scholarly journals Organ-Specificity in a Plant Disease Is Determined Independently of R Gene Signaling

2003 ◽  
Vol 16 (9) ◽  
pp. 752-759 ◽  
Author(s):  
Monika Hermanns ◽  
Alan J. Slusarenko ◽  
Nikolaus L. Schlaich
Keyword(s):  
Defense Mechanisms ◽  
Plant Diseases ◽  
Avirulence Gene ◽  
Organ Specificity ◽  
Dependent Manner ◽  
R Gene ◽  
Hypersensitive Cell Death ◽  
Active Defense ◽  
Hyaloperonospora Parasitica ◽  
Polymerase Chain

The molecular basis of organ specificity in plant diseases is little characterized. Downy mildew of Arabidopsis caused by the oomycete Hyaloperonospora parasitica (formerly Peronospora parasitica) is characteristically a leaf disease. Resistant host genotypes recognize the pathogen in a gene-for-gene dependent manner and respond with the production of H2O2 and the execution of a genetically programmed hypersensitive cell death (HR). We inoculated the roots of Arabidopsis genotypes Col-0, Ws-0, and Wei-0 with the NOCO and WELA races of the pathogen and compared the responses with those observed in leaves. Combinations of incompatible genotypes of host and pathogen showed the expected responses of an oxidative burst and the HR in leaves, but surprisingly, roots showed no signs of active defense and appeared completely susceptible to all the H. parasitica isolates tested. Reverse transcrip tase-polymerase chain reaction showed that the R gene RPP1, which mediates resistance in leaves of accession Ws-0 to the H. parasitica isolate NOCO, was expressed in leaves as well as in roots. Similarly, NDR1 and EDS1, two components of R gene-mediated signaling pathways, are also expressed in both tissues. To our knowledge, it has not been previously demonstrated that expression of R genes and downstream components of the signaling cascade are not sufficient for the induction of avirulence gene-mediated defense mechanisms in roots.

scholarly journals Lack of active defence responses revealed in a soil-free Arabidopsis/Peronospora sterile co-cultivation system

2002 ◽  
Vol 38 (SI 1 - 6th Conf EFPP 2002) ◽  
pp. S136-S138 ◽  
Author(s):  
M. Hermanns ◽  
A.J. Slusarenko ◽  
L.N.L. Schlaich
Keyword(s):  
Plant Diseases ◽  
Avirulence Gene ◽  
Organ Specificity ◽  
Dependent Manner ◽  
R Genes ◽  
Hypersensitive Cell Death ◽  
Cultivation System ◽  
Active Defence ◽  
Defence Responses ◽  
First Time

The molecular basis of organ specificity in plant diseases is little characterised. Downy mildew of Arabidopsis caused by the oomycete Peronospora parasitica is characteristically a leaf disease. Resistant host genotypes recognise the pathogen in a gene-for-gene dependent manner and respond with the production of H<sub>2</sub>O<sub>2</sub> and the execution of a genetically programmed hypersensitive cell death (HR). We inoculated the roots of Arabidopsis genotypes Col-0, Ws-0 and Wei-0 with the NOCO and WELA races of the pathogen and compared the responses with those observed in infected leaves. Combinations of incompatible genotypes of host and pathogen showed the expected responses of an oxidative burst and the HR in leaves but, surprisingly, roots showed no signs of active defence and appeared completely susceptible to all the P. parasitica isolates tested. RT-PCR showed that the R genes RPP1 and RPP13, which mediate resistance in leaves to P. parasitica isolates NOCO and WELA, respectively, were expressed in leaves as well as in roots. Similarly, NDR1 and EDS1, two components of RPP1-mediated gene signalling pathways, are also expressed in both tissues. Thus, we show for the first time that expression of R genes and at least some of the known downstream components of the signalling cascade are not sufficient for the induction of avirulence gene-mediated defence mechanisms.

Enhanced accumulation of pinosylvin stilbenes and related gene expression in Pinus strobus after infection of pine wood nematode

2021 ◽  
Author(s):  
Hwan-Su Hwang ◽  
Jung Yeon Han ◽  
Yong Eui Choi
Keyword(s):  
Transcription Factors ◽  
Defense Mechanisms ◽  
De Novo ◽  
Pinus Strobus ◽  
Pine Wilt Disease ◽  
Monomethyl Ether ◽  
Bursaphelenchus Xylophilus ◽  
Nematicidal Activity ◽  
Dependent Manner ◽  
Pine Wood

Abstract Pine wood nematodes (PWNs: Bursaphelenchus xylophilus) infect pine trees and cause serious pine wilt disease. Eastern white pine (Pinus strobus) has resistance to PWN. However, the detailed defense mechanisms of P. strobus against PWN are not well known. When P. strobus plants were infected with PWNs, the accumulation of stilbenoids, dihydropinosylvin monomethyl ether (DPME) and pinosylvin monomethyl ether (PME), were increased remarkably. DPME and PME had the high nematicidal activity. Interestingly, the nematicidal activity of the two compounds was resulted in a developmental stage-dependent manner. PME was more toxic to adult PWNs than juveniles, whereas DPME was found more toxic to juvenile PWNs than the adults. The genes involved in PME and DPME biosynthesis such as phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase (4CL), pinosylvin synthase (STS), and pinosylvin O-methyltransferase (PMT) were isolated using de novo sequencing of the transcriptome in P. strobus. In addition, transcription factors (bHLH, MYB and WRKY) related to stilbene biosynthesis were isolated. qPCR analyses of the selected genes (PAL, 4CL, STS, and PMT) including transcription factors (bHLH, MYB and WRKY) revealed that the expression level of the selected genes highly enhanced after PWN infection. Our results suggest that pinosylvin-type stilbenoid biosynthesis is highly responsive to PWN infection and plays an important role in PWN resistance of P. strobus trees.

scholarly journals Cloning and Characterization of R3b; Members of the R3 Superfamily of Late Blight Resistance Genes Show Sequence and Functional Divergence

2011 ◽  
Vol 24 (10) ◽  
pp. 1132-1142 ◽  
Author(s):  
Guangcun Li ◽  
Sanwen Huang ◽  
Xiao Guo ◽  
Ying Li ◽  
Yu Yang ◽  
...  
Keyword(s):  
Late Blight ◽  
Positional Cloning ◽  
Sequence Similarity ◽  
Functional Divergence ◽  
Durable Resistance ◽  
Coiled Coil ◽  
Avirulence Gene ◽  
R Gene ◽  
Gene Stacking ◽  
High Sequence Similarity

Massive resistance (R) gene stacking is considered to be one of the most promising approaches to provide durable resistance to potato late blight for both conventional and genetically modified breeding strategies. The R3 complex locus on chromosome XI in potato is an example of natural R gene stacking, because it contains two closely linked R genes (R3a and R3b) with distinct resistance specificities to Phytophthora infestans. Here, we report about the positional cloning of R3b. Both transient and stable transformations of susceptible tobacco and potato plants showed that R3b conferred full resistance to incompatible P. infestans isolates. R3b encodes a coiled-coil nucleotide-binding site leucine-rich repeat protein and exhibits 82% nucleotide identity with R3a located in the same R3 cluster. The R3b gene specifically recognizes Avr3b, a newly identified avirulence factor from P. infestans. R3b does not recognize Avr3a, the corresponding avirulence gene for R3a, showing that, despite their high sequence similarity, R3b and R3a have clearly distinct recognition specificities. In addition to the Rpi-mcd1/Rpi-blb3 locus on chromosome IV, the R3 locus on chromosome XI is the second example of an R-gene cluster with multiple genes recognizing different races of P. infestans.

scholarly journals Kahweol Exerts Skin Moisturizing Activities by Upregulating STAT1 Activity

2021 ◽  
Vol 22 (16) ◽  
pp. 8864
Author(s):  
Hongxi Chen ◽  
Mohammad Amjad Hossain ◽  
Jong-Hoon Kim ◽  
Jae Youl Cho
Keyword(s):  
Proper Time ◽  
Radical Scavenging ◽  
Polymerase Chain Reaction Analysis ◽  
Luciferase Assay ◽  
Dependent Manner ◽  
Diphenyltetrazolium Bromide ◽  
Polymerase Chain ◽  
Radical Scavenging Ability ◽  
The Relationship ◽  
Dose Dependent

Kahweol is a diterpene present in coffee. Until now, several studies have shown that kahweol has anti-inflammatory and anti-angiogenic functions. Due to the limited research available about skin protection, this study aims to discern the potential abilities of kahweol and the possible regulation targets. First, the cytotoxicity of kahweol was checked by 3-4-5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide assay, while 2,20-azino-bis (3ethylbenzothiazoline-6-sulphonic acid) diammonium salt and 1-diphenyl-2-picryl-hydrazyl were used to examine the radical scavenging ability. Polymerase chain reaction analysis was performed to explore the proper time points and doses affecting skin hydration and barrier-related genes. Luciferase assay and Western blotting were used to explore the possible transcription factors. Finally, fludarabine (a STAT1 inhibitor) was chosen to discern the relationship between skin-moisturizing factors and STAT1. We found that HaCaT cells experienced no toxicity from kahweol, and kahweol displayed moderate radical scavenging ability. Moreover, kahweol increased the outcome of HAS1, HAS2, occludin, and TGM-1 from six hours in a dose-dependent manner as well as the activation of STAT1 from six hours. Additionally, kahweol recovered the suppression of HAS2, STAT1-mediated luciferase activity, and HA secretion, which was all downregulated by fludarabine. In this study, we demonstrated that kahweol promotes skin-moisturizing activities by upregulating STAT1.

Betulinic acid induces apoptosis of gallbladder cancer cells via repressing SCD1

2020 ◽  
Vol 52 (2) ◽  
pp. 200-206 ◽  
Author(s):  
Hongfei Wang ◽  
Fangxiao Dong ◽  
Ye Wang ◽  
Xu’an Wang ◽  
Defei Hong ◽  
...  
Keyword(s):  
Gallbladder Cancer ◽  
Betulinic Acid ◽  
Polymerase Chain Reaction Analysis ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Antitumor Effects ◽  
Concentration Dependent Manner ◽  
Polymerase Chain ◽  
Induced Apoptosis ◽  
Scd1 Expression

Abstract Gallbladder cancer (GBC) is the most common and aggressive malignancy of the biliary tract. Betulinic acid (BetA) has been reported to have anti-inflammatory and antitumor effects; however, the effect of BetA on GBC is still unknown. In this study, we investigated the effect of BetA on five GBC cell lines and found that BetA significantly inhibited the proliferation of NOZ cells but had little inhibitory effect on other GBC cells. BetA disturbed mitochondrial membrane potential and induced apoptosis in NOZ cells. Real-time polymerase chain reaction analysis revealed that stearoyl-coenzyme A desaturase 1 (SCD1) was highly expressed in NOZ cells but low expressed in other GBC cells. BetA inhibited SCD1 expression in a concentration-dependent manner in NOZ cells. Downregulation of SCD1 expression by RNA interference inhibited the proliferation of NOZ cells and induced cell apoptosis. Moreover, BetA inhibited the growth of xenografted tumors and suppressed SCD1 expression in nude mice. Thus, our results showed that BetA induced apoptosis through repressing SCD1 expression in GBC, suggesting that BetA might be an effective agent for the treatment of patients with GBC that highly expresses SCD1.

scholarly journals The actin cytoskeleton mediates transmission of Candidatus Liberibacter solanacearum by the carrot psyllid

2020 ◽  
Author(s):  
Poulami Sarkar ◽  
Svetlana Kontsedalov ◽  
Galina Lebedev ◽  
Murad Ghanim
Keyword(s):  
Actin Cytoskeleton ◽  
Defense Mechanisms ◽  
Plant Pathogens ◽  
Molecular Mechanisms ◽  
Plant Diseases ◽  
Citrus Industry ◽  
Citrus Greening Disease ◽  
Associated Diseases ◽  
Novel Approach ◽  
Vector Borne

Several vector-borne plant pathogens have evolved mechanisms to exploit and hijack vector host cellular, molecular and defense mechanisms for their transmission. Over the past few years, Liberibacter species, which are transmitted by several psyllid vectors, have become an economically important group of pathogens that devastated the citrus industry and caused tremendous losses to many other important crops worldwide. The molecular mechanisms underlying the interactions of Liberibacter species with their psyllid vectors are poorly studied. Candidatus Liberibacter solanacearum (CLso) associated with important vegetable diseases is transmitted by the carrot psyllid, Bactericera trigonica in a persistent manner. Here, we elucidated the role of B. trigonica Arp2/3 protein complex, which plays a major role in the regulation of the actin cytoskeleton, in the transmission of CLso. CLso co-localized with ArpC2, a key protein in this complex, and this co-localization strongly associated with actin filaments. Silencing the psyllid ArpC2 disrupted the co-localization and the dynamics of F-actin. Silencing RhoGAP21 and Cdc42, which act in the signaling cascade leading to upregulation of Arp2/3 and F-actin bundling, also showed similar results. On the other hand, silencing ArpC5, another component of the complex, did not induce any significant effects on F-actin formation. Finally, ArpC2 silencing caused 73.4% reduction in CLso transmission by psyllids, strongly suggesting that its transmission by B. trigonica is cytoskeleton-dependent and it interacts with ArpC2 to exploit the intracellular actin nucleation process for transmission. Targeting this unique interaction could lead to developing a novel strategy for the management of Liberibacter-associated diseases. IMPORTANCE Plant diseases caused by vector-borne pathogens are responsible for tremendous losses and threaten some of the most important agricultural crops. A good example is the citrus greening disease caused by bacteria of the genus Liberibacter and transmitted by psyllids, and has devastated the citrus industry in the US, China and Brazil. Here we show that the psyllid-transmitted Candidatus Liberibacter solanacearum (CLso) employs the actin cytoskeleton of psyllid gut cells, specifically the ArpC2 protein in the Arp2/3 complex of this system, for movement and transmission in the vector. Silencing ArpC2 dramatically influenced interaction of CLso with the cytoskeleton and decreased the bacteria transmission to plants. This system could be targeted for developing a novel approach for the control of Liberibacter- associated diseases.

scholarly journals Active defense mechanisms of thorny catfish

2020 ◽  
Vol 38 ◽  
pp. 35-48 ◽  
Author(s):  
Haocheng Quan ◽  
Wen Yang ◽  
Zixiang Tang ◽  
Robert O. Ritchie ◽  
Marc A. Meyers
Keyword(s):  
Defense Mechanisms ◽  
Active Defense

scholarly journals Chondroprotective Activity ofMurraya exoticathrough Inhibitingβ-Catenin Signaling Pathway

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Longhuo Wu ◽  
Haiqing Liu ◽  
Rui Zhang ◽  
Linfu Li ◽  
Jialin Li ◽  
...  
Keyword(s):  
Degenerative Joint Disease ◽  
Joint Disease ◽  
Chondrocyte Apoptosis ◽  
Dependent Manner ◽  
Chain Reaction ◽  
Protein Expressions ◽  
Murraya Exotica ◽  
Oa Chondrocytes ◽  
Polymerase Chain ◽  
Dose Dependent

Osteoarthritis (OA) is a degenerative joint disease that affects millions of people. Currently, there is no effective drug treatment for it. The purpose of this study is to investigate the chondroprotective effects ofMurraya exotica(L.) on OA. The rat OA models were duplicated to prepare for separating OA chondrocytes, synovial fluid (SF), and serum containingM. exotica(50 mg/kg, 100 mg/kg, and 200 mg/kg),M. exoticashowed the activity of decreasing the contents of TNF-αand IL-1βin SF and the chondrocyte apoptosis in a dose-dependent manner. To investigate the probable mechanism, quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were used to determine gene expression and protein profiles, respectively. The results reveal thatM. exoticacan downregulate mRNA and protein expressions ofβ-catenin and COX-2 and reporter activity significantly. Conclusively,M. exoticaexhibits antiapoptotic chondroprotective activity probably through inhibitingβ-catenin signaling.

scholarly journals OsJAZ13 Negatively Regulates Jasmonate Signaling and Activates Hypersensitive Cell Death Response in Rice

2020 ◽  
Vol 21 (12) ◽  
pp. 4379
Author(s):  
Xiujing Feng ◽  
Lei Zhang ◽  
Xiaoli Wei ◽  
Yun Zhou ◽  
Yan Dai ◽  
...  
Keyword(s):  
Cell Death ◽  
Splice Variants ◽  
Adaptor Protein ◽  
Dependent Manner ◽  
Hypersensitive Cell Death ◽  
Cell Death Response ◽  
Jaz Proteins ◽  
Localization Analysis ◽  
And Function

Jasmonate ZIM-domain (JAZ) proteins belong to the subgroup of TIFY family and act as key regulators of jasmonate (JA) responses in plants. To date, only a few JAZ proteins have been characterized in rice. Here, we report the identification and function of rice OsJAZ13 gene. The gene encodes three different splice variants: OsJAZ13a, OsJAZ13b, and OsJAZ13c. The expression of OsJAZ13 was mainly activated in vegetative tissues and transiently responded to JA and ethylene. Subcellular localization analysis indicated OsJAZ13a is a nuclear protein. Yeast two-hybrid assays revealed OsJAZ13a directly interacts with OsMYC2, and also with OsCOI1, in a COR-dependent manner. Furthermore, OsJAZ13a recruited a general co-repressor OsTPL via an adaptor protein OsNINJA. Remarkably, overexpression of OsJAZ13a resulted in the attenuation of root by methyl JA. Furthermore, OsJAZ13a-overexpressing plants developed lesion mimics in the sheath after approximately 30–45 days of growth. Tillers with necrosis died a few days later. Gene-expression analysis suggested the role of OsJAZ13 in modulating the expression of JA/ethylene response-related genes to regulate growth and activate hypersensitive cell death. Taken together, these observations describe a novel regulatory mechanism in rice and provide the basis for elucidating the function of OsJAZ13 in signal transduction and cell death in plants.

Benzodiazepines Block α2-Containing Inhibitory Glycine Receptors in Embryonic Mouse Hippocampal Neurons

2003 ◽  
Vol 90 (1) ◽  
pp. 89-99 ◽  
Author(s):  
Liu Lin Thio ◽  
Ananth Shanmugam ◽  
Keith Isenberg ◽  
Kelvin Yamada
Keyword(s):  
Hippocampal Neurons ◽  
Clinical Effects ◽  
Dependent Manner ◽  
Glycine Receptors ◽  
Binding Studies ◽  
Chloride Currents ◽  
Embryonic Mouse ◽  
Voltage Dependent ◽  
Polymerase Chain ◽  
Dose Dependent

Inhibitory glycine receptors (GlyRs) in the mammalian cortex probably contribute to brain development and to maintaining tonic inhibition. Given their presence throughout the cortex, their modulation likely has important physiological consequences. Although benzodiazepines potentiate γ-aminobutyric acidA receptors (GABAARs), they may also modulate GlyRs because binding studies initially suggested that they act at GlyRs. Furthermore, their diminished ability to potentiate neonatal GABAARs suggests that they may exert their beneficial clinical effects at another site in the developing brain. Therefore we examined the effect of benzodiazepines on whole cell currents mediated by GlyRs in cultured embryonic mouse hippocampal neurons. First, we determined the GlyR subunit composition in this preparation. Glycine, β-alanine, and taurine activate strychnine-sensitive chloride currents in a dose-dependent manner. Maximal concentrations of the three agonists produce equal, nonadditive responses as expected of full agonists. The pharmacological properties of the GlyR currents including their pattern of modulation by picrotoxinin, picrotin, and tropisetron indicate that GlyRs consist of α2β heteromers and α2 homomers. Reverse transcriptase polymerase chain reaction (RTPCR) studies confirmed the presence of α2 and β subunits. Second, we found that micromolar concentrations of some benzodiazepines, including chlordiazepoxide and nitrazepam, inhibit GlyR currents. Nitrazepam inhibition of GlyRs is noncompetitive, is not voltage dependent, and does not reflect enhanced desensitization. Thus benzodiazepines allosterically inhibit α2-containing GlyRs in embryonic mouse hippocampal neurons via a “low”-affinity site.

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