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Shands AC, Xu G, Belisle RJ, Seifbarghi S, Jackson N, Bombarely A, Cano LM, Manosalva PM. Genomic and transcriptomic analyses of Phytophthora cinnamomi reveal complex genome architecture, expansion of pathogenicity factors, and host-dependent gene expression profiles. Front Microbiol 2024; 15:1341803. [PMID: 39211322 PMCID: PMC11357935 DOI: 10.3389/fmicb.2024.1341803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 07/24/2024] [Indexed: 09/04/2024] Open
Abstract
Phytophthora cinnamomi is a hemibiotrophic oomycete causing Phytophthora root rot in over 5,000 plant species, threatening natural ecosystems, forestry, and agriculture. Genomic studies of P. cinnamomi are limited compared to other Phytophthora spp. despite the importance of this destructive and highly invasive pathogen. The genome of two genetically and phenotypically distinct P. cinnamomi isolates collected from avocado orchards in California were sequenced using PacBio and Illumina sequencing. Genome sizes were estimated by flow cytometry and assembled de novo to 140-141 Mb genomes with 21,111-21,402 gene models. Genome analyses revealed that both isolates exhibited complex heterozygous genomes fitting the two-speed genome model. The more virulent isolate encodes a larger secretome and more RXLR effectors when compared to the less virulent isolate. Transcriptome analysis after P. cinnamomi infection in Arabidopsis thaliana, Nicotiana benthamiana, and Persea americana de Mill (avocado) showed that this pathogen deploys common gene repertoires in all hosts and host-specific subsets, especially among effectors. Overall, our results suggested that clonal P. cinnamomi isolates employ similar strategies as other Phytophthora spp. to increase phenotypic diversity (e.g., polyploidization, gene duplications, and a bipartite genome architecture) to cope with environmental changes. Our study also provides insights into common and host-specific P. cinnamomi infection strategies and may serve as a method for narrowing and selecting key candidate effectors for functional studies to determine their contributions to plant resistance or susceptibility.
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Affiliation(s)
- Aidan C. Shands
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Guangyuan Xu
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Rodger J. Belisle
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Shirin Seifbarghi
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Natasha Jackson
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Aureliano Bombarely
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valéncia, Valencia, Spain
| | - Liliana M. Cano
- Department of Plant Pathology, Indian River Research and Education Center (IRREC), Institute of Food and Agricultural Sciences (IFAS), University of Florida, Fort Pierce, FL, United States
| | - Patricia M. Manosalva
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
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Fick A, Swart V, Bombarely A, van den Berg N. Comparative transcriptional analysis of Persea americana MYB, WRKY and AP2/ERF transcription factors following Phytophthora cinnamomi infection. MOLECULAR PLANT PATHOLOGY 2024; 25:e13453. [PMID: 38590150 PMCID: PMC11002358 DOI: 10.1111/mpp.13453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 03/07/2024] [Accepted: 03/20/2024] [Indexed: 04/10/2024]
Abstract
Plant cells undergo extensive transcriptional reprogramming following pathogen infection, with these reprogramming patterns becoming more complex when pathogens, such as hemibiotrophs, exhibit different lifestyles. These transcriptional changes are often orchestrated by MYB, WRKY and AP2/ERF transcription factors (TFs), which modulate both growth and defence-related gene expression. Transcriptional analysis of defence-related genes in avocado (Persea americana) infected with Phytophthora cinnamomi indicated differential immune response activation when comparing a partially resistant and susceptible rootstock. This study identified 226 MYB, 82 WRKY, and 174 AP2/ERF TF-encoding genes in avocado, using a genome-wide approach. Phylogenetic analysis revealed substantial sequence conservation within TF groups underscoring their functional significance. RNA-sequencing analysis in a partially resistant and susceptible avocado rootstock infected with P. cinnamomi was indicative of an immune response switch occurring in either rootstock after 24 and 6 h post-inoculation, respectively. Different clusters of co-expressed TF genes were observed at these times, suggesting the activation of necrotroph-related immune responses at varying intervals between the two rootstocks. This study aids our understanding of avocado immune response activation following P. cinnamomi infection, and the role of the TFs therein, elucidating the transcriptional reprogramming disparities between partially resistant and susceptible rootstocks.
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Affiliation(s)
- Alicia Fick
- Department of Biochemistry, Genetics and MicrobiologyUniversity of PretoriaPretoriaGautengSouth Africa
- Hans Merensky Chair in Avocado Research, Forestry and Agricultural Biotechnology InstituteUniversity of PretoriaPretoriaGautengSouth Africa
| | - Velushka Swart
- Department of Biochemistry, Genetics and MicrobiologyUniversity of PretoriaPretoriaGautengSouth Africa
- Hans Merensky Chair in Avocado Research, Forestry and Agricultural Biotechnology InstituteUniversity of PretoriaPretoriaGautengSouth Africa
| | - Aureliano Bombarely
- Instituto de Biología Molecular y Celular de PlantasConsejo Superior de Investigaciones Científicas‐Universitat Politècnica de València (IBMCP‐CSIC‐UPV)ValenciaSpain
| | - Noëlani van den Berg
- Department of Biochemistry, Genetics and MicrobiologyUniversity of PretoriaPretoriaGautengSouth Africa
- Hans Merensky Chair in Avocado Research, Forestry and Agricultural Biotechnology InstituteUniversity of PretoriaPretoriaGautengSouth Africa
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Madina MH, Santhanam P, Asselin Y, Jaswal R, Bélanger RR. Progress and Challenges in Elucidating the Functional Role of Effectors in the Soybean- Phytophthora sojae Interaction. J Fungi (Basel) 2022; 9:12. [PMID: 36675833 PMCID: PMC9866111 DOI: 10.3390/jof9010012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/16/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Phytophthora sojae, the agent responsible for stem and root rot, is one of the most damaging plant pathogens of soybean. To establish a compatible-interaction, P. sojae secretes a wide array of effector proteins into the host cell. These effectors have been shown to act either in the apoplastic area or the cytoplasm of the cell to manipulate the host cellular processes in favor of the development of the pathogen. Deciphering effector-plant interactions is important for understanding the role of P. sojae effectors in disease progression and developing approaches to prevent infection. Here, we review the subcellular localization, the host proteins, and the processes associated with P. sojae effectors. We also discuss the emerging topic of effectors in the context of effector-resistance genes interaction, as well as model systems and recent developments in resources and techniques that may provide a better understanding of the soybean-P. sojae interaction.
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Andronis CE, Jacques S, Lipscombe R, Tan KC. Comparative sub-cellular proteome analyses reveals metabolic differentiation and production of effector-like molecules in the dieback phytopathogen Phytophthora cinnamomi. J Proteomics 2022; 269:104725. [PMID: 36096432 DOI: 10.1016/j.jprot.2022.104725] [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: 02/16/2022] [Revised: 05/23/2022] [Accepted: 09/06/2022] [Indexed: 11/18/2022]
Abstract
Phytopathogenic oomycetes pose a significant threat to global biodiversity and food security. The proteomes of these oomycetes likely contain important factors that contribute to their pathogenic success, making their discovery crucial for elucidating pathogenicity. Phytophthora cinnamomi is a root pathogen that causes dieback in a wide variety of crops and native vegetation world-wide. Virulence proteins produced by P. cinnamomi are not well defined and a large-scale approach to understand the biochemistry of this pathogen has not been documented. Soluble mycelial, zoospore and secreted proteomes were obtained and label-free quantitative proteomics was used to compare the composition of the three sub-proteomes. A total of 4635 proteins were identified, validating 17.7% of the predicted gene set. The mycelia were abundant in transporters for nutrient acquisition, metabolism and cellular proliferation. The zoospores had less metabolic related ontologies but were abundant in energy generating, motility and signalling associated proteins. Virulence-associated proteins were identified in the secretome such as candidate effector and effector-like proteins, which interfere with the host immune system. These include hydrolases, cell wall degrading enzymes, putative necrosis-inducing proteins and elicitins. The secretome elicited a hypersensitive response on the roots of a model host and thus suggests evidence of effector activity. SIGNIFICANCE: Phytophthora cinnamomi is a phytopathogenic oomycete that causes dieback disease in native vegetation and several horticultural crops such as avocado, pineapple and macadamia. Whilst this pathogen has significance world-wide, its pathogenicity and virulence have not been described in depth. We carried out comparative label-free proteomics of the mycelia, zoospores and secretome of P. cinnamomi. This study highlights the differential metabolism and cellular processes between the sub-proteomes. Proteins associated with metabolism, nutrient transport and cellular proliferation were over represented in the mycelia. The zoospores have a specialised proteome showing increased energy generation geared towards motility. Candidate effectors and effector-like secreted proteins were also identified, which can be exploited for genetic resistance. This demonstrates a better understanding of the biology and pathogenicity of P. cinnamomi infection that can subsequently be used to develop effective methods of disease management.
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Affiliation(s)
- Christina E Andronis
- Centre for Crop and Disease Management, Curtin University, Bentley, WA, Australia; Proteomics International, Nedlands, WA, Australia.
| | - Silke Jacques
- Centre for Crop and Disease Management, Curtin University, Bentley, WA, Australia
| | | | - Kar-Chun Tan
- Centre for Crop and Disease Management, Curtin University, Bentley, WA, Australia.
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Backer R, Engelbrecht J, van den Berg N. Differing Responses to Phytophthora cinnamomi Infection in Susceptible and Partially Resistant Persea americana (Mill.) Rootstocks: A Case for the Role of Receptor-Like Kinases and Apoplastic Proteases. FRONTIERS IN PLANT SCIENCE 2022; 13:928176. [PMID: 35837458 PMCID: PMC9274290 DOI: 10.3389/fpls.2022.928176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
The hemibiotrophic plant pathogen Phytophthora cinnamomi Rands is the most devastating pathogen of avocado (Persea americana Mill.) and, as such, causes significant annual losses in the industry. Although the molecular basis of P. cinnamomi resistance in avocado and P. cinnamomi virulence determinants have been the subject of recent research, none have yet attempted to compare the transcriptomic responses of both pathogen and host during their interaction. In the current study, the transcriptomes of both avocado and P. cinnamomi were explored by dual RNA sequencing. The basis for partial resistance was sought by the inclusion of both susceptible (R0.12) and partially resistant (Dusa®) rootstocks sampled at early (6, 12 and 24 hours post-inoculation, hpi) and late time-points (120 hpi). Substantial differences were noted in the number of differentially expressed genes found in Dusa® and R0.12, specifically at 12 and 24 hpi. Here, the partially resistant rootstock perpetuated defense responses initiated at 6 hpi, while the susceptible rootstock abruptly reversed course. Instead, gene ontology enrichment confirmed that R0.12 activated pathways related to growth and development, essentially rendering its response at 12 and 24 hpi no different from that of the mock-inoculated controls. As expected, several classes of P. cinnamomi effector genes were differentially expressed in both Dusa® and R0.12. However, their expression differed between rootstocks, indicating that P. cinnamomi might alter the expression of its effector arsenal based on the rootstock. Based on some of the observed differences, several P. cinnamomi effectors were highlighted as potential candidates for further research. Similarly, the receptor-like kinase (RLK) and apoplastic protease coding genes in avocado were investigated, focusing on their potential role in differing rootstock responses. This study suggests that the basis of partial resistance in Dusa® is predicated on its ability to respond appropriately during the early stages following P. cinnamomi inoculation, and that important components of the first line of inducible defense, apoplastic proteases and RLKs, are likely to be important to the observed outcome.
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Affiliation(s)
- Robert Backer
- Hans Merensky Chair in Avocado Research, University of Pretoria, Pretoria, South Africa
- Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
- Forestry and Agricultural Biotechnology Institute, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
| | - Juanita Engelbrecht
- Hans Merensky Chair in Avocado Research, University of Pretoria, Pretoria, South Africa
- Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
- Forestry and Agricultural Biotechnology Institute, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
| | - Noëlani van den Berg
- Hans Merensky Chair in Avocado Research, University of Pretoria, Pretoria, South Africa
- Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
- Forestry and Agricultural Biotechnology Institute, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
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Midgley KA, van den Berg N, Swart V. Unraveling Plant Cell Death during Phytophthora Infection. Microorganisms 2022; 10:microorganisms10061139. [PMID: 35744657 PMCID: PMC9229607 DOI: 10.3390/microorganisms10061139] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 05/25/2022] [Accepted: 05/30/2022] [Indexed: 01/02/2023] Open
Abstract
Oomycetes form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, of which several hundred organisms are considered among the most devastating plant pathogens—especially members of the genus Phytophthora. Phytophthora spp. have a large repertoire of effectors that aid in eliciting a susceptible response in host plants. What is of increasing interest is the involvement of Phytophthora effectors in regulating programed cell death (PCD)—in particular, the hypersensitive response. There have been numerous functional characterization studies, which demonstrate Phytophthora effectors either inducing or suppressing host cell death, which may play a crucial role in Phytophthora’s ability to regulate their hemi-biotrophic lifestyle. Despite several advances in techniques used to identify and characterize Phytophthora effectors, knowledge is still lacking for some important species, including Phytophthora cinnamomi. This review discusses what the term PCD means and the gap in knowledge between pathogenic and developmental forms of PCD in plants. We also discuss the role cell death plays in the virulence of Phytophthora spp. and the effectors that have so far been identified as playing a role in cell death manipulation. Finally, we touch on the different techniques available to study effector functions, such as cell death induction/suppression.
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Fick A, Swart V, Backer R, Bombarely A, Engelbrecht J, van den Berg N. Partially Resistant Avocado Rootstock Dusa ® Shows Prolonged Upregulation of Nucleotide Binding-Leucine Rich Repeat Genes in Response to Phytophthora cinnamomi Infection. FRONTIERS IN PLANT SCIENCE 2022; 13:793644. [PMID: 35360305 PMCID: PMC8963474 DOI: 10.3389/fpls.2022.793644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 02/22/2022] [Indexed: 06/14/2023]
Abstract
Avocado is an important agricultural food crop in many countries worldwide. Phytophthora cinnamomi, a hemibiotrophic oomycete, remains one of the most devastating pathogens within the avocado industry, as it is near impossible to eradicate from areas where the pathogen is present. A key aspect to Phytophthora root rot disease management is the use of avocado rootstocks partially resistant to P. cinnamomi, which demonstrates an increased immune response following infection. In plant species, Nucleotide binding-Leucine rich repeat (NLR) proteins form an integral part of pathogen recognition and Effector triggered immune responses (ETI). To date, a comprehensive set of Persea americana NLR genes have yet to be identified, though their discovery is crucial to understanding the molecular mechanisms underlying P. americana-P. cinnamomi interactions. In this study, a total of 161 PaNLR genes were identified in the P. americana West-Indian pure accession genome. These putative resistance genes were characterized using bioinformatic approaches and grouped into 13 distinct PaNLR gene clusters, with phylogenetic analysis revealing high sequence similarity within these clusters. Additionally, PaNLR expression levels were analyzed in both a partially resistant (Dusa®) and a susceptible (R0.12) avocado rootstock infected with P. cinnamomi using an RNA-sequencing approach. The results showed that the partially resistant rootstock has increased expression levels of 84 PaNLRs observed up to 24 h post-inoculation, while the susceptible rootstock only showed increased PaNLR expression during the first 6 h post-inoculation. Results of this study may indicate that the partially resistant avocado rootstock has a stronger, more prolonged ETI response which enables it to suppress P. cinnamomi growth and combat disease caused by this pathogen. Furthermore, the identification of PaNLRs may be used to develop resistant rootstock selection tools, which can be employed in the avocado industry to accelerate rootstock screening programs.
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Affiliation(s)
- Alicia Fick
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Velushka Swart
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Robert Backer
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Aureliano Bombarely
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas - Universitat Politècnica de València (IBMCP-CSIC-UPV), Valencia, Spain
| | - Juanita Engelbrecht
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Noëlani van den Berg
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
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