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Chapman AVE, Elmore JM, McReynolds M, Walley JW, Wise RP. SGT1-Specific Domain Mutations Impair Interactions with the Barley MLA6 Immune Receptor in Association with Loss of NLR Protein. Mol Plant Microbe Interact 2022; 35:274-289. [PMID: 34889653 DOI: 10.1094/mpmi-08-21-0217-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The Mla (Mildew resistance locus a) of barley (Hordeum vulgare L.) is an effective model for cereal immunity against fungal pathogens. Like many resistance proteins, variants of the MLA coiled-coil nucleotide-binding leucine-rich repeat (CC-NLR) receptor often require the HRS complex (HSP90, RAR1, and SGT1) to function. However, functional analysis of Sgt1 has been particularly difficult, as deletions are often lethal. Recently, we identified rar3 (required for Mla6 resistance 3), an in-frame Sgt1ΔKL308-309 mutation in the SGT1-specific domain, that alters resistance conferred by MLA but without lethality. Here, we use autoactive MLA6 and recombinant yeast-two-hybrid strains with stably integrated HvRar1 and HvHsp90 to determine that this mutation weakens but does not entirely disrupt the interaction between SGT1 and MLA. This causes a concomitant reduction in MLA6 protein accumulation below the apparent threshold required for effective resistance. The ΔKL308-309 deletion had a lesser effect on intramolecular interactions than alanine or arginine substitutions, and MLA variants that display diminished interactions with SGT1 appear to be disproportionately affected by the SGT1ΔKL308-309 mutation. We hypothesize that those dimeric plant CC-NLRs that appear unaffected by Sgt1 silencing are those with the strongest intermolecular interactions with it. Combining our data with recent work in CC-NLRs, we propose a cyclical model of the MLA-HRS resistosome interactions.[Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 "No Rights Reserved" license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2022.
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Affiliation(s)
- Antony V E Chapman
- Interdepartmental Genetics & Genomics, Iowa State University, Ames, IA 50011, U.S.A
- Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, U.S.A
| | - J Mitch Elmore
- Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, U.S.A
| | - Maxwell McReynolds
- Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, U.S.A
- Interdepartmental Plant Biology, Iowa State University, Ames, IA 50011, U.S.A
| | - Justin W Walley
- Interdepartmental Genetics & Genomics, Iowa State University, Ames, IA 50011, U.S.A
- Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, U.S.A
- Interdepartmental Plant Biology, Iowa State University, Ames, IA 50011, U.S.A
| | - Roger P Wise
- Interdepartmental Genetics & Genomics, Iowa State University, Ames, IA 50011, U.S.A
- Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, U.S.A
- Corn Insects and Crop Genetics Research Unit, USDA-Agricultural Research Service, Ames, IA 50011, U.S.A
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Chapman AVE, Hunt M, Surana P, Velásquez-Zapata V, Xu W, Fuerst G, Wise RP. Disruption of barley immunity to powdery mildew by an in-frame Lys-Leu deletion in the essential protein SGT1. Genetics 2021; 217:6043926. [PMID: 33724411 DOI: 10.1093/genetics/iyaa026] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 12/04/2020] [Indexed: 01/22/2023] Open
Abstract
Barley (Hordeum vulgare L.) Mla (Mildew resistance locus a) and its nucleotide-binding, leucine-rich-repeat receptor (NLR) orthologs protect many cereal crops from diseases caused by fungal pathogens. However, large segments of the Mla pathway and its mechanisms remain unknown. To further characterize the molecular interactions required for NLR-based immunity, we used fast-neutron mutagenesis to screen for plants compromised in MLA-mediated response to the powdery mildew fungus, Blumeria graminis f. sp. hordei. One variant, m11526, contained a novel mutation, designated rar3 (required for Mla6 resistance3), that abolishes race-specific resistance conditioned by the Mla6, Mla7, and Mla12 alleles, but does not compromise immunity mediated by Mla1, Mla9, Mla10, and Mla13. This is analogous to, but unique from, the differential requirement of Mla alleles for the co-chaperone Rar1 (required for Mla12 resistance1). We used bulked-segregant-exome capture and fine mapping to delineate the causal mutation to an in-frame Lys-Leu deletion within the SGS domain of SGT1 (Suppressor of G-two allele of Skp1, Sgt1ΔKL308-309), the structural region that interacts with MLA proteins. In nature, mutations to Sgt1 usually cause lethal phenotypes, but here we pinpoint a unique modification that delineates its requirement for some disease resistances, while unaffecting others as well as normal cell processes. Moreover, the data indicate that the requirement of SGT1 for resistance signaling by NLRs can be delimited to single sites on the protein. Further study could distinguish the regions by which pathogen effectors and host proteins interact with SGT1, facilitating precise editing of effector incompatible variants.
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Affiliation(s)
- Antony V E Chapman
- Interdepartmental Genetics & Genomics, Iowa State University, Ames, IA 50011, USA.,Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, USA
| | - Matthew Hunt
- Interdepartmental Genetics & Genomics, Iowa State University, Ames, IA 50011, USA.,Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, USA
| | - Priyanka Surana
- Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, USA.,Program in Bioinformatics & Computational Biology, Iowa State University, Ames, IA 50011, USA
| | - Valeria Velásquez-Zapata
- Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, USA.,Program in Bioinformatics & Computational Biology, Iowa State University, Ames, IA 50011, USA
| | - Weihui Xu
- Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, USA
| | - Greg Fuerst
- Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, USA.,Corn Insects and Crop Genetics Research, USDA-Agricultural Research Service, Ames, IA 50011, USA
| | - Roger P Wise
- Interdepartmental Genetics & Genomics, Iowa State University, Ames, IA 50011, USA.,Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, USA.,Program in Bioinformatics & Computational Biology, Iowa State University, Ames, IA 50011, USA.,Corn Insects and Crop Genetics Research, USDA-Agricultural Research Service, Ames, IA 50011, USA
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Carter ME, Helm M, Chapman AVE, Wan E, Restrepo Sierra AM, Innes RW, Bogdanove AJ, Wise RP. Convergent Evolution of Effector Protease Recognition by Arabidopsis and Barley. Mol Plant Microbe Interact 2019; 32:550-565. [PMID: 30480480 DOI: 10.1094/mpmi-07-18-0202-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: 06/09/2023]
Abstract
The Pseudomonas syringae cysteine protease AvrPphB activates the Arabidopsis resistance protein RPS5 by cleaving a second host protein, PBS1. AvrPphB induces defense responses in other plant species, but the genes and mechanisms mediating AvrPphB recognition in those species have not been defined. Here, we show that AvrPphB induces defense responses in diverse barley cultivars. We also show that barley contains two PBS1 orthologs, that their products are cleaved by AvrPphB, and that the barley AvrPphB response maps to a single locus containing a nucleotide-binding leucine-rich repeat (NLR) gene, which we termed AvrPphB Response 1 (Pbr1). Transient coexpression of PBR1 with wild-type AvrPphB but not with a protease inactive mutant triggered defense responses, indicating that PBR1 detects AvrPphB protease activity. Additionally, PBR1 coimmunoprecipitated with barley and Nicotiana benthamiana PBS1 proteins, suggesting mechanistic similarity to detection by RPS5. Lastly, we determined that wheat cultivars also recognize AvrPphB protease activity and contain two putative Pbr1 orthologs. Phylogenetic analyses showed, however, that Pbr1 is not orthologous to RPS5. Our results indicate that the ability to recognize AvrPphB evolved convergently and imply that selection to guard PBS1-like proteins occurs across species. Also, these results suggest that PBS1-based decoys may be used to engineer protease effector recognition-based resistance in barley and wheat.
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Affiliation(s)
- Morgan E Carter
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
| | - Matthew Helm
- 2 Department of Biology, Indiana University, Bloomington, IN, U.S.A
| | - Antony V E Chapman
- 3 Interdepartmental Genetics & Genomics Graduate Program and
- 4 Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA, U.S.A
| | - Emily Wan
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
| | - Ana Maria Restrepo Sierra
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
- 5 Facultad de Ciencias, Universidad Nacional de Colombia Sede Medellín, Medellín, Colombia; and
| | - Roger W Innes
- 2 Department of Biology, Indiana University, Bloomington, IN, U.S.A
| | - Adam J Bogdanove
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
| | - Roger P Wise
- 3 Interdepartmental Genetics & Genomics Graduate Program and
- 4 Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA, U.S.A
- 6 Corn Insects and Crop Genetics Research, USDA-Agricultural Research Service, Ames, IA, U.S.A
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Bao Y, Zarecor S, Shah D, Tuel T, Campbell DA, Chapman AVE, Imberti D, Kiekhaefer D, Imberti H, Lübberstedt T, Yin Y, Nettleton D, Lawrence-Dill CJ, Whitham SA, Tang L, Howell SH. Assessing plant performance in the Enviratron. Plant Methods 2019; 15:117. [PMID: 31660060 PMCID: PMC6806530 DOI: 10.1186/s13007-019-0504-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 10/15/2019] [Indexed: 05/05/2023]
Abstract
BACKGROUND Assessing the impact of the environment on plant performance requires growing plants under controlled environmental conditions. Plant phenotypes are a product of genotype × environment (G × E), and the Enviratron at Iowa State University is a facility for testing under controlled conditions the effects of the environment on plant growth and development. Crop plants (including maize) can be grown to maturity in the Enviratron, and the performance of plants under different environmental conditions can be monitored 24 h per day, 7 days per week throughout the growth cycle. RESULTS The Enviratron is an array of custom-designed plant growth chambers that simulate different environmental conditions coupled with precise sensor-based phenotypic measurements carried out by a robotic rover. The rover has workflow instructions to periodically visit plants growing in the different chambers where it measures various growth and physiological parameters. The rover consists of an unmanned ground vehicle, an industrial robotic arm and an array of sensors including RGB, visible and near infrared (VNIR) hyperspectral, thermal, and time-of-flight (ToF) cameras, laser profilometer and pulse-amplitude modulated (PAM) fluorometer. The sensors are autonomously positioned for detecting leaves in the plant canopy, collecting various physiological measurements based on computer vision algorithms and planning motion via "eye-in-hand" movement control of the robotic arm. In particular, the automated leaf probing function that allows the precise placement of sensor probes on leaf surfaces presents a unique advantage of the Enviratron system over other types of plant phenotyping systems. CONCLUSIONS The Enviratron offers a new level of control over plant growth parameters and optimizes positioning and timing of sensor-based phenotypic measurements. Plant phenotypes in the Enviratron are measured in situ-in that the rover takes sensors to the plants rather than moving plants to the sensors.
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Affiliation(s)
- Yin Bao
- Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA USA
- Present Address: Department of Biosystems Engineering, Auburn University, 213 Corley Building, 350 Mell St, Auburn, AL 36830 USA
| | - Scott Zarecor
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA USA
| | - Dylan Shah
- Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA USA
- Present Address: The Faboratory, Yale University, 9 Hillhouse Ave, ML 118, New Haven, CT 06511 USA
| | - Taylor Tuel
- Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA USA
| | - Darwin A. Campbell
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA USA
| | - Antony V. E. Chapman
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA USA
| | | | | | | | | | - Yanhai Yin
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA USA
| | - Dan Nettleton
- Department of Statistics, Iowa State University, Ames, IA USA
| | - Carolyn J. Lawrence-Dill
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA USA
- Department of Agronomy, Iowa State University, Ames, IA USA
| | - Steven A. Whitham
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA USA
| | - Lie Tang
- Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA USA
| | - Stephen H. Howell
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA USA
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