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Wanke A, van Boerdonk S, Mahdi LK, Wawra S, Neidert M, Chandrasekar B, Saake P, Saur IML, Derbyshire P, Holton N, Menke FLH, Brands M, Pauly M, Acosta IF, Zipfel C, Zuccaro A. A GH81-type β-glucan-binding protein enhances colonization by mutualistic fungi in barley. Curr Biol 2023; 33:5071-5084.e7. [PMID: 37977140 DOI: 10.1016/j.cub.2023.10.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 08/06/2023] [Accepted: 10/25/2023] [Indexed: 11/19/2023]
Abstract
Cell walls are important interfaces of plant-fungal interactions, acting as robust physical and chemical barriers against invaders. Upon fungal colonization, plants deposit phenolics and callose at the sites of fungal penetration to prevent further fungal progression. Alterations in the composition of plant cell walls significantly impact host susceptibility. Furthermore, plants and fungi secrete glycan hydrolases acting on each other's cell walls. These enzymes release various sugar oligomers into the apoplast, some of which activate host immunity via surface receptors. Recent characterization of cell walls from plant-colonizing fungi has emphasized the abundance of β-glucans in different cell wall layers, which makes them suitable targets for recognition. To characterize host components involved in immunity against fungi, we performed a protein pull-down with the biotinylated β-glucan laminarin. Thereby, we identified a plant glycoside hydrolase family 81-type glucan-binding protein (GBP) as a β-glucan interactor. Mutation of GBP1 and its only paralog, GBP2, in barley led to decreased colonization by the beneficial root endophytes Serendipita indica and S. vermifera, as well as the arbuscular mycorrhizal fungus Rhizophagus irregularis. The reduction of colonization was accompanied by enhanced responses at the host cell wall, including an extension of callose-containing cell wall appositions. Moreover, GBP mutation in barley also reduced fungal biomass in roots by the hemibiotrophic pathogen Bipolaris sorokiniana and inhibited the penetration success of the obligate biotrophic leaf pathogen Blumeria hordei. These results indicate that GBP1 is involved in the establishment of symbiotic associations with beneficial fungi-a role that has potentially been appropriated by barley-adapted pathogens.
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Affiliation(s)
- Alan Wanke
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Sarah van Boerdonk
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Lisa Katharina Mahdi
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Stephan Wawra
- Institute for Plant Sciences, University of Cologne, Cologne, Germany
| | - Miriam Neidert
- Institute for Plant Sciences, University of Cologne, Cologne, Germany
| | - Balakumaran Chandrasekar
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Cologne, Germany
| | - Pia Saake
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Cologne, Germany
| | - Isabel M L Saur
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Cologne, Germany
| | - Paul Derbyshire
- The Sainsbury Laboratory, University of East Anglia, Norwich, UK
| | - Nicholas Holton
- The Sainsbury Laboratory, University of East Anglia, Norwich, UK
| | - Frank L H Menke
- The Sainsbury Laboratory, University of East Anglia, Norwich, UK
| | - Mathias Brands
- Institute for Plant Sciences, University of Cologne, Cologne, Germany
| | - Markus Pauly
- Institute of Plant Cell Biology and Biotechnology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Düsseldorf, Germany
| | - Ivan F Acosta
- Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Cyril Zipfel
- The Sainsbury Laboratory, University of East Anglia, Norwich, UK; Institute of Plant and Microbial Biology, University of Zurich, and Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Alga Zuccaro
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Cologne, Germany.
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Crean EE, Bilstein-Schloemer M, Maekawa T, Schulze-Lefert P, Saur IML. A dominant-negative avirulence effector of the barley powdery mildew fungus provides mechanistic insight into barley MLA immune receptor activation. J Exp Bot 2023; 74:5854-5869. [PMID: 37474129 PMCID: PMC10540733 DOI: 10.1093/jxb/erad285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 07/18/2023] [Indexed: 07/22/2023]
Abstract
Nucleotide-binding leucine-rich repeat receptors (NLRs) recognize pathogen effectors to mediate plant disease resistance often involving host cell death. Effectors escape NLR recognition through polymorphisms, allowing the pathogen to proliferate on previously resistant host plants. The powdery mildew effector AVRA13-1 is recognized by the barley NLR MLA13 and activates host cell death. We demonstrate here that a virulent form of AVRA13, called AVRA13-V2, escapes MLA13 recognition by substituting a serine for a leucine residue at the C-terminus. Counterintuitively, this substitution in AVRA13-V2 resulted in an enhanced MLA13 association and prevented the detection of AVRA13-1 by MLA13. Therefore, AVRA13-V2 is a dominant-negative form of AVRA13 and has probably contributed to the breakdown of Mla13 resistance. Despite this dominant-negative activity, AVRA13-V2 failed to suppress host cell death mediated by the MLA13 autoactive MHD variant. Neither AVRA13-1 nor AVRA13-V2 interacted with the MLA13 autoactive variant, implying that the binding moiety in MLA13 that mediates association with AVRA13-1 is altered after receptor activation. We also show that mutations in the MLA13 coiled-coil domain, which were thought to impair Ca2+ channel activity and NLR function, instead resulted in MLA13 autoactive cell death. Our results constitute an important step to define intermediate receptor conformations during NLR activation.
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Affiliation(s)
- Emma E Crean
- Institute for Plant Sciences, University of Cologne, D-50674 Cologne, Germany
| | | | - Takaki Maekawa
- Institute for Plant Sciences, University of Cologne, D-50674 Cologne, Germany
- Department for Plant Microbe Interactions, Max-Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Germany
| | - Paul Schulze-Lefert
- Department for Plant Microbe Interactions, Max-Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Germany
| | - Isabel M L Saur
- Institute for Plant Sciences, University of Cologne, D-50674 Cologne, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Germany
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Shi W, Stolze SC, Nakagami H, Misas Villamil JC, Saur IML, Doehlemann G. Combination of in vivo proximity labeling and co-immunoprecipitation identifies the host target network of a tumor-inducing effector in the fungal maize pathogen Ustilago maydis. J Exp Bot 2023; 74:4736-4750. [PMID: 37225161 PMCID: PMC10433927 DOI: 10.1093/jxb/erad188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 05/18/2023] [Indexed: 05/26/2023]
Abstract
Plant pathogens secrete effectors, which target host proteins to facilitate infection. The Ustilago maydis effector UmSee1 is required for tumor formation in the leaf during infection of maize. UmSee1 interacts with maize SGT1 (suppressor of G2 allele of skp1) and blocks its phosphorylation in vivo. In the absence of UmSee1, U. maydis cannot trigger tumor formation in the bundle sheath. However, it remains unclear which host processes are manipulated by UmSee1 and the UmSee1-SGT1 interaction to cause the observed phenotype. Proximity-dependent protein labeling involving the turbo biotin ligase tag (TurboID) for proximal labeling of proteins is a powerful tool for identifying the protein interactome. We have generated transgenic U. maydis that secretes biotin ligase-fused See1 effector (UmSee1-TurboID-3HA) directly into maize cells. This approach, in combination with conventional co-immunoprecipitation, allowed the identification of additional UmSee1 interactors in maize cells. Collectively, our data identified three ubiquitin-proteasome pathway-related proteins (ZmSIP1, ZmSIP2, and ZmSIP3) that either interact with or are close to UmSee1 during host infection of maize with U. maydis. ZmSIP3 represents a cell cycle regulator whose degradation appears to be promoted in the presence of UmSee1. Our data provide a possible explanation of the requirement for UmSee1 in tumor formation during U. maydis-Zea mays interaction.
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Affiliation(s)
- Wei Shi
- Institute for Plant Sciences University of Cologne, D-50674 Cologne, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Germany
| | - Sara C Stolze
- Protein Mass Spectrometry, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, D-50829 Cologne, Germany
| | - Hirofumi Nakagami
- Protein Mass Spectrometry, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, D-50829 Cologne, Germany
- Basic Immune System of Plants, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, D-50829 Cologne, Germany
| | - Johana C Misas Villamil
- Institute for Plant Sciences University of Cologne, D-50674 Cologne, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Germany
| | - Isabel M L Saur
- Institute for Plant Sciences University of Cologne, D-50674 Cologne, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Germany
| | - Gunther Doehlemann
- Institute for Plant Sciences University of Cologne, D-50674 Cologne, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Germany
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Saur IML, Lawson AW, Schulze-Lefert P. Buy one, get two. Nat Plants 2022; 8:100-101. [PMID: 35105950 DOI: 10.1038/s41477-022-01097-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Affiliation(s)
- Isabel M L Saur
- Institute for Plant Sciences, University of Cologne, Cologne, Germany.
- Cluster of Excellence on Plant Sciences (CEPLAS), Cologne, Germany.
| | - Aaron W Lawson
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Paul Schulze-Lefert
- Cluster of Excellence on Plant Sciences (CEPLAS), Cologne, Germany.
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany.
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Bauer S, Yu D, Lawson AW, Saur IML, Frantzeskakis L, Kracher B, Logemann E, Chai J, Maekawa T, Schulze-Lefert P. The leucine-rich repeats in allelic barley MLA immune receptors define specificity towards sequence-unrelated powdery mildew avirulence effectors with a predicted common RNase-like fold. PLoS Pathog 2021; 17:e1009223. [PMID: 33534797 PMCID: PMC7857584 DOI: 10.1371/journal.ppat.1009223] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 12/07/2020] [Indexed: 12/15/2022] Open
Abstract
Nucleotide-binding domain leucine-rich repeat-containing receptors (NLRs) in plants can detect avirulence (AVR) effectors of pathogenic microbes. The Mildew locus a (Mla) NLR gene has been shown to confer resistance against diverse fungal pathogens in cereal crops. In barley, Mla has undergone allelic diversification in the host population and confers isolate-specific immunity against the powdery mildew-causing fungal pathogen Blumeria graminis forma specialis hordei (Bgh). We previously isolated the Bgh effectors AVRA1, AVRA7, AVRA9, AVRA13, and allelic AVRA10/AVRA22, which are recognized by matching MLA1, MLA7, MLA9, MLA13, MLA10 and MLA22, respectively. Here, we extend our knowledge of the Bgh effector repertoire by isolating the AVRA6 effector, which belongs to the family of catalytically inactive RNase-Like Proteins expressed in Haustoria (RALPHs). Using structural prediction, we also identified RNase-like folds in AVRA1, AVRA7, AVRA10/AVRA22, and AVRA13, suggesting that allelic MLA recognition specificities could detect structurally related avirulence effectors. To better understand the mechanism underlying the recognition of effectors by MLAs, we deployed chimeric MLA1 and MLA6, as well as chimeric MLA10 and MLA22 receptors in plant co-expression assays, which showed that the recognition specificity for AVRA1 and AVRA6 as well as allelic AVRA10 and AVRA22 is largely determined by the receptors' C-terminal leucine-rich repeats (LRRs). The design of avirulence effector hybrids allowed us to identify four specific AVRA10 and five specific AVRA22 aa residues that are necessary to confer MLA10- and MLA22-specific recognition, respectively. This suggests that the MLA LRR mediates isolate-specific recognition of structurally related AVRA effectors. Thus, functional diversification of multi-allelic MLA receptors may be driven by a common structural effector scaffold, which could be facilitated by proliferation of the RALPH effector family in the pathogen genome.
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Affiliation(s)
- Saskia Bauer
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Dongli Yu
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Institute of Biochemistry, University of Cologne at Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Aaron W. Lawson
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Isabel M. L. Saur
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | | | - Barbara Kracher
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Elke Logemann
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Jijie Chai
- Institute of Biochemistry, University of Cologne at Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Takaki Maekawa
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Paul Schulze-Lefert
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
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Saur IML, Hückelhoven R. Recognition and defence of plant-infecting fungal pathogens. J Plant Physiol 2021; 256:153324. [PMID: 33249386 DOI: 10.1016/j.jplph.2020.153324] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 11/04/2020] [Accepted: 11/04/2020] [Indexed: 06/12/2023]
Abstract
Attempted infections of plants with fungi result in diverse outcomes ranging from symptom-less resistance to severe disease and even death of infected plants. The deleterious effect on crop yield have led to intense focus on the cellular and molecular mechanisms that explain the difference between resistance and susceptibility. This research has uncovered plant resistance or susceptibility genes that explain either dominant or recessive inheritance of plant resistance with many of them coding for receptors that recognize pathogen invasion. Approaches based on cell biology and phytochemistry have contributed to identifying factors that halt an invading fungal pathogen from further invasion into or between plant cells. Plant chemical defence compounds, antifungal proteins and structural reinforcement of cell walls appear to slow down fungal growth or even prevent fungal penetration in resistant plants. Additionally, the hypersensitive response, in which a few cells undergo a strong local immune reaction, including programmed cell death at the site of infection, stops in particular biotrophic fungi from spreading into surrounding tissue. In this review, we give a general overview of plant recognition and defence of fungal parasites tracing back to the early 20th century with a special focus on Triticeae and on the progress that was made in the last 30 years.
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Affiliation(s)
- Isabel M L Saur
- Max Planck Institute for Plant Breeding Research, Department of Plant-Microbe Interactions, Carl-von-Linné-Weg 10, 50829 Cologne, Germany.
| | - Ralph Hückelhoven
- Phytopathology, TUM School of Life Sciences Weihenstephan, Technical University of Munich, Ramann-Straße 2, 85354 Freising, Germany.
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Saur IML, Bauer S, Lu X, Schulze-Lefert P. A cell death assay in barley and wheat protoplasts for identification and validation of matching pathogen AVR effector and plant NLR immune receptors. Plant Methods 2019; 15:118. [PMID: 31666804 PMCID: PMC6813131 DOI: 10.1186/s13007-019-0502-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 10/14/2019] [Indexed: 05/08/2023]
Abstract
BACKGROUND Plant disease resistance to host-adapted pathogens is often mediated by host nucleotide-binding and leucine-rich repeat (NLR) receptors that detect matching pathogen avirulence effectors (AVR) inside plant cells. AVR-triggered NLR activation is typically associated with a rapid host cell death at sites of attempted infection and this response constitutes a widely used surrogate for NLR activation. However, it is challenging to assess this cell death in cereal hosts. RESULTS Here we quantify cell death upon NLR-mediated recognition of fungal pathogen AVRs in mesophyll leaf protoplasts of barley and wheat. We provide measurements for the recognition of the fungal AVRs AvrSr50 and AVR a1 by their respective cereal NLRs Sr50 and Mla1 upon overexpression of the AVR and NLR pairs in mesophyll protoplast of both, wheat and barley. CONCLUSIONS Our data demonstrate that the here described approach can be effectively used to detect and quantify death of wheat and barley cells induced by overexpression of NLR and AVR effectors or AVR effector candidate genes from diverse fungal pathogens within 24 h.
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Affiliation(s)
- Isabel M. L. Saur
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
| | - Saskia Bauer
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
| | - Xunli Lu
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
- Present Address: Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, 100193 China
| | - Paul Schulze-Lefert
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
- Cluster of Excellence on Plant Sciences, 40225 Düsseldorf, Germany
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Maekawa T, Kracher B, Saur IML, Yoshikawa-Maekawa M, Kellner R, Pankin A, von Korff M, Schulze-Lefert P. Subfamily-Specific Specialization of RGH1/MLA Immune Receptors in Wild Barley. Mol Plant Microbe Interact 2019; 32:107-119. [PMID: 30295580 DOI: 10.1094/mpmi-07-18-0186-fi] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The barley disease resistance (R) gene locus mildew locus A (Mla) provides isolate-specific resistance against the powdery mildew fungus Blumeria graminis hordei and has been introgressed into modern cultivars from diverse germplasms, including the wild relative Hordeum spontaneum. Known Mla disease resistance specificities to B. graminis hordei appear to encode allelic variants of the R gene homolog 1 (RGH1) family of nucleotide-binding domain and leucine-rich repeat (NLR) proteins. Here, we sequenced and assembled the transcriptomes of 50 H. spontaneum accessions representing nine populations distributed throughout the Fertile Crescent. The assembled Mla transcripts exhibited rich sequence diversity, linked neither to geographic origin nor population structure, and could be grouped into two similar-sized subfamilies based on two major N-terminal coiled-coil (CC) signaling domains that are both capable of eliciting cell death. The presence of positively selected sites located mainly in the C-terminal leucine-rich repeats of both MLA subfamilies, together with the fact that both CC signaling domains mediate cell death, implies that the two subfamilies are actively maintained in the population. Unexpectedly, known MLA receptor variants that confer B. graminis hordei resistance belong exclusively to one subfamily. Thus, signaling domain divergence, potentially as adaptation to distinct pathogen populations, is an evolutionary signature of functional diversification of an immune receptor. Copyright © 2018 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)
- Takaki Maekawa
- 1 Max Planck Institute for Plant Breeding Research, Cologne, Germany; and
| | - Barbara Kracher
- 1 Max Planck Institute for Plant Breeding Research, Cologne, Germany; and
| | - Isabel M L Saur
- 1 Max Planck Institute for Plant Breeding Research, Cologne, Germany; and
| | | | - Ronny Kellner
- 1 Max Planck Institute for Plant Breeding Research, Cologne, Germany; and
| | - Artem Pankin
- 1 Max Planck Institute for Plant Breeding Research, Cologne, Germany; and
- 2 Institute of Plant Genetics, Heinrich-Heine-University and Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Maria von Korff
- 1 Max Planck Institute for Plant Breeding Research, Cologne, Germany; and
- 2 Institute of Plant Genetics, Heinrich-Heine-University and Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
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Thynne E, Saur IML, Simbaqueba J, Ogilvie HA, Gonzalez‐Cendales Y, Mead O, Taranto A, Catanzariti A, McDonald MC, Schwessinger B, Jones DA, Rathjen JP, Solomon PS. Fungal phytopathogens encode functional homologues of plant rapid alkalinization factor (RALF) peptides. Mol Plant Pathol 2017; 18:811-824. [PMID: 27291634 PMCID: PMC6638259 DOI: 10.1111/mpp.12444] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 06/08/2016] [Accepted: 06/09/2016] [Indexed: 05/19/2023]
Abstract
In this article, we describe the presence of genes encoding close homologues of an endogenous plant peptide, rapid alkalinization factor (RALF), within the genomes of 26 species of phytopathogenic fungi. Members of the RALF family are key growth factors in plants, and the sequence of the RALF active region is well conserved between plant and fungal proteins. RALF1-like sequences were observed in most cases; however, RALF27-like sequences were present in the Sphaerulina musiva and Septoria populicola genomes. These two species are pathogens of poplar and, interestingly, the closest relative to their respective RALF genes is a poplar RALF27-like sequence. RALF peptides control cellular expansion during plant development, but were originally defined on the basis of their ability to induce rapid alkalinization in tobacco cell cultures. To test whether the fungal RALF peptides were biologically active in plants, we synthesized RALF peptides corresponding to those encoded by two sequenced genomes of the tomato pathogen Fusarium oxysporum f. sp. lycopersici. One of these peptides inhibited the growth of tomato seedlings and elicited responses in tomato and Nicotiana benthamiana typical of endogenous plant RALF peptides (reactive oxygen species burst, induced alkalinization and mitogen-activated protein kinase activation). Gene expression analysis confirmed that a RALF-encoding gene in F. oxysporum f. sp. lycopersici was expressed during infection on tomato. However, a subsequent reverse genetics approach revealed that the RALF peptide was not required by F. oxysporum f. sp. lycopersici for infection on tomato roots. This study has demonstrated the presence of functionally active RALF peptides encoded within phytopathogens that harbour an as yet undetermined role in plant-pathogen interactions.
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Affiliation(s)
- Elisha Thynne
- Plant Sciences DivisionThe Australian National UniversityCanberra2601Australia
| | - Isabel M. L. Saur
- Plant Sciences DivisionThe Australian National UniversityCanberra2601Australia
| | - Jaime Simbaqueba
- Plant Sciences DivisionThe Australian National UniversityCanberra2601Australia
| | - Huw A. Ogilvie
- Evolution, Ecology and Genetics Division, Research School of BiologyThe Australian National UniversityCanberra2601Australia
- Computational Evolution Group, The University of AucklandAuckland1142New Zealand
| | | | - Oliver Mead
- Plant Sciences DivisionThe Australian National UniversityCanberra2601Australia
| | - Adam Taranto
- Plant Sciences DivisionThe Australian National UniversityCanberra2601Australia
| | | | - Megan C. McDonald
- Plant Sciences DivisionThe Australian National UniversityCanberra2601Australia
| | | | - David A. Jones
- Plant Sciences DivisionThe Australian National UniversityCanberra2601Australia
| | - John P. Rathjen
- Plant Sciences DivisionThe Australian National UniversityCanberra2601Australia
| | - Peter S. Solomon
- Plant Sciences DivisionThe Australian National UniversityCanberra2601Australia
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Saur IML, Kadota Y, Sklenar J, Holton NJ, Smakowska E, Belkhadir Y, Zipfel C, Rathjen JP. NbCSPR underlies age-dependent immune responses to bacterial cold shock protein in Nicotiana benthamiana. Proc Natl Acad Sci U S A 2016; 113:3389-94. [PMID: 26944079 PMCID: PMC4812737 DOI: 10.1073/pnas.1511847113] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Plants use receptor kinases (RKs) and receptor-like proteins (RLPs) as pattern recognition receptors (PRRs) to sense pathogen-associated molecular patterns (PAMPs) that are typical of whole classes of microbes. After ligand perception, many leucine-rich repeat (LRR)-containing PRRs interact with the LRR-RK BRI1-ASSOCIATED KINASE 1 (BAK1). BAK1 is thus expected to interact with unknown PRRs. Here, we used BAK1 as molecular bait to identify a previously unknown LRR-RLP required for the recognition of the csp22 peptide derived from bacterial cold shock protein. We established a method to identify proteins that interact with BAK1 only after csp22 treatment. BAK1 was expressed transiently in Nicotiana benthamiana and immunopurified after treatment with csp22. BAK1-associated proteins were identified by mass spectrometry. We identified several proteins including known BAK1 interactors and a previously uncharacterized LRR-RLP that we termed RECEPTOR-LIKE PROTEIN REQUIRED FOR CSP22 RESPONSIVENESS (NbCSPR). This RLP associates with BAK1 upon csp22 treatment, and NbCSPR-silenced plants are impaired in csp22-induced defense responses. NbCSPR confers resistance to bacteria in an age-dependent and flagellin-induced manner. As such, it limits bacterial growth and Agrobacterium-mediated transformation of flowering N. benthamiana plants. Transgenic expression of NbCSPR into Arabidopsis thaliana conferred responsiveness to csp22 and antibacterial resistance. Our method may be used to identify LRR-type RKs and RLPs required for PAMP perception/responsiveness, even when the active purified PAMP has not been defined.
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Affiliation(s)
- Isabel M L Saur
- Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Yasuhiro Kadota
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Jan Sklenar
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Nicholas J Holton
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Elwira Smakowska
- Gregor Mendel Institute of Molecular Plant Biology GmbH, Austrian Academy of Sciences, 1030 Vienna, Austria
| | - Youssef Belkhadir
- Gregor Mendel Institute of Molecular Plant Biology GmbH, Austrian Academy of Sciences, 1030 Vienna, Austria
| | - Cyril Zipfel
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, United Kingdom;
| | - John P Rathjen
- Research School of Biology, The Australian National University, Acton, ACT 2601, Australia;
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Ntoukakis V, Saur IML, Conlan B, Rathjen JP. The changing of the guard: the Pto/Prf receptor complex of tomato and pathogen recognition. Curr Opin Plant Biol 2014; 20:69-74. [PMID: 24845576 DOI: 10.1016/j.pbi.2014.04.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 04/07/2014] [Accepted: 04/17/2014] [Indexed: 05/05/2023]
Abstract
One important model for disease resistance is the Prf recognition complex of tomato, which responds to different bacterial effectors. Prf incorporates a protein kinase called Pto as its recognition domain that mimics effector virulence targets, and activates resistance after interaction with specific effectors. Recent findings show that this complex is oligomeric, and reveal how this impacts mechanism. Oligomerisation brings two or more kinases into proximity, where they can phosphorylate each other after effector perception. Effector attack on one kinase activates another in trans, constituting a molecular trap for the effector. Oligomerisation of plant resistance proteins may be a general concept that broadens pathogen recognition and restricts the ability of pathogens to evolve virulence.
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Affiliation(s)
- Vardis Ntoukakis
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Isabel M L Saur
- Research School of Biology, The Australian National University, Acton 0200, Australian Capital Territory, Australia
| | - Brendon Conlan
- Research School of Biology, The Australian National University, Acton 0200, Australian Capital Territory, Australia
| | - John P Rathjen
- Research School of Biology, The Australian National University, Acton 0200, Australian Capital Territory, Australia.
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12
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Saur IML, Oakes M, Djordjevic MA, Imin N. Crosstalk between the nodulation signaling pathway and the autoregulation of nodulation in Medicago truncatula. New Phytol 2011; 190:865-874. [PMID: 21507004 DOI: 10.1111/j.1469-8137.2011.03738.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A subset of CLAVATA3/endosperm-surrounding region-related (CLE) peptides are involved in autoregulation of nodulation (AON) in Medicago truncatula (e.g. MtCLE12 and MtCLE13). However, their linkage to other components of the AON pathways downstream of the shoot-derived inhibitor (SDI) is not understood. We have ectopically expressed the putative peptide ligand encoding genes MtCLE12 and MtCLE13 in M. truncatula which abolished nodulation completely in wild-type roots but not in the supernodulating null mutant sunn-4. Further, root growth inhibition was detected when MtCLE12 was ectopically expressed in wild-type roots or synthetic CLE12 peptide was applied exogenously. To identify downstream genes, roots of wild-type and sunn-4 mutant overexpressing MtCLE12 were used for quantitative gene expression analysis. We found that, in 35S:MtCLE12 roots, NODULE INCEPTION (NIN, a central regulator of nodulation) was down-regulated, whereas MtEFD (ethylene response factor required for nodule differentiation) and MtRR8 (a type-A response regulator thought to be involved in the negative regulation of cytokinin signaling), were up-regulated. Moreover, we found that the up-regulation of MtEFD and MtRR8 caused by overexpressing MtCLE12 is SUNN-dependent. Hence, our data link for the first time the pathways for Nod factor signaling, cytokinin perception and AON.
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Affiliation(s)
- Isabel M L Saur
- Australian Research Council Centre of Excellence for Integrative Legume Research, Plant Science Division, Research School of Biology, The Australian National University, Canberra 0200, Australia
| | - Marie Oakes
- Australian Research Council Centre of Excellence for Integrative Legume Research, Plant Science Division, Research School of Biology, The Australian National University, Canberra 0200, Australia
| | - Michael A Djordjevic
- Australian Research Council Centre of Excellence for Integrative Legume Research, Plant Science Division, Research School of Biology, The Australian National University, Canberra 0200, Australia
| | - Nijat Imin
- Australian Research Council Centre of Excellence for Integrative Legume Research, Plant Science Division, Research School of Biology, The Australian National University, Canberra 0200, Australia
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