | - Yao Ren
- College of Biomass Science and Engineering, Healthy Food Evaluation Research Center, Sichuan University, Chengdu, 610065, China
| | - Keqing Mu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, 712100, China
| | - Qiang He
- College of Biomass Science and Engineering, Healthy Food Evaluation Research Center, Sichuan University, Chengdu, 610065, China
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, 712100, China
| | - Ruijie Deng
- College of Biomass Science and Engineering, Healthy Food Evaluation Research Center, Sichuan University, Chengdu, 610065, China.
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Aiying W, Ju L, Cilin W, Yuxuan H, Baojun Y, Jian T, Shuhua L. Establishment and application of the Recombinase-Aided Amplification-Lateral Flow Dipstick detection method for Pantoea ananatis on rice. AUSTRALASIAN PLANT PATHOLOGY : APP 2023; 52:1-9. [PMID: 37363287 PMCID: PMC10193322 DOI: 10.1007/s13313-023-00918-8] [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: 11/02/2022] [Accepted: 04/14/2023] [Indexed: 06/28/2023]
Abstract
Pantoea ananatis is a major pathogen that causes the new bacterial blight in rice, and its symptoms very similar to rice bacterial blight. Therefore, there is a dire need for an accurate and rapid method for detecting P. ananatis. In this study, an early and rapid visual detection method for P. ananatis was established. Using GyrB gene as the target sequence, an innovative recombinase-aided amplification detection system integrated with a lateral flow dipstick (RAA-LFD) was constructed. The optimized RAA-LFD detection method can be initiated at body temperature and does not rely on precise instruments. It does not require DNA extraction and can be used directly with plant tissue fluids. The results can be visualized after 10 minutes of amplification. The specificity and sensitivity tests showed that the RAA-LFD method could detect P. ananatis, whereas other common plant pathogens were not detected, and its detection sensitivity for P. ananatis DNA reached 100 copies/µL. The detection of diseased tissues indicated that this method could accurately detect P. ananatis in artificially inoculated rice tissues in the early stages of infection before symptoms. The RAA-LFD detection system established in this study is simple and fast, with visual results, excellent specificity, and high sensitivity. It is semi-quantitative and should be used for the early detection and rapid field diagnosis of new leaf blight, which provides technical support for the early warning and real-time detection of field samples.
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Affiliation(s)
- Wang Aiying
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Hangzhou, 310006 China
| | - Luo Ju
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Hangzhou, 310006 China
| | - Wang Cilin
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Hangzhou, 310006 China
| | - Hou Yuxuan
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Hangzhou, 310006 China
| | - Yang Baojun
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Hangzhou, 310006 China
| | - Tang Jian
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Hangzhou, 310006 China
| | - Liu Shuhua
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Hangzhou, 310006 China
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Shin GY, Smith A, Coutinho TA, Dutta B, Kvitko BH. Validation of Species-Specific PCR Assays for the Detection of Pantoea ananatis, P. agglomerans, P. allii, and P. stewartii. PLANT DISEASE 2022; 106:2563-2570. [PMID: 35171633 DOI: 10.1094/pdis-08-21-1810-sc] [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
Species of Pantoea represent a group of plant pathogenic bacteria that infect a variety of agro-economically important plant species. Among these, a complex of P. ananatis, P. allii, P. agglomerans, and P. stewartii subsp. indologenes cause center rot in onion, resulting in significant economic losses. As species of Pantoea are phenotypically closely related, identification of Pantoea species relies on the sequencing and phylogenetic analysis of housekeeping genes. To aid in rapid identification of Pantoea species, efforts have been made in developing species-specific primers to be used in PCR assays. In the current study, two P. ananatis, one P. allii, one P. agglomerans, and three P. stewartii published primers as well as newly developed P. agglomerans PagR primers were evaluated for their specificity against 79 Pantoea strains, belonging to 15 different species. To ensure that selected primers were evaluated against accurately identified species, sequencing and phylogenetic analysis of housekeeping gene infB were conducted. Thereafter, PCR assays using selected species-specific primers were performed. The results showed that previously described P. ananatis-specific PANA_1008; P. allii-specific allii-leuS; P. stewartii-specific PANST_rpoB, 3614galE, and DC283galE primers; and one newly designed P. agglomerans-specific PagR primer pair were highly specific for their target Pantoea species. They accurately identified these strains into their species and, in some cases, their subspecies level. The findings of the current study will facilitate rapid and reliable identification of P. ananatis, P. agglomerans, P. allii, and P. stewartii.
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Affiliation(s)
- Gi Yoon Shin
- Department of Plant Pathology, University of Georgia, Athens, GA 30602, U.S.A
| | - Amy Smith
- Department of Plant Pathology, University of Georgia, Athens, GA 30602, U.S.A
| | - Teresa A Coutinho
- Department of Biochemistry, Genetics, and Microbiology, University of Pretoria, Pretoria 0002, South Africa
| | - Bhabesh Dutta
- Department of Plant Pathology, University of Georgia, Tifton, GA 31793, U.S.A
| | - Brian H Kvitko
- Department of Plant Pathology, University of Georgia, Athens, GA 30602, U.S.A
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Tambong JT, Xu R, Gerdis S, Daniels GC, Chabot D, Hubbard K, Harding MW. Molecular Analysis of Bacterial Isolates From Necrotic Wheat Leaf Lesions Caused by Xanthomonas translucens, and Description of Three Putative Novel Species, Sphingomonas albertensis sp. nov., Pseudomonas triticumensis sp. nov. and Pseudomonas foliumensis sp. nov. Front Microbiol 2021; 12:666689. [PMID: 34093484 PMCID: PMC8170138 DOI: 10.3389/fmicb.2021.666689] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 03/22/2021] [Indexed: 11/13/2022] Open
Abstract
Xanthomonas translucens is the etiological agent of the wheat bacterial leaf streak (BLS) disease. The isolation of this pathogen is usually based on the Wilbrink's-boric acid-cephalexin semi-selective medium which eliminates 90% of other bacteria, some of which might be novel species. In our study, a general purpose nutrient agar was used to isolate 49 bacterial strains including X. translucens from necrotic wheat leaf tissues. Maximum likelihood cluster analysis of 16S rRNA sequences grouped the strains into 10 distinct genera. Pseudomonas (32.7%) and Pantoea (28.6%) were the dominant genera while Xanthomonas, Clavibacter and Curtobacterium had 8.2%, each. Erwinia and Sphingomonas had two strains, each. BLAST and phylogenetic analyses of multilocus sequence analysis (MLSA) of specific housekeeping genes taxonomically assigned all the strains to validly described bacterial species, except three strains (10L4B, 12L4D and 32L3A) of Pseudomonas and two (23L3C and 15L3B) of Sphingomonas. Strains 10L4B and12L4D had Pseudomonas caspiana as their closest known type strain while strain 32L3A was closest to Pseudomonas asturiensis. Sphingomonas sp. strains 23L3C and 15L3B were closest to S. faeni based on MLSA analysis. Our data on MLSA, whole genome-based cluster analysis, DNA-DNA hybridization and average nucleotide identity, matrix-assisted laser desorption/ionization-time-of-flight, chemotaxonomy and phenotype affirmed that these 5 strains constitute three novel lineages and are taxonomically described in this study. We propose the names, Sphingomonas albertensis sp. nov. (type strain 23L3CT = DOAB 1063T = CECT 30248T = LMG 32139T), Pseudomonas triticumensis sp. nov. (type strain 32L3AT = DOAB 1067T = CECT 30249T = LMG 32140T) and Pseudomonas foliumensis sp. nov. (type strain 10L4BT = DOAB 1069T = CECT 30250T = LMG 32142T). Comparative genomics of these novel species, relative to their closest type strains, revealed unique repertoires of core secretion systems and secondary metabolites/antibiotics. Also, the detection of CRISPR-Cas systems in the genomes of these novel species suggests an acquired mechanism for resistance against foreign mobile genetic elements. The results presented here revealed a cohabitation, within the BLS lesions, of diverse bacterial species, including novel lineages.
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Affiliation(s)
- James T Tambong
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada
| | - Renlin Xu
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada
| | - Suzanne Gerdis
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada
| | - Greg C Daniels
- Crop Diversification Centre South, Alberta Agriculture and Forestry, Brooks, AB, Canada
| | - Denise Chabot
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada
| | - Keith Hubbard
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada
| | - Michael W Harding
- Crop Diversification Centre South, Alberta Agriculture and Forestry, Brooks, AB, Canada
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