scholarly journals Alloxan Disintegrates the Plant Cytoskeleton and Suppresses mlo-Mediated Powdery Mildew Resistance

2019 ◽  
Vol 61 (3) ◽  
pp. 505-518
Author(s):  
Hongpo Wu ◽  
Weiwei Zhang ◽  
Martin Schuster ◽  
Marcin Moch ◽  
Reinhard Windoffer ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Plant Immunity ◽  
Snare Protein ◽  
Animal Cells ◽  
Callose Deposition ◽  
Cellular Processes ◽  
Hydrogen Peroxide Accumulation ◽  
Ros Burst ◽  
Plant Cytoskeleton ◽  
Cellular Organelles

Abstract Recessively inherited mutant alleles of Mlo genes (mlo) confer broad-spectrum penetration resistance to powdery mildew pathogens in angiosperm plants. Although a few components are known to be required for mlo resistance, the detailed molecular mechanism underlying this type of immunity remains elusive. In this study, we identified alloxan (5,5-dihydroxyl pyrimidine-2,4,6-trione) and some of its structural analogs as chemical suppressors of mlo-mediated resistance in monocotyledonous barley (Hordeum vulgare) and dicotyledonous Arabidopsis thaliana. Apart from mlo resistance, alloxan impairs nonhost resistance in Arabidopsis. Histological analysis revealed that the chemical reduces callose deposition and hydrogen peroxide accumulation at attempted fungal penetration sites. Fluorescence microscopy revealed that alloxan interferes with the motility of cellular organelles (peroxisomes, endosomes and the endoplasmic reticulum) and the pathogen-triggered redistribution of the PEN1/SYP121 t-SNARE protein. These cellular defects are likely the consequence of disassembly of actin filaments and microtubules upon alloxan treatment. Similar to the situation in animal cells, alloxan elicited the temporary accumulation of reactive oxygen species (ROS) in cotyledons and rosette leaves of Arabidopsis plants. Our results suggest that alloxan may destabilize cytoskeletal architecture via induction of an early transient ROS burst, further leading to the failure of molecular and cellular processes that are critical for plant immunity.

HbLFG1, a rubber tree (Hevea brasiliensis) lifeguard protein, can facilitate powdery mildew infection by regulating plant immunity

2021 ◽  
Author(s):  
Xiao Li ◽  
Sipeng Li ◽  
Yuhan Liu ◽  
Qiguang He ◽  
Wenbo Liu ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Host Plant ◽  
Hevea Brasiliensis ◽  
Plant Immunity ◽  
Rubber Tree ◽  
Negative Regulator ◽  
Economic Plant ◽  
Callose Deposition ◽  
Erysiphe Quercicola ◽  
Powdery Mildew Infection

Powdery mildew causes substantial losses in crop and economic plant yields worldwide. Although powdery mildew infection of rubber trees (Hevea brasiliensis), caused by the biotrophic fungus Erysiphe quercicola, severely threatens natural rubber production, little is known regarding the mechanism by which E. quercicola adapts to H. brasiliensis to invade the host plant. In barley and Arabidopsis thaliana, lifeguard (LFG) proteins, which have topological similarity to BAX INHIBITOR-1, are involved in host plant susceptibility to powdery mildew infection. In this study, we characterized an H. brasiliensis LFG protein, HbLFG1, with a focus on its function in regulating defence against powdery mildew. HbLFG1 gene expression was found to be upregulated during E. quercicola infection. HbLFG1 showed conserved functions in cell death inhibition and membrane localization. Expression of HbLFG1 in Nicotiana benthamiana leaves and A. thaliana Col-0 was demonstrated to significantly suppress callose deposition induced by conserved pathogen-associated molecular patterns chitin and flg22. Furthermore, we found that overexpression of HbLFG1 in H. brasiliensis mesophyll protoplasts significantly suppressed the chitin-induced burst of reactive oxygen species. Although A. thaliana Col-0 and E. quercicola displayed an incompatible interaction, Col-0 transformants overexpressing HbLFG1 were shown to be susceptible to E. quercicola. Collectively, the findings of this study provide evidence that HbLFG1 acts as a negative regulator of plant immunity that facilitates E. quercicola infection in H. brasiliensis.

scholarly journals Role of glutathione on cell adhesion and volume.

2021 ◽  
Author(s):  
Alain Geloen ◽  
Emmanuelle Danty
Keyword(s):  
Cell Adhesion ◽  
Cell Volume ◽  
Reduced Glutathione ◽  
Self Regulation ◽  
Cell Types ◽  
Self Control ◽  
Animal Cells ◽  
Cellular Processes ◽  
Proliferation And Apoptosis ◽  
Glutamylcysteine Synthetase

Glutathione is the most abundant thiol in animal cells. Reduced glutathione (GSH) is a major intracellular antioxidant neutralizing free radicals and detoxifying electrophiles. It plays important roles in many cellular processes, including cell differentiation, proliferation, and apoptosis. In the present study we demonstrate that extracellular concentration of reduced glutathione markedly increases cell volume within few hours, in a dose-response manner. Pre-incubation of cells with BSO, the inhibitor of 7-glutamylcysteine synthetase, responsible for the first step in intracellular glutathione synthesis did not change the effect of reduced glutathione on cell volume suggesting a mechanism limited to the interaction of extracellular reduced glutathione on cell membrane. Results show that reduced GSH decreases cell adhesion resulting in an increased cell volume. Since many cell types are able to transport of GSH out, the present results suggest that this could be a fundamental self-regulation of cell volume, giving the cells a self-control on their adhesion proteins.

A putative effector of the rubber-tree powdery mildew fungus has elicitor activity that can trigger plant immunity

Planta ◽  
2022 ◽  
Vol 255 (2) ◽  
Author(s):  
Xiao Li ◽  
Mengyao Liu ◽  
Yuhan Liu ◽  
Wenyuan Zhao ◽  
Sipeng Li ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Plant Immunity ◽  
Rubber Tree ◽  
Powdery Mildew Fungus

scholarly journals Bacillus amyloliquefaciens Strain PMB05 Intensifies Plant Immune Responses to Confer Resistance Against Bacterial Wilt of Tomato

2020 ◽  
Vol 110 (12) ◽  
pp. 1877-1885
Author(s):  
Ting-Hsin Ho ◽  
Chiao-Yu Chuang ◽  
Jing-Lin Zheng ◽  
Hong-Hua Chen ◽  
Yu-Shen Liang ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Bacterial Wilt ◽  
Bacillus Amyloliquefaciens ◽  
Plant Immunity ◽  
Reactive Oxygen Species Generation ◽  
Soft Rot ◽  
Limiting Factors ◽  
Callose Deposition ◽  
Bacillus Spp ◽  
Tomato Bacterial Wilt

Tomato is an economic crop worldwide. Many limiting factors reduce the production of tomato, with bacterial wilt caused by Ralstonia solanacearum being the most destructive disease. Our previous study showed that the disease resistance to bacterial soft rot is enhanced by Bacillus amyloliquefaciens strain PMB05. This enhanced resistance is associated with the intensification of pathogen-associated molecular patterns (PAMP)-triggered immunity (PTI). To determine whether the PTI-intensifying Bacillus spp. strains are able to confer disease resistance to bacterial wilt, their effects on PTI signals triggered by PAMP from R. solanacearum and on the occurrence of bacterial wilt were assayed. Before assay, a gene that encodes harpin from R. solanacearum, PopW, was applied as a PAMP. Results revealed that the B. amyloliquefaciens strain PMB05 was the one strain among 9 Bacillus rhizobacterial strains which could significantly intensify the PopW-induced hypersensitive response (HR) on Arabidopsis leaves. Moreover, we observed that the signals of PopW-induced reactive oxygen species generation and callose deposition were increased, confirming that the PTI was intensified by PMB05. The intensification of the PopW-triggered HR by PMB05 in Arabidopsis was reduced upon treatment with inhibitors in PTI pathways. Furthermore, the application of Bacillus spp. strains on tomato plants showed that only the use of PMB05 resulted in significantly increased resistance to bacterial wilt. Moreover, the PTI signals were also intensified in the tomato leaves. Taken together, we demonstrated that PMB05 is a PTI-intensifying bacterium that confers resistance to tomato bacterial wilt. Screening of plant immunity intensifying rhizobacteria is a possible strategy to control tomato bacterial wilt. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

scholarly journals Small RNA Functions as a Trafficking Effector in Plant Immunity

2019 ◽  
Vol 20 (11) ◽  
pp. 2816 ◽  
Author(s):  
Chen Zhu ◽  
Ting Liu ◽  
Ya-Nan Chang ◽  
Cheng-Guo Duan
Keyword(s):  
Small Rna ◽  
Stress Responses ◽  
Small Rnas ◽  
Plant Immunity ◽  
Arms Race ◽  
Abiotic And Biotic Stress ◽  
Plant Adaptation ◽  
Cellular Processes ◽  
Challenging Environment ◽  
Rna Export

Small RNAs represent a class of small but powerful agents that regulate development and abiotic and biotic stress responses during plant adaptation to a constantly challenging environment. Previous findings have revealed the important roles of small RNAs in diverse cellular processes. The recent discovery of bidirectional trafficking of small RNAs between different kingdoms has raised many interesting questions. The subsequent demonstration of exosome-mediated small RNA export provided a possible tool for further investigating how plants use small RNAs as a weapon during the arms race between plant hosts and pathogens. This review will focus on discussing the roles of small RNAs in plant immunity in terms of three aspects: the biogenesis of extracellular small RNAs and the transportation and trafficking small RNA-mediated gene silencing in pathogens.

scholarly journals Novel molecular components involved in callose-mediated Arabidopsis defense against Salmonella enterica and Escherichia coli O157:H7

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Paula Rodrigues Oblessuc ◽  
Cleverson Carlos Matiolli ◽  
Maeli Melotto
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Syringae ◽  
Salmonella Enterica ◽  
Plant Pathogens ◽  
Dependent Manner ◽  
Callose Deposition ◽  
E Coli ◽  
Genetic Components ◽  
Ros Burst ◽  
Sa Signaling

Abstract Background Food contamination with Salmonella enterica and enterohemorrhagic Escherichia coli is among the leading causes of foodborne illnesses worldwide and crop plants are associated with > 50% of the disease outbreaks. However, the mechanisms underlying the interaction of these human pathogens with plants remain elusive. In this study, we have explored plant resistance mechanisms against these enterobacteria and the plant pathogen Pseudomonas syringae pv. tomato (Pst) DC3118, as an opportunity to improve food safety. Results We found that S. enterica serovar Typhimurium (STm) transcriptionally modulates stress responses in Arabidopsis leaves, including induction of two hallmark processes of plant defense: ROS burst and cell wall modifications. Analyses of plants with a mutation in the potentially STm-induced gene EXO70H4 revealed that its encoded protein is required for stomatal defense against STm and E. coli O157:H7, but not against Pst DC3118. In the apoplast however, EXO70H4 is required for defense against STm and Pst DC3118, but not against E. coli O157:H7. Moreover, EXO70H4 is required for callose deposition, but had no function in ROS burst, triggered by all three bacteria. The salicylic acid (SA) signaling and biosynthesis proteins NPR1 and ICS1, respectively, were involved in stomatal and apoplastic defense, as well as callose deposition, against human and plant pathogens. Conclusions The results show that EXO70H4 is involved in stomatal and apoplastic defenses in Arabidopsis and suggest that EXO70H4-mediated defense play a distinct role in guard cells and leaf mesophyll cells in a bacteria-dependent manner. Nonetheless, EXO70H4 contributes to callose deposition in response to both human and plant pathogens. NPR1 and ICS1, two proteins involved in the SA signaling pathway, are important to inhibit leaf internalization and apoplastic persistence of enterobacteria and proliferation of phytopathogens. These findings highlight the existence of unique and shared plant genetic components to fight off diverse bacterial pathogens providing specific targets for the prevention of foodborne diseases.

scholarly journals Functional Interplay between Cristae Biogenesis, Mitochondrial Dynamics and Mitochondrial DNA Integrity

2019 ◽  
Vol 20 (17) ◽  
pp. 4311 ◽  
Author(s):  
Arun Kumar Kondadi ◽  
Ruchika Anand ◽  
Andreas S. Reichert
Keyword(s):  
Mitochondrial Dna ◽  
Unique Feature ◽  
Mitochondrial Dynamics ◽  
Human Diseases ◽  
Dna Integrity ◽  
Cellular Processes ◽  
The Past ◽  
Mitochondrial Structure ◽  
Mitochondrial Functions ◽  
Cellular Organelles

Mitochondria are vital cellular organelles involved in a plethora of cellular processes such as energy conversion, calcium homeostasis, heme biogenesis, regulation of apoptosis and ROS reactive oxygen species (ROS) production. Although they are frequently depicted as static bean-shaped structures, our view has markedly changed over the past few decades as many studies have revealed a remarkable dynamicity of mitochondrial shapes and sizes both at the cellular and intra-mitochondrial levels. Aberrant changes in mitochondrial dynamics and cristae structure are associated with ageing and numerous human diseases (e.g., cancer, diabetes, various neurodegenerative diseases, types of neuro- and myopathies). Another unique feature of mitochondria is that they harbor their own genome, the mitochondrial DNA (mtDNA). MtDNA exists in several hundreds to thousands of copies per cell and is arranged and packaged in the mitochondrial matrix in structures termed mt-nucleoids. Many human diseases are mechanistically linked to mitochondrial dysfunction and alteration of the number and/or the integrity of mtDNA. In particular, several recent studies identified remarkable and partly unexpected links between mitochondrial structure, fusion and fission dynamics, and mtDNA. In this review, we will provide an overview about these recent insights and aim to clarify how mitochondrial dynamics, cristae ultrastructure and mtDNA structure influence each other and determine mitochondrial functions.

scholarly journals Cyclophilins: Less Studied Proteins with Critical Roles in Pathogenesis

2018 ◽  
Vol 108 (1) ◽  
pp. 6-14 ◽  
Author(s):  
Khushwant Singh ◽  
Mark Winter ◽  
Miloslav Zouhar ◽  
Pavel Ryšánek
Keyword(s):  
Abiotic Stresses ◽  
Plant Immunity ◽  
Puccinia Triticina ◽  
Cryphonectria Parasitica ◽  
Immunosuppressive Drug ◽  
Biotic And Abiotic Stresses ◽  
Isomerase Activity ◽  
Cellular Processes ◽  
High Affinity ◽  
Fk506 Binding Proteins

Cyclophilins (EC 5.2.1.8) belong to a subgroup of proteins known as immunophilins, which also include FK506-binding proteins and parvulins. Members of the immunophilins have two main characteristic properties: (i) peptidyl-prolyl cis-trans isomerase activity and (ii) the ability to bind immunosuppressant molecules of fungal origin. Cyclophilins are some of the most conserved proteins present in eukaryotes and prokaryotes, and they have been implicated in diverse cellular processes and responses to multiple biotic and abiotic stresses. Cyclophilins have been exploited in humans and plants extensively, but they have only recently received attention in regard to phytopathogens. In Phellinus sulphurascens and species of the genus Leptosphaeria and Phytophthora, high expression of cyclophilins was found to be related to infection. Moreover, recent studies of cyclophilins in certain phytopathogens, such as Magnaporthe oryzae, Botrytis cinerea, Cryphonectria parasitica, and Puccinia triticina, demonstrated their roles as a pathogenicity factors. In addition to pathogenicity, cyclophilins have high affinity for the immunosuppressive drug cyclosporin A, which is a potent antifungal agent. Although cyclophilins are highly conserved in phytopathogens, because they have been less studied, their role remains largely unknown. In this review, we provide detailed information on the cyclophilins in several phytopathogens, including fungi and oomycetes, as well as their role in suppressing plant immunity.

Cell biology of early events in the plant resistance response to infection by pathogenic fungi

1995 ◽  
Vol 73 (S1) ◽  
pp. 418-425 ◽  
Author(s):  
I. Kobayashi ◽  
L. J. Murdoch ◽  
A. R. Hardham ◽  
H. Kunoh
Keyword(s):  
Plant Resistance ◽  
Cell Biology ◽  
Fungal Pathogens ◽  
Plant Defence ◽  
Pathogenic Fungi ◽  
Callose Deposition ◽  
Resistance Response ◽  
New Genes ◽  
Host Cell Wall ◽  
Plant Cytoskeleton

In addition to passive (or constitutive) defence mechanisms, plants have evolved a range of active (or inducible) responses that occur rapidly on infection with an incompatible (avirulent) pathogen and that are thought to play a major role in the expression of resistance. These defence reactions are only induced if the plant possesses the ability to recognize and respond to the pathogen. Signal reception by the host must initiate a cascade of events that lead to the expression of resistance. Some resistance responses, such as callose deposition, do not require the expression of new genes. Many responses, for example the synthesis and secretion of toxic compounds or molecules that enhance the strength of physical barriers, result from changes in the pattern of gene transcription. Other defence phenomena include hypersensitive cell collapse, intercellular signalling, and the induction of defence gene transcripts in surrounding cells. Changes in cell biochemistry and physiology are accompanied by characteristic structural modifications in the infected cells, such as the redeployment of selected organelles and dramatic modifications of the host cell wall. Recent evidence indicates that microtubules and microfilaments of the plant cytoskeleton facilitate the rapid localization of these and other plant defence responses to the region of infection. Key words: plant resistance, plant cytoskeleton, microtubules, microfilaments, fungal pathogens, polarity of defence response.

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