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Xue C, Zhang L, Li H, Liu Z, Zhang Y, Liu M, Zhao J. The effector PHYL1 JWB from Candidatus Phytoplasma ziziphi induces abnormal floral development by destabilising flower development proteins. PLANT, CELL & ENVIRONMENT 2024. [PMID: 39119795 DOI: 10.1111/pce.15079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 07/01/2024] [Accepted: 07/26/2024] [Indexed: 08/10/2024]
Abstract
Phytoplasmas can induce complex and substantial phenotypic changes in their hosts in ways that favour their colonisation, but the mechanisms underlying these changes remain largely unknown. Jujube witches' broom (JWB) disease is a typical phytoplasma disease causing great economic loss in Chinese jujube (Ziziphus jujuba Mill.). Here, we reported an effector, PHYL1JWB from Candidatus Phytoplasma ziziphi, which implicated in inducing abnormal floral organogenesis. Utilising a combination of in vivo and in vitro methods, we investigated the influence of PHYL1JWB on the proteins associated with floral development. Our findings reveal that PHYL1JWB facilitates the proteasome-mediated degradation of essential flower morphogenetic regulators, including AP1, SEP1, SEP2, SEP3, SEP4, CAL, and AGL6, through a distinctive pathway that is dependent on the activity of the 26S proteasome, thus obviating the requirement for lysine ubiquitination of the substrates. Further, the Y2H analysis showed that the leucine at position 75th in second α helix of PHYL1JWB is fundamental for the interactions of PHYL1JWB with AP1 and SEP1-4 in jujube and Arabidopsis. Our research carry profound implications for elucidating the contribution of PHYL1JWB to the aberrant floral development in diseased jujube, and help to establish a robust theoretical underpinning for the prophylaxis and therapy of JWB disease.
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Affiliation(s)
- Chaoling Xue
- College of Life Science, Hebei Agricultural University, Baoding, Hebei, China
- Shanxi Sericulture Science Research Institute, Shanxi Agricultural University, Yuncheng, Shanxi, China
| | - Liman Zhang
- College of Life Science, Hebei Agricultural University, Baoding, Hebei, China
- Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology, Hebei Agricultural University, Baoding, Hebei, China
| | - Hongtai Li
- College of Life Science, Hebei Agricultural University, Baoding, Hebei, China
- Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology, Hebei Agricultural University, Baoding, Hebei, China
| | - Zhiguo Liu
- Research Center of Chinese Jujube, Hebei Agricultural University, Baoding, Hebei, China
| | - Yao Zhang
- College of Life Science, Hebei Agricultural University, Baoding, Hebei, China
- Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology, Hebei Agricultural University, Baoding, Hebei, China
| | - Mengjun Liu
- Research Center of Chinese Jujube, Hebei Agricultural University, Baoding, Hebei, China
| | - Jin Zhao
- College of Life Science, Hebei Agricultural University, Baoding, Hebei, China
- Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology, Hebei Agricultural University, Baoding, Hebei, China
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2
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Cui W, Muñoz V, Navarrete M, Cabrera S, Campodonico J, Estrada M, Zamorano A, Fiore N. Insect Vector and Reservoir Plant of ' Fragaria × ananassa' Phyllody Phytoplasma (16SrXIII-F) in Central Region of Chile. PLANT DISEASE 2024; 108:1861-1868. [PMID: 38319626 DOI: 10.1094/pdis-12-23-2552-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: 02/07/2024]
Abstract
Strawberry phyllody has emerged as a prevalent disease affecting Chilean strawberry in recent years. The causal pathogen, 'Fragaria × ananassa' phyllody phytoplasma (StrPh), is categorized within the 16S ribosomal group XIII that is exclusively found in the Americas. In the context of economically significant crops, hemipteran insect vectors and alternative host plants play a pivotal role in their natural dissemination. This study comprehensively examined the key epidemiological facets of StrPh in the central region of Chile: the insect vector and alternative hosts. Through field surveys, we identified an abundance of an insect species, Cixiosoma sp., in an StrPh-infected strawberry field and confirmed its role as a vector of this phytoplasma through subsequent transmission assays. Moreover, we found a spontaneous weed species, Galega officinalis, to be infected with StrPh, raising the possibility of it being a potential alternative host plant for this phytoplasma. StrPh was also detected in cold-stored strawberry runners purchased from a nursery that supplies the local strawberry cultivation, suggesting a potential source of this phytoplasma in Chile. Collectively, these findings provide a significant epidemiological source of StrPh dissemination in central Chile.
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Affiliation(s)
- Weier Cui
- Department of Plant Health, Faculty of Agricultural Sciences, University of Chile, Santiago, RM 8820808, Chile
| | - Valentina Muñoz
- Department of Plant Health, Faculty of Agricultural Sciences, University of Chile, Santiago, RM 8820808, Chile
| | - Melisa Navarrete
- Department of Plant Health, Faculty of Agricultural Sciences, University of Chile, Santiago, RM 8820808, Chile
| | - Sebastian Cabrera
- Department of Plant Health, Faculty of Agricultural Sciences, University of Chile, Santiago, RM 8820808, Chile
| | - Juan Campodonico
- Ph.D. Program in Science, Ecology, and Evolution Mention, Faculty of Sciences, University Austral of Chile, Valdivia, Chile
| | - Mauricio Estrada
- Department of Plant Health, Faculty of Agricultural Sciences, University of Chile, Santiago, RM 8820808, Chile
| | - Alan Zamorano
- Department of Plant Health, Faculty of Agricultural Sciences, University of Chile, Santiago, RM 8820808, Chile
| | - Nicola Fiore
- Department of Plant Health, Faculty of Agricultural Sciences, University of Chile, Santiago, RM 8820808, Chile
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3
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Correa Marrero M, Capdevielle S, Huang W, Al-Subhi AM, Busscher M, Busscher-Lange J, van der Wal F, de Ridder D, van Dijk ADJ, Hogenhout SA, Immink RGH. Protein interaction mapping reveals widespread targeting of development-related host transcription factors by phytoplasma effectors. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:1281-1297. [PMID: 37965720 DOI: 10.1111/tpj.16546] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 10/27/2023] [Accepted: 10/31/2023] [Indexed: 11/16/2023]
Abstract
Phytoplasmas are pathogenic bacteria that reprogram plant host development for their own benefit. Previous studies have characterized a few different phytoplasma effector proteins that destabilize specific plant transcription factors. However, these are only a small fraction of the potential effectors used by phytoplasmas; therefore, the molecular mechanisms through which phytoplasmas modulate their hosts require further investigation. To obtain further insights into the phytoplasma infection mechanisms, we generated a protein-protein interaction network between a broad set of phytoplasma effectors and a large, unbiased collection of Arabidopsis thaliana transcription factors and transcriptional regulators. We found widespread, but specific, interactions between phytoplasma effectors and host transcription factors, especially those related to host developmental processes. In particular, many unrelated effectors target specific sets of TCP transcription factors, which regulate plant development and immunity. Comparison with other host-pathogen protein interaction networks shows that phytoplasma effectors have unusual targets, indicating that phytoplasmas have evolved a unique and unusual infection strategy. This study contributes a rich and solid data source that guides further investigations of the functions of individual effectors, as demonstrated for some herein. Moreover, the dataset provides insights into the underlying molecular mechanisms of phytoplasma infection.
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Affiliation(s)
- Miguel Correa Marrero
- Bioinformatics Group, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
| | - Sylvain Capdevielle
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, Norfolk, NR4 7UH, UK
| | - Weijie Huang
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, Norfolk, NR4 7UH, UK
| | - Ali M Al-Subhi
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, Norfolk, NR4 7UH, UK
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, 11 Al Khod 123, al-Seeb, Oman
| | - Marco Busscher
- Laboratory of Molecular Biology, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
- Bioscience, Wageningen Plant Research, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
| | - Jacqueline Busscher-Lange
- Laboratory of Molecular Biology, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
- Bioscience, Wageningen Plant Research, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
| | - Froukje van der Wal
- Laboratory of Molecular Biology, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
- Bioscience, Wageningen Plant Research, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
| | - Dick de Ridder
- Bioinformatics Group, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
| | - Aalt D J van Dijk
- Bioinformatics Group, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
- Biometris, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
| | - Saskia A Hogenhout
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, Norfolk, NR4 7UH, UK
| | - Richard G H Immink
- Laboratory of Molecular Biology, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
- Bioscience, Wageningen Plant Research, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
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4
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Wang R, Bai B, Li D, Wang J, Huang W, Wu Y, Zhao L. Phytoplasma: A plant pathogen that cannot be ignored in agricultural production-Research progress and outlook. MOLECULAR PLANT PATHOLOGY 2024; 25:e13437. [PMID: 38393681 PMCID: PMC10887288 DOI: 10.1111/mpp.13437] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 02/01/2024] [Accepted: 02/04/2024] [Indexed: 02/25/2024]
Abstract
Phytoplasmas are phloem-restricted plant-pathogenic bacteria transmitted by insects. They cause diseases in a wide range of host plants, resulting in significant economic and ecological losses worldwide. Research on phytoplasmas has a long history, with significant progress being made in the past 30 years. Notably, with the rapid development of phytoplasma research, scientists have identified the primary agents involved in phytoplasma transmission, established classification and detection systems for phytoplasmas, and 243 genomes have been sequenced and assembled completely or to draft quality. Multiple possible phytoplasma effectors have been investigated, elucidating the molecular mechanisms by which phytoplasmas manipulate their hosts. This review summarizes recent advances in phytoplasma research, including identification techniques, host range studies, whole- or draft-genome sequencing, effector pathogenesis and disease control methods. Additionally, future research directions in the field of phytoplasma research are discussed.
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Affiliation(s)
- Ruotong Wang
- State Key Laboratory for Crop Stress Resistance and High‐Efficiency ProductionNorthwest A&F UniversityYanglingShaanxiChina
- Key Laboratory of Integrated Pest Management on Crops in Northwestern Loess Plateau, Ministry of Agriculture and Rural Affairs, College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxiChina
- Key Laboratory of Plant Protection Resources and Pest Management, Ministry of Education, College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxiChina
| | - Bixin Bai
- State Key Laboratory for Crop Stress Resistance and High‐Efficiency ProductionNorthwest A&F UniversityYanglingShaanxiChina
- Key Laboratory of Integrated Pest Management on Crops in Northwestern Loess Plateau, Ministry of Agriculture and Rural Affairs, College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxiChina
- Key Laboratory of Plant Protection Resources and Pest Management, Ministry of Education, College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxiChina
| | - Danyang Li
- State Key Laboratory for Crop Stress Resistance and High‐Efficiency ProductionNorthwest A&F UniversityYanglingShaanxiChina
- Key Laboratory of Integrated Pest Management on Crops in Northwestern Loess Plateau, Ministry of Agriculture and Rural Affairs, College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxiChina
- Key Laboratory of Plant Protection Resources and Pest Management, Ministry of Education, College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxiChina
| | - Jingke Wang
- State Key Laboratory for Crop Stress Resistance and High‐Efficiency ProductionNorthwest A&F UniversityYanglingShaanxiChina
- Key Laboratory of Integrated Pest Management on Crops in Northwestern Loess Plateau, Ministry of Agriculture and Rural Affairs, College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxiChina
- Key Laboratory of Plant Protection Resources and Pest Management, Ministry of Education, College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxiChina
| | - Weijie Huang
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
| | - Yunfeng Wu
- State Key Laboratory for Crop Stress Resistance and High‐Efficiency ProductionNorthwest A&F UniversityYanglingShaanxiChina
- Key Laboratory of Integrated Pest Management on Crops in Northwestern Loess Plateau, Ministry of Agriculture and Rural Affairs, College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxiChina
- Key Laboratory of Plant Protection Resources and Pest Management, Ministry of Education, College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxiChina
| | - Lei Zhao
- State Key Laboratory for Crop Stress Resistance and High‐Efficiency ProductionNorthwest A&F UniversityYanglingShaanxiChina
- Key Laboratory of Integrated Pest Management on Crops in Northwestern Loess Plateau, Ministry of Agriculture and Rural Affairs, College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxiChina
- Key Laboratory of Plant Protection Resources and Pest Management, Ministry of Education, College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxiChina
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5
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Suzuki M, Kitazawa Y, Iwabuchi N, Maejima K, Matsuyama J, Matsumoto O, Oshima K, Namba S, Yamaji Y. Target degradation specificity of phytoplasma effector phyllogen is regulated by the recruitment of host proteasome shuttle protein. MOLECULAR PLANT PATHOLOGY 2024; 25:e13410. [PMID: 38105442 PMCID: PMC10799209 DOI: 10.1111/mpp.13410] [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: 09/01/2023] [Revised: 11/16/2023] [Accepted: 11/17/2023] [Indexed: 12/19/2023]
Abstract
Phytoplasmas infect a wide variety of plants and can cause distinctive symptoms including the conversion of floral organs into leaf-like organs, known as phyllody. Phyllody is induced by an effector protein family called phyllogens, which interact with floral MADS-box transcription factors (MTFs) responsible for determining the identity of floral organs. The MTF/phyllogen complex then interacts with the proteasomal shuttle protein RADIATION SENSITIVE23 (RAD23), which facilitates delivery of the MTF/phyllogen complex to the host proteasome for MTF degradation. Previous studies have indicated that the MTF degradation specificity of phyllogens is determined by their ability to bind to MTFs. However, in the present study, we discovered a novel mechanism determining the degradation specificity through detailed functional analyses of a phyllogen homologue of rice yellow dwarf phytoplasma (PHYLRYD ). PHYLRYD degraded a narrower range of floral MTFs than other phyllody-inducing phyllogens, resulting in compromised phyllody phenotypes in plants. Interestingly, PHYLRYD was able to bind to some floral MTFs that PHYLRYD was unable to efficiently degrade. However, the complex of PHYLRYD and the non-degradable MTF could not interact with RAD23. These results indicate that the MTF degradation specificity of PHYLRYD is correlated with the ability to form the MTF/PHYLRYD /RAD23 ternary complex, rather than the ability to bind to MTF. This study elucidated that phyllogen target specificity is regulated by both the MTF-binding ability and RAD23 recruitment ability of the MTF/phyllogen complex.
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Affiliation(s)
- Masato Suzuki
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Yugo Kitazawa
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Nozomu Iwabuchi
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Kensaku Maejima
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Juri Matsuyama
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Oki Matsumoto
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Kenro Oshima
- Faculty of Bioscience, Hosei UniversityTokyoJapan
| | - Shigetou Namba
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Yasuyuki Yamaji
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
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6
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Moyano A, Croce AC, Scolari F. Pathogen-Mediated Alterations of Insect Chemical Communication: From Pheromones to Behavior. Pathogens 2023; 12:1350. [PMID: 38003813 PMCID: PMC10675518 DOI: 10.3390/pathogens12111350] [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: 10/12/2023] [Revised: 11/10/2023] [Accepted: 11/11/2023] [Indexed: 11/26/2023] Open
Abstract
Pathogens can influence the physiology and behavior of both animal and plant hosts in a manner that promotes their own transmission and dispersal. Recent research focusing on insects has revealed that these manipulations can extend to the production of pheromones, which are pivotal in chemical communication. This review provides an overview of the current state of research and available data concerning the impacts of bacterial, viral, fungal, and eukaryotic pathogens on chemical communication across different insect orders. While our understanding of the influence of pathogenic bacteria on host chemical profiles is still limited, viral infections have been shown to induce behavioral changes in the host, such as altered pheromone production, olfaction, and locomotion. Entomopathogenic fungi affect host chemical communication by manipulating cuticular hydrocarbons and pheromone production, while various eukaryotic parasites have been observed to influence insect behavior by affecting the production of pheromones and other chemical cues. The effects induced by these infections are explored in the context of the evolutionary advantages they confer to the pathogen. The molecular mechanisms governing the observed pathogen-mediated behavioral changes, as well as the dynamic and mutually influential relationships between the pathogen and its host, are still poorly understood. A deeper comprehension of these mechanisms will prove invaluable in identifying novel targets in the perspective of practical applications aimed at controlling detrimental insect species.
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Affiliation(s)
- Andrea Moyano
- Institute of Molecular Genetics, Italian National Research Council (CNR), Via Abbiategrasso 207, I-27100 Pavia, Italy; (A.M.); (A.C.C.)
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, I-27100 Pavia, Italy
| | - Anna Cleta Croce
- Institute of Molecular Genetics, Italian National Research Council (CNR), Via Abbiategrasso 207, I-27100 Pavia, Italy; (A.M.); (A.C.C.)
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, I-27100 Pavia, Italy
| | - Francesca Scolari
- Institute of Molecular Genetics, Italian National Research Council (CNR), Via Abbiategrasso 207, I-27100 Pavia, Italy; (A.M.); (A.C.C.)
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, I-27100 Pavia, Italy
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7
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The Complete Genome of the “Flavescence Dorée” Phytoplasma Reveals Characteristics of Low Genome Plasticity. BIOLOGY 2022; 11:biology11070953. [PMID: 36101334 PMCID: PMC9312162 DOI: 10.3390/biology11070953] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/20/2022] [Accepted: 06/21/2022] [Indexed: 12/22/2022]
Abstract
Members of the genus ‘Candidatus Phytoplasma’ are obligate intracellular bacteria restricted to phloem sieve elements and are able to colonize several tissues and the hemolymph in their insect vectors. The current unfeasibility of axenic culture and the low complexity of genomic sequences are obstacles in assembling complete chromosomes. Here, a method combining pathogen DNA enrichment from infected insects and dual deep-sequencing technologies was used to obtain the complete genome of a phytoplasma causing Grapevine Flavescence dorée. The de novo assembly generated a circular chromosome of 654,223 bp containing 506 protein-coding genes. Quality assessment of the draft showed a high degree of completeness. Comparative analysis with other phytoplasmas revealed the absence of potential mobile units and a reduced amount of putative phage-derived segments, suggesting a low genome plasticity. Phylogenetic analyses identified Candidatus Phytoplasma ziziphi as the closest fully sequenced relative. The “Flavescence dorée” phytoplasma strain CH genome also encoded for several putative effector proteins potentially playing a role in pathogen virulence. The availability of this genome provides the basis for the study of the pathogenicity mechanisms and evolution of the Flavescence dorée phytoplasma.
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Kitazawa Y, Iwabuchi N, Maejima K, Sasano M, Matsumoto O, Koinuma H, Tokuda R, Suzuki M, Oshima K, Namba S, Yamaji Y. A phytoplasma effector acts as a ubiquitin-like mediator between floral MADS-box proteins and proteasome shuttle proteins. THE PLANT CELL 2022; 34:1709-1723. [PMID: 35234248 PMCID: PMC9048881 DOI: 10.1093/plcell/koac062] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 02/14/2022] [Indexed: 06/01/2023]
Abstract
Plant pathogenic bacteria have developed effectors to manipulate host cell functions to facilitate infection. A certain number of effectors use the conserved ubiquitin-proteasome system in eukaryotic to proteolyze targets. The proteasome utilization mechanism is mainly mediated by ubiquitin interaction with target proteins destined for degradation. Phyllogens are a family of protein effectors produced by pathogenic phytoplasmas that transform flowers into leaves in diverse plants. Here, we present a noncanonical mechanism for phyllogen action that involves the proteasome and is ubiquitin-independent. Phyllogens induce proteasomal degradation of floral MADS-box transcription factors (MTFs) in the presence of RADIATION-SENSITIVE23 (RAD23) shuttle proteins, which recruit ubiquitinated proteins to the proteasome. Intracellular localization analysis revealed that phyllogen induced colocalization of MTF with RAD23. The MTF/phyllogen/RAD23 ternary protein complex was detected not only in planta but also in vitro in the absence of ubiquitin, showing that phyllogen directly mediates interaction between MTF and RAD23. A Lys-less nonubiquitinated phyllogen mutant induced degradation of MTF or a Lys-less mutant of MTF. Furthermore, the method of sequential formation of the MTF/phyllogen/RAD23 protein complex was elucidated, first by MTF/phyllogen interaction and then RAD23 recruitment. Phyllogen recognized both the evolutionarily conserved tetramerization region of MTF and the ubiquitin-associated domain of RAD23. Our findings indicate that phyllogen functionally mimics ubiquitin as a mediator between MTF and RAD23.
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Affiliation(s)
- Yugo Kitazawa
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Nozomu Iwabuchi
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | | | - Momoka Sasano
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Oki Matsumoto
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Hiroaki Koinuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Ryosuke Tokuda
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Masato Suzuki
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Kenro Oshima
- Faculty of Bioscience and Applied Chemistry, Hosei University, Tokyo 184-8584, Japan
| | - Shigetou Namba
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yasuyuki Yamaji
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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9
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Huang CT, Cho ST, Lin YC, Tan CM, Chiu YC, Yang JY, Kuo CH. Comparative Genome Analysis of ‘Candidatus Phytoplasma luffae’ Reveals the Influential Roles of Potential Mobile Units in Phytoplasma Evolution. Front Microbiol 2022; 13:773608. [PMID: 35300489 PMCID: PMC8923039 DOI: 10.3389/fmicb.2022.773608] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 02/07/2022] [Indexed: 12/23/2022] Open
Abstract
Phytoplasmas are insect-transmitted plant pathogens that cause substantial losses in agriculture. In addition to economic impact, phytoplasmas induce distinct disease symptoms in infected plants, thus attracting attention for research on molecular plant-microbe interactions and plant developmental processes. Due to the difficulty of establishing an axenic culture of these bacteria, culture-independent genome characterization is a crucial tool for phytoplasma research. However, phytoplasma genomes have strong nucleotide composition biases and are repetitive, which make it challenging to produce complete assemblies. In this study, we utilized Illumina and Oxford Nanopore sequencing technologies to obtain the complete genome sequence of ‘Candidatus Phytoplasma luffae’ strain NCHU2019 that is associated with witches’ broom disease of loofah (Luffa aegyptiaca) in Taiwan. The fully assembled circular chromosome is 769 kb in size and is the first representative genome sequence of group 16SrVIII phytoplasmas. Comparative analysis with other phytoplasmas revealed that NCHU2019 has a remarkably repetitive genome, possessing a pair of 75 kb repeats and at least 13 potential mobile units (PMUs) that account for ∼25% of its chromosome. This level of genome repetitiveness is exceptional for bacteria, particularly among obligate pathogens with reduced genomes. Our genus-level analysis of PMUs demonstrated that these phytoplasma-specific mobile genetic elements can be classified into three major types that differ in gene organization and phylogenetic distribution. Notably, PMU abundance explains nearly 80% of the variance in phytoplasma genome sizes, a finding that provides a quantitative estimate for the importance of PMUs in phytoplasma genome variability. Finally, our investigation found that in addition to horizontal gene transfer, PMUs also contribute to intra-genomic duplications of effector genes, which may provide redundancy for subfunctionalization or neofunctionalization. Taken together, this work improves the taxon sampling for phytoplasma genome research and provides novel information regarding the roles of mobile genetic elements in phytoplasma evolution.
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Affiliation(s)
- Ching-Ting Huang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Shu-Ting Cho
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Yu-Chen Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Choon-Meng Tan
- Institute of Biochemistry, National Chung Hsing University, Taichung, Taiwan
| | - Yi-Ching Chiu
- Institute of Biochemistry, National Chung Hsing University, Taichung, Taiwan
- Ph.D. Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, Taichung, Taiwan
| | - Jun-Yi Yang
- Institute of Biochemistry, National Chung Hsing University, Taichung, Taiwan
- Ph.D. Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, Taichung, Taiwan
- Advanced Plant Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
- *Correspondence: Jun-Yi Yang,
| | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Ph.D. Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, Taichung, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan
- Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
- Chih-Horng Kuo,
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10
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Omenge KM, Rümpler F, Kathalingam SS, Furch ACU, Theißen G. Studying the Function of Phytoplasma Effector Proteins Using a Chemical-Inducible Expression System in Transgenic Plants. Int J Mol Sci 2021; 22:ijms222413582. [PMID: 34948378 PMCID: PMC8703313 DOI: 10.3390/ijms222413582] [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: 11/05/2021] [Revised: 12/14/2021] [Accepted: 12/15/2021] [Indexed: 11/17/2022] Open
Abstract
Phytoplasmas are bacterial pathogens that live mainly in the phloem of their plant hosts. They dramatically manipulate plant development by secreting effector proteins that target developmental proteins of their hosts. Traditionally, the effects of individual effector proteins have been studied by ectopic overexpression using strong, ubiquitously active promoters in transgenic model plants. However, the impact of phytoplasma infection on the host plants depends on the intensity and timing of infection with respect to the developmental stage of the host. To facilitate investigations addressing the timing of effector protein activity, we have established chemical-inducible expression systems for the three most well-characterized phytoplasma effector proteins, SECRETED ASTER YELLOWS WITCHES’ BROOM PROTEIN 11 (SAP11), SAP54 and TENGU in transgenic Arabidopsis thaliana. We induced gene expression either continuously, or at germination stage, seedling stage, or flowering stage. mRNA expression was determined by quantitative reverse transcription PCR, protein accumulation by confocal laser scanning microscopy of GFP fusion proteins. Our data reveal tight regulation of effector gene expression and strong upregulation after induction. Phenotypic analyses showed differences in disease phenotypes depending on the timing of induction. Comparative phenotype analysis revealed so far unreported similarities in disease phenotypes, with all three effector proteins interfering with flower development and shoot branching, indicating a surprising functional redundancy of SAP54, SAP11 and TENGU. However, subtle but mechanistically important differences were also observed, especially affecting the branching pattern of the plants.
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Affiliation(s)
- Keziah M. Omenge
- Department of Genetics, Matthias Schleiden Institute for Genetics, Bioinformatics and Molecular Botany, Friedrich Schiller University Jena, Philosophenweg 12, 07743 Jena, Germany; (K.M.O.); (F.R.); (S.S.K.)
| | - Florian Rümpler
- Department of Genetics, Matthias Schleiden Institute for Genetics, Bioinformatics and Molecular Botany, Friedrich Schiller University Jena, Philosophenweg 12, 07743 Jena, Germany; (K.M.O.); (F.R.); (S.S.K.)
| | - Subha Suvetha Kathalingam
- Department of Genetics, Matthias Schleiden Institute for Genetics, Bioinformatics and Molecular Botany, Friedrich Schiller University Jena, Philosophenweg 12, 07743 Jena, Germany; (K.M.O.); (F.R.); (S.S.K.)
| | - Alexandra C. U. Furch
- Department of Plant Physiology, Matthias Schleiden Institute for Genetics, Bioinformatics and Molecular Botany, Friedrich Schiller University Jena, Dornburger Str. 159, 07743 Jena, Germany;
| | - Günter Theißen
- Department of Genetics, Matthias Schleiden Institute for Genetics, Bioinformatics and Molecular Botany, Friedrich Schiller University Jena, Philosophenweg 12, 07743 Jena, Germany; (K.M.O.); (F.R.); (S.S.K.)
- Correspondence:
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11
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Huang W, MacLean AM, Sugio A, Maqbool A, Busscher M, Cho ST, Kamoun S, Kuo CH, Immink RGH, Hogenhout SA. Parasitic modulation of host development by ubiquitin-independent protein degradation. Cell 2021; 184:5201-5214.e12. [PMID: 34536345 DOI: 10.1016/j.cell.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 07/14/2021] [Accepted: 08/24/2021] [Indexed: 05/27/2023]
Abstract
Certain obligate parasites induce complex and substantial phenotypic changes in their hosts in ways that favor their transmission to other trophic levels. However, the mechanisms underlying these changes remain largely unknown. Here we demonstrate how SAP05 protein effectors from insect-vectored plant pathogenic phytoplasmas take control of several plant developmental processes. These effectors simultaneously prolong the host lifespan and induce witches' broom-like proliferations of leaf and sterile shoots, organs colonized by phytoplasmas and vectors. SAP05 acts by mediating the concurrent degradation of SPL and GATA developmental regulators via a process that relies on hijacking the plant ubiquitin receptor RPN10 independent of substrate ubiquitination. RPN10 is highly conserved among eukaryotes, but SAP05 does not bind insect vector RPN10. A two-amino-acid substitution within plant RPN10 generates a functional variant that is resistant to SAP05 activities. Therefore, one effector protein enables obligate parasitic phytoplasmas to induce a plethora of developmental phenotypes in their hosts.
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Affiliation(s)
- Weijie Huang
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Allyson M MacLean
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Akiko Sugio
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Abbas Maqbool
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, UK
| | - Marco Busscher
- Laboratory of Molecular Biology, Wageningen University and Research, Wageningen 6708 PB, the Netherlands; Plant Developmental Systems, Bioscience, Wageningen University and Research, Wageningen 6708 PB, the Netherlands
| | - Shu-Ting Cho
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Sophien Kamoun
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, UK
| | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Richard G H Immink
- Laboratory of Molecular Biology, Wageningen University and Research, Wageningen 6708 PB, the Netherlands; Plant Developmental Systems, Bioscience, Wageningen University and Research, Wageningen 6708 PB, the Netherlands
| | - Saskia A Hogenhout
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
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12
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Huang W, MacLean AM, Sugio A, Maqbool A, Busscher M, Cho ST, Kamoun S, Kuo CH, Immink RGH, Hogenhout SA. Parasitic modulation of host development by ubiquitin-independent protein degradation. Cell 2021; 184:5201-5214.e12. [PMID: 34536345 PMCID: PMC8525514 DOI: 10.1016/j.cell.2021.08.029] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 07/14/2021] [Accepted: 08/24/2021] [Indexed: 01/08/2023]
Abstract
Certain obligate parasites induce complex and substantial phenotypic changes in their hosts in ways that favor their transmission to other trophic levels. However, the mechanisms underlying these changes remain largely unknown. Here we demonstrate how SAP05 protein effectors from insect-vectored plant pathogenic phytoplasmas take control of several plant developmental processes. These effectors simultaneously prolong the host lifespan and induce witches' broom-like proliferations of leaf and sterile shoots, organs colonized by phytoplasmas and vectors. SAP05 acts by mediating the concurrent degradation of SPL and GATA developmental regulators via a process that relies on hijacking the plant ubiquitin receptor RPN10 independent of substrate ubiquitination. RPN10 is highly conserved among eukaryotes, but SAP05 does not bind insect vector RPN10. A two-amino-acid substitution within plant RPN10 generates a functional variant that is resistant to SAP05 activities. Therefore, one effector protein enables obligate parasitic phytoplasmas to induce a plethora of developmental phenotypes in their hosts.
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Affiliation(s)
- Weijie Huang
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Allyson M MacLean
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Akiko Sugio
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Abbas Maqbool
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, UK
| | - Marco Busscher
- Laboratory of Molecular Biology, Wageningen University and Research, Wageningen 6708 PB, the Netherlands; Plant Developmental Systems, Bioscience, Wageningen University and Research, Wageningen 6708 PB, the Netherlands
| | - Shu-Ting Cho
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Sophien Kamoun
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, UK
| | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Richard G H Immink
- Laboratory of Molecular Biology, Wageningen University and Research, Wageningen 6708 PB, the Netherlands; Plant Developmental Systems, Bioscience, Wageningen University and Research, Wageningen 6708 PB, the Netherlands
| | - Saskia A Hogenhout
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
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13
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Al-Subhi AM, Al-Sadi AM, Al-Yahyai RA, Chen Y, Mathers T, Orlovskis Z, Moro G, Mugford S, Al-Hashmi KS, Hogenhout SA. Witches' Broom Disease of Lime Contributes to Phytoplasma Epidemics and Attracts Insect Vectors. PLANT DISEASE 2021; 105:2637-2648. [PMID: 33349007 DOI: 10.1094/pdis-10-20-2112-re] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
An insect-transmitted phytoplasma causing Witches' Broom Disease of Lime (WBDL) is responsible for the drastic decline in lime production in several countries. However, it is unclear how WBDL phytoplasma (WBDLp) induces witches' broom symptoms and if these symptoms contribute to the spread of phytoplasma. Here we show that the gene encoding SAP11 of WBDLp (SAP11WBDL) is present in all WBDLp isolates collected from diseased trees. SAP11WBDL interacts with acid lime (Citrus aurantifolia) TCP transcription factors, specifically members of the TB1/CYC class that have a role in suppressing axillary branching in plants. Sampling of WBDLp-infected lime trees revealed that WBDLp titers and SAP11WBDL expression levels were higher in symptomatic leaves compared with asymptomatic sections of the same trees. Moreover, the witches' brooms were found to attract the vector leafhopper. Defense genes that have a role in plant defense responses to bacteria and insects are more downregulated in witches' brooms compared with asymptomatic sections of trees. These findings suggest that witches' broom-affected parts of the trees contribute to WBDL epidemics by supporting higher phytoplasma titers and attracting insect vectors.
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Affiliation(s)
- A M Al-Subhi
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al Khod 123, Oman
| | - A M Al-Sadi
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al Khod 123, Oman
| | - R A Al-Yahyai
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al Khod 123, Oman
| | - Y Chen
- John Innes Centre, Department of Crop Genetics, Norwich NR4 7UH, United Kingdom
| | - T Mathers
- John Innes Centre, Department of Crop Genetics, Norwich NR4 7UH, United Kingdom
| | - Z Orlovskis
- John Innes Centre, Department of Crop Genetics, Norwich NR4 7UH, United Kingdom
| | - G Moro
- John Innes Centre, Department of Crop Genetics, Norwich NR4 7UH, United Kingdom
| | - S Mugford
- John Innes Centre, Department of Crop Genetics, Norwich NR4 7UH, United Kingdom
| | - K S Al-Hashmi
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al Khod 123, Oman
| | - S A Hogenhout
- John Innes Centre, Department of Crop Genetics, Norwich NR4 7UH, United Kingdom
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14
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Garcion C, Béven L, Foissac X. Comparison of Current Methods for Signal Peptide Prediction in Phytoplasmas. Front Microbiol 2021; 12:661524. [PMID: 33841387 PMCID: PMC8026896 DOI: 10.3389/fmicb.2021.661524] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 03/02/2021] [Indexed: 11/13/2022] Open
Abstract
Although phytoplasma studies are still hampered by the lack of axenic cultivation methods, the availability of genome sequences allowed dramatic advances in the characterization of the virulence mechanisms deployed by phytoplasmas, and highlighted the detection of signal peptides as a crucial step to identify effectors secreted by phytoplasmas. However, various signal peptide prediction methods have been used to mine phytoplasma genomes, and no general evaluation of these methods is available so far for phytoplasma sequences. In this work, we compared the prediction performance of SignalP versions 3.0, 4.0, 4.1, 5.0 and Phobius on several sequence datasets originating from all deposited phytoplasma sequences. SignalP 4.1 with specific parameters showed the most exhaustive and consistent prediction ability. However, the configuration of SignalP 4.1 for increased sensitivity induced a much higher rate of false positives on transmembrane domains located at N-terminus. Moreover, sensitive signal peptide predictions could similarly be achieved by the transmembrane domain prediction ability of TMHMM and Phobius, due to the relatedness between signal peptides and transmembrane regions. Beyond the results presented herein, the datasets assembled in this study form a valuable benchmark to compare and evaluate signal peptide predictors in a field where experimental evidence of secretion is scarce. Additionally, this study illustrates the utility of comparative genomics to strengthen confidence in bioinformatic predictions.
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Affiliation(s)
- Christophe Garcion
- INRAE, Univ. Bordeaux, Biologie du Fruit et Pathologie, UMR 1332, Villenave d'Ornon, France
| | - Laure Béven
- INRAE, Univ. Bordeaux, Biologie du Fruit et Pathologie, UMR 1332, Villenave d'Ornon, France
| | - Xavier Foissac
- INRAE, Univ. Bordeaux, Biologie du Fruit et Pathologie, UMR 1332, Villenave d'Ornon, France
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15
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Wei W, Trivellone V, Dietrich CH, Zhao Y, Bottner-Parker KD, Ivanauskas A. Identification of Phytoplasmas Representing Multiple New Genetic Lineages from Phloem-Feeding Leafhoppers Highlights the Diversity of Phytoplasmas and Their Potential Vectors. Pathogens 2021; 10:352. [PMID: 33809759 PMCID: PMC8002289 DOI: 10.3390/pathogens10030352] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/10/2021] [Accepted: 03/13/2021] [Indexed: 01/18/2023] Open
Abstract
Phytoplasmas are obligate transkingdom bacterial parasites that infect a variety of plant species and replicate in phloem-feeding insects in the order Hemiptera, mainly leafhoppers (Cicadellidae). The insect capacity in acquisition, transmission, survival, and host range directly determines the epidemiology of phytoplasmas. However, due to the difficulty of insect sampling and the lack of follow-up transmission trials, the confirmed phytoplasma insect hosts are still limited compared with the identified plant hosts. Recently, quantitative polymerase chain reaction (qPCR)-based quick screening of 227 leafhoppers collected in natural habitats unveiled the presence of previously unknown phytoplasmas in six samples. In the present study, 76 leafhoppers, including the six prescreened positive samples, were further examined to identify and characterize the phytoplasma strains by semi-nested PCR. A total of ten phytoplasma strains were identified in leafhoppers from four countries including South Africa, Kyrgyzstan, Australia, and China. Based on virtual restriction fragment length polymorphism (RFLP) analysis, these ten phytoplasma strains were classified into four distinct ribosomal (16Sr) groups (16SrI, 16SrIII, 16SrXIV, and 16SrXV), representing five new subgroups (16SrI-AO, 16SrXIV-D, 16SrXIV-E, 16SrXIV-F, and 16SrXV-C). The results strongly suggest that the newly identified phytoplasma strains not only represent new genetic subgroup lineages, but also extend previously undiscovered geographical distributions. In addition, ten phytoplasma-harboring leafhoppers belonged to seven known leafhopper species, none of which were previously reported insect vectors of phytoplasmas. The findings from this study provide fresh insight into genetic diversity, geographical distribution, and insect host range of phytoplasmas. Further transmission trials and screening of new potential host plants and weed reservoirs in areas adjacent to collection sites of phytoplasma harboring leafhoppers will contribute to a better understanding of phytoplasma transmission and epidemiology.
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Affiliation(s)
- Wei Wei
- Beltsville Agricultural Research Center, Molecular Plant Pathology Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705, USA; (Y.Z.); (K.D.B.-P.); (A.I.)
| | - Valeria Trivellone
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois, Champaign, IL 61820, USA; (V.T.); (C.H.D.)
| | - Christopher H. Dietrich
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois, Champaign, IL 61820, USA; (V.T.); (C.H.D.)
| | - Yan Zhao
- Beltsville Agricultural Research Center, Molecular Plant Pathology Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705, USA; (Y.Z.); (K.D.B.-P.); (A.I.)
| | - Kristi D. Bottner-Parker
- Beltsville Agricultural Research Center, Molecular Plant Pathology Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705, USA; (Y.Z.); (K.D.B.-P.); (A.I.)
| | - Algirdas Ivanauskas
- Beltsville Agricultural Research Center, Molecular Plant Pathology Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705, USA; (Y.Z.); (K.D.B.-P.); (A.I.)
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16
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Clements J, Bradford BZ, Garcia M, Piper S, Huang W, Zwolinska A, Lamour K, Hogenhout S, Groves RL. 'Candidatus Phytoplasma asteris' subgroups display distinct disease progression dynamics during the carrot growing season. PLoS One 2021; 16:e0239956. [PMID: 33539350 PMCID: PMC7861454 DOI: 10.1371/journal.pone.0239956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 01/20/2021] [Indexed: 11/19/2022] Open
Abstract
Aster Yellows phytoplasma (AYp; ‘Candidatus Phytoplasma asteris’) is an obligate bacterial pathogen that is the causative agent of multiple diseases in herbaceous plants. While this phytoplasma has been examined in depth for its disease characteristics, knowledge about the spatial and temporal dynamics of pathogen spread is lacking. The phytoplasma is found in plant’s phloem and is vectored by leafhoppers (Cicadellidae: Hemiptera), including the aster leafhopper, Macrosteles quadrilineatus Forbes. The aster leafhopper is a migratory insect pest that overwinters in the southern United States, and historical data suggest these insects migrate from southern overwintering locations to northern latitudes annually, transmitting and driving phytoplasma infection rates as they migrate. A more in-depth understanding of the spatial, temporal and genetic determinants of Aster Yellows disease progress will lead to better integrated pest management strategies for Aster Yellows disease control. Carrot, Daucus carota L., plots were established at two planting densities in central Wisconsin and monitored during the 2018 growing season for Aster Yellows disease progression. Symptomatic carrots were sampled and assayed for the presence of the Aster Yellows phytoplasma. Aster Yellows disease progression was determined to be significantly associated with calendar date, crop density, location within the field, and phytoplasma subgroup.
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Affiliation(s)
- Justin Clements
- Department of Entomology, Plant Pathology, and Nematology, University of Idaho, Parma, ID, United States of America
| | - Benjamin Z. Bradford
- Department of Entomology, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Marjorie Garcia
- Department of Entomology, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Shannon Piper
- Department of Entomology, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Weijie Huang
- Department of Crop Genetics, John Innes Centre, Norwich, United Kingdom
| | - Agnieszka Zwolinska
- Department of Virology and Bacteriology, National Research Institute, Poznan, Poland
| | - Kurt Lamour
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN, United States of America
| | - Saskia Hogenhout
- Department of Crop Genetics, John Innes Centre, Norwich, United Kingdom
| | - Russell L. Groves
- Department of Entomology, University of Wisconsin-Madison, Madison, WI, United States of America
- * E-mail:
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17
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Huang W, Reyes-Caldas P, Mann M, Seifbarghi S, Kahn A, Almeida RPP, Béven L, Heck M, Hogenhout SA, Coaker G. Bacterial Vector-Borne Plant Diseases: Unanswered Questions and Future Directions. MOLECULAR PLANT 2020; 13:1379-1393. [PMID: 32835885 PMCID: PMC7769051 DOI: 10.1016/j.molp.2020.08.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/18/2020] [Accepted: 08/18/2020] [Indexed: 06/01/2023]
Abstract
Vector-borne plant diseases have significant ecological and economic impacts, affecting farm profitability and forest composition throughout the world. Bacterial vector-borne pathogens have evolved sophisticated strategies to interact with their hemipteran insect vectors and plant hosts. These pathogens reside in plant vascular tissue, and their study represents an excellent opportunity to uncover novel biological mechanisms regulating intracellular pathogenesis and to contribute to the control of some of the world's most invasive emerging diseases. In this perspective, we highlight recent advances and major unanswered questions in the realm of bacterial vector-borne disease, focusing on liberibacters, phytoplasmas, spiroplasmas, and Xylella fastidiosa.
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Affiliation(s)
- Weijie Huang
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Paola Reyes-Caldas
- Department of Plant Pathology, University of California, Davis, CA, 95616, USA
| | - Marina Mann
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Shirin Seifbarghi
- Department of Plant Pathology, University of California, Davis, CA, 95616, USA
| | - Alexandra Kahn
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
| | - Rodrigo P P Almeida
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
| | - Laure Béven
- UMR 1332 Biologie du Fruit et Pathologie, Univ. Bordeaux, INRAE, Villenave d'Ornon 33882 France
| | - Michelle Heck
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA; Boyce Thompson Institute, Ithaca, NY 14853, USA; Emerging Pests and Pathogens Research Unit, Robert W. Holley Center, USDA ARS, Ithaca, NY 14853, USA
| | - Saskia A Hogenhout
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK; School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, CA, 95616, USA.
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18
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Iwabuchi N, Kitazawa Y, Maejima K, Koinuma H, Miyazaki A, Matsumoto O, Suzuki T, Nijo T, Oshima K, Namba S, Yamaji Y. Functional variation in phyllogen, a phyllody-inducing phytoplasma effector family, attributable to a single amino acid polymorphism. MOLECULAR PLANT PATHOLOGY 2020; 21:1322-1336. [PMID: 32813310 PMCID: PMC7488466 DOI: 10.1111/mpp.12981] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/25/2020] [Accepted: 07/05/2020] [Indexed: 05/08/2023]
Abstract
Flower malformation represented by phyllody is a common symptom of phytoplasma infection induced by a novel family of phytoplasma effectors called phyllogens. Despite the accumulation of functional and structural phyllogen information, the molecular mechanisms of phyllody have not yet been integrated with their evolutionary aspects due to the limited data on their homologs across diverse phytoplasma lineages. Here, we developed a novel universal PCR-based approach to identify 25 phytoplasma phyllogens related to nine "Candidatus Phytoplasma" species, including four species whose phyllogens have not yet been identified. Phylogenetic analyses showed that the phyllogen family consists of four groups (phyl-A, -B, -C, and -D) and that the evolutionary relationships of phyllogens were significantly distinct from those of phytoplasmas, suggesting that phyllogens were transferred horizontally among phytoplasma strains and species. Although phyllogens belonging to the phyl-A, -C, and -D groups induced phyllody, the phyl-B group lacked the ability to induce phyllody. Comparative functional analyses of phyllogens revealed that a single amino acid polymorphism in phyl-B group phyllogens prevented interactions between phyllogens and A- and E-class MADS domain transcription factors (MTFs), resulting in the inability to degrade several MTFs and induce phyllody. Our finding of natural variation in the function of phytoplasma effectors provides new insights into molecular mechanisms underlying the aetiology of phytoplasma diseases.
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Affiliation(s)
- Nozomu Iwabuchi
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Yugo Kitazawa
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Kensaku Maejima
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Hiroaki Koinuma
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Akio Miyazaki
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Ouki Matsumoto
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Takumi Suzuki
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Takamichi Nijo
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | | | - Shigetou Namba
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Yasuyuki Yamaji
- Department of Agricultural and Environmental BiologyGraduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
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19
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Ramos A, Esteves MB, Cortés MTB, Lopes JRS. Maize Bushy Stunt Phytoplasma Favors Its Spread by Changing Host Preference of the Insect Vector. INSECTS 2020; 11:insects11090600. [PMID: 32899467 PMCID: PMC7565095 DOI: 10.3390/insects11090600] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/30/2020] [Accepted: 09/03/2020] [Indexed: 01/20/2023]
Abstract
Simple Summary Phytopathogenic bacteria such as phytoplasmas induce physiological changes in their host plants that may modulate the behavior of an insect vector in favor of their own spread. In this study we investigate changes in the host selection behavior of the leafhopper vector, Dalbulus maidis (DeLong and Wolcott), in choice tests between healthy vs. maize bushy stunt phytoplasma (MBSP)-infected maize leaves (Zea mays L.), for insects previously exposed to infected plants (named “bacteriliferous”) or not (naive). The results showed that males and naive females of D. maids did not distinguish the treatments when infected leaves were still asymptomatic, whereas bacteriliferous females prefer to settle on healthy leaves, a behavior that favors pathogen inoculation and primary spread at early crop stages. During the symptomatic phase of maize infection, naive males and females were initially attracted to infected leaves, favoring pathogen acquisition; interestingly, the females tend to move towards healthy leaves a few hours later, a behavioral shift that promotes secondary spread. Overall, this study presents evidences that MBSP optimizes its spread in maize crops by influencing the host selection behavior of the leafhopper vector. Abstract Plant pathogenic bacteria may influence vector behavior by inducing physiological changes in host plants, with implications for their spread. Here, we studied the effects of maize bushy stunt phytoplasma (MBSP) on the host selection behavior of the leafhopper vector, Dalbulus maidis (DeLong and Wolcott). Choice assays contrasting leaves of healthy (mock-inoculated) vs. infected maize (Zea mays L.) were conducted during the asymptomatic and symptomatic phases of plant infection, with leafhopper males or females previously exposed to infected plants (bacteriliferous insects) or not. In each assay, 40 adults were released in choice arenas where only the leaves of two plants from each treatment were offered and visible, and the insects landed on the leaves were counted 1, 2, 3, 5, 7, 9, 11 and 23 h after release. During the asymptomatic phase of plant infection, an effect was observed only on bacteriliferous females, who preferred leaves of healthy plants 5 h after release or later. The symptomatic phase triggered a pull–push effect on non-bacteriliferous females, who were first attracted to symptomatic leaves but hours later moved to healthy leaves. Non-bacteriliferous males initially preferred symptomatic leaves (up to 5 h after release) and later became equally distributed between treatments. Bacteriliferous males and females initially did not discriminate between healthy and symptomatic leaves, but only the females tended to move to healthy leaves 9 h after release. Oviposition was drastically reduced on symptomatic leaves. The changes in vector behavior induced by MBSP favor its primary spread, since bacteriliferous females prefer healthy leaves at early (asymptomatic) stages of the crop. At later stages, secondary spread may be favored because non-bacteriliferous females are initially attracted to infected (symptomatic) leaves, allowing pathogen acquisition and subsequent transmission as they move to healthy plants.
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Affiliation(s)
- Anderson Ramos
- Departamento de Entomologia e Acarologia, Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ), Universidade de São Paulo (USP), Avenida Padua Dias, 11, Piracicaba 13418-900, Brazil
| | - Mariana Bossi Esteves
- Departamento de Entomologia e Acarologia, Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ), Universidade de São Paulo (USP), Avenida Padua Dias, 11, Piracicaba 13418-900, Brazil
| | - Mayerli Tatiana Borbón Cortés
- Departamento de Entomologia e Acarologia, Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ), Universidade de São Paulo (USP), Avenida Padua Dias, 11, Piracicaba 13418-900, Brazil
| | - João Roberto Spotti Lopes
- Departamento de Entomologia e Acarologia, Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ), Universidade de São Paulo (USP), Avenida Padua Dias, 11, Piracicaba 13418-900, Brazil
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Cho ST, Kung HJ, Huang W, Hogenhout SA, Kuo CH. Species Boundaries and Molecular Markers for the Classification of 16SrI Phytoplasmas Inferred by Genome Analysis. Front Microbiol 2020; 11:1531. [PMID: 32754131 PMCID: PMC7366425 DOI: 10.3389/fmicb.2020.01531] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 06/12/2020] [Indexed: 11/29/2022] Open
Abstract
Phytoplasmas are plant-pathogenic bacteria that impact agriculture worldwide. The commonly adopted classification system for phytoplasmas is based on the restriction fragment length polymorphism (RFLP) analysis of their 16S rRNA genes. With the increased availability of phytoplasma genome sequences, the classification system can now be refined. This work examined 11 strains in the 16SrI group within the genus ‘Candidatus Phytoplasma’ and investigated the possible species boundaries. We confirmed that the RFLP classification method is problematic due to intragenomic variation of the 16S rRNA genes and uneven weighing of different nucleotide positions. Importantly, our results based on the molecular phylogeny, differentiations in chromosomal segments and gene content, and divergence in homologous sequences, all supported that these strains may be classified into multiple operational taxonomic units (OTUs) equivalent to species. Strains assigned to the same OTU share >97% genome-wide average nucleotide identity (ANI) and >78% of their protein-coding genes. In comparison, strains assigned to different OTUs share < 94% ANI and < 75% of their genes. Reduction in homologous recombination between OTUs is one possible explanation for the discontinuity in genome similarities, and these findings supported the proposal that 95% ANI could serve as a cutoff for distinguishing species in bacteria. Additionally, critical examination of these results and the raw sequencing reads led to the identification of one genome that was presumably mis-assembled by combining two sequencing libraries built from phytoplasmas belonging to different OTUs. This finding provided a cautionary tale for working on uncultivated bacteria. Based on the new understanding of phytoplasma divergence and the current genome availability, we developed five molecular markers that could be used for multilocus sequence analysis (MLSA). By selecting markers that are short yet highly informative, and are distributed evenly across the chromosome, these markers provided a cost-effective system that is robust against recombination. Finally, examination of the effector gene distribution further confirmed the rapid gains and losses of these genes, as well as the involvement of potential mobile units (PMUs) in their molecular evolution. Future improvements on the taxon sampling of phytoplasma genomes will allow further expansions of similar analysis, and thus contribute to phytoplasma taxonomy and diagnostics.
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Affiliation(s)
- Shu-Ting Cho
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Hung-Jui Kung
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Weijie Huang
- Department of Crop Genetics, John Innes Centre, Norwich, United Kingdom
| | | | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
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Clements J, Garcia M, Bradford B, Crubaugh L, Piper S, Duerr E, Zwolinska A, Hogenhout S, Groves RL. Genetic Variation Among Geographically Disparate Isolates of Aster Yellows Phytoplasma in the Contiguous United States. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:604-611. [PMID: 31900490 PMCID: PMC7136194 DOI: 10.1093/jee/toz356] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Indexed: 06/10/2023]
Abstract
Aster Yellows phytoplasma (AYp; Candidatus Phytoplasma asteris) is associated with diseases of herbaceous plants, including ornamentals and important commercial vegetable and grain crops. The aster leafhopper (ALH; Macrosteles quadrilineatus Forbes) is the predominant vector of these bacteria, though other leafhopper species can acquire and transmit AYp. Potentially inoculative leafhoppers are reported to overwinter in the southern United States and migrate to northern latitudes in the spring. Examining the genetic similarities and differences in AYp associated with southern and northern populations of ALH may provide insight into the role that migrating ALH play in AYp disease development. To investigate similarities among geographically distinct populations of ALH and characterize the variation in AYp associated within these populations, we identified genetic variations in subgroup designation and the relative proportions of secreted AY-WB proteins from field-collected populations of AYp isolated from ALH from select locations in the southern (Arkansas, Kansas, Oklahoma, and Texas) and the northern United States (Wisconsin) in 2016, 2017, and 2018. Isolated phytoplasma were tested for variation of AYp genotypes, numbers of potentially inoculative (AYp-positive) ALH, and presence of specific AYp virulence (effector) genes. Geographically distinct populations of ALH collected in northern and southern regions were similar in CO1 genotype but carried different proportions of AYp genotypes. While similar AYp strains were detected in geographically distinct locations, the proportion of each genotype varied over time.
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Affiliation(s)
- Justin Clements
- Department of Entomology, University of Wisconsin-Madison, Madison, WI
| | - Marjorie Garcia
- Department of Entomology, University of Wisconsin-Madison, Madison, WI
| | - Benjamin Bradford
- Department of Entomology, University of Wisconsin-Madison, Madison, WI
| | - Linda Crubaugh
- Department of Entomology, University of Wisconsin-Madison, Madison, WI
| | - Shannon Piper
- Department of Entomology, University of Wisconsin-Madison, Madison, WI
| | - Emily Duerr
- Department of Entomology, University of Wisconsin-Madison, Madison, WI
| | | | | | - Russell L Groves
- Department of Entomology, University of Wisconsin-Madison, Madison, WI
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Harris MO, Pitzschke A. Plants make galls to accommodate foreigners: some are friends, most are foes. THE NEW PHYTOLOGIST 2020; 225:1852-1872. [PMID: 31774564 DOI: 10.1111/nph.16340] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 07/24/2019] [Indexed: 06/10/2023]
Abstract
At the colonization site of a foreign entity, plant cells alter their trajectory of growth and development. The resulting structure - a plant gall - accommodates various needs of the foreigner, which are phylogenetically diverse: viruses, bacteria, protozoa, oomycetes, true fungi, parasitic plants, and many types of animals, including rotifers, nematodes, insects, and mites. The plant species that make galls also are diverse. We assume gall production costs the plant. All is well if the foreigner provides a gift that makes up for the cost. Nitrogen-fixing nodule-inducing bacteria provide nutritional services. Gall wasps pollinate fig trees. Unfortunately for plants, most galls are made for foes, some of which are deeply studied pathogens and pests: Agrobacterium tumefaciens, Rhodococcus fascians, Xanthomonas citri, Pseudomonas savastanoi, Pantoea agglomerans, 'Candidatus' phytoplasma, rust fungi, Ustilago smuts, root knot and cyst nematodes, and gall midges. Galls are an understudied phenomenon in plant developmental biology. We propose gall inception for discovering unifying features of the galls that plants make for friends and foes, talk about molecules that plants and gall-inducers use to get what they want from each other, raise the question of whether plants colonized by arbuscular mycorrhizal fungi respond in a gall-like manner, and present a research agenda.
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Affiliation(s)
- Marion O Harris
- Department of Entomology, North Dakota State University, Fargo, ND, 58014, USA
| | - Andrea Pitzschke
- Department of Biosciences, Salzburg University, Hellbrunner Strasse 34, A-5020, Salzburg, Austria
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Pecher P, Moro G, Canale MC, Capdevielle S, Singh A, MacLean A, Sugio A, Kuo CH, Lopes JRS, Hogenhout SA. Phytoplasma SAP11 effector destabilization of TCP transcription factors differentially impact development and defence of Arabidopsis versus maize. PLoS Pathog 2019; 15:e1008035. [PMID: 31557268 PMCID: PMC6802841 DOI: 10.1371/journal.ppat.1008035] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 10/21/2019] [Accepted: 08/20/2019] [Indexed: 12/13/2022] Open
Abstract
Phytoplasmas are insect-transmitted bacterial pathogens that colonize a wide range of plant species, including vegetable and cereal crops, and herbaceous and woody ornamentals. Phytoplasma-infected plants often show dramatic symptoms, including proliferation of shoots (witch's brooms), changes in leaf shapes and production of green sterile flowers (phyllody). Aster Yellows phytoplasma Witches' Broom (AY-WB) infects dicots and its effector, secreted AYWB protein 11 (SAP11), was shown to be responsible for the induction of shoot proliferation and leaf shape changes of plants. SAP11 acts by destabilizing TEOSINTE BRANCHED 1-CYCLOIDEA-PROLIFERATING CELL FACTOR (TCP) transcription factors, particularly the class II TCPs of the CYCLOIDEA/TEOSINTE BRANCHED 1 (CYC/TB1) and CINCINNATA (CIN)-TCP clades. SAP11 homologs are also present in phytoplasmas that cause economic yield losses in monocot crops, such as maize, wheat and coconut. Here we show that a SAP11 homolog of Maize Bushy Stunt Phytoplasma (MBSP), which has a range primarily restricted to maize, destabilizes specifically TB1/CYC TCPs. SAP11MBSP and SAP11AYWB both induce axillary branching and SAP11AYWB also alters leaf development of Arabidopsis thaliana and maize. However, only in maize, SAP11MBSP prevents female inflorescence development, phenocopying maize tb1 lines, whereas SAP11AYWB prevents male inflorescence development and induces feminization of tassels. SAP11AYWB promotes fecundity of the AY-WB leafhopper vector on A. thaliana and modulates the expression of A. thaliana leaf defence response genes that are induced by this leafhopper, in contrast to SAP11MBSP. Neither of the SAP11 effectors promote fecundity of AY-WB and MBSP leafhopper vectors on maize. These data provide evidence that class II TCPs have overlapping but also distinct roles in regulating development and defence in a dicot and a monocot plant species that is likely to shape SAP11 effector evolution depending on the phytoplasma host range.
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Affiliation(s)
- Pascal Pecher
- John Innes Centre, Department of Crop Genetics, Norwich Research Park, Norwich, United Kingdom
| | - Gabriele Moro
- John Innes Centre, Department of Crop Genetics, Norwich Research Park, Norwich, United Kingdom
| | - Maria Cristina Canale
- John Innes Centre, Department of Crop Genetics, Norwich Research Park, Norwich, United Kingdom
- Luiz de Queiroz College of Agriculture, Department of Entomology and Acarology, University of São Paulo, Piracicaba, Brazil
| | - Sylvain Capdevielle
- John Innes Centre, Department of Crop Genetics, Norwich Research Park, Norwich, United Kingdom
| | - Archana Singh
- John Innes Centre, Department of Crop Genetics, Norwich Research Park, Norwich, United Kingdom
| | - Allyson MacLean
- John Innes Centre, Department of Crop Genetics, Norwich Research Park, Norwich, United Kingdom
| | - Akiko Sugio
- John Innes Centre, Department of Crop Genetics, Norwich Research Park, Norwich, United Kingdom
| | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Joao R. S. Lopes
- Luiz de Queiroz College of Agriculture, Department of Entomology and Acarology, University of São Paulo, Piracicaba, Brazil
| | - Saskia A. Hogenhout
- John Innes Centre, Department of Crop Genetics, Norwich Research Park, Norwich, United Kingdom
- * E-mail:
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Cho ST, Lin CP, Kuo CH. Genomic Characterization of the Periwinkle Leaf Yellowing (PLY) Phytoplasmas in Taiwan. Front Microbiol 2019; 10:2194. [PMID: 31608032 PMCID: PMC6761752 DOI: 10.3389/fmicb.2019.02194] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 09/06/2019] [Indexed: 12/17/2022] Open
Abstract
The periwinkle leaf yellowing (PLY) disease was first reported in Taiwan in 2005. This disease was caused by an uncultivated bacterium in the genus “Candidatus phytoplasma.” In subsequent years, this bacterium was linked to other plant diseases and caused losses in agriculture. For genomic investigation of this bacterium and its relatives, we conducted whole genome sequencing of a PLY phytoplasma from an infected periwinkle collected in Taoyuan. The de novo genome assembly produced eight contigs with a total length of 824,596 bp. The annotation contains 775 protein-coding genes, 63 pseudogenes, 32 tRNA genes, and two sets of rRNA operons. To characterize the genomic diversity across populations, a second strain that infects green onions in Yilan was collected for re-sequencing analysis. Comparison between these two strains identified 337 sequence polymorphisms and 10 structural variations. The metabolic pathway analysis indicated that the PLY phytoplasma genome contains two regions with highly conserved gene composition for carbohydrate metabolism. Intriguingly, each region contains several pseudogenes and the remaining functional genes in these two regions complement each other, suggesting a case of duplication followed by differential gene losses. Comparative analysis with other available phytoplasma genomes indicated that this PLY phytoplasma belongs to the 16SrI-B subgroup in the genus, with “Candidatus Phytoplasma asteris” that causes the onion yellowing (OY) disease in Japan as the closest known relative. For characterized effectors that these bacteria use to manipulate their plant hosts, the PLY phytoplasma has homologs for SAP11, SAP54/PHYL1, and TENGU. For genome structure comparison, we found that potential mobile unit (PMU) insertions may be the main factor that drives genome rearrangements in these bacteria. A total of 10 PMU-like regions were found in the PLY phytoplasma genome. Two of these PMUs were found to harbor one SAP11 homolog each, with one more similar to the 16SrI-B type and the other more similar to the 16SrI-A type, suggesting possible horizontal transfer. Taken together, this work provided a first look into population genomics of the PLY phytoplasmas in Taiwan, as well as identified several evolutionary processes that contributed to the genetic diversification of these plant-pathogenic bacteria.
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Affiliation(s)
- Shu-Ting Cho
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Chan-Pin Lin
- Department of Plant Pathology and Microbiology, National Taiwan University, Taipei, Taiwan
| | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
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25
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Pradit N, Rodriguez-Saona C, Kawash J, Polashock J. Phytoplasma Infection Influences Gene Expression in American Cranberry. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00178] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Pradit N, Mescher MC, Wang Y, Vorsa N, Rodriguez-Saona C. Phytoplasma Infection of Cranberries Benefits Non-vector Phytophagous Insects. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00181] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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27
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Tomkins M, Kliot A, Marée AF, Hogenhout SA. A multi-layered mechanistic modelling approach to understand how effector genes extend beyond phytoplasma to modulate plant hosts, insect vectors and the environment. CURRENT OPINION IN PLANT BIOLOGY 2018; 44:39-48. [PMID: 29547737 DOI: 10.1016/j.pbi.2018.02.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 02/05/2018] [Accepted: 02/06/2018] [Indexed: 05/13/2023]
Abstract
Members of the Candidatus genus Phytoplasma are small bacterial pathogens that hijack their plant hosts via the secretion of virulence proteins (effectors) leading to a fascinating array of plant phenotypes, such as witch's brooms (stem proliferations) and phyllody (retrograde development of flowers into vegetative tissues). Phytoplasma depend on insect vectors for transmission, and interestingly, these insect vectors were found to be (in)directly attracted to plants with these phenotypes. Therefore, phytoplasma effectors appear to reprogram plant development and defence to lure insect vectors, similarly to social engineering malware, which employs tricks to lure people to infected computers and webpages. A multi-layered mechanistic modelling approach will enable a better understanding of how phytoplasma effector-mediated modulations of plant host development and insect vector behaviour contribute to phytoplasma spread, and ultimately to predict the long reach of phytoplasma effector genes.
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Affiliation(s)
- Melissa Tomkins
- Department of Computational and Systems Biology, The John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Adi Kliot
- Department of Crop Genetics, The John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Athanasius Fm Marée
- Department of Computational and Systems Biology, The John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom.
| | - Saskia A Hogenhout
- Department of Crop Genetics, The John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom.
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28
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Bendix C, Lewis JD. The enemy within: phloem-limited pathogens. MOLECULAR PLANT PATHOLOGY 2018; 19:238-254. [PMID: 27997761 PMCID: PMC6638166 DOI: 10.1111/mpp.12526] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 12/06/2016] [Accepted: 12/08/2016] [Indexed: 05/06/2023]
Abstract
The growing impact of phloem-limited pathogens on high-value crops has led to a renewed interest in understanding how they cause disease. Although these pathogens cause substantial crop losses, many are poorly characterized. In this review, we present examples of phloem-limited pathogens that include intracellular bacteria with and without cell walls, and viruses. Phloem-limited pathogens have small genomes and lack many genes required for core metabolic processes, which is, in part, an adaptation to the unique phloem environment. For each pathogen class, we present multiple case studies to highlight aspects of disease caused by phloem-limited pathogens. The pathogens presented include Candidatus Liberibacter asiaticus (citrus greening), Arsenophonus bacteria, Serratia marcescens (cucurbit yellow vine disease), Candidatus Phytoplasma asteris (Aster Yellows Witches' Broom), Spiroplasma kunkelii, Potato leafroll virus and Citrus tristeza virus. We focus on commonalities in the virulence strategies of these pathogens, and aim to stimulate new discussions in the hope that widely applicable disease management strategies can be found.
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Affiliation(s)
- Claire Bendix
- United States Department of AgriculturePlant Gene Expression CenterAlbanyCA94710USA
| | - Jennifer D. Lewis
- United States Department of AgriculturePlant Gene Expression CenterAlbanyCA94710USA
- Department of Plant and Microbial BiologyUniversity of California, BerkeleyBerkeleyCA94720USA
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29
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Chrostek E, Pelz-Stelinski K, Hurst GDD, Hughes GL. Horizontal Transmission of Intracellular Insect Symbionts via Plants. Front Microbiol 2017; 8:2237. [PMID: 29234308 PMCID: PMC5712413 DOI: 10.3389/fmicb.2017.02237] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 10/31/2017] [Indexed: 11/16/2022] Open
Abstract
Experimental evidence is accumulating that endosymbionts of phytophagous insects may transmit horizontally via plants. Intracellular symbionts known for manipulating insect reproduction and altering fitness (Rickettsia, Cardinium, Wolbachia, and bacterial parasite of the leafhopper Euscelidius variegatus) have been found to travel from infected insects into plants. Other insects, either of the same or different species can acquire the symbiont from the plant through feeding, and in some cases transfer it to their progeny. These reports prompt many questions regarding how intracellular insect symbionts are delivered to plants and how they affect them. Are symbionts passively transported along the insect-plant-insect path, or do they actively participate in the process? How widespread are these interactions? How does symbiont presence influence the plant? And what conditions are required for the new infection to establish in an insect? From an ecological, evolutionary, and applied perspective, this mode of horizontal transmission could have profound implications if occurring frequently enough or if new stable symbiont infections are established. Transmission of symbionts through plants likely represents an underappreciated means of infection, both in terms of symbiont epidemiology and the movement of symbionts to new host species.
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Affiliation(s)
- Ewa Chrostek
- Department of Vector Biology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Kirsten Pelz-Stelinski
- Department of Entomology and Nematology, University of Florida, Gainesville, FL, United States
| | - Gregory D. D. Hurst
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Grant L. Hughes
- Department of Pathology, Institute for Human Infections and Immunity, Center for Biodefense and Emerging Infectious Disease, Center for Tropical Diseases, University of Texas Medical Branch, Galveston, TX, United States
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30
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Keesey IW, Koerte S, Khallaf MA, Retzke T, Guillou A, Grosse-Wilde E, Buchon N, Knaden M, Hansson BS. Pathogenic bacteria enhance dispersal through alteration of Drosophila social communication. Nat Commun 2017; 8:265. [PMID: 28814724 PMCID: PMC5559524 DOI: 10.1038/s41467-017-00334-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 06/21/2017] [Indexed: 11/23/2022] Open
Abstract
Pathogens and parasites can manipulate their hosts to optimize their own fitness. For instance, bacterial pathogens have been shown to affect their host plants' volatile and non-volatile metabolites, which results in increased attraction of insect vectors to the plant, and, hence, to increased pathogen dispersal. Behavioral manipulation by parasites has also been shown for mice, snails and zebrafish as well as for insects. Here we show that infection by pathogenic bacteria alters the social communication system of Drosophila melanogaster. More specifically, infected flies and their frass emit dramatically increased amounts of fly odors, including the aggregation pheromones methyl laurate, methyl myristate, and methyl palmitate, attracting healthy flies, which in turn become infected and further enhance pathogen dispersal. Thus, olfactory cues for attraction and aggregation are vulnerable to pathogenic manipulation, and we show that the alteration of social pheromones can be beneficial to the microbe while detrimental to the insect host.Behavioral manipulation of host by pathogens has been observed in vertebrates, invertebrates, and plants. Here the authors show that in Drosophila, infection with pathogenic bacteria leads to increased pheromone release, which attracts healthy flies. This process benefits the pathogen since it enhances bacterial dispersal, but is detrimental to the host.
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Affiliation(s)
- Ian W Keesey
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knöll-Straße 8, D-07745, Jena, Germany
| | - Sarah Koerte
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knöll-Straße 8, D-07745, Jena, Germany
| | - Mohammed A Khallaf
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knöll-Straße 8, D-07745, Jena, Germany
| | - Tom Retzke
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knöll-Straße 8, D-07745, Jena, Germany
| | - Aurélien Guillou
- Department of Entomology, Cornell University, 5124 Comstock Hall, Ithaca, NY, 14853, USA
| | - Ewald Grosse-Wilde
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knöll-Straße 8, D-07745, Jena, Germany
| | - Nicolas Buchon
- Department of Entomology, Cornell University, 5124 Comstock Hall, Ithaca, NY, 14853, USA
| | - Markus Knaden
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knöll-Straße 8, D-07745, Jena, Germany.
| | - Bill S Hansson
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knöll-Straße 8, D-07745, Jena, Germany.
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Kitazawa Y, Iwabuchi N, Himeno M, Sasano M, Koinuma H, Nijo T, Tomomitsu T, Yoshida T, Okano Y, Yoshikawa N, Maejima K, Oshima K, Namba S. Phytoplasma-conserved phyllogen proteins induce phyllody across the Plantae by degrading floral MADS domain proteins. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:2799-2811. [PMID: 28505304 PMCID: PMC5853863 DOI: 10.1093/jxb/erx158] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 04/13/2017] [Indexed: 05/21/2023]
Abstract
ABCE-class MADS domain transcription factors (MTFs) are key regulators of floral organ development in angiosperms. Aberrant expression of these genes can result in abnormal floral traits such as phyllody. Phyllogen is a virulence factor conserved in phytoplasmas, plant pathogenic bacteria of the class Mollicutes. It triggers phyllody in Arabidopsis thaliana by inducing degradation of A- and E-class MTFs. However, it is still unknown whether phyllogen can induce phyllody in plants other than A. thaliana, although phytoplasma-associated phyllody symptoms are observed in a broad range of angiosperms. In this study, phyllogen was shown to cause phyllody phenotypes in several eudicot species belonging to three different families. Moreover, phyllogen can interact with MTFs of not only angiosperm species including eudicots and monocots but also gymnosperms and a fern, and induce their degradation. These results suggest that phyllogen induces phyllody in angiosperms and inhibits MTF function in diverse plant species.
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Affiliation(s)
- Yugo Kitazawa
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Nozomu Iwabuchi
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Misako Himeno
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Momoka Sasano
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Hiroaki Koinuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Takamichi Nijo
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Tatsuya Tomomitsu
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Tetsuya Yoshida
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Yukari Okano
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Nobuyuki Yoshikawa
- Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka-shi, Iwate, Japan
| | - Kensaku Maejima
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Kenro Oshima
- Faculty of Bioscience, Hosei University, 3-7-2 Kajino-cho, Koganei-shi, Tokyo, Japan
| | - Shigetou Namba
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
- Correspondence:
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Orlovskis Z, Canale MC, Haryono M, Lopes JRS, Kuo CH, Hogenhout SA. A few sequence polymorphisms among isolates of Maize bushy stunt phytoplasma associate with organ proliferation symptoms of infected maize plants. ANNALS OF BOTANY 2017; 119:869-884. [PMID: 28069632 PMCID: PMC5379588 DOI: 10.1093/aob/mcw213] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 08/16/2016] [Indexed: 05/18/2023]
Abstract
Background and Aims Maize bushy stunt phytoplasma (MBSP) is a bacterial pathogen of maize ( Zea mays L.) across Latin America. MBSP belongs to the 16SrI-B sub-group within the genus ' Candidatus Phytoplasma'. MBSP and its insect vector Dalbulus maidis (Hemiptera: Cicadellidae) are restricted to maize; both are thought to have coevolved with maize during its domestication from a teosinte-like ancestor. MBSP-infected maize plants show a diversity of symptoms. and it is likely that MBSP is under strong selection for increased virulence and insect transmission on maize hybrids that are widely grown in Brazil. In this study it was investigated whether the differences in genome sequences of MBSP isolates from two maize-growing regions in South-east Brazil explain variations in symptom severity of the MBSP isolates on various maize genotypes. Methods MBSP isolates were collected from maize production fields in Guaíra and Piracicaba in South-east Brazil for infection assays. One representative isolate was chosen for de novo whole-genome assembly and for the alignment of sequence reads from the genomes of other phytoplasma isolates to detect polymorphisms. Statistical methods were applied to investigate the correlation between variations in disease symptoms of infected maize plants and MBSP sequence polymorphisms. Key Results MBSP isolates contributed consistently to organ proliferation symptoms and maize genotype to leaf necrosis, reddening and yellowing of infected maize plants. The symptom differences are associated with polymorphisms in a phase-variable lipoprotein, which is a candidate effector, and an ATP-dependent lipoprotein ABC export protein, whereas no polymorphisms were observed in other candidate effector genes. Lipoproteins and ABC export proteins activate host defence responses, regulate pathogen attachment to host cells and activate effector secretion systems in other pathogens. Conclusions Polymorphisms in two putative virulence genes among MBSP isolates from maize-growing regions in South-east Brazil are associated with variations in organ proliferation symptoms of MBSP-infected maize plants.
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Affiliation(s)
- Zigmunds Orlovskis
- John Innes Centre, Department of Cell and Developmental Biology, Norwich Research Park, Norwich NR4 7UH, UK
| | - Maria Cristina Canale
- John Innes Centre, Department of Cell and Developmental Biology, Norwich Research Park, Norwich NR4 7UH, UK
- Luiz de Queiroz College of Agriculture, University of São Paulo, Department of Entomology and Acarology, Piracicaba 13·418-900, Brazil
| | - Mindia Haryono
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - João Roberto Spotti Lopes
- Luiz de Queiroz College of Agriculture, University of São Paulo, Department of Entomology and Acarology, Piracicaba 13·418-900, Brazil
| | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Saskia A. Hogenhout
- John Innes Centre, Department of Cell and Developmental Biology, Norwich Research Park, Norwich NR4 7UH, UK
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