scholarly journals The Mechanosensitive Ion Channel MSL10 Modulates Susceptibility to Pseudomonas syringae in Arabidopsis thaliana

2021 ◽  
Author(s):  
Debarati Basu ◽  
Jennette Codjoe ◽  
Kira Veley ◽  
Elizabeth Haswell
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Death ◽  
Ion Channel ◽  
Pseudomonas Syringae ◽  
Stomatal Closure ◽  
Avirulence Genes ◽  
Loss Of Function ◽  
Susceptibility To Infection ◽  
Mechanical Signals ◽  
Mechanosensitive Ion Channel

Plants sense and respond to molecular signals associated with the presence of pathogens and their virulence factors. Mechanical signals generated during pathogenic invasion may also be important, but their contributions have rarely been studied. Here we investigate the potential role of a mechanosensitive ion channel, MscS-Like (MSL)10, in defense against the bacterial pathogen Pseudomonas syringae in Arabidopsis thaliana. We previously showed that overexpression of MSL10-GFP, phospho-mimetic versions of MSL10, and the gain-of-function allele msl10-3G all produce dwarfing, spontaneous cell death, and the hyperaccumulation of reactive oxygen species. These phenotypes are shared by many autoimmune mutants and are frequently suppressed by growth at high temperature in those lines. Here, we found that the same was true for all three MSL10 hypermorphs. In addition, we show that the SGT1/RAR1/HSP90 co-chaperone complex was required for dwarfing and ectopic cell death, PAD4 and SID2 were partially required, and the immune regulators EDS1 and NDR1 were dispensable. All MSL10 hypermorphs exhibited reduced susceptibility to infection by P. syringae strain Pto DC3000, Pto DC3000 expressing the avirulence genes avrRpt2 or avrRpm1, but not Pto DC3000 hrpL, and showed an accelerated induction of PR1 expression compared to wild-type plants. Null msl10-1 mutants were delayed in PR1 induction and displayed modest susceptibility to infection by COR-deficient Pst. Finally, stomatal closure was reduced in msl10-1 loss-of-function mutants in response to Pst COR−. These data show that MSL10 modulates pathogen responses and begin to address the possibility that mechanical signals are exploited by the plant for pathogen perception.

scholarly journals The Mechanosensitive Ion Channel MSL10 Modulates Susceptibility to Pseudomonas syringae in Arabidopsis thaliana

2021 ◽  
Author(s):  
Debarati Basu ◽  
Jennette M. Codjoe ◽  
Kira Veley ◽  
Elizabeth Haswell
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Death ◽  
Ion Channel ◽  
Pseudomonas Syringae ◽  
Stomatal Closure ◽  
Avirulence Genes ◽  
Loss Of Function ◽  
Susceptibility To Infection ◽  
Mechanical Signals ◽  
Mechanosensitive Ion Channel

Plants sense and respond to molecular signals associated with the presence of pathogens and their virulence factors. Mechanical signals generated during pathogenic invasion may also be important, but their contributions have rarely been studied. Here we investigate the potential role of a mechanosensitive ion channel, MscS-Like (MSL)10, in defense against the bacterial pathogen Pseudomonas syringae in Arabidopsis thaliana. We previously showed that overexpression of MSL10-GFP, phospho-mimetic versions of MSL10, and the gain-of-function allele msl10-3G all produce dwarfing, spontaneous cell death, and the hyperaccumulation of reactive oxygen species. These phenotypes are shared by many autoimmune mutants and are frequently suppressed by growth at high temperature in those lines. Here, we found that the same was true for all three MSL10 hypermorphs. In addition, we show that the SGT1/RAR1/HSP90 co-chaperone complex was required for dwarfing and ectopic cell death, PAD4 and SID2 were partially required, and the immune regulators EDS1 and NDR1 were dispensable. All MSL10 hypermorphs exhibited reduced susceptibility to infection by P. syringae strain Pto DC3000, Pto DC3000 expressing the avirulence genes avrRpt2 or avrRpm1, but not Pto DC3000 hrpL, and showed an accelerated induction of PR1 expression compared to wild-type plants. Null msl10-1 mutants were delayed in PR1 induction and displayed modest susceptibility to infection by COR-deficient Pst. Finally, stomatal closure was reduced in msl10-1 loss-of-function mutants in response to Pst COR−. These data show that MSL10 modulates pathogen responses and begin to address the possibility that mechanical signals are exploited by the plant for pathogen perception.

scholarly journals Arabidopsis MSL10 Has a Regulated Cell Death Signaling Activity That Is Separable from Its Mechanosensitive Ion Channel Activity

2014 ◽  
Vol 26 (7) ◽  
pp. 3115-3131 ◽  
Author(s):  
Kira M. Veley ◽  
Grigory Maksaev ◽  
Elizabeth M. Frick ◽  
Emma January ◽  
Sarah C. Kloepper ◽  
...  
Keyword(s):  
Cell Death ◽  
Ion Channel ◽  
Channel Activity ◽  
Regulated Cell Death ◽  
Mechanosensitive Ion Channel ◽  
Cell Death Signaling ◽  
Signaling Activity

scholarly journals Single-stranded oligodeoxynucleotides induce plant defence in Arabidopsis thaliana

2020 ◽  
Vol 126 (3) ◽  
pp. 413-422
Author(s):  
Laila Toum ◽  
Gabriela Conti ◽  
Francesca Coppola Guerriero ◽  
Valeria P Conforte ◽  
Franco A Garolla ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Nadph Oxidase ◽  
Pseudomonas Syringae ◽  
Plant Immunity ◽  
Stomatal Closure ◽  
Plant Defence ◽  
Oxidase Inhibitor ◽  
Bacterial Toxin ◽  
Dependent Manner ◽  
Concentration Dependent Manner

Abstract Background and Aims Single-stranded DNA oligodeoxynucleotides (ssODNs) have been shown to elicit immune responses in mammals. In plants, RNA and genomic DNA can activate immunity, although the exact mechanism through which they are sensed is not clear. The aim of this work was to study the possible effect of ssODNs on plant immunity. Key Results The ssODNs IMT504 and 2006 increased protection against the pathogens Pseudomonas syringae pv. tomato DC3000 and Botrytis cinerea but not against tobacco mosaic virus-Cg when infiltrated in Arabidopsis thaliana. In addition, ssODNs inhibited root growth and promoted stomatal closure in a concentration-dependent manner, with half-maximal effective concentrations between 0.79 and 2.06 µm. Promotion of stomatal closure by ssODNs was reduced by DNase I treatment. It was also diminished by the NADPH oxidase inhibitor diphenyleneiodonium and by coronatine, a bacterial toxin that inhibits NADPH oxidase-dependent reactive oxygen species (ROS) synthesis in guard cells. In addition it was found that ssODN-mediated stomatal closure was impaired in bak1-5, bak1-5/bkk1, mpk3 and npr1-3 mutants. ssODNs also induced early expression of MPK3, WRKY33, PROPEP1 and FRK1 genes involved in plant defence, an effect that was reduced in bak1-5 and bak1-5/bkk1 mutants. Conclusions ssODNs are capable of inducing protection against pathogens through the activation of defence genes and promotion of stomatal closure through a mechanism similar to that of other elicitors of plant immunity, which involves the BAK1 co-receptor, and ROS synthesis.

scholarly journals Bacterial Growth Restriction During Host Resistance to Pseudomonas syringae Is Associated with Leaf Water Loss and Localized Cessation of Vascular Activity in Arabidopsis thaliana

2009 ◽  
Vol 22 (7) ◽  
pp. 857-867 ◽  
Author(s):  
Brian C. Freeman ◽  
Gwyn A. Beattie
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Death ◽  
Pseudomonas Syringae ◽  
Plant Cell ◽  
Bacterial Growth ◽  
Water Loss ◽  
Leaf Water ◽  
Infection Site ◽  
Vascular Activity ◽  
Leaf Water Loss

The physiological mechanisms by which plants limit the growth of bacterial pathogens during gene-for-gene resistance are poorly understood. We characterized early events in the Arabidopsis thaliana–Pseudomonas syringae pathosystem to identify physiological changes for which the kinetics are consistent with bacterial growth restriction. Using a safranine-O dye solution to detect vascular activity, we demonstrated that A. thaliana Col-0 resistance to P. syringae pv. tomato DC3000 cells expressing avrRpm1 involved virtually complete cessation of vascular water movement into the infection site within only 3 h postinoculation (hpi), under the conditions tested. This vascular restriction preceded or was simultaneous with precipitous decreases in photosynthesis, stomatal conductance, and leaf transpiration, with the latter two remaining at detectable levels. Microscopic plant cell death was detected as early as 2 hpi. Interestingly, suppression of bacterial growth during AvrRpm1-mediated resistance was eliminated by physically blocking leaf water loss through the stomata without altering plant cell death and was nearly eliminated by incubating plants at high relative humidity. The majority of the population growth benefit from blocking leaf water loss occurred early after inoculation, i.e., between 4 and 8 hpi. Collectively, these results support a model in which A. thaliana suppresses P. syringae growth during gene-for-gene resistance, at least in part, by coupling restricted vascular flow to the infection site with water loss through partially open stomata; that is, the plants effectively starve the invading bacteria for water.

scholarly journals LSD1 Regulates Salicylic Acid Induction of Copper Zinc Superoxide Dismutase in Arabidopsis thaliana

1999 ◽  
Vol 12 (11) ◽  
pp. 1022-1026 ◽  
Author(s):  
Daniel J. Kliebenstein ◽  
Robert A. Dietrich ◽  
Adam C. Martin ◽  
Robert L. Last ◽  
Jeffery L. Dangl
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Death ◽  
Salicylic Acid ◽  
Pseudomonas Syringae ◽  
Lesion Formation ◽  
Copper Zinc Superoxide Dismutase ◽  
Zinc Superoxide Dismutase ◽  
A Cell ◽  
Copper Zinc ◽  
Cell Death Cascade

We characterized the accumulation patterns of Arabidopsis thaliana proteins, two CuZnSODs, FeSOD, MnSOD, PR1, PR5, and GST1, in response to various pathogen-associated treatments. These treatments included inoculation with virulent and avirulent Pseudomonas syringae strains, spontaneous lesion formation in the lsd1 mutant, and treatment with the salicylic acid (SA) analogs INA (2,6-dichloroisonicotinic acid) and BTH (benzothiadia-zole). The PR1, PR5, and GST1 proteins were inducible by all treatments tested, as expected from previous mRNA blot analysis. The two CuZnSOD proteins were induced by SA analogs and in conjunction with lsd1-mediated spreading cell death. Additionally, LSD1 is a part of a signaling pathway for the induction of the CuZnSOD proteins in response to SA but not in lsd1-mediated cell death. We suggest that the spreading lesion phenotype of lsd1 results from a lack of up-regulation of a CuZnSOD responsible for detoxification of accumulating superoxide before the reactive oxygen species can trigger a cell death cascade.

scholarly journals MicroRNA844-Guided Downregulation of Cytidinephosphate Diacylglycerol Synthase3 (CDS3) mRNA Affects the Response of Arabidopsis thaliana to Bacteria and Fungi

2015 ◽  
Vol 28 (8) ◽  
pp. 892-900 ◽  
Author(s):  
Hwa Jung Lee ◽  
Young Ju Park ◽  
Kyung Jin Kwak ◽  
Donghyun Kim ◽  
June Hyun Park ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Pseudomonas Syringae ◽  
Defense Response ◽  
Cleavage Site ◽  
Severe Disease ◽  
Mrna Level ◽  
Transcript Level ◽  
Loss Of Function ◽  
Pathogen Challenge ◽  
Bacteria And Fungi

Despite the fact that a large number of miRNA sequences have been determined in diverse plant species, reports demonstrating the functional roles of miRNAs in the plant response to pathogens are severely limited. Here, Arabidopsis thaliana miRNA844 (miR844) was investigated for its functional role in the defense response to diverse pathogens. Transgenic Arabidopsis plants overexpressing miR844 (35S::miR844) displayed much more severe disease symptoms than the wild-type plants when challenged with the bacterium Pseudomonas syringae pv. tomato DC3000 or the fungus Botrytis cinerea. By contrast, a loss-of-function mir844 mutant showed an enhanced resistance against the pathogens. Although no cleavage was observed at the predicted cleavage site of the putative target mRNA, cytidinephosphate diacylglycerol synthase3 (CDS3), cleavage was observed at 6, 12, 21, or 52 bases upstream of the predicted cleavage site of CDS3 mRNA, and the level of CDS3 mRNA was downregulated by the overexpression of miR844, implying that miR844 influences CDS3 transcript level. To further confirm that the miR844-mediated defense response was due to the decrease in CDS3 mRNA level, the disease response of a CDS3 loss-of-function mutant was analyzed upon pathogen challenge. Increased susceptibility of both cds3 mutant and 35S::miR844 plants to pathogens confirmed that miR844 affected the defense response by downregulating CDS3 mRNA. The expression of miR844 was decreased, and the CDS3 transcript level increased upon pathogen challenge. Taken together, these results provide evidence that downregulation of miR844 and a concomitant increase in CDS3 expression is a defensive response of Arabidopsis to bacteria and fungi.

scholarly journals Interactions between the N- and C-termini of the mechanosensitive ion channel AtMSL10 are consistent with a three-step mechanism for activation

2020 ◽  
Vol 71 (14) ◽  
pp. 4020-4032 ◽  
Author(s):  
Debarati Basu ◽  
Jennette M Shoots ◽  
Elizabeth S Haswell
Keyword(s):  
Cell Death ◽  
Ion Channel ◽  
Conformational Changes ◽  
Molecular Mechanisms ◽  
Fluorescent Protein ◽  
Adaptive Responses ◽  
C Terminus ◽  
N Terminus ◽  
Mechanosensitive Ion Channel ◽  
Green Fluorescent

Abstract Although a growing number of mechanosensitive ion channels are being identified in plant systems, the molecular mechanisms by which they function are still under investigation. Overexpression of the mechanosensitive ion channel MSL (MscS-Like)10 fused to green fluorescent protein (GFP) triggers a number of developmental and cellular phenotypes including the induction of cell death, and this function is influenced by seven phosphorylation sites in its soluble N-terminus. Here, we show that these and other phenotypes required neither overexpression nor a tag, and could also be induced by a previously identified point mutation in the soluble C-terminus (S640L). The promotion of cell death and hyperaccumulation of H2O2 in 35S:MSL10S640L-GFP overexpression lines was suppressed by N-terminal phosphomimetic substitutions, and the soluble N- and C-terminal domains of MSL10 physically interacted. We propose a three-step model by which tension-induced conformational changes in the C-terminus could be transmitted to the N-terminus, leading to its dephosphorylation and the induction of adaptive responses. Taken together, this work expands our understanding of the molecular mechanisms of mechanotransduction in plants.

Heterotrimeric G-proteins involved in the MeJA regulated ion flux and stomatal closure in Arabidopsis thaliana

2015 ◽  
Vol 42 (2) ◽  
pp. 126 ◽  
Author(s):  
Suli Yan ◽  
Shuitian Luo ◽  
Shanshan Dong ◽  
Ting Zhang ◽  
Jingru Sun ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
G Proteins ◽  
Stomatal Closure ◽  
Guard Cells ◽  
Ion Flux ◽  
Heterotrimeric G Proteins ◽  
Loss Of Function ◽  
Test Technique ◽  
In The Wild ◽  
Pre Treatment

Heterotrimeric G-proteins play an important role in plant signalling pathways. The plant hormone methyl jasmonate (MeJA) can induce stomatal closure in many plant species. The signal cascade in MeJA-induced stomatal closure has been studied previously. However, the function of G proteins in this process has not yet been evaluated. In this study, the stomatal movement induced by MeJA in the wild-type Arabidopsis thaliana (L. Heynh.) (WS), Gα subunit loss-of-function mutant gpa1–1 and gpa1–2 guard cells were measured. Further, the transmembrane ion flux (H+, Ca2+ and K+) and reactive oxygen species (ROS) experiments were performed in guard cells from WS, GDP-β-S pre-treated WS, gpa1–1 and gpa1–2 using non-invasive micro-test technique (NMT) and confocal technique. It was observed that the MeJA-induced stomatal closure was abolished in guard cells of gpa1 mutants. GDP-β-S pre-treatment and gpa1 mutants impaired the MeJA-activated H+ efflux, Ca2+ influx and K+ efflux. The accumulation of ROS in gpa1–1 and gpa1–2 guard cells was also lower than that in WS guard cells under MeJA treatment. These results suggested that Gα subunits are involved in regulating the signal events in JA signal pathway and stomatal closure.

scholarly journals Interactions between the N- and C- termini of mechanosensitive ion channel AtMSL10 are consistent with a three-step mechanism for activation

2019 ◽  
Author(s):  
Debarati Basu ◽  
Jennette M. Shoots ◽  
Elizabeth S. Haswell
Keyword(s):  
Cell Death ◽  
Ion Channel ◽  
Conformational Changes ◽  
Molecular Mechanisms ◽  
Adaptive Responses ◽  
C Terminus ◽  
Step Model ◽  
N Terminus ◽  
Mechanosensitive Ion Channel ◽  
Cellular Phenotypes

ABSTRACTAlthough a growing number of mechanosensitive ion channels are being identified in plant systems, the molecular mechanisms by which they function are still under investigation. Overexpression of the mechanosensitive ion channel MSL (MscS-Like)10 fused to GFP triggers a number of developmental and cellular phenotypes including the induction of cell death, and this function is influenced by seven phosphorylation sites in its soluble N-terminus. Here, we show that these and other phenotypes required neither overexpression nor a tag and could be also induced by a previously identified point mutation in the soluble C-terminus (S640L). The promotion of cell death and hyperaccumulation of H2O2 in 35S:MSL10S640L-GFP overexpression lines was suppressed by N-terminal phosphomimetic substitutions, and the soluble N- and C-terminal domains of MSL10 physically interacted. We propose a three-step model by which tension-induced conformational changes in the C-terminus are transmitted to the N-terminus, leading to its dephosphorylation and the induction of adaptive responses. Taken together, this work expands our understanding of the molecular mechanisms of mechanotransduction in plants.HIGHLIGHTCell death is triggered by mutations in either the cytoplasmic N- or C-terminus of AìMSLlü. Our proposed model explains how membrane tension may activate signaling through the interaction of these two domains.

scholarly journals The Mechanosensitive Ion Channel MSL10 Potentiates Responses to Cell Swelling in Arabidopsis Seedlings

2020 ◽  
Author(s):  
Debarati Basu ◽  
Elizabeth S. Haswell
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Ion Channel ◽  
Osmotic Shock ◽  
Fundamental Property ◽  
Calcium Transient ◽  
Cell Swelling ◽  
Dependent Manner ◽  
Mechanosensitive Ion Channel ◽  
Osmotic Treatment

SUMMARYThe ability to respond to unanticipated increases in volume is a fundamental property of cells, essential for cellular integrity in the face of osmotic challenges. Plants must manage cell swelling during flooding, rehydration, and pathogenesis–but little is known about the mechanisms by which this occurs. It has been proposed that plant cells could sense and respond to cell swelling through the action of mechanosensitive ion channels. Here we develop and characterize a new assay to study the effects of cell swelling on Arabidopsis thaliana seedlings and to test the contributions of the mechanosensitive ion channel MscS-Like10 (MSL10). The assay incorporates both cell wall softening and hypo-osmotic treatment to induce cell swelling. We show that MSL10 is required for previously demonstrated responses to hypo-osmotic shock, including a cytoplasmic calcium transient within the first few seconds, accumulation of ROS within the first 30 minutes, and increased transcript levels of mechano-inducible genes within 60 minutes. We also show that cell swelling induces programmed cell death within 3 hours, also in a MSL10-dependent manner. Finally, we show that MSL10 is unable to potentiate cell swelling-induced death when phosphomimetic residues are introduced into its soluble N-terminus. Thus, MSL10 functions as a phospho-regulated membrane-based sensor that connects the perception of cell swelling to a downstream signaling cascade and programmed cell death.

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