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Jin BJ, Chun HJ, Choi CW, Lee SH, Cho HM, Park MS, Baek D, Park SY, Lee YH, Kim MC. Host-induced gene silencing is a promising biological tool to characterize the pathogenicity of Magnaporthe oryzae and control fungal disease in rice. PLANT, CELL & ENVIRONMENT 2024; 47:319-336. [PMID: 37700662 DOI: 10.1111/pce.14721] [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: 03/23/2023] [Revised: 08/25/2023] [Accepted: 09/04/2023] [Indexed: 09/14/2023]
Abstract
The rice blast fungus Magnaporthe oryzae is a devastating plant pathogen that threatens rice production worldwide. Host-induced gene silencing (HIGS) has been effectively applied to study pathogenic gene function during host-microbe interactions and control fungal diseases in various crops. In this study, the HIGS system of M. oryzae was established using transgenic fungus expressing green fluorescence protein (GFP), KJ201::eGFP and 35S::dsRNAi plants, which produce small interfering RNAs targeting fungal genes. Through this system, we verified the HIGS of rice blast fungus quantitatively and qualitatively in both Arabidopsis and rice. Then, we showed that the HIGS of M. oryzae's pathogenic genes, including RGS1, MgAPT2 and LHS1, significantly alter its virulence. Both 35S::dsRNAi_MgAPT2 and 35S::dsRNAi_LHS1 plants showed a considerably enhanced fungal resistance, characterized by the formation of H2 O2 -containing defensive granules and induction of rice pathogenesis-related (PR) genes. In addition, the enhanced susceptibility of 35S::dsRNAi_RGS1 plants to blast fungus suggested a novel mode of action of this gene during fungal infection. Overall, the results of this study demonstrate that HIGS is a very effective and efficient biological tool not only to accurately characterize the functions of fungal pathogenic genes during rice-M. oryzae interactions, but also to control fungal disease and ensure a successful rice production.
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Affiliation(s)
- Byung Jun Jin
- Institute of Agriculture & Life Science, Gyeongsang National University, Jinju, Korea
| | - Hyun Jin Chun
- Institute of Agriculture & Life Science, Gyeongsang National University, Jinju, Korea
| | - Cheol Woo Choi
- Division of Applied Life Science (BK21 Four), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Korea
| | - Su Hyeon Lee
- Division of Applied Life Science (BK21 Four), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Korea
| | - Hyun Min Cho
- Division of Applied Life Science (BK21 Four), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Korea
| | - Mi Suk Park
- Division of Applied Life Science (BK21 Four), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Korea
| | - Dongwon Baek
- Division of Applied Life Science (BK21 Four), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Korea
| | - Sook-Young Park
- Department of Plant Medicine, Sunchon National University, Suncheon, Korea
| | - Yong-Hwan Lee
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Korea
| | - Min Chul Kim
- Institute of Agriculture & Life Science, Gyeongsang National University, Jinju, Korea
- Division of Applied Life Science (BK21 Four), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Korea
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2
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Degnan RM, Shuey LS, Radford-Smith J, Gardiner DM, Carroll BJ, Mitter N, McTaggart AR, Sawyer A. Double-stranded RNA prevents and cures infection by rust fungi. Commun Biol 2023; 6:1234. [PMID: 38057635 PMCID: PMC10700371 DOI: 10.1038/s42003-023-05618-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 11/21/2023] [Indexed: 12/08/2023] Open
Abstract
Fungal pathogens that impact perennial plants or natural ecosystems require management strategies beyond fungicides and breeding for resistance. Rust fungi, some of the most economically and environmentally important plant pathogens, have shown amenability to double-stranded RNA (dsRNA) mediated control. To date, dsRNA treatments have been applied prior to infection or together with the inoculum. Here we show that a dsRNA spray can effectively prevent and cure infection by Austropuccinia psidii (cause of myrtle rust) at different stages of the disease cycle. Significant reductions in disease coverage were observed in plants treated with dsRNA targeting essential fungal genes 48 h pre-infection through to 14 days post-infection. For curative treatments, improvements in plant health and photosynthetic capacity were seen 2-6 weeks post-infection. Two-photon microscopy suggests inhibitory activity of dsRNA on intercellular hyphae or haustoria. Our results show that dsRNA acts both preventively and curatively against myrtle rust disease, with treated plants recovering from severe infection. These findings have immediate potential in the management of the more than 10-year epidemic of myrtle rust in Australia.
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Affiliation(s)
- Rebecca M Degnan
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland, Australia.
| | - Louise S Shuey
- Department of Agriculture and Fisheries, Queensland Government, Ecosciences Precinct, Dutton Park, Queensland, Australia
| | - Julian Radford-Smith
- School of the Environment, The University of Queensland, St Lucia, Queensland, Australia
| | - Donald M Gardiner
- Queensland Alliance for Agriculture and Food Innovation, Centre for Horticultural Science, The University of Queensland, St Lucia, Queensland, Australia
| | - Bernard J Carroll
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Neena Mitter
- Queensland Alliance for Agriculture and Food Innovation, Centre for Horticultural Science, The University of Queensland, St Lucia, Queensland, Australia
| | - Alistair R McTaggart
- Queensland Alliance for Agriculture and Food Innovation, Centre for Horticultural Science, The University of Queensland, St Lucia, Queensland, Australia
| | - Anne Sawyer
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland, Australia.
- Queensland Alliance for Agriculture and Food Innovation, Centre for Horticultural Science, The University of Queensland, St Lucia, Queensland, Australia.
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3
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Mann CWG, Sawyer A, Gardiner DM, Mitter N, Carroll BJ, Eamens AL. RNA-Based Control of Fungal Pathogens in Plants. Int J Mol Sci 2023; 24:12391. [PMID: 37569766 PMCID: PMC10418863 DOI: 10.3390/ijms241512391] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/01/2023] [Accepted: 08/01/2023] [Indexed: 08/13/2023] Open
Abstract
Our duty to conserve global natural ecosystems is increasingly in conflict with our need to feed an expanding population. The use of conventional pesticides not only damages the environment and vulnerable biodiversity but can also still fail to prevent crop losses of 20-40% due to pests and pathogens. There is a growing call for more ecologically sustainable pathogen control measures. RNA-based biopesticides offer an eco-friendly alternative to the use of conventional fungicides for crop protection. The genetic modification (GM) of crops remains controversial in many countries, though expression of transgenes inducing pathogen-specific RNA interference (RNAi) has been proven effective against many agronomically important fungal pathogens. The topical application of pathogen-specific RNAi-inducing sprays is a more responsive, GM-free approach to conventional RNAi transgene-based crop protection. The specific targeting of essential pathogen genes, the development of RNAi-nanoparticle carrier spray formulations, and the possible structural modifications to the RNA molecules themselves are crucial to the success of this novel technology. Here, we outline the current understanding of gene silencing pathways in plants and fungi and summarize the pioneering and recent work exploring RNA-based biopesticides for crop protection against fungal pathogens, with a focus on spray-induced gene silencing (SIGS). Further, we discuss factors that could affect the success of RNA-based control strategies, including RNA uptake, stability, amplification, and movement within and between the plant host and pathogen, as well as the cost and design of RNA pesticides.
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Affiliation(s)
- Christopher W. G. Mann
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia; (C.W.G.M.); (A.S.); (B.J.C.)
| | - Anne Sawyer
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia; (C.W.G.M.); (A.S.); (B.J.C.)
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, QLD 4072, Australia; (D.M.G.); (N.M.)
| | - Donald M. Gardiner
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, QLD 4072, Australia; (D.M.G.); (N.M.)
| | - Neena Mitter
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, QLD 4072, Australia; (D.M.G.); (N.M.)
| | - Bernard J. Carroll
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia; (C.W.G.M.); (A.S.); (B.J.C.)
| | - Andrew L. Eamens
- School of Health, University of the Sunshine Coast, Maroochydore, QLD 4558, Australia
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4
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Beernink BM, Whitham SA. Foxtail mosaic virus: A tool for gene function analysis in maize and other monocots. MOLECULAR PLANT PATHOLOGY 2023; 24:811-822. [PMID: 37036421 PMCID: PMC10257046 DOI: 10.1111/mpp.13330] [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: 10/31/2022] [Revised: 02/20/2023] [Accepted: 03/08/2023] [Indexed: 06/11/2023]
Abstract
Many plant viruses have been engineered into vectors for use in functional genomics studies, expression of heterologous proteins, and, most recently, gene editing applications. The use of viral vectors overcomes bottlenecks associated with mutagenesis and transgenesis approaches often implemented for analysis of gene function. There are several engineered viruses that are demonstrated or suggested to be useful in maize through proof-of-concept studies. However, foxtail mosaic virus (FoMV), which has a relatively broad host range, is emerging as a particularly useful virus for gene function studies in maize and other monocot crop or weed species. A few clones of FoMV have been independently engineered, and they have different features and capabilities for virus-induced gene silencing (VIGS) and virus-mediated overexpression (VOX) of proteins. In addition, FoMV can be used to deliver functional guide RNAs in maize and other plants expressing the Cas9 protein, demonstrating its potential utility in virus-induced gene editing applications. There is a growing number of studies in which FoMV vectors are being applied for VIGS or VOX in maize and the vast majority of these are related to maize-microbe interactions. In this review, we highlight the biology and engineering of FoMV as well as its applications in maize-microbe interactions and more broadly in the context of the monocot functional genomics toolbox.
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Affiliation(s)
- Bliss M. Beernink
- Department of Plant Pathology, Entomology, and MicrobiologyIowa State UniversityAmesIowaUSA
- Department of BiologyUniversity of ManitobaWinnipegManitobaCanada
| | - Steven A. Whitham
- Department of Plant Pathology, Entomology, and MicrobiologyIowa State UniversityAmesIowaUSA
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5
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Padilla-Roji I, Ruiz-Jiménez L, Bakhat N, Vielba-Fernández A, Pérez-García A, Fernández-Ortuño D. RNAi Technology: A New Path for the Research and Management of Obligate Biotrophic Phytopathogenic Fungi. Int J Mol Sci 2023; 24:ijms24109082. [PMID: 37240427 DOI: 10.3390/ijms24109082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/05/2023] [Accepted: 05/10/2023] [Indexed: 05/28/2023] Open
Abstract
Powdery mildew and rust fungi are major agricultural problems affecting many economically important crops and causing significant yield losses. These fungi are obligate biotrophic parasites that are completely dependent on their hosts for growth and reproduction. Biotrophy in these fungi is determined by the presence of haustoria, specialized fungal cells that are responsible for nutrient uptake and molecular dialogue with the host, a fact that undoubtedly complicates their study under laboratory conditions, especially in terms of genetic manipulation. RNA interference (RNAi) is the biological process of suppressing the expression of a target gene through double-stranded RNA that induces mRNA degradation. RNAi technology has revolutionized the study of these obligate biotrophic fungi by enabling the analysis of gene function in these fungal. More importantly, RNAi technology has opened new perspectives for the management of powdery mildew and rust diseases, first through the stable expression of RNAi constructs in transgenic plants and, more recently, through the non-transgenic approach called spray-induced gene silencing (SIGS). In this review, the impact of RNAi technology on the research and management of powdery mildew and rust fungi will be addressed.
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Affiliation(s)
- Isabel Padilla-Roji
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Málaga, Spain
| | - Laura Ruiz-Jiménez
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Málaga, Spain
| | - Nisrine Bakhat
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Málaga, Spain
| | - Alejandra Vielba-Fernández
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Málaga, Spain
| | - Alejandro Pérez-García
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Málaga, Spain
| | - Dolores Fernández-Ortuño
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Málaga, Spain
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6
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Degnan RM, McTaggart AR, Shuey LS, Pame LJS, Smith GR, Gardiner DM, Nock V, Soffe R, Sale S, Garrill A, Carroll BJ, Mitter N, Sawyer A. Exogenous double-stranded RNA inhibits the infection physiology of rust fungi to reduce symptoms in planta. MOLECULAR PLANT PATHOLOGY 2023; 24:191-207. [PMID: 36528383 PMCID: PMC9923395 DOI: 10.1111/mpp.13286] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 06/01/2023]
Abstract
Rust fungi (Pucciniales) are a diverse group of plant pathogens in natural and agricultural systems. They pose ongoing threats to the diversity of native flora and cause annual crop yield losses. Agricultural rusts are predominantly managed with fungicides and breeding for resistance, but new control strategies are needed on non-agricultural plants and in fragile ecosystems. RNA interference (RNAi) induced by exogenous double-stranded RNA (dsRNA) has promise as a sustainable approach for managing plant-pathogenic fungi, including rust fungi. We investigated the mechanisms and impact of exogenous dsRNA on rust fungi through in vitro and whole-plant assays using two species as models, Austropuccinia psidii (the cause of myrtle rust) and Coleosporium plumeriae (the cause of frangipani rust). In vitro, dsRNA either associates externally or is internalized by urediniospores during the early stages of germination. The impact of dsRNA on rust infection architecture was examined on artificial leaf surfaces. dsRNA targeting predicted essential genes significantly reduced germination and inhibited development of infection structures, namely appressoria and penetration pegs. Exogenous dsRNA sprayed onto 1-year-old trees significantly reduced myrtle rust symptoms. Furthermore, we used comparative genomics to assess the wide-scale amenability of dsRNA to control rust fungi. We sequenced genomes of six species of rust fungi, including three new families (Araucariomyceaceae, Phragmidiaceae, and Skierkaceae) and identified key genes of the RNAi pathway across 15 species in eight families of Pucciniales. Together, these findings indicate that dsRNA targeting essential genes has potential for broad-use management of rust fungi across natural and agricultural systems.
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Affiliation(s)
- Rebecca M. Degnan
- School of Chemistry and Molecular BiosciencesThe University of QueenslandSt LuciaQueenslandAustralia
| | - Alistair R. McTaggart
- Queensland Alliance for Agriculture and Food Innovation, Centre for Horticultural ScienceThe University of QueenslandSt LuciaQueenslandAustralia
| | - Louise S. Shuey
- Queensland Department of Agriculture and FisheriesEcosciences PrecinctDutton ParkQueenslandAustralia
| | - Leny Jane S. Pame
- School of Chemistry and Molecular BiosciencesThe University of QueenslandSt LuciaQueenslandAustralia
| | - Grant R. Smith
- The New Zealand Institute for Plant and Food Research LimitedLincolnNew Zealand
| | - Donald M. Gardiner
- Queensland Alliance for Agriculture and Food Innovation, Centre for Horticultural ScienceThe University of QueenslandSt LuciaQueenslandAustralia
| | - Volker Nock
- Department of Electrical and Computer EngineeringUniversity of CanterburyChristchurchNew Zealand
| | - Rebecca Soffe
- Department of Electrical and Computer EngineeringUniversity of CanterburyChristchurchNew Zealand
- Present address:
School of EngineeringRMIT UniversityMelbourneVictoriaAustralia
| | - Sarah Sale
- Department of Electrical and Computer EngineeringUniversity of CanterburyChristchurchNew Zealand
- School of Biological SciencesUniversity of CanterburyChristchurchNew Zealand
| | - Ashley Garrill
- School of Biological SciencesUniversity of CanterburyChristchurchNew Zealand
| | - Bernard J. Carroll
- School of Chemistry and Molecular BiosciencesThe University of QueenslandSt LuciaQueenslandAustralia
| | - Neena Mitter
- Queensland Alliance for Agriculture and Food Innovation, Centre for Horticultural ScienceThe University of QueenslandSt LuciaQueenslandAustralia
| | - Anne Sawyer
- School of Chemistry and Molecular BiosciencesThe University of QueenslandSt LuciaQueenslandAustralia
- Queensland Alliance for Agriculture and Food Innovation, Centre for Horticultural ScienceThe University of QueenslandSt LuciaQueenslandAustralia
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7
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Mapuranga J, Chang J, Zhang L, Zhang N, Yang W. Fungal Secondary Metabolites and Small RNAs Enhance Pathogenicity during Plant-Fungal Pathogen Interactions. J Fungi (Basel) 2022; 9:jof9010004. [PMID: 36675825 PMCID: PMC9862911 DOI: 10.3390/jof9010004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/16/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Fungal plant pathogens use proteinaceous effectors as well as newly identified secondary metabolites (SMs) and small non-coding RNA (sRNA) effectors to manipulate the host plant's defense system via diverse plant cell compartments, distinct organelles, and many host genes. However, most molecular studies of plant-fungal interactions have focused on secreted effector proteins without exploring the possibly equivalent functions performed by fungal (SMs) and sRNAs, which are collectively known as "non-proteinaceous effectors". Fungal SMs have been shown to be generated throughout the plant colonization process, particularly in the early biotrophic stages of infection. The fungal repertoire of non-proteinaceous effectors has been broadened by the discovery of fungal sRNAs that specifically target plant genes involved in resistance and defense responses. Many RNAs, particularly sRNAs involved in gene silencing, have been shown to transmit bidirectionally between fungal pathogens and their hosts. However, there are no clear functional approaches to study the role of these SM and sRNA effectors. Undoubtedly, fungal SM and sRNA effectors are now a treasured land to seek. Therefore, understanding the role of fungal SM and sRNA effectors may provide insights into the infection process and identification of the interacting host genes that are targeted by these effectors. This review discusses the role of fungal SMs and sRNAs during plant-fungal interactions. It will also focus on the translocation of sRNA effectors across kingdoms, the application of cross-kingdom RNA interference in managing plant diseases and the tools that can be used to predict and study these non-proteinaceous effectors.
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8
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Mueth NA, Hulbert SH. Small RNAs target native and cross-kingdom transcripts on both sides of the wheat stripe rust interaction. Genomics 2022; 114:110526. [PMID: 36427746 DOI: 10.1016/j.ygeno.2022.110526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 11/08/2022] [Accepted: 11/21/2022] [Indexed: 11/23/2022]
Abstract
The wheat stripe rust fungus (Puccinia striiformis f.sp. tritici) threatens global wheat production. Small RNAs (sRNAs) modulate plant defense induction, and RNA exchange between host and microbe causes cross-kingdom gene silencing, but few examples are known in rust fungi. This study combined sRNA, parallel analysis of RNA ends, and gene expression data to discover sRNA-target pairs on each side of the interaction. Specific wheat 24 nt sRNAs were suppressed, while particular 35 nt fragments were strongly induced upon infection. Wheat sRNAs cleaved fungal transcripts coding for a ribosomal protein and a glycosyl hydrolase effector. Fungal microRNA-like and phased 21 nt sRNAs originated from long inverted repeats near protein coding genes. Fungal sRNAs targeted native transcripts: transposons and kinases; and cross-kingdom transcripts: a wheat nucleotide-binding domain leucine-rich repeat receptor (NLR) and multiple defense-related transcription factor families. This work sheds light on host-microbe coevolution and delivers prospects for developing pathogen control biotechnology.
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Affiliation(s)
- Nicholas A Mueth
- Molecular Plant Sciences Program, Washington State University, Pullman, WA, USA; Department of Plant Pathology, Washington State University, Pullman, WA, USA.
| | - Scot H Hulbert
- Molecular Plant Sciences Program, Washington State University, Pullman, WA, USA; Department of Plant Pathology, Washington State University, Pullman, WA, USA
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9
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Ding Y, Chen Y, Yan B, Liao H, Dong M, Meng X, Wan H, Qian W. Host-Induced Gene Silencing of a Multifunction Gene Sscnd1 Enhances Plant Resistance Against Sclerotinia sclerotiorum. Front Microbiol 2021; 12:693334. [PMID: 34690946 PMCID: PMC8531507 DOI: 10.3389/fmicb.2021.693334] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 09/08/2021] [Indexed: 11/22/2022] Open
Abstract
Sclerotinia sclerotiorum is a devastating necrotrophic fungal pathogen and has a substantial economic impact on crop production worldwide. Magnaporthe appressoria-specific (MAS) proteins have been suggested to be involved in the appressorium formation in Magnaporthe oryzae. Sscnd1, an MAS homolog gene, is highly induced at the early infection stage of S. sclerotiorum. Knock-down the expression of Sscnd1 gene severely reduced the virulence of S. sclerotiorum on intact rapeseed leaves, and their virulence was partially restored on wounded leaves. The Sscnd1 gene-silenced strains exhibited a defect in compound appressorium formation and cell integrity. The instantaneous silencing of Sscnd1 by tobacco rattle virus (TRV)-mediated host-induced gene silencing (HIGS) resulted in a significant reduction in disease development in tobacco. Three transgenic HIGS Arabidopsis lines displayed high levels of resistance to S. sclerotiorum and decreased Sscnd1 expression. Production of specific Sscnd1 siRNA in transgenic HIGS Arabidopsis lines was confirmed by stem-loop qRT-PCR. This study revealed that the compound appressorium-related gene Sscnd1 is required for cell integrity and full virulence in S. sclerotiorum and that Sclerotinia stem rot can be controlled by expressing the silencing constructs of Sscnd1 in host plants.
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Affiliation(s)
- Yijuan Ding
- College of Agronomy and Biotechnology, Southwest University, Chongqing, China.,Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing, China
| | - Yangui Chen
- College of Agronomy and Biotechnology, Southwest University, Chongqing, China.,Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing, China
| | - Baoqin Yan
- College of Agronomy and Biotechnology, Southwest University, Chongqing, China.,Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing, China
| | - Hongmei Liao
- College of Agronomy and Biotechnology, Southwest University, Chongqing, China.,Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing, China
| | - Mengquan Dong
- College of Agronomy and Biotechnology, Southwest University, Chongqing, China.,Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing, China
| | - Xinran Meng
- College of Agronomy and Biotechnology, Southwest University, Chongqing, China.,Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing, China
| | - Huafang Wan
- College of Agronomy and Biotechnology, Southwest University, Chongqing, China.,Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing, China
| | - Wei Qian
- College of Agronomy and Biotechnology, Southwest University, Chongqing, China.,Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing, China
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10
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McCaghey M, Shao D, Kurcezewski J, Lindstrom A, Ranjan A, Whitham SA, Conley SP, Williams B, Smith DL, Kabbage M. Host-Induced Gene Silencing of a Sclerotinia sclerotiorum oxaloacetate acetylhydrolase Using Bean Pod Mottle Virus as a Vehicle Reduces Disease on Soybean. FRONTIERS IN PLANT SCIENCE 2021; 12:677631. [PMID: 34354721 PMCID: PMC8329588 DOI: 10.3389/fpls.2021.677631] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 05/26/2021] [Indexed: 05/05/2023]
Abstract
A lack of complete resistance in the current germplasm complicates the management of Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum in soybean. In this study, we used bean pod mottle virus (BPMV) as a vehicle to down-regulate expression of a key enzyme in the production of an important virulence factor in S. sclerotiorum, oxalic acid (OA). Specifically, we targeted a gene encoding oxaloacetate acetylhydrolase (Ssoah1), because Ssoah1 deletion mutants are OA deficient and non-pathogenic on soybean. We first established that S. sclerotiorum can uptake environmental RNAs by monitoring the translocation of Cy3-labeled double-stranded and small interfering RNA (ds/siRNAs) into fungal hyphae using fluorescent confocal microscopy. This translocation led to a significant decrease in Ssoah1 transcript levels in vitro. Inoculation of soybean plants with BPMV vectors targeting Ssoah1 (pBPMV-OA) also led to decreased expression of Ssoah1. Importantly, pBPMV-OA inoculated plants showed enhanced resistance to S. sclerotiorum compared to empty-vector control plants. Our combined results provide evidence supporting the use of HIGS and exogenous applications of ds/siRNAs targeting virulence factors such as OA as viable strategies for the control of SSR in soybean and as discovery tools that can be used to identify previously unknown virulence factors.
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Affiliation(s)
- Megan McCaghey
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States
| | - Dandan Shao
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States
| | - Jake Kurcezewski
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States
| | - Ally Lindstrom
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States
| | - Ashish Ranjan
- Department of Plant Pathology, University of Minnesota, St. Paul, MN, United States
| | - Steven A. Whitham
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, United States
| | - Shawn P. Conley
- Department of Agronomy, University of Wisconsin-Madison, Madison, WI, United States
| | - Brett Williams
- Centre for Tropical Crops and Biocommodities, Queensland University of Technology, Brisbane, QLD, Australia
| | - Damon L. Smith
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States
- Damon L. Smith
| | - Mehdi Kabbage
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States
- *Correspondence: Mehdi Kabbage
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Jaswal R, Rajarammohan S, Dubey H, Sharma TR. Smut fungi as a stratagem to characterize rust effectors: opportunities and challenges. World J Microbiol Biotechnol 2020; 36:150. [PMID: 32924088 DOI: 10.1007/s11274-020-02927-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 09/05/2020] [Indexed: 11/30/2022]
Abstract
The rust pathogens are one of the most complex fungi in the Basidiomycetes. The development of genomic resources for rust and other plant pathogens has opened the opportunities for functional genomics of fungal genes. Despite significant progress in the field of fungal genomics, functional characterization of the genome components has lacked, especially for the rust pathogens. Their obligate nature and lack of standard stable transformation protocol are the primary reasons for rusts to be one of the least explored genera despite its significance. In the recently sequenced rust genomes, a vast catalogue of predicted effectors and pathogenicity genes have been reported. However, most of these candidate genes remained unexplored due to the lack of suitable characterization methods. The heterologous expression of putative effectors in Nicotiana benthamiana and Arabidopsis thaliana has proved to be a rapid screening method for identifying the role of these effectors in virulence. However, no fungal system has been used for the functional validation of these candidate genes. The smuts, from the evolutionary point of view, are closely related to the rust pathogens. Moreover, they have been widely studied and hence could be a suitable model system for expressing rust fungal genes heterologously. The genetic manipulation methods for smuts are also well standardized. Complementation assays can be used for functional validation of the homologous genes present in rust and smut fungal pathogens, while the species-specific proteins can be expressed in the mutant strains of smut pathogens having reduced or no virulence for virulence analysis. We propose that smuts, especially Ustilago maydis, may prove to be a good model system to characterize rust effector proteins in the absence of methods to manipulate the rust genomes directly.
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Affiliation(s)
- Rajdeep Jaswal
- National Agri-Food Biotechnology Institute (NABI), Sector-81 (Knowledge City), PO Manauli, S.A.S. Nagar, Mohali, Punjab, 140306, India
| | - Sivasubramanian Rajarammohan
- National Agri-Food Biotechnology Institute (NABI), Sector-81 (Knowledge City), PO Manauli, S.A.S. Nagar, Mohali, Punjab, 140306, India
| | - Himanshu Dubey
- ICAR-National Institute for Plant Biotechnology, Pusa Campus, New Delhi, 110012, India
| | - T R Sharma
- National Agri-Food Biotechnology Institute (NABI), Sector-81 (Knowledge City), PO Manauli, S.A.S. Nagar, Mohali, Punjab, 140306, India.
- Crop Science Division, Indian Council of Agricultural Research, New Delhi, 110001, India.
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12
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Jaswal R, Kiran K, Rajarammohan S, Dubey H, Singh PK, Sharma Y, Deshmukh R, Sonah H, Gupta N, Sharma TR. Effector Biology of Biotrophic Plant Fungal Pathogens: Current Advances and Future Prospects. Microbiol Res 2020; 241:126567. [PMID: 33080488 DOI: 10.1016/j.micres.2020.126567] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 07/21/2020] [Accepted: 07/25/2020] [Indexed: 12/13/2022]
Abstract
The interaction of fungal pathogens with their host requires a novel invading mechanism and the presence of various virulence-associated components responsible for promoting the infection. The small secretory proteins, explicitly known as effector proteins, are one of the prime mechanisms of host manipulation utilized by the pathogen to disarm the host. Several effector proteins are known to translocate from fungus to the plant cell for host manipulation. Many fungal effectors have been identified using genomic, transcriptomic, and bioinformatics approaches. Most of the effector proteins are devoid of any conserved signatures, and their prediction based on sequence homology is very challenging, therefore by combining the sequence consensus based upon machine learning features, multiple tools have also been developed for predicting apoplastic and cytoplasmic effectors. Various post-genomics approaches like transcriptomics of virulent isolates have also been utilized for identifying active consortia of effectors. Significant progress has been made in understanding biotrophic effectors; however, most of it is underway due to their complex interaction with host and complicated recognition and signaling networks. This review discusses advances, and challenges in effector identification and highlighted various features of the potential effector proteins and approaches for understanding their genetics and strategies for regulation.
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Affiliation(s)
- Rajdeep Jaswal
- National Agri-Food Biotechnology Institute (NABI), Mohali, Punjab, 140306, India; Department of Microbiology, Panjab University, Chandigarh, Punjab, 160014, India
| | - Kanti Kiran
- ICAR-National Institute for Plant Biotechnology, Pusa Campus New Delhi, 110012, India
| | | | - Himanshu Dubey
- ICAR-National Institute for Plant Biotechnology, Pusa Campus New Delhi, 110012, India
| | - Pankaj Kumar Singh
- National Agri-Food Biotechnology Institute (NABI), Mohali, Punjab, 140306, India
| | - Yogesh Sharma
- National Agri-Food Biotechnology Institute (NABI), Mohali, Punjab, 140306, India
| | - Rupesh Deshmukh
- National Agri-Food Biotechnology Institute (NABI), Mohali, Punjab, 140306, India
| | - Humira Sonah
- National Agri-Food Biotechnology Institute (NABI), Mohali, Punjab, 140306, India
| | - Naveen Gupta
- Department of Microbiology, Panjab University, Chandigarh, Punjab, 160014, India.
| | - T R Sharma
- National Agri-Food Biotechnology Institute (NABI), Mohali, Punjab, 140306, India.
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13
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Wang M, Dean RA. Movement of small RNAs in and between plants and fungi. MOLECULAR PLANT PATHOLOGY 2020; 21:589-601. [PMID: 32027079 PMCID: PMC7060135 DOI: 10.1111/mpp.12911] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 12/02/2019] [Accepted: 12/06/2019] [Indexed: 05/12/2023]
Abstract
RNA interference is a biological process whereby small RNAs inhibit gene expression through neutralizing targeted mRNA molecules. This process is conserved in eukaryotes. Here, recent work regarding the mechanisms of how small RNAs move within and between organisms is examined. Small RNAs can move locally and systemically in plants through plasmodesmata and phloem, respectively. In fungi, transportation of small RNAs may also be achieved by septal pores and vesicles. Recent evidence also supports bidirectional cross-kingdom communication of small RNAs between host plants and adapted fungal pathogens to affect the outcome of infection. We discuss several mechanisms for small RNA trafficking and describe evidence for transport through naked form, combined with RNA-binding proteins or enclosed by vesicles.
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Affiliation(s)
- Mengying Wang
- Fungal Genomics LaboratoryCenter for Integrated Fungal ResearchDepartment of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNCUSA
| | - Ralph A. Dean
- Fungal Genomics LaboratoryCenter for Integrated Fungal ResearchDepartment of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNCUSA
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14
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Abstract
Among the thousands of rust species described, many are known for their devastating effects on their hosts, which include major agriculture crops and trees. Hence, for over a century, these basidiomycete pathogenic fungi have been researched and experimented with. However, due to their biotrophic nature, they are challenging organisms to work with and, needing their hosts for propagation, represent pathosystems that are not easily experimentally accessible. Indeed, efforts to perform genetics have been few and far apart for the rust fungi, though one study performed in the 1940s was famously instrumental in formulating the gene-for-gene hypothesis describing pathogen-host interactions. By taking full advantage of the molecular genetic tools developed in the 1980s, research on many plant pathogenic microbes thrived, yet similar work on the rusts remained very challenging though not without some successes. However, the genomics era brought real breakthrough research for the biotrophic fungi and with innovative experimentation and the use of heterologous systems, molecular genetic analyses over the last 2 decades have significantly advanced our insight into the function of many rust fungus genes and their role in the interaction with their hosts. This has allowed optimizing efforts for resistance breeding and the design and testing of various novel strategies to reduce the devastating diseases they cause.
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Affiliation(s)
- Guus Bakkeren
- Agriculture and Agri-Food Canada, Summerland Research & Development Centre, 4200 Hwy 97, Summerland, BC, Canada V0H 1Z0
| | - Les J Szabo
- U.S. Department of Agriculture-Agriculture Research Service, Cereal Disease Laboratory and University of Minnesota, 1551 Lindig Street, St. Paul, MN 55108, U.S.A
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15
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Prasad P, Savadi S, Bhardwaj SC, Gangwar OP, Kumar S. Rust pathogen effectors: perspectives in resistance breeding. PLANTA 2019; 250:1-22. [PMID: 30980247 DOI: 10.1007/s00425-019-03167-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/09/2019] [Indexed: 06/09/2023]
Abstract
Identification and functional characterization of plant pathogen effectors promise to ameliorate future research and develop effective and sustainable strategies for controlling or containing crop diseases. Wheat is the second most important food crop of the world after rice. Rust pathogens, one of the major biotic stresses in wheat production, are capable of threatening the world food security. Understanding the molecular basis of plant-pathogen interactions is essential for devising novel strategies for resistance breeding and disease management. Now, it has been established that effectors, the proteins secreted by pathogens, play a key role in plant-pathogen interactions. Therefore, effector biology has emerged as one of the most important research fields in plant biology. Recent advances in genomics and bioinformatics have allowed identification of a large repertoire of candidate effectors, while the evolving high-throughput tools have continued to assist in their functional characterization. The repertoires of effectors have become an important resource for better understanding of effector biology of pathosystems and resistance breeding of crop plants. In recent years, a significant progress has been made in the field of rust effector biology. This review describes the recent advances in effector biology of obligate fungal pathogens, identification and functional analysis of wheat rust pathogens effectors and the potential applications of effectors in molecular plant biology and rust resistance breeding in wheat.
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Affiliation(s)
- Pramod Prasad
- ICAR-Indian Institute of Wheat and Barley Research, Regional Station, Shimla, Himachal Pradesh, 171002, India
| | - Siddanna Savadi
- ICAR-Directorate of Cashew Research, Puttur, Karnataka, 574202, India
| | - S C Bhardwaj
- ICAR-Indian Institute of Wheat and Barley Research, Regional Station, Shimla, Himachal Pradesh, 171002, India.
| | - O P Gangwar
- ICAR-Indian Institute of Wheat and Barley Research, Regional Station, Shimla, Himachal Pradesh, 171002, India
| | - Subodh Kumar
- ICAR-Indian Institute of Wheat and Barley Research, Regional Station, Shimla, Himachal Pradesh, 171002, India
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16
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Yin C, Ramachandran SR, Zhai Y, Bu C, Pappu HR, Hulbert SH. A novel fungal effector from Puccinia graminis suppressing RNA silencing and plant defense responses. THE NEW PHYTOLOGIST 2019; 222:1561-1572. [PMID: 30623449 DOI: 10.1111/nph.15676] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 01/03/2019] [Indexed: 05/11/2023]
Abstract
Fungal plant pathogens, like rust-causing biotrophic fungi, secrete hundreds of effectors into plant cells to subvert host immunity and promote pathogenicity on their host plants by manipulating specific physiological processes or signal pathways, but the actual function has been demonstrated for very few of these proteins. Here, we show that the PgtSR1 effector proteins, encoded by two allelic genes (PgtSR1-a and PgtSR1-b), from the wheat stem rust pathogen Puccinia graminis f. sp. tritici (Pgt), suppress RNA silencing in plants and impede plant defenses by altering the abundance of small RNAs that serve as defense regulators. Expression of the PgtSR1s in plants revealed that the PgtSR1s promote susceptibility to multiple pathogens and partially suppress cell death triggered by multiple R proteins. Overall, our study provides the first evidence that the filamentous fungus P. graminis has evolved to produce fungal suppressors of RNA silencing and indicates that PgtSR1s suppress both basal defenses and effector triggered immunity.
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Affiliation(s)
- Chuntao Yin
- Department of Plant Pathology, Washington State University, Pullman, WA, 99164-6430, USA
| | - Sowmya R Ramachandran
- Department of Plant Pathology, Washington State University, Pullman, WA, 99164-6430, USA
| | - Ying Zhai
- Department of Plant Pathology, Washington State University, Pullman, WA, 99164-6430, USA
| | - Chunya Bu
- College of Biological Science and Engineering, Beijing University of Agriculture, Beijing, 102206, China
| | - Hanu R Pappu
- Department of Plant Pathology, Washington State University, Pullman, WA, 99164-6430, USA
| | - Scot H Hulbert
- Department of Plant Pathology, Washington State University, Pullman, WA, 99164-6430, USA
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17
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Lorrain C, Gonçalves Dos Santos KC, Germain H, Hecker A, Duplessis S. Advances in understanding obligate biotrophy in rust fungi. THE NEW PHYTOLOGIST 2019; 222:1190-1206. [PMID: 30554421 DOI: 10.1111/nph.15641] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Accepted: 11/13/2018] [Indexed: 05/18/2023]
Abstract
Contents Summary 1190 I. Introduction 1190 II. Rust fungi: a diverse and serious threat to agriculture 1191 III. The different facets of rust life cycles and unresolved questions about their evolution 1191 IV. The biology of rust infection 1192 V. Rusts in the genomics era: the ever-expanding list of candidate effector genes 1195 VI. Functional characterization of rust effectors 1197 VII. Putting rusts to sleep: Pucciniales research outlooks 1201 Acknowledgements 1202 References 1202 SUMMARY: Rust fungi (Pucciniales) are the largest group of plant pathogens and represent one of the most devastating threats to agricultural crops worldwide. Despite the economic importance of these highly specialized pathogens, many aspects of their biology remain obscure, largely because rust fungi are obligate biotrophs. The rise of genomics and advances in high-throughput sequencing technology have presented new options for identifying candidate effector genes involved in pathogenicity mechanisms of rust fungi. Transcriptome analysis and integrated bioinformatics tools have led to the identification of key genetic determinants of host susceptibility to infection by rusts. Thousands of genes encoding secreted proteins highly expressed during host infection have been reported for different rust species, which represents significant potential towards understanding rust effector function. Recent high-throughput in planta expression screen approaches (effectoromics) have pushed the field ahead even further towards predicting high-priority effectors and identifying avirulence genes. These new insights into rust effector biology promise to inform future research and spur the development of effective and sustainable strategies for managing rust diseases.
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Affiliation(s)
- Cécile Lorrain
- INRA Centre Grand Est - Nancy, UMR 1136 INRA/Université de Lorraine Interactions Arbres/Microorganismes, Champenoux, 54280, France
| | | | - Hugo Germain
- Department of Chemistry, Biochemistry and Physics, Université du Quebec à Trois-Rivières, Trois-Rivières, QC, G9A 5H7, Canada
| | - Arnaud Hecker
- Université de Lorraine, UMR 1136 Université de Lorraine/INRA Interactions Arbres/Microorganismes, Vandoeuvre-lès-Nancy, France
| | - Sébastien Duplessis
- INRA Centre Grand Est - Nancy, UMR 1136 INRA/Université de Lorraine Interactions Arbres/Microorganismes, Champenoux, 54280, France
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18
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RNA Interference: A Natural Immune System of Plants to Counteract Biotic Stressors. Cells 2019; 8:cells8010038. [PMID: 30634662 PMCID: PMC6356646 DOI: 10.3390/cells8010038] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 01/01/2019] [Accepted: 01/07/2019] [Indexed: 02/06/2023] Open
Abstract
During plant-pathogen interactions, plants have to defend the living transposable elements from pathogens. In response to such elements, plants activate a variety of defense mechanisms to counteract the aggressiveness of biotic stressors. RNA interference (RNAi) is a key biological process in plants to inhibit gene expression both transcriptionally and post-transcriptionally, using three different groups of proteins to resist the virulence of pathogens. However, pathogens trigger an anti-silencing mechanism through the expression of suppressors to block host RNAi. The disruption of the silencing mechanism is a virulence strategy of pathogens to promote infection in the invaded hosts. In this review, we summarize the RNA silencing pathway, anti-silencing suppressors, and counter-defenses of plants to viral, fungal, and bacterial pathogens.
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19
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Wang Z, Gudibanda A, Ugwuowo U, Trail F, Townsend JP. Using evolutionary genomics, transcriptomics, and systems biology to reveal gene networks underlying fungal development. FUNGAL BIOL REV 2018. [DOI: 10.1016/j.fbr.2018.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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20
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Panwar V, Jordan M, McCallum B, Bakkeren G. Host-induced silencing of essential genes in Puccinia triticina through transgenic expression of RNAi sequences reduces severity of leaf rust infection in wheat. PLANT BIOTECHNOLOGY JOURNAL 2018; 16:1013-1023. [PMID: 28941315 PMCID: PMC5902777 DOI: 10.1111/pbi.12845] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 08/18/2017] [Accepted: 09/20/2017] [Indexed: 05/05/2023]
Abstract
Leaf rust, caused by the pathogenic fungus Puccinia triticina (Pt), is one of the most serious biotic threats to sustainable wheat production worldwide. This obligate biotrophic pathogen is prevalent worldwide and is known for rapid adaptive evolution to overcome resistant wheat varieties. Novel disease control approaches are therefore required to minimize the yield losses caused by Pt. Having shown previously the potential of host-delivered RNA interference (HD-RNAi) in functional screening of Pt genes involved in pathogenesis, we here evaluated the use of this technology in transgenic wheat plants as a method to achieve protection against wheat leaf rust (WLR) infection. Stable expression of hairpin RNAi constructs with sequence homology to Pt MAP-kinase (PtMAPK1) or a cyclophilin (PtCYC1) encoding gene in susceptible wheat plants showed efficient silencing of the corresponding genes in the interacting fungus resulting in disease resistance throughout the T2 generation. Inhibition of Pt proliferation in transgenic lines by in planta-induced RNAi was associated with significant reduction in target fungal transcript abundance and reduced fungal biomass accumulation in highly resistant plants. Disease protection was correlated with the presence of siRNA molecules specific to targeted fungal genes in the transgenic lines harbouring the complementary HD-RNAi construct. This work demonstrates that generating transgenic wheat plants expressing RNAi-inducing transgenes to silence essential genes in rust fungi can provide effective disease resistance, thus opening an alternative way for developing rust-resistant crops.
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Affiliation(s)
- Vinay Panwar
- Agriculture and Agri‐Food CanadaMorden Research and Development CentreMordenMBCanada
- Agriculture and Agri‐Food CanadaSummerland Research and Development CentreSummerlandBCCanada
| | - Mark Jordan
- Agriculture and Agri‐Food CanadaMorden Research and Development CentreMordenMBCanada
| | - Brent McCallum
- Agriculture and Agri‐Food CanadaMorden Research and Development CentreMordenMBCanada
| | - Guus Bakkeren
- Agriculture and Agri‐Food CanadaSummerland Research and Development CentreSummerlandBCCanada
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21
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Gressel J, Polturak G. Suppressing aflatoxin biosynthesis is not a breakthrough if not useful. PEST MANAGEMENT SCIENCE 2018; 74:17-21. [PMID: 28762637 DOI: 10.1002/ps.4694] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 07/24/2017] [Accepted: 07/27/2017] [Indexed: 06/07/2023]
Abstract
Liver-affecting, carcinogenic aflatoxins produced by Aspergillus spp. are a major problem, especially in the humid developing world where storage conditions are often optimal for the fungi. Peanuts and maize have been transformed with RNAi constructs targeting Aspergillus flavus polyketide-synthase, an early key enzyme in aflatoxin biosynthesis. Aflatoxin biosynthesis was suppressed in developing immature grain, less so in late maturing grain, and it is doubtful that the technology will be effective in near dry mature grain. The infected grain was still mouldy. As Aspergillus that infects grain preharvest can continue to grow and produce aflatoxin in poorly stored grain, and grain storage insects vector further infections, this technology seems to have little potential utility in the humid tropics. The biotechnological approaches of RNAi directly targeting Aspergillus, coupled with transgenic insecticidal proteins should be far more effective. These biotechnological approaches can be used in tandem with the RNAi against polyketide-synthase, as well as with irradiation, biocontrol and better grain drying and hermetic dry storage in a controlled atmosphere. © 2017 Society of Chemical Industry.
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Affiliation(s)
- Jonathan Gressel
- Plant & Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Guy Polturak
- Plant & Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
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22
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Song Y, Thomma BPHJ. Host-induced gene silencing compromises Verticillium wilt in tomato and Arabidopsis. MOLECULAR PLANT PATHOLOGY 2018; 19:77-89. [PMID: 27749994 PMCID: PMC6638114 DOI: 10.1111/mpp.12500] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 10/11/2016] [Accepted: 10/12/2016] [Indexed: 05/03/2023]
Abstract
Verticillium wilt, caused by soil-borne fungi of the genus Verticillium, is an economically important disease that affects a wide range of host plants. Unfortunately, host resistance against Verticillium wilts is not available for many plant species, and the disease is notoriously difficult to combat. Host-induced gene silencing (HIGS) is an RNA interference (RNAi)-based process in which small RNAs are produced by the host plant to target parasite transcripts. HIGS has emerged as a promising strategy for the improvement of plant resistance against pathogens by silencing genes that are essential for these pathogens. Here, we assessed whether HIGS can be utilized to suppress Verticillium wilt disease by silencing three previously identified virulence genes of V. dahliae (encoding Ave1, Sge1 and NLP1) through the host plants tomato and Arabidopsis. In transient assays, tomato plants were agroinfiltrated with Tobacco rattle virus (TRV) constructs to target V. dahliae transcripts. Subsequent V. dahliae inoculation revealed the suppression of Verticillium wilt disease on treatment with only one of the three TRV constructs. Next, expression of RNAi constructs targeting transcripts of the same three V. dahliae virulence genes was pursued in stable transgenic Arabidopsis thaliana plants. In this host, V. dahliae inoculation revealed reduced Verticillium wilt disease in two of the three targets. Thus, our study suggests that, depending on the target gene chosen, HIGS against V. dahliae is operational in tomato and A. thaliana plants and may be exploited to engineer resistance in Verticillium wilt-susceptible crops.
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Affiliation(s)
- Yin Song
- Laboratory of PhytopathologyWageningen University, Droevendaalsesteeg 1Wageningen6708 PBthe Netherlands
| | - Bart P. H. J. Thomma
- Laboratory of PhytopathologyWageningen University, Droevendaalsesteeg 1Wageningen6708 PBthe Netherlands
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23
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Yin C, Hulbert SH. Host-Induced Gene Silencing (HIGS) for Elucidating Puccinia Gene Function in Wheat. Methods Mol Biol 2018; 1848:139-150. [PMID: 30182235 DOI: 10.1007/978-1-4939-8724-5_12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Biotrophic fungi (Puccinia spp.) cause devastating diseases of wheat and other cereal species globally. The function of large repertories of genes from Puccinia spp. still needs to be discovered to understand the infection process of these obligate parasites, eventually to protect plants from rust diseases. Functional analysis of targeted genes is challenging due to the inherent difficulties with culturing the fungus and transforming the host. RNA interference (RNAi) is a conserved gene regulation process in eukaryotes and known to be a powerful genetic tool in plant biotechnology. More recently, host-induced gene silencing (HIGS) has been developed to assess pathogen gene function in plants. HIGS is an RNAi-based process where double stranded RNA (dsRNA) homologous to a pathogen gene can be expressed in a plant to induce targeted silencing of the pathogen gene. Here we described a detailed HIGS protocol for functional analysis of rust genes from Puccinia species in cereals. As an example we describe an experiment silencing the tryptophan 2-monooxygenase gene (Pgt-IaaM) from Puccinia graminis f. sp. tritici (Pgt) that is involved in virulence to wheat.
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Affiliation(s)
- Chuntao Yin
- Department of Plant Pathology, Washington State University, Pullman, WA, USA
| | - Scot H Hulbert
- Department of Plant Pathology, Washington State University, Pullman, WA, USA.
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24
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Xia C, Wang M, Cornejo OE, Jiwan DA, See DR, Chen X. Secretome Characterization and Correlation Analysis Reveal Putative Pathogenicity Mechanisms and Identify Candidate Avirulence Genes in the Wheat Stripe Rust Fungus Puccinia striiformis f. sp. tritici. Front Microbiol 2017; 8:2394. [PMID: 29312156 PMCID: PMC5732408 DOI: 10.3389/fmicb.2017.02394] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Accepted: 11/20/2017] [Indexed: 12/30/2022] Open
Abstract
Stripe (yellow) rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases of wheat worldwide. Planting resistant cultivars is an effective way to control this disease, but race-specific resistance can be overcome quickly due to the rapid evolving Pst population. Studying the pathogenicity mechanisms is critical for understanding how Pst virulence changes and how to develop wheat cultivars with durable resistance to stripe rust. We re-sequenced 7 Pst isolates and included additional 7 previously sequenced isolates to represent balanced virulence/avirulence profiles for several avirulence loci in seretome analyses. We observed an uneven distribution of heterozygosity among the isolates. Secretome comparison of Pst with other rust fungi identified a large portion of species-specific secreted proteins, suggesting that they may have specific roles when interacting with the wheat host. Thirty-two effectors of Pst were identified from its secretome. We identified candidates for Avr genes corresponding to six Yr genes by correlating polymorphisms for effector genes to the virulence/avirulence profiles of the 14 Pst isolates. The putative AvYr76 was present in the avirulent isolates, but absent in the virulent isolates, suggesting that deleting the coding region of the candidate avirulence gene has produced races virulent to resistance gene Yr76. We conclude that incorporating avirulence/virulence phenotypes into correlation analysis with variations in genomic structure and secretome, particularly presence/absence polymorphisms of effectors, is an efficient way to identify candidate Avr genes in Pst. The candidate effector genes provide a rich resource for further studies to determine the evolutionary history of Pst populations and the co-evolutionary arms race between Pst and wheat. The Avr candidates identified in this study will lead to cloning avirulence genes in Pst, which will enable us to understand molecular mechanisms underlying Pst-wheat interactions, to determine the effectiveness of resistance genes and further to develop durable resistance to stripe rust.
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Affiliation(s)
- Chongjing Xia
- Department of Plant Pathology, Washington State University, Pullman, WA, United States
| | - Meinan Wang
- Department of Plant Pathology, Washington State University, Pullman, WA, United States
| | - Omar E. Cornejo
- School of Biological Sciences, Washington State University, Pullman, WA, United States
| | - Derick A. Jiwan
- Wheat Health, Genetics, and Quality Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Pullman, WA, United States
| | - Deven R. See
- Department of Plant Pathology, Washington State University, Pullman, WA, United States
- Wheat Health, Genetics, and Quality Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Pullman, WA, United States
| | - Xianming Chen
- Department of Plant Pathology, Washington State University, Pullman, WA, United States
- Wheat Health, Genetics, and Quality Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Pullman, WA, United States
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25
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Kachroo A, Vincelli P, Kachroo P. Signaling Mechanisms Underlying Resistance Responses: What Have We Learned, and How Is It Being Applied? PHYTOPATHOLOGY 2017; 107:1452-1461. [PMID: 28609156 DOI: 10.1094/phyto-04-17-0130-rvw] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Plants have evolved highly specific mechanisms to resist pathogens including preformed barriers and the induction of elaborate signaling pathways. Induced signaling requires recognition of the pathogen either via conserved pathogen-derived factors or specific pathogen-encoded proteins called effectors. Recognition of these factors by host encoded receptor proteins can result in the elicitation of different tiers of resistance at the site of pathogen infection. In addition, plants induce a type of systemic immunity which is effective at the whole plant level and protects against a broad spectrum of pathogens. Advances in our understanding of pathogen-recognition mechanisms, identification of the underlying molecular components, and their significant conservation across diverse plant species has enabled the development of novel strategies to combat plant diseases. This review discusses key advances in plant defense signaling that have been adapted or have the potential to be adapted for plant protection against microbial diseases.
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Affiliation(s)
- Aardra Kachroo
- Department of Plant Pathology, University of Kentucky, Lexington 40546
| | - Paul Vincelli
- Department of Plant Pathology, University of Kentucky, Lexington 40546
| | - Pradeep Kachroo
- Department of Plant Pathology, University of Kentucky, Lexington 40546
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26
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Cooper B, Campbell KB. Protection Against Common Bean Rust Conferred by a Gene-Silencing Method. PHYTOPATHOLOGY 2017; 107:920-927. [PMID: 28437139 DOI: 10.1094/phyto-03-17-0095-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Rust disease of the dry bean plant, Phaseolus vulgaris, is caused by the fungus Uromyces appendiculatus. The fungus acquires its nutrients and energy from bean leaves using a specialized cell structure, the haustorium, through which it secretes effector proteins that contribute to pathogenicity by defeating the plant immune system. Candidate effectors have been identified by DNA sequencing and motif analysis, and some candidates have been observed in infected leaves by mass spectrometry. To assess their roles in pathogenicity, we have inserted small fragments of genes for five candidates into Bean pod mottle virus. Plants were infected with recombinant virus and then challenged with U. appendiculatus. Virus-infected plants expressing gene fragments for four of five candidate effectors accumulated lower amounts of rust and had dramatically less rust disease. By contrast, controls that included a fungal gene fragment for a septin protein not expressed in the haustorium died from a synergistic reaction between the virus and the fungus. The results imply that RNA generated in the plant moved across the fungal haustorium to silence effector genes important to fungal pathogenicity. This study shows that four bean rust fungal genes encode pathogenicity determinants and that the expression of fungal RNA in the plant can be an effective method for protecting bean plants from rust.
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Affiliation(s)
- Bret Cooper
- Soybean Genomics and Improvement Laboratory, United States Department of Agriculture-Agricultural Research Service, Beltsville, MD 20705
| | - Kimberly B Campbell
- Soybean Genomics and Improvement Laboratory, United States Department of Agriculture-Agricultural Research Service, Beltsville, MD 20705
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Wang B, Sun Y, Song N, Zhao M, Liu R, Feng H, Wang X, Kang Z. Puccinia striiformis f. sp. tritici microRNA-like RNA 1 (Pst-milR1), an important pathogenicity factor of Pst, impairs wheat resistance to Pst by suppressing the wheat pathogenesis-related 2 gene. THE NEW PHYTOLOGIST 2017; 215:338-350. [PMID: 28464281 DOI: 10.1111/nph.14577] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 03/16/2017] [Indexed: 05/22/2023]
Abstract
Small RNAs (sRNAs), an important type of pathogenicity factor, contribute to impairing host immune responses. However, little is known about sRNAs in Puccinia striiformis f. sp. tritici (Pst), one of the most destructive pathogens of wheat (Triticum aestivum L.). Here, we report a novel microRNA-like RNA (milRNA) from Pst termed microRNA-like RNA 1 (Pst-milR1), which suppresses wheat defenses during wheat-Pst interactions. We identified Pst-milR1 as a novel milRNA in Pst. Biological prediction and co-transformation showed that Pst-milR1 takes part in cross-kingdom RNA interference (RNAi) events by binding the wheat pathogenesis-related 2 (PR2) gene. Silencing of the Pst-milR1 precursor resulted in increased wheat resistance to the virulent Pst isolate CYR31. PR2 knock-down plants increased the susceptibility of wheat to the avirulent Pst isolate CYR23. This suggests that Pst-milR1 represses the plant immune response by suppressing the expression of PR2. Taking our findings together, we postulate that Pst-milR1 is an important pathogenicity factor in Pst, which acts as an effector to suppress host immunity. Our results provide significant new insights into the pathogenicity of the stripe rust pathogen.
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Affiliation(s)
- Bing Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Yanfei Sun
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, No. 3 Taicheng Road, Yangling, Shaanxi, 712100, China
| | - Na Song
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, No. 3 Taicheng Road, Yangling, Shaanxi, 712100, China
| | - Mengxin Zhao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, No. 3 Taicheng Road, Yangling, Shaanxi, 712100, China
| | - Rui Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, No. 3 Taicheng Road, Yangling, Shaanxi, 712100, China
| | - Hao Feng
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, No. 3 Taicheng Road, Yangling, Shaanxi, 712100, China
| | - Xiaojie Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, No. 3 Taicheng Road, Yangling, Shaanxi, 712100, China
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, No. 3 Taicheng Road, Yangling, Shaanxi, 712100, China
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28
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Dhariwal GK, Laroche A. The future of genetically engineered plants to stabilize yield and improve feed. Anim Front 2017. [DOI: 10.2527/af.2017.0112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Gaganpreet Kaur Dhariwal
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, 5401 1st Avenue S., Lethbridge, AB CANADA T1J 4B1
| | - André Laroche
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, 5401 1st Avenue S., Lethbridge, AB CANADA T1J 4B1
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Ramachandran SR, Yin C, Kud J, Tanaka K, Mahoney AK, Xiao F, Hulbert SH. Effectors from Wheat Rust Fungi Suppress Multiple Plant Defense Responses. PHYTOPATHOLOGY 2017; 107:75-83. [PMID: 27503371 DOI: 10.1094/phyto-02-16-0083-r] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Fungi that cause cereal rust diseases (genus Puccinia) are important pathogens of wheat globally. Upon infection, the fungus secretes a number of effector proteins. Although a large repository of putative effectors has been predicted using bioinformatic pipelines, the lack of available high-throughput effector screening systems has limited functional studies on these proteins. In this study, we mined the available transcriptomes of Puccinia graminis and P. striiformis to look for potential effectors that suppress host hypersensitive response (HR). Twenty small (<300 amino acids), secreted proteins, with no predicted functions were selected for the HR suppression assay using Nicotiana benthamiana, in which each of the proteins were transiently expressed and evaluated for their ability to suppress HR caused by four cytotoxic effector-R gene combinations (Cp/Rx, ATR13/RPP13, Rpt2/RPS-2, and GPA/RBP-1) and one mutated R gene-Pto(Y207D). Nine out of twenty proteins, designated Shr1 to Shr9 (suppressors of hypersensitive response), were found to suppress HR in N. benthamiana. These effectors varied in the effector-R gene defenses they suppressed, indicating these pathogens can interfere with a variety of host defense pathways. In addition to HR suppression, effector Shr7 also suppressed PAMP-triggered immune response triggered by flg22. Finally, delivery of Shr7 through Pseudomonas fluorescens EtHAn suppressed nonspecific HR induced by Pseudomonas syringae DC3000 in wheat, confirming its activity in a homologous system. Overall, this study provides the first evidence for the presence of effectors in Puccinia species suppressing multiple plant defense responses.
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Affiliation(s)
- Sowmya R Ramachandran
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| | - Chuntao Yin
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| | - Joanna Kud
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| | - Kiwamu Tanaka
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| | - Aaron K Mahoney
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| | - Fangming Xiao
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
| | - Scot H Hulbert
- First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339
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30
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Cheng Y, Yao J, Zhang Y, Li S, Kang Z. Characterization of a Ran gene from Puccinia striiformis f. sp. tritici involved in fungal growth and anti-cell death. Sci Rep 2016; 6:35248. [PMID: 27734916 PMCID: PMC5062253 DOI: 10.1038/srep35248] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/23/2016] [Indexed: 11/09/2022] Open
Abstract
Ran, an important family of small GTP-binding proteins, has been shown to regulate a variety of important cellular processes in many eukaryotes. However, little is known about Ran function in pathogenic fungi. In this study, we report the identification and functional analysis of a Ran gene (designated PsRan) from Puccinia striiformis f. sp. tritici (Pst), an important fungal pathogen affecting wheat production worldwide. The PsRan protein contains all conserved domains of Ran GTPases and shares more than 70% identity with Ran proteins from other organisms, indicating that Ran proteins are conserved in different organisms. PsRan shows a low level of intra-species polymorphism and is localized to the nucleus. qRT-PCR analysis showed that transcript level of PsRan was induced in planta during Pst infection. Silencing of PsRan did not alter Pst virulence phenotype but impeded fungal growth of Pst. In addition, heterologous overexpression of PsRan in plant failed to induce cell death but suppressed cell death triggered by a mouse BAX gene or a Pst Ras gene. Our results suggest that PsRan is involved in the regulation of fungal growth and anti-cell death, which provides significant insight into Ran function in pathogenic fungi.
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Affiliation(s)
- Yulin Cheng
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Juanni Yao
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Yanru Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Shumin Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling 712100, Shaanxi, China
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31
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Liu C, Pedersen C, Schultz-Larsen T, Aguilar GB, Madriz-Ordeñana K, Hovmøller MS, Thordal-Christensen H. The stripe rust fungal effector PEC6 suppresses pattern-triggered immunity in a host species-independent manner and interacts with adenosine kinases. THE NEW PHYTOLOGIST 2016. [PMID: 27252028 DOI: 10.1111/nph.14034] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 04/25/2016] [Indexed: 05/20/2023]
Abstract
We identified a wheat stripe rust (Puccinia striiformis) effector candidate (PEC6) with pattern-triggered immunity (PTI) suppression function and its corresponding host target. PEC6 compromised PTI host species-independently. In Nicotiana benthamiana, it hampers reactive oxygen species (ROS) accumulation and callose deposition induced by Pseudomonas fluorescens. In Arabidopsis, plants expressing PEC6 were more susceptible to Pseudomonas syringae pv. tomato (Pto) DC3000 ΔAvrPto/ΔAvrPtoB. In wheat, PEC6-suppression of P. fluorescens-elicited PTI was revealed by the fact that it allowed activation of effector-triggered immunity by Pto DC3000. Knocking down of PEC6 expression by virus-mediated host-induced gene silencing decreased the number of rust pustules, uncovering PEC6 as an important pathogenicity factor. PEC6, overexpressed in plant cells without its signal peptide, was localized to the nucleus and cytoplasm. A yeast two-hybrid assay showed that PEC6 interacts with both wheat and Arabidopsis adenosine kinases (ADKs). Knocking down wheat ADK expression by virus-induced gene silencing reduced leaf growth and enhanced the number of rust pustules, indicating that ADK is important in plant development and defence. ADK plays essential roles in regulating metabolism, cytokinin interconversion and methyl transfer reactions, and our data propose a model where PEC6 may affect one of these processes by targeting ADK to favour fungal growth.
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Affiliation(s)
- Changhai Liu
- Section for Plant and Soil Science, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Frederiksberg C, DK-1871, Denmark
| | - Carsten Pedersen
- Section for Plant and Soil Science, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Frederiksberg C, DK-1871, Denmark
| | - Torsten Schultz-Larsen
- Section for Plant and Soil Science, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Frederiksberg C, DK-1871, Denmark
| | - Geziel B Aguilar
- Section for Plant and Soil Science, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Frederiksberg C, DK-1871, Denmark
| | - Kenneth Madriz-Ordeñana
- Section for Plant and Soil Science, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Frederiksberg C, DK-1871, Denmark
| | - Mogens S Hovmøller
- Department of Agroecology, Aarhus University, Forsøgsvej 1, Slagelse, DK-4200, Denmark
| | - Hans Thordal-Christensen
- Section for Plant and Soil Science, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Frederiksberg C, DK-1871, Denmark
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32
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Barakate A, Stephens J. An Overview of CRISPR-Based Tools and Their Improvements: New Opportunities in Understanding Plant-Pathogen Interactions for Better Crop Protection. FRONTIERS IN PLANT SCIENCE 2016; 7:765. [PMID: 27313592 PMCID: PMC4887484 DOI: 10.3389/fpls.2016.00765] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 05/17/2016] [Indexed: 05/04/2023]
Abstract
Modern omics platforms have made the determination of susceptible/resistance genes feasible in any species generating huge numbers of potential targets for crop protection. However, the efforts to validate these targets have been hampered by the lack of a fast, precise, and efficient gene targeting system in plants. Now, the repurposing of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system has solved this problem. CRISPR/Cas9 is the latest synthetic endonuclease that has revolutionized basic research by allowing facile genome editing in prokaryotes and eukaryotes. Gene knockout is now feasible at an unprecedented efficiency with the possibility of multiplexing several targets and even genome-wide mutagenesis screening. In a short time, this powerful tool has been engineered for an array of applications beyond gene editing. Here, we briefly describe the CRISPR/Cas9 system, its recent improvements and applications in gene manipulation and single DNA/RNA molecule analysis. We summarize a few recent tests targeting plant pathogens and discuss further potential applications in pest control and plant-pathogen interactions that will inform plant breeding for crop protection.
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33
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Selin C, de Kievit TR, Belmonte MF, Fernando WGD. Elucidating the Role of Effectors in Plant-Fungal Interactions: Progress and Challenges. Front Microbiol 2016; 7:600. [PMID: 27199930 PMCID: PMC4846801 DOI: 10.3389/fmicb.2016.00600] [Citation(s) in RCA: 127] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 04/11/2016] [Indexed: 11/13/2022] Open
Abstract
Pathogenic fungi have diverse growth lifestyles that support fungal colonization on plants. Successful colonization and infection for all lifestyles depends upon the ability to modify living host plants to sequester the necessary nutrients required for growth and reproduction. Secretion of virulence determinants referred to as “effectors” is assumed to be the key governing factor that determines host infection and colonization. Effector proteins are capable of suppressing plant defense responses and alter plant physiology to accommodate fungal invaders. This review focuses on effector molecules of biotrophic and hemibiotrophic plant pathogenic fungi, and the mechanism required for the release and uptake of effector molecules by the fungi and plant cells, respectively. We also place emphasis on the discovery of effectors, difficulties associated with predicting the effector repertoire, and fungal genomic features that have helped promote effector diversity leading to fungal evolution. We discuss the role of specific effectors found in biotrophic and hemibiotrophic fungi and examine how CRISPR/Cas9 technology may provide a new avenue for accelerating our ability in the discovery of fungal effector function.
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Affiliation(s)
- Carrie Selin
- Department of Plant Science, University of Manitoba Winnipeg, MB, Canada
| | | | - Mark F Belmonte
- Department of Biological Sciences, University of Manitoba Winnipeg, MB, Canada
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Figueroa M, Upadhyaya NM, Sperschneider J, Park RF, Szabo LJ, Steffenson B, Ellis JG, Dodds PN. Changing the Game: Using Integrative Genomics to Probe Virulence Mechanisms of the Stem Rust Pathogen Puccinia graminis f. sp. tritici. FRONTIERS IN PLANT SCIENCE 2016; 7:205. [PMID: 26941766 PMCID: PMC4764693 DOI: 10.3389/fpls.2016.00205] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 02/06/2016] [Indexed: 05/03/2023]
Abstract
The recent resurgence of wheat stem rust caused by new virulent races of Puccinia graminis f. sp. tritici (Pgt) poses a threat to food security. These concerns have catalyzed an extensive global effort toward controlling this disease. Substantial research and breeding programs target the identification and introduction of new stem rust resistance (Sr) genes in cultivars for genetic protection against the disease. Such resistance genes typically encode immune receptor proteins that recognize specific components of the pathogen, known as avirulence (Avr) proteins. A significant drawback to deploying cultivars with single Sr genes is that they are often overcome by evolution of the pathogen to escape recognition through alterations in Avr genes. Thus, a key element in achieving durable rust control is the deployment of multiple effective Sr genes in combination, either through conventional breeding or transgenic approaches, to minimize the risk of resistance breakdown. In this situation, evolution of pathogen virulence would require changes in multiple Avr genes in order to bypass recognition. However, choosing the optimal Sr gene combinations to deploy is a challenge that requires detailed knowledge of the pathogen Avr genes with which they interact and the virulence phenotypes of Pgt existing in nature. Identifying specific Avr genes from Pgt will provide screening tools to enhance pathogen virulence monitoring, assess heterozygosity and propensity for mutation in pathogen populations, and confirm individual Sr gene functions in crop varieties carrying multiple effective resistance genes. Toward this goal, much progress has been made in assembling a high quality reference genome sequence for Pgt, as well as a Pan-genome encompassing variation between multiple field isolates with diverse virulence spectra. In turn this has allowed prediction of Pgt effector gene candidates based on known features of Avr genes in other plant pathogens, including the related flax rust fungus. Upregulation of gene expression in haustoria and evidence for diversifying selection are two useful parameters to identify candidate Avr genes. Recently, we have also applied machine learning approaches to agnostically predict candidate effectors. Here, we review progress in stem rust pathogenomics and approaches currently underway to identify Avr genes recognized by wheat Sr genes.
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Affiliation(s)
- Melania Figueroa
- Department of Plant Pathology and the Stakman-Borlaug Center for Sustainable Plant Health, University of MinnesotaSt. Paul, MN, USA
| | - Narayana M. Upadhyaya
- Agriculture, Commonwealth Scientific and Industrial Research OrganisationCanberra, ACT, Australia
| | - Jana Sperschneider
- Agriculture, Centre for Environment and Life Sciences, Commonwealth Scientific and Industrial Research OrganisationPerth, WA, Australia
| | - Robert F. Park
- Faculty of Agriculture and Environment, Plant Breeding Institute, The University of SydneyNarellan, NSW, Australia
| | - Les J. Szabo
- Department of Plant Pathology and the Stakman-Borlaug Center for Sustainable Plant Health, University of MinnesotaSt. Paul, MN, USA
- Cereal Disease Laboratory, United States Department of Agriculture-Agricultural Research ServiceSt. Paul, MN, USA
| | - Brian Steffenson
- Department of Plant Pathology and the Stakman-Borlaug Center for Sustainable Plant Health, University of MinnesotaSt. Paul, MN, USA
| | - Jeff G. Ellis
- Agriculture, Commonwealth Scientific and Industrial Research OrganisationCanberra, ACT, Australia
| | - Peter N. Dodds
- Agriculture, Commonwealth Scientific and Industrial Research OrganisationCanberra, ACT, Australia
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