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Rahman MS, Madina MH, Plourde MB, dos Santos KCG, Huang X, Zhang Y, Laliberté JF, Germain H. The Fungal Effector Mlp37347 Alters Plasmodesmata Fluxes and Enhances Susceptibility to Pathogen. Microorganisms 2021; 9:microorganisms9061232. [PMID: 34204123 PMCID: PMC8228402 DOI: 10.3390/microorganisms9061232] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 05/28/2021] [Accepted: 06/03/2021] [Indexed: 12/15/2022] Open
Abstract
Melampsora larici-populina (Mlp) is a devastating pathogen of poplar trees, causing the defoliating poplar leaf rust disease. Genomic studies have revealed that Mlp possesses a repertoire of 1184 small secreted proteins (SSPs), some of them being characterized as candidate effectors. However, how they promote virulence is still unclear. This study investigates the candidate effector Mlp37347’s role during infection. We developed a stable Arabidopsis transgenic line expressing Mlp37347 tagged with the green fluorescent protein (GFP). We found that the effector accumulated exclusively at plasmodesmata (PD). Moreover, the presence of the effector at plasmodesmata favors enhanced plasmodesmatal flux and reduced callose deposition. Transcriptome profiling and a gene ontology (GO) analysis of transgenic Arabidopsis plants expressing the effector revealed that the genes involved in glucan catabolic processes are up-regulated. This effector has previously been shown to interact with glutamate decarboxylase 1 (GAD1), and in silico docking analysis supported the strong binding between Mlp37347 and GAD1 in this study. In infection assays, the effector promoted Hyalonoperospora arabidopsidis growth but not bacterial growth. Our investigation suggests that the effector Mlp37347 targets PD in host cells and promotes parasitic growth.
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Affiliation(s)
- Md. Saifur Rahman
- Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, QC G8Z 4M3, Canada; (M.S.R.); (M.H.M.); (M.B.P.); (K.C.G.d.S.)
- Department of Computational Medicine and Bioinformatics, University of Michigan, 100 Washtenaw Avenue, Ann Arbor, MI 48109, USA; (X.H.); (Y.Z.)
| | - Mst Hur Madina
- Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, QC G8Z 4M3, Canada; (M.S.R.); (M.H.M.); (M.B.P.); (K.C.G.d.S.)
| | - Mélodie B. Plourde
- Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, QC G8Z 4M3, Canada; (M.S.R.); (M.H.M.); (M.B.P.); (K.C.G.d.S.)
| | - Karen Cristine Gonçalves dos Santos
- Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, QC G8Z 4M3, Canada; (M.S.R.); (M.H.M.); (M.B.P.); (K.C.G.d.S.)
| | - Xiaoqiang Huang
- Department of Computational Medicine and Bioinformatics, University of Michigan, 100 Washtenaw Avenue, Ann Arbor, MI 48109, USA; (X.H.); (Y.Z.)
| | - Yang Zhang
- Department of Computational Medicine and Bioinformatics, University of Michigan, 100 Washtenaw Avenue, Ann Arbor, MI 48109, USA; (X.H.); (Y.Z.)
| | - Jean-François Laliberté
- Institut National de la Recherche Scientifique-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada;
| | - Hugo Germain
- Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, QC G8Z 4M3, Canada; (M.S.R.); (M.H.M.); (M.B.P.); (K.C.G.d.S.)
- Correspondence:
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Madina MH, Rahman MS, Huang X, Zhang Y, Zheng H, Germain H. A Poplar Rust Effector Protein Associates with Protein Disulfide Isomerase and Enhances Plant Susceptibility. BIOLOGY 2020; 9:E294. [PMID: 32947987 PMCID: PMC7564345 DOI: 10.3390/biology9090294] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 09/04/2020] [Accepted: 09/07/2020] [Indexed: 11/17/2022]
Abstract
Melampsora larici-populina (Mlp), the causal agent of Populus leaf rust, secretes an array of effectors into the host through the haustorium to gain nutrients and suppress immunity. The precise mechanisms by which these effectors promote virulence remain unclear. To address this question, we developed a transgenic Arabidopsis line expressing a candidate effector, Mlp124357. Constitutive expression of the effector increased plant susceptibility to pathogens. A GxxxG motif present in Mlp124357 is required for its subcellular localization at the vacuolar membrane of the plant cell, as replacement of the glycine residues with alanines led to the delocalization of Mlp124357 to the nucleus and cytoplasm. We used immunoprecipitation and mass spectrometry (MS) to identify Mlp124357 interaction partners. Only one of the putative interaction partners knock-out line caused delocalization of the effector, indicating that Arabidopsis protein disulfide isomerase-11 (AtPDI-11) is required for the effector localization. This interaction was further confirmed by a complementation test, a yeast-two hybrid assay and a molecular modeling experiment. Moreover, localization results and infection assays suggest that AtPDI-11 act as a helper for Mlp124357. In summary, our findings established that one of Mlp effectors resides at the vacuole surface and modulates plant susceptibility.
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Affiliation(s)
- Mst Hur Madina
- Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, 3351 boulevard des Forges, Trois-Rivières, QC G9A 5H7, Canada; (M.H.M.); (M.S.R.)
| | - Md Saifur Rahman
- Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, 3351 boulevard des Forges, Trois-Rivières, QC G9A 5H7, Canada; (M.H.M.); (M.S.R.)
| | - Xiaoqiang Huang
- Department of Computational Medicine and Bioinformatics, University of Michigan, 100 Washtenaw Avenue, Ann Arbor, MI 48109, USA; (X.H.); (Y.Z.)
| | - Yang Zhang
- Department of Computational Medicine and Bioinformatics, University of Michigan, 100 Washtenaw Avenue, Ann Arbor, MI 48109, USA; (X.H.); (Y.Z.)
| | - Huanquan Zheng
- Department of Biology, McGill University, 1205 Dr. Penfield Avenue, Montreal, QC H3A 1B1, Canada;
| | - Hugo Germain
- Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, 3351 boulevard des Forges, Trois-Rivières, QC G9A 5H7, Canada; (M.H.M.); (M.S.R.)
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Benhamman R, Bai F, Drory SB, Loubert-Hudon A, Ellis B, Matton DP. The Arabidopsis Mitogen-Activated Protein Kinase Kinase Kinase 20 (MKKK20) Acts Upstream of MKK3 and MPK18 in Two Separate Signaling Pathways Involved in Root Microtubule Functions. FRONTIERS IN PLANT SCIENCE 2017; 8:1352. [PMID: 28848569 PMCID: PMC5550695 DOI: 10.3389/fpls.2017.01352] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 07/19/2017] [Indexed: 05/04/2023]
Abstract
Mitogen-activated protein kinase (MAPK) signaling networks represent important means of signal transduction in plants and other eukaryotes, controlling intracellular signaling by linking perception of environmental or developmental cues to downstream targets. In the Arabidopsis MEKK subfamily, the MKKK19, 20, and 21 form a highly supported clade with the Solanaceous Fertilization-Related Kinases. In Arabidopsis, little is known about this group, except for MKKK20, which is involved in osmotic stress. Using a directed MKKK-MKK yeast two-hybrid (Y2H) screen, MKKK20 was found to interact only with MKK3, while a MKKK20 large-scale Y2H screen retrieved MPK18 as a direct interactant. In vitro phosphorylation assays showed that MKKK20 phosphorylates both MKK3 and MPK18. However, when all three kinases are combined, no synergistic effect is observed on MPK18 phosphorylation, suggesting a direct access to MPK18, consistent with the absence of interaction between MKK3 and MPK18 in protein-protein interaction assays. Since mpk18 mutant plants were previously shown to be defective in microtubule-related functions, phenotypes of mkkk20 single and mkkk20/mpk18 double mutants were investigated to determine if MKKK20 acts upstream of MPK18. This was the case, as mkkk20 root length was shorter than WT in media containing microtubule-disrupting drugs as previously observed for mpk18 plants. Surprisingly, mkk3 plants were also similarly affected, suggesting the presence of two non-complementary pathways involved in Arabidopsis cortical microtubule function, the first including MKKK20, MKK3 and an unknown MPK; the second, a non-canonical MAPK cascade made of MKKK20 and MPK18 that bypasses the need for an MKK intermediate.
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Affiliation(s)
- Rachid Benhamman
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, MontréalQC, Canada
| | - Fangwen Bai
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, MontréalQC, Canada
| | - Samuel B. Drory
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, MontréalQC, Canada
| | - Audrey Loubert-Hudon
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, MontréalQC, Canada
| | - Brian Ellis
- Michael Smith Laboratories, University of British Columbia, VancouverBC, Canada
| | - Daniel P. Matton
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, MontréalQC, Canada
- *Correspondence: Daniel P. Matton,
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Lafleur E, Kapfer C, Joly V, Liu Y, Tebbji F, Daigle C, Gray-Mitsumune M, Cappadocia M, Nantel A, Matton DP. The FRK1 mitogen-activated protein kinase kinase kinase (MAPKKK) from Solanum chacoense is involved in embryo sac and pollen development. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:1833-43. [PMID: 25576576 PMCID: PMC4378624 DOI: 10.1093/jxb/eru524] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The fertilization-related kinase 1 (ScFRK1), a nuclear-localized mitogen-activated protein kinase kinase kinase (MAPKKK) from the wild potato species Solanum chacoense, belongs to a small group of pMEKKs that do not possess an extended N- or C-terminal regulatory domain. Initially selected based on its highly specific expression profile following fertilization, in situ expression analyses revealed that the ScFRK1 gene is also expressed early on during female gametophyte development in the integument and megaspore mother cell and, later, in the synergid and egg cells of the embryo sac. ScFRK1 mRNAs are also detected in pollen mother cells. Transgenic plants with lower or barely detectable levels of ScFRK1 mRNAs lead to the production of small fruits with severely reduced seed set, resulting from a concomitant decline in the number of normal embryo sacs produced. Megagametogenesis and microgametogenesis were affected, as megaspores did not progress beyond the functional megaspore (FG1) stage and the microspore collapsed around the first pollen mitosis. As for other mutants that affect embryo sac development, pollen tube guidance was severely affected in the ScFRK1 transgenic lines. Gametophyte to sporophyte communication was also affected, as observed from a marked change in the transcriptomic profiles of the sporophytic tissues of the ovule. The ScFRK1 MAPKKK is thus involved in a signalling cascade that regulates both male and female gamete development.
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Affiliation(s)
- Edith Lafleur
- Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC H1X 2B2, Canada
| | - Christelle Kapfer
- Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC H1X 2B2, Canada
| | - Valentin Joly
- Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC H1X 2B2, Canada
| | - Yang Liu
- Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC H1X 2B2, Canada
| | - Faiza Tebbji
- Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC H1X 2B2, Canada Institut de recherche en biotechnologie, Conseil national de recherches du Canada, 6100 Avenue Royalmount, Montréal, QC H4P 2R2, Canada
| | - Caroline Daigle
- Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC H1X 2B2, Canada
| | - Madoka Gray-Mitsumune
- Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC H1X 2B2, Canada
| | - Mario Cappadocia
- Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC H1X 2B2, Canada
| | - André Nantel
- Institut de recherche en biotechnologie, Conseil national de recherches du Canada, 6100 Avenue Royalmount, Montréal, QC H4P 2R2, Canada
| | - Daniel P Matton
- Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC H1X 2B2, Canada
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de Oliveira LFV, Christoff AP, de Lima JC, de Ross BCF, Sachetto-Martins G, Margis-Pinheiro M, Margis R. The Wall-associated Kinase gene family in rice genomes. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2014; 229:181-192. [PMID: 25443845 DOI: 10.1016/j.plantsci.2014.09.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Revised: 09/10/2014] [Accepted: 09/12/2014] [Indexed: 05/26/2023]
Abstract
The environment is a dynamic system in which life forms adapt. Wall-Associated Kinases (WAK) are a subfamily of receptor-like kinases associated with the cell wall. These genes have been suggested as sensors of the extracellular environment and triggers of intracellular signals. They belong to the ePK superfamily with or without a conserved arginine before the catalytic subdomain VIB, which characterizes RD and non-RD WAKs. WAK is a large subfamily in rice. We performed an extensive comparison of WAK genes from A. thaliana (AtWAK), O. sativa japonica and indica subspecies (OsWAK). Phylogenetic studies and WAK domain characterization allowed for the identification of two distinct groups of WAK genes in Arabidopsis and rice. One group corresponds to a cluster containing only OsWAKs that most likely expanded after the monocot-dicot separation, which evolved into a non-RD kinase class. The other group comprises classical RD-kinases with both AtWAK and OsWAK representatives. Clusterization analysis using extracellular and kinase domains demonstrated putative functional redundancy for some genes, but also highlighted genes that could recognize similar extracellular stimuli and activate different cascades. The gene expression pattern of WAKs in response to cold suggests differences in the regulation of the OsWAK genes in the indica and japonica subspecies. Our results also confirm the hypothesis of functional diversification between A. thaliana and O. sativa WAK genes. Furthermore, we propose that plant WAKs constitute two evolutionarily related but independent subfamilies: WAK-RD and WAK-nonRD. Recognition of this structural division will further provide insights to understanding WAK functions and regulations.
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Affiliation(s)
- Luiz Felipe Valter de Oliveira
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Brazil; Centro de Biotecnologia e Programa de Pós-Graduação em Biologia Celular e Molecular, Universidade Federal do Rio Grande do Sul, Brazil
| | - Ana Paula Christoff
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Brazil; Centro de Biotecnologia e Programa de Pós-Graduação em Biologia Celular e Molecular, Universidade Federal do Rio Grande do Sul, Brazil
| | - Júlio Cesar de Lima
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Brazil; Centro de Biotecnologia e Programa de Pós-Graduação em Biologia Celular e Molecular, Universidade Federal do Rio Grande do Sul, Brazil
| | - Bruno Comparsi Feijó de Ross
- Centro de Biotecnologia e Programa de Pós-Graduação em Biologia Celular e Molecular, Universidade Federal do Rio Grande do Sul, Brazil
| | | | - Marcia Margis-Pinheiro
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Brazil
| | - Rogerio Margis
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Brazil; Centro de Biotecnologia e Programa de Pós-Graduação em Biologia Celular e Molecular, Universidade Federal do Rio Grande do Sul, Brazil; Departamento de Biofísica, Universidade Federal do Rio Grande do Sul, Brazil.
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Germain H, Gray-Mitsumune M, Houde J, Benhamman R, Sawasaki T, Endo Y, Matton DP. The Solanum chacoense ovary receptor kinase 11 (ScORK11) undergoes tissue-dependent transcriptional, translational and post-translational regulation. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2013; 70:261-268. [PMID: 23800661 DOI: 10.1016/j.plaphy.2013.05.036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 05/20/2013] [Indexed: 06/02/2023]
Abstract
Using a subtraction screen to isolate weakly expressed transcripts from ovule and ovary libraries, we uncovered 30 receptor-like kinases that were predominantly expressed in ovary and fruit tissues following fertilization [1]. Here we describe the analysis of Solanum chacoense ovule receptor kinase 11 (ScORK11), a member of the large LRR III receptor kinase subfamily that localizes to the plasma membrane. In situ analyses demonstrated that ScORK11 gene expression was mainly restricted to the ovule integument, the embryo sac and the pericarp of the fruit. Tight regulation of ScORK11 expression at the mRNA level was also accompanied by both translational and post-translational regulation of protein levels.
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Affiliation(s)
- Hugo Germain
- Département de chimie et physique, Université du Québec à Trois-Rivières, 3351 boulevard des Forges, Trois-Rivières, QC G9A 5H7, Canada.
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Sun X, Sun M, Luo X, Ding X, Ji W, Cai H, Bai X, Liu X, Zhu Y. A Glycine soja ABA-responsive receptor-like cytoplasmic kinase, GsRLCK, positively controls plant tolerance to salt and drought stresses. PLANTA 2013; 237:1527-45. [PMID: 23494614 DOI: 10.1007/s00425-013-1864-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Accepted: 02/25/2013] [Indexed: 05/27/2023]
Abstract
Receptor such as protein kinases are proposed to work as sensors to initiate signaling cascades in higher plants. However, little is known about the precise functions of receptor such as protein kinases in abiotic stress response in plants, especially in wild soybean. Here, we focused on characterization of the biological functions of a receptor-like cytoplasmic serine/threonine protein kinase gene, GsRLCK, which was previously identified as a putative salt-alkali stress-related gene from the transcriptome profiles of Glycine soja. Bioinformatic analysis showed that GsRLCK protein contained a conserved kinase catalytic domain and two transmembrane domains at the N-terminus, but no typical extracellular domain. Consistently, GsRLCK-eGFP fusion protein was observed on the plasma membrane, but eGFP alone was distributing throughout the cytoplasm in onion epidermal cells. Quantitative real-time PCR analysis revealed the induced expression of GsRLCK by ABA, salt, alkali, and drought stresses. However, the expression levels of GsRLCK seemed to be similar in different tissues, except soybean pod. Phenotypic assays demonstrated that GsRLCK overexpression decreased ABA sensitivity and altered expression levels of ABA-responsive genes. Furthermore, we also found that GsRLCK conferred increased tolerance to salt and drought stresses and increased expression levels of a handful of stress-responsive genes, when overexpressing in Arabidopsis. In a word, we gave exact evidence that GsRLCK was a novel receptor-like cytoplasmic protein kinase and played a crucial role in plant responses to ABA, salt, and drought stresses.
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MESH Headings
- Abscisic Acid/pharmacology
- Adaptation, Physiological/drug effects
- Adaptation, Physiological/genetics
- Amino Acid Sequence
- Arabidopsis/drug effects
- Arabidopsis/genetics
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Droughts
- Gene Expression Profiling
- Gene Expression Regulation, Plant/drug effects
- Genes, Plant/genetics
- Germination/drug effects
- Germination/genetics
- Molecular Sequence Data
- Phylogeny
- Plant Epidermis/cytology
- Plant Epidermis/drug effects
- Plant Proteins/chemistry
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Plants, Genetically Modified
- Protein Transport/drug effects
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptor Protein-Tyrosine Kinases/chemistry
- Receptor Protein-Tyrosine Kinases/genetics
- Receptor Protein-Tyrosine Kinases/metabolism
- Salinity
- Sequence Alignment
- Sequence Analysis, DNA
- Sodium Chloride/pharmacology
- Glycine max/drug effects
- Glycine max/enzymology
- Glycine max/genetics
- Glycine max/physiology
- Stress, Physiological/drug effects
- Stress, Physiological/genetics
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Affiliation(s)
- XiaoLi Sun
- Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030, China
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Chevalier E, Loubert-Hudon A, Matton DP. ScRALF3, a secreted RALF-like peptide involved in cell-cell communication between the sporophyte and the female gametophyte in a solanaceous species. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:1019-33. [PMID: 23237060 DOI: 10.1111/tpj.12096] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 11/29/2012] [Accepted: 12/06/2012] [Indexed: 05/16/2023]
Abstract
Small peptides have been shown to regulate numerous aspects of plant development through cell-cell communication. These signaling events are particularly important during reproduction, regulating gamete development and embryogenesis. Rapid alkalinization factor (RALF)-like genes, a large gene family that encodes secreted peptides, have specific or ubiquitous expression patterns. Previously, five RALF-like genes with potential involvement during reproduction were isolated from Solanum chacoense. Here, we show that ScRALF3 is an important peptide regulator of female gametophyte development. Its expression, which is auxin-inducible, is strictly regulated before and after fertilization. Down-regulation of ScRALF3 expression by RNA interference leads to the production of smaller fruits that produce fewer seeds, due to improper development of the embryo sacs. Defects include loss of embryo sac nuclei polarization, as well as an increase in asynchronous division, accounting for cellular dysfunctions and premature embryo sac development arrest during megagametogenesis. ScRALF3 is expressed in the sporophytic tissue surrounding the embryo sac, the integument and the nucellus, as revealed by in situ hybridization and GUS staining. As expected for a secreted peptide, fluorescence from an ScRALF3-GFP fusion construct is detected throughout the secretory pathway. Therefore, the ScRALF3 secreted peptide may be directly involved in the regulation of multiple aspects of cell-cell communication between the female gametophyte and its surrounding sporophytic tissue during ovule development.
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Affiliation(s)
- Eric Chevalier
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques Université de Montréal, 4101 rue Sherbrooke est, Montréal, Québec, H1X 2B2, Canada
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Häweker H, Rips S, Koiwa H, Salomon S, Saijo Y, Chinchilla D, Robatzek S, von Schaewen A. Pattern recognition receptors require N-glycosylation to mediate plant immunity. J Biol Chem 2009; 285:4629-36. [PMID: 20007973 DOI: 10.1074/jbc.m109.063073] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
N-Glycans attached to the ectodomains of plasma membrane pattern recognition receptors constitute likely initial contact sites between plant cells and invading pathogens. To assess the role of N-glycans in receptor-mediated immune responses, we investigated the functionality of Arabidopsis receptor kinases EFR and FLS2, sensing bacterial translation elongation factor Tu (elf18) and flagellin (flg22), respectively, in N-glycosylation mutants. As revealed by binding and responses to elf18 or flg22, both receptors tolerated immature N-glycans induced by mutations in various Golgi modification steps. EFR was specifically impaired by loss-of-function mutations in STT3A, a subunit of the endoplasmic reticulum resident oligosaccharyltransferase complex. FLS2 tolerated mild underglycosylation occurring in stt3a but was sensitive to severe underglycosylation induced by tunicamycin treatment. EFR accumulation was significantly reduced when synthesized without N-glycans but to lesser extent when underglycosylated in stt3a or mutated in single amino acid positions. Interestingly, EFR(N143Q) lacking a single conserved N-glycosylation site from the EFR ectodomain accumulated to reduced levels and lost the ability to bind its ligand and to mediate elf18-elicited oxidative burst. However, EFR-YFP protein localization and peptide:N-glycosidase F digestion assays support that both EFR produced in stt3a and EFR(N143Q) in wild type cells correctly targeted to the plasma membrane via the Golgi apparatus. These results indicate that a single N-glycan plays a critical role for receptor abundance and ligand recognition during plant-pathogen interactions at the cell surface.
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Affiliation(s)
- Heidrun Häweker
- Max-Planck-Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, 50829 Cologne, Germany
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