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McRae AG, Taneja J, Yee K, Shi X, Haridas S, LaButti K, Singan V, Grigoriev IV, Wildermuth MC. Spray-induced gene silencing to identify powdery mildew gene targets and processes for powdery mildew control. MOLECULAR PLANT PATHOLOGY 2023; 24:1168-1183. [PMID: 37340595 PMCID: PMC10423327 DOI: 10.1111/mpp.13361] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 05/09/2023] [Accepted: 05/11/2023] [Indexed: 06/22/2023]
Abstract
Spray-induced gene silencing (SIGS) is an emerging tool for crop pest protection. It utilizes exogenously applied double-stranded RNA to specifically reduce pest target gene expression using endogenous RNA interference machinery. In this study, SIGS methods were developed and optimized for powdery mildew fungi, which are widespread obligate biotrophic fungi that infect agricultural crops, using the known azole-fungicide target cytochrome P450 51 (CYP51) in the Golovinomyces orontii-Arabidopsis thaliana pathosystem. Additional screening resulted in the identification of conserved gene targets and processes important to powdery mildew proliferation: apoptosis-antagonizing transcription factor in essential cellular metabolism and stress response; lipid catabolism genes lipase a, lipase 1, and acetyl-CoA oxidase in energy production; and genes involved in manipulation of the plant host via abscisic acid metabolism (9-cis-epoxycarotenoid dioxygenase, xanthoxin dehydrogenase, and a putative abscisic acid G-protein coupled receptor) and secretion of the effector protein, effector candidate 2. Powdery mildew is the dominant disease impacting grapes and extensive powdery mildew resistance to applied fungicides has been reported. We therefore developed SIGS for the Erysiphe necator-Vitis vinifera system and tested six successful targets identified using the G. orontii-A. thaliana system. For all targets tested, a similar reduction in powdery mildew disease was observed between systems. This indicates screening of broadly conserved targets in the G. orontii-A. thaliana pathosystem identifies targets and processes for the successful control of other powdery mildew fungi. The efficacy of SIGS on powdery mildew fungi makes SIGS an exciting prospect for commercial powdery mildew control.
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Affiliation(s)
- Amanda G. McRae
- Department of Plant and Microbial BiologyUniversity of CaliforniaBerkeleyCaliforniaUSA
| | - Jyoti Taneja
- Department of Plant and Microbial BiologyUniversity of CaliforniaBerkeleyCaliforniaUSA
| | - Kathleen Yee
- Department of Plant and Microbial BiologyUniversity of CaliforniaBerkeleyCaliforniaUSA
| | - Xinyi Shi
- Department of Plant and Microbial BiologyUniversity of CaliforniaBerkeleyCaliforniaUSA
| | - Sajeet Haridas
- US Department of Energy Joint Genome InstituteLawrence Berkeley National LaboratoryBerkeleyCaliforniaUSA
| | - Kurt LaButti
- US Department of Energy Joint Genome InstituteLawrence Berkeley National LaboratoryBerkeleyCaliforniaUSA
| | - Vasanth Singan
- US Department of Energy Joint Genome InstituteLawrence Berkeley National LaboratoryBerkeleyCaliforniaUSA
| | - Igor V. Grigoriev
- Department of Plant and Microbial BiologyUniversity of CaliforniaBerkeleyCaliforniaUSA
- US Department of Energy Joint Genome InstituteLawrence Berkeley National LaboratoryBerkeleyCaliforniaUSA
| | - Mary C. Wildermuth
- Department of Plant and Microbial BiologyUniversity of CaliforniaBerkeleyCaliforniaUSA
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Bakhat N, Vielba-Fernández A, Padilla-Roji I, Martínez-Cruz J, Polonio Á, Fernández-Ortuño D, Pérez-García A. Suppression of Chitin-Triggered Immunity by Plant Fungal Pathogens: A Case Study of the Cucurbit Powdery Mildew Fungus Podosphaera xanthii. J Fungi (Basel) 2023; 9:771. [PMID: 37504759 PMCID: PMC10381495 DOI: 10.3390/jof9070771] [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: 06/15/2023] [Revised: 07/17/2023] [Accepted: 07/17/2023] [Indexed: 07/29/2023] Open
Abstract
Fungal pathogens are significant plant-destroying microorganisms that present an increasing threat to the world's crop production. Chitin is a crucial component of fungal cell walls and a conserved MAMP (microbe-associated molecular pattern) that can be recognized by specific plant receptors, activating chitin-triggered immunity. The molecular mechanisms underlying the perception of chitin by specific receptors are well known in plants such as rice and Arabidopsis thaliana and are believed to function similarly in many other plants. To become a plant pathogen, fungi have to suppress the activation of chitin-triggered immunity. Therefore, fungal pathogens have evolved various strategies, such as prevention of chitin digestion or interference with plant chitin receptors or chitin signaling, which involve the secretion of fungal proteins in most cases. Since chitin immunity is a very effective defensive response, these fungal mechanisms are believed to work in close coordination. In this review, we first provide an overview of the current understanding of chitin-triggered immune signaling and the fungal proteins developed for its suppression. Second, as an example, we discuss the mechanisms operating in fungal biotrophs such as powdery mildew fungi, particularly in the model species Podosphaera xanthii, the main causal agent of powdery mildew in cucurbits. The key role of fungal effector proteins involved in the modification, degradation, or sequestration of immunogenic chitin oligomers is discussed in the context of fungal pathogenesis and the promotion of powdery mildew disease. Finally, the use of this fundamental knowledge for the development of intervention strategies against powdery mildew fungi is also discussed.
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Affiliation(s)
- Nisrine Bakhat
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Malaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Malaga, Spain
| | - Alejandra Vielba-Fernández
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Malaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Malaga, Spain
| | - Isabel Padilla-Roji
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Malaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Malaga, Spain
| | - Jesús Martínez-Cruz
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Malaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Malaga, Spain
| | - Álvaro Polonio
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Malaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Malaga, Spain
| | - Dolores Fernández-Ortuño
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Malaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Malaga, Spain
| | - Alejandro Pérez-García
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Malaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), 29071 Malaga, Spain
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Suppression of Chitin-Triggered Immunity by a New Fungal Chitin-Binding Effector Resulting from Alternative Splicing of a Chitin Deacetylase Gene. J Fungi (Basel) 2022; 8:jof8101022. [PMID: 36294587 PMCID: PMC9605236 DOI: 10.3390/jof8101022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/24/2022] [Accepted: 09/25/2022] [Indexed: 11/16/2022] Open
Abstract
Phytopathogenic fungi have evolved mechanisms to manipulate plant defences, such as chitin-triggered immunity, a plant defensive response based on the recognition of chitin oligomers by plant-specific receptors. To cope with chitin resistance, fungal pathogens have developed different strategies to prevent chitin recognition, such as binding, breaking, or modifying immunogenic oligomers. In powdery mildew fungi, the activity of chitin deacetylase (CDA) is crucial for this purpose, since silencing of the CDA gene leads to a rapid activation of chitin signalling and the subsequent suppression of fungal growth. In this work, we have identified an unusually short CDA transcript in Podosphaera xanthii, the cucurbit powdery mildew pathogen. This transcript, designated PxCDA3, appears to encode a truncated version of CDA resulting from an alternative splicing of the PxCDA gene, which lacked most of the chitin deacetylase activity domain but retained the carbohydrate-binding module. Experiments with the recombinant protein showed its ability to bind to chitin oligomers and prevent the activation of chitin signalling. Furthermore, the use of fluorescent fusion proteins allowed its localization in plant papillae at pathogen penetration sites. Our results suggest the occurrence of a new fungal chitin-binding effector, designated CHBE, involved in the manipulation of chitin-triggered immunity in powdery mildew fungi.
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Gene Mining for Conserved, Non-Annotated Proteins of Podosphaera xanthii Identifies Novel Target Candidates for Controlling Powdery Mildews by Spray-Induced Gene Silencing. J Fungi (Basel) 2021; 7:jof7090735. [PMID: 34575773 PMCID: PMC8465782 DOI: 10.3390/jof7090735] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 08/31/2021] [Accepted: 09/06/2021] [Indexed: 11/17/2022] Open
Abstract
The powdery mildew fungus Podosphaera xanthii is one of the most important limiting factors for cucurbit production worldwide. Despite the significant efforts made by breeding and chemical companies, effective control of this pathogen remains elusive to growers. In this work, we examined the suitability of RNAi technology called spray-induced gene silencing (SIGS) for controlling cucurbit powdery mildew. Using leaf disc and cotyledon infiltration assays, we tested the efficacy of dsRNA applications to induce gene silencing in P. xanthii. Furthermore, to identify new target candidate genes, we analyzed sixty conserved and non-annotated proteins (CNAPs) deduced from the P. xanthii transcriptome in silico. Six proteins presumably involved in essential functions, specifically respiration (CNAP8878, CNAP9066, CNAP10905 and CNAP30520), glycosylation (CNAP1048) and efflux transport (CNAP948), were identified. Functional analysis of these CNAP coding genes by dsRNA-induced gene silencing resulted in strong silencing phenotypes with large reductions in fungal growth and disease symptoms. Due to their important contributions to fungal development, the CNAP1048, CNAP10905 and CNAP30520 genes were selected as targets to conduct SIGS assays under plant growth chamber conditions. The spray application of these dsRNAs induced high levels of disease control, supporting that SIGS could be a sustainable approach to combat powdery mildew diseases.
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Mart Nez-Cruz JS, Romero D, Hierrezuelo JS, Thon M, de Vicente A, P Rez-Garc A A. Effectors with chitinase activity (EWCAs), a family of conserved, secreted fungal chitinases that suppress chitin-triggered immunity. THE PLANT CELL 2021; 33:1319-1340. [PMID: 33793825 DOI: 10.1093/plcell/koab011] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 12/11/2020] [Indexed: 05/23/2023]
Abstract
In plants, chitin-triggered immunity is one of the first lines of defense against fungi, but phytopathogenic fungi have developed different strategies to prevent the recognition of chitin. Obligate biotrophs such as powdery mildew fungi suppress the activation of host responses; however, little is known about how these fungi subvert the immunity elicited by chitin. During epiphytic growth, the cucurbit powdery mildew fungus Podosphaera xanthii expresses a family of candidate effector genes comprising nine members with an unknown function. In this work, we examine the role of these candidates in the infection of melon (Cucumis melo L.) plants, using gene expression analysis, RNAi silencing assays, protein modeling and protein-ligand predictions, enzymatic assays, and protein localization studies. Our results show that these proteins are chitinases that are released at pathogen penetration sites to break down immunogenic chitin oligomers, thus preventing the activation of chitin-triggered immunity. In addition, these effectors, designated effectors with chitinase activity (EWCAs), are widely distributed in pathogenic fungi. Our findings reveal a mechanism by which fungi suppress plant immunity and reinforce the idea that preventing the perception of chitin by the host is mandatory for survival and development of fungi in plant environments.
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Affiliation(s)
- Jes S Mart Nez-Cruz
- Departamento de Microbiolog�a, Facultad de Ciencias, Universidad de M�laga, M�laga 29071, Spain
- Instituto de Hortofruticultura Subtropical y Mediterr�nea "La Mayora", Universidad de M�laga, Consejo Superior de Investigaciones Cient�ficas (IHSM‒UMA‒CSIC), M�laga 29071, Spain
| | - Diego Romero
- Departamento de Microbiolog�a, Facultad de Ciencias, Universidad de M�laga, M�laga 29071, Spain
- Instituto de Hortofruticultura Subtropical y Mediterr�nea "La Mayora", Universidad de M�laga, Consejo Superior de Investigaciones Cient�ficas (IHSM‒UMA‒CSIC), M�laga 29071, Spain
| | - Jes S Hierrezuelo
- Departamento de Microbiolog�a, Facultad de Ciencias, Universidad de M�laga, M�laga 29071, Spain
- Instituto de Hortofruticultura Subtropical y Mediterr�nea "La Mayora", Universidad de M�laga, Consejo Superior de Investigaciones Cient�ficas (IHSM‒UMA‒CSIC), M�laga 29071, Spain
| | - Michael Thon
- Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Universidad de Salamanca, Salamanca 37185, Spain
| | - Antonio de Vicente
- Departamento de Microbiolog�a, Facultad de Ciencias, Universidad de M�laga, M�laga 29071, Spain
- Instituto de Hortofruticultura Subtropical y Mediterr�nea "La Mayora", Universidad de M�laga, Consejo Superior de Investigaciones Cient�ficas (IHSM‒UMA‒CSIC), M�laga 29071, Spain
| | - Alejandro P Rez-Garc A
- Departamento de Microbiolog�a, Facultad de Ciencias, Universidad de M�laga, M�laga 29071, Spain
- Instituto de Hortofruticultura Subtropical y Mediterr�nea "La Mayora", Universidad de M�laga, Consejo Superior de Investigaciones Cient�ficas (IHSM‒UMA‒CSIC), M�laga 29071, Spain
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6
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Hammoudi V. The art of passing unnoticed: pathogenic fungi remain incognito thanks to EWCA effectors. THE PLANT CELL 2021; 33:1097-1098. [PMID: 35234965 PMCID: PMC8889946 DOI: 10.1093/plcell/koab017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 01/07/2021] [Indexed: 06/14/2023]
Affiliation(s)
- Valentin Hammoudi
- Institute of Biology, Applied Genetics, Freie Universit�t Berlin, Albrecht-Thaer-Weg 6, 14195 Berlin, Germany
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7
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Polonio Á, Díaz-Martínez L, Fernández-Ortuño D, de Vicente A, Romero D, López-Ruiz FJ, Pérez-García A. A Hybrid Genome Assembly Resource for Podosphaera xanthii, the Main Causal Agent of Powdery Mildew Disease in Cucurbits. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:319-324. [PMID: 33141618 DOI: 10.1094/mpmi-08-20-0237-a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Podosphaera xanthii is the main causal agent of powdery mildew in cucurbits and, arguably, the most important fungal pathogen of cucurbit crops. Here, we present the first reference genome assembly for P. xanthii. We performed a hybrid genome assembly, using reads from Illumina NextSeq550 and PacBio Sequel S3. The short and long reads were assembled into 1,727 scaffolds with an N50 size of 163,173 bp, resulting in a 142-Mb genome size. The combination of homology-based and ab initio predictions allowed the prediction of 14,911 complete genes. Repetitive sequences comprised 76.2% of the genome. Our P. xanthii genome assembly improves considerably the molecular resources for research on P. xanthii-cucurbit interactions and provides new opportunities for further genomics, transcriptomics, and evolutionary studies in powdery mildew fungi.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Álvaro Polonio
- 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
| | - Luis Díaz-Martínez
- 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
| | - Antonio de Vicente
- 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
| | - Diego Romero
- 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
| | - Francisco J López-Ruiz
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA 6102, Australia
| | - 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
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