scholarly journals CaWRKY30 Positively Regulates Pepper Immunity by Targeting CaWRKY40 against Ralstonia solanacearum Inoculation through Modulating Defense-Related Genes

2021 ◽  
Vol 22 (21) ◽  
pp. 12091
Author(s):  
Ansar Hussain ◽  
Muhammad Ifnan Khan ◽  
Mohammed Albaqami ◽  
Shahzadi Mahpara ◽  
Ijaz Rasool Noorka ◽  
...  
Keyword(s):  
Cell Death ◽  
Ralstonia Solanacearum ◽  
Foliar Application ◽  
Critical Role ◽  
Underlying Mechanism ◽  
Marker Genes ◽  
Transcriptional Expression ◽  
Virus Induced Gene Silencing ◽  
Expression Levels ◽  
Over Expression

The WRKY transcription factors (TFs) network is composed of WRKY TFs’ subset, which performs a critical role in immunity regulation of plants. However, functions of WRKY TFs’ network remain unclear, particularly in non-model plants such as pepper (Capsicum annuum L.). This study functionally characterized CaWRKY30—a member of group III Pepper WRKY protein—for immunity of pepper against Ralstonia solanacearum infection. The CaWRKY30 was detected in nucleus, and its transcriptional expression levels were significantly upregulated by R. solanacearum inoculation (RSI), and foliar application ethylene (ET), abscisic acid (ABA), and salicylic acid (SA). Virus induced gene silencing (VIGS) of CaWRKY30 amplified pepper’s vulnerability to RSI. Additionally, the silencing of CaWRKY30 by VIGS compromised HR-like cell death triggered by RSI and downregulated defense-associated marker genes, like CaPR1, CaNPR1, CaDEF1, CaABR1, CaHIR1, and CaWRKY40. Conversely, transient over-expression of CaWRKY30 in pepper leaves instigated HR-like cell death and upregulated defense-related maker genes. Furthermore, transient over-expression of CaWRKY30 upregulated transcriptional levels of CaWRKY6, CaWRKY22, CaWRKY27, and CaWRKY40. On the other hand, transient over-expression of CaWRKY6, CaWRKY22, CaWRKY27, and CaWRKY40 upregulated transcriptional expression levels of CaWRKY30. The results recommend that newly characterized CaWRKY30 positively regulates pepper’s immunity against Ralstonia attack, which is governed by synergistically mediated signaling by phytohormones like ET, ABA, and SA, and transcriptionally assimilating into WRKY TFs networks, consisting of CaWRKY6, CaWRKY22, CaWRKY27, and CaWRKY40. Collectively, our data will facilitate to explicate the underlying mechanism of crosstalk between pepper’s immunity and response to RSI.

scholarly journals CaCBL1 Acts as a Positive Regulator in Pepper Response to Ralstonia solanacearum

2020 ◽  
Vol 33 (7) ◽  
pp. 945-957 ◽  
Author(s):  
Lei Shen ◽  
Sheng Yang ◽  
Feng Yang ◽  
Deyi Guan ◽  
Shuilin He
Keyword(s):  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Marker Genes ◽  
Virus Induced Gene Silencing ◽  
Mobility Shift ◽  
Positive Regulator ◽  
Positive Regulators ◽  
Mobility Shift Assay ◽  
Transient Overexpression ◽  
Important Disease

Bacterial wilt caused by Ralstonia solanacearum is an important disease of pepper (Capsicum annuum), an economically important solanaceous vegetable worldwide, in particular, under high temperature (HT) conditions. However, the molecular mechanism underlying pepper immunity against bacterial wilt remains poorly understood. Herein, CaCBL1, a putative calcineurin B-like protein, was functionally characterized in the pepper response to R. solanacearum inoculation (RSI) under HT (RSI/HT). CaCBL1 was significantly upregulated by RSI at room temperature (RSI/RT), HT, or RSI/HT. CaCBL1-GFP fused protein targeted to whole epidermal cells of Nicotiana benthamiana when transiently overexpressed. CaCBL1 silencing by virus-induced gene silencing significantly enhanced pepper susceptibility to RSI under RT or HT, while its transient overexpression triggered hypersensitive response mimic cell death and upregulation of immunity-associated marker genes, including CabZIP63, CaWRKY40, and CaCDPK15, the positive regulators in the pepper response to RSI or HT found in our previous studies. In addition, by chromatin immunoprecipitation PCR and electrophoretic mobility shift assay, CaCBL1 was found to be directly targeted by CaWRKY40, although not by CaWRKY27 or CaWRKY58, via the W-box-2 within its promoter, and its transcription was found to be downregulated by silencing of CaWRKY40 while it was enhanced by its transient overexpression. These results suggest that CaCBL1 acts as a positive regulator in pepper immunity against R. solanacearum infection, constituting a positive feedback loop with CaWRKY40.

scholarly journals A Biostimulant Obtained from the Seaweed Ascophyllum nodosum Protects Arabidopsis thaliana from Severe Oxidative Stress

2020 ◽  
Vol 21 (2) ◽  
pp. 474 ◽  
Author(s):  
Mohammad Amin Omidbakhshfard ◽  
Neerakkal Sujeeth ◽  
Saurabh Gupta ◽  
Nooshin Omranian ◽  
Kieran J. Guinan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Arabidopsis Thaliana ◽  
Cell Death ◽  
Foliar Application ◽  
Tricarboxylic Acid Cycle ◽  
Ascophyllum Nodosum ◽  
Marker Genes ◽  
Lipidome Analysis ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Carbohydrate Metabolism Genes

Abiotic stresses cause oxidative damage in plants. Here, we demonstrate that foliar application of an extract from the seaweed Ascophyllum nodosum, SuperFifty (SF), largely prevents paraquat (PQ)-induced oxidative stress in Arabidopsis thaliana. While PQ-stressed plants develop necrotic lesions, plants pre-treated with SF (i.e., primed plants) were unaffected by PQ. Transcriptome analysis revealed induction of reactive oxygen species (ROS) marker genes, genes involved in ROS-induced programmed cell death, and autophagy-related genes after PQ treatment. These changes did not occur in PQ-stressed plants primed with SF. In contrast, upregulation of several carbohydrate metabolism genes, growth, and hormone signaling as well as antioxidant-related genes were specific to SF-primed plants. Metabolomic analyses revealed accumulation of the stress-protective metabolite maltose and the tricarboxylic acid cycle intermediates fumarate and malate in SF-primed plants. Lipidome analysis indicated that those lipids associated with oxidative stress-induced cell death and chloroplast degradation, such as triacylglycerols (TAGs), declined upon SF priming. Our study demonstrated that SF confers tolerance to PQ-induced oxidative stress in A. thaliana, an effect achieved by modulating a range of processes at the transcriptomic, metabolic, and lipid levels.

scholarly journals The Pepper Mitogen-Activated Protein Kinase CaMAPK7 Acts as a Positive Regulator in Response to Ralstonia solanacearum Infection

2021 ◽  
Vol 12 ◽  
Author(s):  
Lanping Shi ◽  
Kan Zhang ◽  
Linjing Xie ◽  
Mingxing Yang ◽  
Baixue Xie ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Ralstonia Solanacearum ◽  
Target Genes ◽  
Vital Role ◽  
Mitogen Activated Protein Kinase ◽  
Marker Genes ◽  
Virus Induced Gene Silencing ◽  
Mitogen Activated Protein ◽  
Pepper Genome ◽  
Pepper Plants

Mitogen-activated protein kinase (MAPK) pathways play a vital role in multiple plant processes, including growth, development, and stress signaling, but their involvement in response to Ralstonia solanacearum is poorly understood, particularly in pepper plants. Herein, CaMAPK7 was identified from the pepper genome and functionally analyzed. The accumulations of CaMAPK7 transcripts and promoter activities were both significantly induced in response to R. solanacearum strain FJC100301 infection, and exogenously applied phytohormones, including methyl jasmonate (MeJA), brassinolide (BR), salicylic acid (SA), and ethephon (ETN), were decreased by abscisic acid (ABA) treatment. Virus-induced gene silencing (VIGS) of CaMAPK7 significantly enhanced the susceptibility of pepper plants to infection by R. solanacearum and downregulated the defense-related marker genes, including CaDEF1, CaPO2, CaSAR82A, and CaWRKY40. In contrast, the ectopic overexpression of CaMAPK7 in transgenic tobacco enhanced resistance to R. solanacearum and upregulated the defense-associated marker genes, including NtHSR201, NtHSR203, NtPR4, PR1a/c, NtPR1b, NtCAT1, and NtACC. Furthermore, transient overexpression of CaMAPK7 in pepper leaves triggered intensive hypersensitive response (HR)-like cell death, H2O2 accumulation, and enriched CaWRKY40 at the promoters of its target genes and drove their transcript accumulations, including CaDEF1, CaPO2, and CaSAR82A. Taken together, these data indicate that R. solanacearum infection induced the expression of CaMAPK7, which indirectly modifies the binding of CaWRKY40 to its downstream targets, including CaDEF1, CaPO2, and CaSAR82A, ultimately leading to the activation of pepper immunity against R. solanacearum. The protein that responds to CaMAPK7 in pepper plants should be isolated in the future to build a signaling bridge between CaMAPK7 and CaWRKY40.

scholarly journals The E3 Ubiquitin Ligase ATL9 Affects Expression of Defense Related Genes, Cell Death and Callose Deposition in Response to Fungal Infection

Pathogens ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 68
Author(s):  
Tingwei Guo ◽  
Feng Kong ◽  
Carter Burton ◽  
Steven Scaglione ◽  
Blake Beagles ◽  
...  
Keyword(s):  
Cell Death ◽  
Fungal Infection ◽  
Ubiquitin Ligase ◽  
Critical Role ◽  
E3 Ubiquitin Ligase ◽  
Defense Responses ◽  
Callose Deposition ◽  
Expression Levels ◽  
Insertional Mutants ◽  
Protein Ubiquitination

Plants use diverse strategies to defend themselves from biotic stresses in nature, which include the activation of defense gene expression and a variety of signal transduction pathways. Previous studies have shown that protein ubiquitination plays a critical role in plant defense responses, however the details of its function remain unclear. Our previous work has shown that increasing expression levels of ATL9, an E3 ubiquitin ligase in Arabidopsis thaliana, increased resistance to infection by the fungal pathogen, Golovinomyces cichoracearum. In this study, we demonstrate that the defense-related proteins PDF1.2, PCC1 and FBS1 directly interact with ATL9 and are targeted for degradation to the proteasome by ATL9. The expression levels of PDF1.2, PCC1 and FBS1 are decreased in T-DNA insertional mutants of atl9 and T-DNA insertional mutants of pdf1.2, pcc1 and fbs1 are more susceptible to fungal infection. In addition, callose is more heavily deposited at infection sites in the mutants of atl9, fbs1, pcc1 and pdf1.2. Overexpression of ATL9 and of mutants in fbs1, pcc1 and pdf1.2 showed increased levels of cell death during infection. Together these results indicate that ubiquitination, cell death and callose deposition may work together to enhance defense responses to fungal pathogens.

scholarly journals A novel pathway of LPS uptake through syndecan-1 leading to pyroptotic cell death

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Shigetoshi Yokoyama ◽  
Yan Cai ◽  
Miyuki Murata ◽  
Takeshi Tomita ◽  
Mitsuhiro Yoneda ◽  
...  
Keyword(s):  
Cell Death ◽  
Cancer Cells ◽  
Immune Cells ◽  
Critical Role ◽  
Underlying Mechanism ◽  
Innate Immune ◽  
Cell Surface Receptor ◽  
Innate Immune Cells ◽  
Surface Receptor

Intracellular lipopolysaccharide (LPS) triggers the non-canonical inflammasome pathway, resulting in pyroptosis of innate immune cells. In addition to its well-known proinflammatory role, LPS can directly cause regression of some tumors, although the underlying mechanism has remained unknown. Here we show that secretoglobin(SCGB)3A2, a small protein predominantly secreted in airways, chaperones LPS to the cytosol through the cell surface receptor syndecan-1; this leads to pyroptotic cell death driven by caspase-11. SCGB3A2 and LPS co-treatment significantly induced pyroptosis of macrophage RAW264.7 cells and decreased cancer cell proliferation in vitro, while SCGB3A2 treatment resulted in reduced progression of xenograft tumors in mice. These data suggest a conserved function for SCGB3A2 in the innate immune system and cancer cells. These findings demonstrate a critical role for SCGB3A2 as an LPS delivery vehicle; they reveal one mechanism whereby LPS enters innate immune cells leading to pyroptosis, and they clarify the direct effect of LPS on cancer cells.

scholarly journals DNMT3b/OCT4 expression confers sorafenib resistance and poor prognosis of hepatocellular carcinoma through IL-6/STAT3 regulation

2019 ◽  
Vol 38 (1) ◽  
Author(s):  
Ssu-Chuan Lai ◽  
Yu-Ting Su ◽  
Ching-Chi Chi ◽  
Yung-Che Kuo ◽  
Kam-Fai Lee ◽  
...  
Keyword(s):  
Poor Prognosis ◽  
Dna Methyltransferase ◽  
Critical Role ◽  
Underlying Mechanism ◽  
Clinical Prognosis ◽  
Expression Levels ◽  
Oct4 Expression ◽  
Hep3b Cells

Abstract Background The inflammatory cytokine interleukin-6 (IL-6) is critical for the expression of octamer-binding transcription factor 4 (OCT4), which is highly associated with early tumor recurrence and poor prognosis of hepatocellular carcinomas (HCC). DNA methyltransferase (DNMT) family is closely linked with OCT4 expression and drug resistance. However, the underlying mechanism regarding the interplay between DNMTs and IL-6-induced OCT4 expression and the sorafenib resistance of HCC remains largely unclear. Methods HCC tissue samples were used to examine the association between DNMTs/OCT4 expression levels and clinical prognosis. Serum levels of IL-6 were detected using ELISA assays (n = 144). Gain- and loss-of-function experiments were performed in cell lines and mouse xenograft models to determine the underlying mechanism in vitro and in vivo. Results We demonstrate that levels of DNA methyltransferase 3 beta (DNMT3b) are significantly correlated with the OCT4 levels in HCC tissues (n = 144), and the OCT4 expression levels are positively associated with the serum IL-6 levels. Higher levels of IL-6, DNMT3b, or OCT4 predicted early HCC recurrence and poor prognosis. We show that IL-6/STAT3 activation increases DNMT3b/1 and OCT4 in HCC. Activated phospho-STAT3 (STAT-Y640F) significantly increased DNMT3b/OCT4, while dominant negative phospho-STAT3 (STAT-Y705F) was suppressive. Inhibiting DNMT3b with RNA interference or nanaomycin A (a selective DNMT3b inhibitor) effectively suppressed the IL-6 or STAT-Y640F-induced increase of DNMT3b-OCT4 and ALDH activity in vitro and in vivo. The fact that OCT4 regulates the DNMT1 expressions were further demonstrated either by OCT4 forced expression or DNMT1 silence. Additionally, the DNMT3b silencing reduced the OCT4 expression in sorafenib-resistant Hep3B cells with or without IL-6 treatment. Notably, targeting DNMT3b with nanaomycin A significantly increased the cell sensitivity to sorafenib, with a synergistic combination index (CI) in sorafenib-resistant Hep3B cells. Conclusions The DNMT3b plays a critical role in the IL-6-mediated OCT4 expression and the drug sensitivity of sorafenib-resistant HCC. The p-STAT3 activation increases the DNMT3b/OCT4 which confers the tumor early recurrence and poor prognosis of HCC patients. Findings from this study highlight the significance of IL-6-DNMT3b–mediated OCT4 expressions in future therapeutic target for patients expressing cancer stemness-related properties or sorafenib resistance in HCC.

scholarly journals CaHDZ27, a Homeodomain-Leucine Zipper I Protein, Positively Regulates the Resistance to Ralstonia solanacearum Infection in Pepper

2017 ◽  
Vol 30 (12) ◽  
pp. 960-973 ◽  
Author(s):  
Shaoliang Mou ◽  
Zhiqin Liu ◽  
Feng Gao ◽  
Sheng Yang ◽  
Meixia Su ◽  
...  
Keyword(s):  
Ralstonia Solanacearum ◽  
Leucine Zipper ◽  
Fluorescent Protein ◽  
Plant Immunity ◽  
Bimolecular Fluorescence Complementation ◽  
Marker Genes ◽  
Plant Responses ◽  
Dependent Manner ◽  
Virus Induced Gene Silencing ◽  
Green Fluorescent

Homeodomain-leucine zipper class I (HD-Zip I) transcription factors have been functionally characterized in plant responses to abiotic stresses, but their roles in plant immunity are poorly understood. Here, a HD-Zip I gene, CaHZ27, was isolated from pepper (Capsicum annum) and characterized for its role in pepper immunity. Quantitative real-time polymerase chain reaction showed that CaHDZ27 was transcriptionally induced by Ralstonia solanacearum inoculation and exogenous application of methyl jasmonate, salicylic acid, or ethephon. The CaHDZ27-green fluorescent protein fused protein was targeted exclusively to the nucleus. Chromatin immunoprecipitation demonstrated that CaHDZ27 bound to the 9-bp pseudopalindromic element (CAATAATTG) and triggered β-glucuronidase expression in a CAATAATTG-dependent manner. Virus-induced gene silencing of CaHDZ27 significantly attenuated the resistance of pepper plants against R. solanacearum and downregulated defense-related marker genes, including CaHIR1, CaACO1, CaPR1, CaPR4, CaPO2, and CaBPR1. By contrast, transient overexpression of CaHDZ27 triggered strong cell death mediated by the hypersensitive response and upregulated the tested immunity-associated marker genes. Ectopic CaHDZ27 expression in tobacco enhances its resistance against R. solanacearum. These results collectively suggest that CaHDZ27 functions as a positive regulator in pepper resistance against R. solanacearum. Bimolecular fluorescence complementation and coimmunoprecipitation assays indicate that CaHDZ27 monomers bind with each other, and this binding is enhanced significantly by R. solanacearum inoculation. We speculate that homodimerization of CaHZ27 might play a role in pepper response to R. solanacearum, further direct evidence is required to confirm it.

scholarly journals Deregulation of Plant Cell Death Through Disruption of Chloroplast Functionality Affects Asexual Sporulation of Zymoseptoria tritici on Wheat

2015 ◽  
Vol 28 (5) ◽  
pp. 590-604 ◽  
Author(s):  
Wing-Sham Lee ◽  
B. Jean Devonshire ◽  
Kim E. Hammond-Kosack ◽  
Jason J. Rudd ◽  
Kostya Kanyuka
Keyword(s):  
Cell Death ◽  
Plant Cell ◽  
Major Gene ◽  
Chlorophyll Biosynthesis ◽  
Critical Role ◽  
Virus Induced Gene Silencing ◽  
Zymoseptoria Tritici ◽  
Asexual Sporulation ◽  
Species Production ◽  
Mg Chelatase

Chloroplasts have a critical role in plant defense as sites for the biosynthesis of the signaling compounds salicylic acid (SA), jasmonic acid (JA), and nitric oxide (NO) and as major sites of reactive oxygen species production. Chloroplasts, therefore, regarded as important players in the induction and regulation of programmed cell death (PCD) in response to abiotic stresses and pathogen attack. The predominantly foliar pathogen of wheat Zymoseptoria tritici is proposed to exploit the plant PCD, which is associated with the transition in the fungus to the necrotrophic phase of infection. In this study virus-induced gene silencing was used to silence two key genes in carotenoid and chlorophyll biosynthesis, phytoene desaturase (PDS) and Mg-chelatase H subunit (ChlH). The chlorophyll-deficient, PDS- and ChlH-silenced leaves of susceptible plants underwent more rapid pathogen-induced PCD but were significantly less able to support the subsequent asexual sporulation of Z. tritici. Conversely, major gene (Stb6)-mediated resistance to Z. tritici was partially compromised in PDS- and ChlH-silenced leaves. Chlorophyll-deficient wheat ears also displayed increased Z. tritici disease lesion formation accompanied by increased asexual sporulation. These data highlight the importance of chloroplast functionality and its interaction with regulated plant cell death in mediating different genotype and tissue-specific interactions between Z. tritici and wheat.

scholarly journals Pepper CaMLO6 Negatively Regulates Ralstonia solanacearum Resistance and Positively Regulates High Temperature and High Humidity Responses

2020 ◽  
Vol 61 (7) ◽  
pp. 1223-1238
Author(s):  
Sheng Yang ◽  
Yuanyuan Shi ◽  
Longyun Zou ◽  
Jinfeng Huang ◽  
Lei Shen ◽  
...  
Keyword(s):  
High Temperature ◽  
Ralstonia Solanacearum ◽  
Negative Regulator ◽  
Marker Genes ◽  
Plant Responses ◽  
Resistance Locus ◽  
High Humidity ◽  
Virus Induced Gene Silencing ◽  
Transcriptional Responses ◽  
Pepper Plants

Abstract Plant mildew-resistance locus O (MLO) proteins influence susceptibility to powdery mildew. However, their roles in plant responses to other pathogens and heat stress remain unclear. Here, we showed that CaMLO6, a pepper (Capsicum annuum) member of MLO clade V, is a protein targeted to plasma membrane and probably endoplasmic reticulum. The transcript expression level of CaMLO6 was upregulated in the roots and leaves of pepper plants challenged with high temperature and high humidity (HTHH) and was upregulated in leaves but downregulated in roots of plants infected with the bacterial pathogen Ralstonia solanacearum. CaMLO6 was also directly upregulated by CaWRKY40 upon HTHH but downregulated by CaWRKY40 upon R. solanacearum infection. Virus-induced gene silencing of CaMLO6 significantly decreased pepper HTHH tolerance and R. solanacearum susceptibility. Moreover, CaMLO6 overexpression enhanced the susceptibility of Nicotiana benthamiana and pepper plants to R. solanacearum and their tolerance to HTHH, effects that were associated with the expression of immunity- and thermotolerance-associated marker genes, respectively. These results suggest that CaMLO6 acts as a positive regulator in response to HTHH but a negative regulator in response to R. solanacearum. Moreover, CaMLO6 is transcriptionally affected by R. solanacearum and HTHH; these transcriptional responses are at least partially regulated by CaWRKY40.

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