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Eichstädt B, Lederer S, Trempel F, Jiang X, Guerra T, Waadt R, Lee J, Liese A, Romeis T. Plant Immune Memory in Systemic Tissue Does Not Involve Changes in Rapid Calcium Signaling. FRONTIERS IN PLANT SCIENCE 2021; 12:798230. [PMID: 34970294 PMCID: PMC8712724 DOI: 10.3389/fpls.2021.798230] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 11/26/2021] [Indexed: 05/09/2023]
Abstract
Upon pathogen recognition, a transient rise in cytoplasmic calcium levels is one of the earliest events in plants and a prerequisite for defense initiation and signal propagation from a local site to systemic plant tissues. However, it is unclear if calcium signaling differs in the context of priming: Do plants exposed to a first pathogen stimulus and have consequently established systemic acquired resistance (SAR) display altered calcium responses to a second pathogen stimulus? Several calcium indicator systems including aequorin, YC3.6 or R-GECO1 have been used to document local calcium responses to the bacterial flg22 peptide but systemic calcium imaging within a single plant remains a technical challenge. Here, we report on an experimental approach to monitor flg22-induced calcium responses in systemic leaves of primed plants. The calcium-dependent protein kinase CPK5 is a key calcium sensor and regulator of the NADPH oxidase RBOHD and plays a role in the systemic calcium-ROS signal propagation. We therefore compared flg22-induced cytoplasmic calcium changes in Arabidopsis wild-type, cpk5 mutant and CPK5-overexpressing plants (exhibiting constitutive priming) by introgressing the calcium indicator R-GECO1-mTurquoise that allows internal normalization through mTurquoise fluorescence. Aequorin-based analyses were included for comparison. Based on the R-GECO1-mTurquoise data, CPK5-OE appears to reinforce an "oscillatory-like" Ca2+ signature in flg22-treated local tissues. However, no change was observed in the flg22-induced calcium response in the systemic tissues of plants that had been pre-challenged by a priming stimulus - neither in wild-type nor in cpk5 or CPK5-OE-lines. These data indicate that the mechanistic manifestation of a plant immune memory in distal plant parts required for enhanced pathogen resistance does not include changes in rapid calcium signaling upstream of CPK5 but rather relies on downstream defense responses.
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Affiliation(s)
| | - Sarah Lederer
- Department for Biochemistry of Plant Interactions, Leibniz Institute of Plant Biochemistry, Halle (Saale), Germany
| | - Fabian Trempel
- Department for Biochemistry of Plant Interactions, Leibniz Institute of Plant Biochemistry, Halle (Saale), Germany
| | - Xiyuan Jiang
- Department for Biochemistry of Plant Interactions, Leibniz Institute of Plant Biochemistry, Halle (Saale), Germany
| | - Tiziana Guerra
- Dahlem Centre of Plant Sciences, Freie Universität Berlin, Berlin, Germany
- Leibniz Institute of Vegetable and Ornamental Crops, Großbeeren, Germany
| | - Rainer Waadt
- Entwicklungsbiologie der Pflanzen, Centre for Organismal Studies, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
- Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Justin Lee
- Department for Biochemistry of Plant Interactions, Leibniz Institute of Plant Biochemistry, Halle (Saale), Germany
| | - Anja Liese
- Department for Biochemistry of Plant Interactions, Leibniz Institute of Plant Biochemistry, Halle (Saale), Germany
| | - Tina Romeis
- Dahlem Centre of Plant Sciences, Freie Universität Berlin, Berlin, Germany
- Department for Biochemistry of Plant Interactions, Leibniz Institute of Plant Biochemistry, Halle (Saale), Germany
- *Correspondence: Tina Romeis,
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Trempel F, Eschen-Lippold L, Bauer N, Ranf S, Westphal L, Scheel D, Lee J. A mutation in Asparagine-Linked Glycosylation 12 (ALG12) leads to receptor misglycosylation and attenuated responses to multiple microbial elicitors. FEBS Lett 2020; 594:2440-2451. [PMID: 32484235 DOI: 10.1002/1873-3468.13850] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 05/11/2020] [Accepted: 05/15/2020] [Indexed: 01/06/2023]
Abstract
Changes in cellular calcium levels are one of the earliest signalling events in plants exposed to pathogens or other exogenous factors. In a genetic screen, we identified an Arabidopsis thaliana 'changed calcium elevation 1' (cce1) mutant with attenuated calcium response to the bacterial flagellin flg22 peptide and several other elicitors. Whole-genome resequencing revealed a mutation in asparagine-linked glycosylation 12 that encodes the mannosyltransferase responsible for adding the eighth mannose residue in an α-1,6 linkage to the dolichol-PP-oligosaccharide N-glycosylation glycan tree precursors. While properly targeted to the plasma membrane, misglycosylation of several receptors in the cce1 background suggests that N-glycosylation is required for proper functioning of client proteins.
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Affiliation(s)
| | | | - Nicole Bauer
- Leibniz Institute of Plant Biochemistry, Halle, Germany
| | - Stefanie Ranf
- Leibniz Institute of Plant Biochemistry, Halle, Germany
| | - Lore Westphal
- Leibniz Institute of Plant Biochemistry, Halle, Germany
| | - Dierk Scheel
- Leibniz Institute of Plant Biochemistry, Halle, Germany
| | - Justin Lee
- Leibniz Institute of Plant Biochemistry, Halle, Germany
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Westphal L, Strehmel N, Eschen-Lippold L, Bauer N, Westermann B, Rosahl S, Scheel D, Lee J. pH effects on plant calcium fluxes: lessons from acidification-mediated calcium elevation induced by the γ-glutamyl-leucine dipeptide identified from Phytophthora infestans. Sci Rep 2019; 9:4733. [PMID: 30894659 PMCID: PMC6426842 DOI: 10.1038/s41598-019-41276-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 03/01/2019] [Indexed: 12/16/2022] Open
Abstract
Cytosolic Ca2+ ([Ca2+]cyt) elevation is an early signaling response upon exposure to pathogen-derived molecules (so-called microbe-associated molecular patterns, MAMPs) and has been successfully used as a quantitative read-out in genetic screens to identify MAMP receptors or their associated components. Here, we isolated and identified by mass spectrometry the dipeptide γ-Glu-Leu as a component of a Phytophthora infestans mycelium extract that induces [Ca2+]cyt elevation. Treatment of Arabidopsis seedlings with synthetic γ-Glu-Leu revealed stimulatory effects on defense signaling, including a weak enhancement of the expression of some MAMP-inducible genes or affecting the refractory period to a second MAMP elicitation. However, γ-Glu-Leu is not a classical MAMP since pH adjustment abolished these activities and importantly, the observed effects of γ-Glu-Leu could be recapitulated by mimicking extracellular acidification. Thus, although γ-Glu-Leu can act as a direct agonist of calcium sensing receptors in animal systems, the Ca2+-mobilizing activity in plants reported here is due to acidification. Low pH also shapes the Ca2+ signature of well-studied MAMPs (e.g. flg22) or excitatory amino acids such as glutamate. Overall, this work serves as a cautionary reminder that in defense signaling studies where Ca2+ flux measurements are concerned, it is important to monitor and consider the effects of pH.
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Affiliation(s)
- Lore Westphal
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry (IPB), Halle (Saale), Germany
| | - Nadine Strehmel
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry (IPB), Halle (Saale), Germany
| | - Lennart Eschen-Lippold
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry (IPB), Halle (Saale), Germany
| | - Nicole Bauer
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry (IPB), Halle (Saale), Germany
| | - Bernhard Westermann
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry (IPB), Halle (Saale), Germany
- Department of Bioorganic Chemistry, IPB, Halle (Saale), Germany
| | - Sabine Rosahl
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry (IPB), Halle (Saale), Germany
| | - Dierk Scheel
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry (IPB), Halle (Saale), Germany
| | - Justin Lee
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry (IPB), Halle (Saale), Germany.
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