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Engelhardt S, Trutzenberg A, Kopischke M, Probst K, McCollum C, Hofer J, Hückelhoven R. Barley RIC157, a potential RACB scaffold protein, is involved in susceptibility to powdery mildew. PLANT MOLECULAR BIOLOGY 2023; 111:329-344. [PMID: 36562946 PMCID: PMC10090020 DOI: 10.1007/s11103-022-01329-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 12/03/2022] [Indexed: 06/15/2023]
Abstract
CRIB motif-containing barley RIC157 is a novel ROP scaffold protein that interacts directly with barley RACB, promotes susceptibility to fungal penetration, and colocalizes with RACB at the haustorial neck. Successful obligate pathogens benefit from host cellular processes. For the biotrophic ascomycete fungus Blumeria hordei (Bh) it has been shown that barley RACB, a small monomeric G-protein (ROP, Rho of plants), is required for full susceptibility to fungal penetration. The susceptibility function of RACB probably lies in its role in cell polarity, which may be co-opted by the pathogen for invasive ingrowth of its haustorium. However, how RACB supports fungal penetration success and which other host proteins coordinate this process is incompletely understood. RIC (ROP-Interactive and CRIB-(Cdc42/Rac Interactive Binding) motif-containing) proteins are considered scaffold proteins which can interact directly with ROPs via a conserved CRIB motif. Here we describe a previously uncharacterized barley RIC protein, RIC157, which can interact directly with RACB in planta. We show that, in the presence of constitutively activated RACB, RIC157 shows a localization at the cell periphery/plasma membrane, whereas it otherwise localizes to the cytoplasm. RIC157 appears to mutually stabilize the plasma membrane localization of the activated ROP. During fungal infection, RIC157 and RACB colocalize at the penetration site, particularly at the haustorial neck. Additionally, transiently overexpressed RIC157 renders barley epidermal cells more susceptible to fungal penetration. We discuss that RIC157 may promote fungal penetration into barley epidermal cells by operating probably downstream of activated RACB.
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Affiliation(s)
- Stefan Engelhardt
- Phytopathology, TUM School of Life Sciences, Technical University of Munich, Emil- Ramann-Str.2, 85354, Freising-Weihenstephan, Germany
| | - Adriana Trutzenberg
- Phytopathology, TUM School of Life Sciences, Technical University of Munich, Emil- Ramann-Str.2, 85354, Freising-Weihenstephan, Germany
| | - Michaela Kopischke
- Phytopathology, TUM School of Life Sciences, Technical University of Munich, Emil- Ramann-Str.2, 85354, Freising-Weihenstephan, Germany
| | - Katja Probst
- Phytopathology, TUM School of Life Sciences, Technical University of Munich, Emil- Ramann-Str.2, 85354, Freising-Weihenstephan, Germany
| | - Christopher McCollum
- Phytopathology, TUM School of Life Sciences, Technical University of Munich, Emil- Ramann-Str.2, 85354, Freising-Weihenstephan, Germany
| | - Johanna Hofer
- Phytopathology, TUM School of Life Sciences, Technical University of Munich, Emil- Ramann-Str.2, 85354, Freising-Weihenstephan, Germany
| | - Ralph Hückelhoven
- Phytopathology, TUM School of Life Sciences, Technical University of Munich, Emil- Ramann-Str.2, 85354, Freising-Weihenstephan, Germany.
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Affiliation(s)
- Minhang Yuan
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Boying Cai
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Xiu-Fang Xin
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of the Chinese Academy of Sciences, Beijing, China
- CAS-JIC Center of Excellence for Plant and Microbial Sciences (CEPAMS), Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- * E-mail:
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Comprehensive Analysis of Subcellular Localization, Immune Function and Role in Bacterial wilt Disease Resistance of Solanum lycopersicum Linn. ROP Family Small GTPases. Int J Mol Sci 2022; 23:ijms23179727. [PMID: 36077125 PMCID: PMC9456112 DOI: 10.3390/ijms23179727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 08/22/2022] [Accepted: 08/24/2022] [Indexed: 11/26/2022] Open
Abstract
ROPs (Rho-like GTPases from plants) belong to the Rho-GTPase subfamily and serve as molecular switches for regulating diverse cellular events, including morphogenesis and stress responses. However, the immune functions of ROPs in Solanum lycopersicum Linn. (tomato) is still largely unclear. The tomato genome contains nine genes encoding ROP-type small GTPase family proteins (namely SlRop1–9) that fall into five distinct groups as revealed by phylogenetic tree. We studied the subcellular localization and immune response induction of nine SlRops by using a transient overexpression system in Nicotiana benthamiana Domin. Except for SlRop1 and SlRop3, which are solely localized at the plasma membrane, most of the remaining ROPs have additional nuclear and/or cytoplasmic distributions. We also revealed that the number of basic residues in the polybasic region of ROPs tends to be correlated with their membrane accumulation. Though nine SlRops are highly conserved at the RHO (Ras Homology) domains, only seven constitutively active forms of SlRops were able to trigger hypersensitive responses. Furthermore, we analyzed the tissue-specific expression patterns of nine ROPs and found that the expression levels of SlRop3, 4 and 6 were generally high in different tissues. The expression levels of SlRop1, 2 and 7 significantly decreased in tomato seedlings after infection with Ralstonia solanacearum (E.F. Smith) Yabuuchi et al. (GMI1000); the others did not respond. Infection assays among nine ROPs showed that SlRop3 and SlRop4 might be positive regulators of tomato bacterial wilt disease resistance, whereas the rest of the ROPs may not contribute to defense. Our study provides systematic evidence of tomato Rho-related small GTPases for localization, immune response, and disease resistance.
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Nakano RT. A Friend in Common: A Small GTPase in Independent PTI and ETI Immune Receptor Complexes. PLANT & CELL PHYSIOLOGY 2021; 62:1645-1647. [PMID: 34698866 DOI: 10.1093/pcp/pcab154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 10/20/2021] [Accepted: 10/21/2021] [Indexed: 06/13/2023]
Affiliation(s)
- Ryohei Thomas Nakano
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, Cologne 50829, Germany
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