NTPR1A - Word Related Documents




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9500.8625NtPR1a regulates resistance to Ralstonia solanacearum in Nicotiana tabacum via activating the defense-related genes. Pathogenesis-related proteins (PRs) are associated with the development of systemic acquired resistance (SAR) against further infection enforced by fungi, bacteria and viruses. PR1a is the first PR-1 member that could be purified and characterized. Previous studies have reported its role in plants' resistance system against oomycete pathogens. However, the role of PR1a in Solanaceae plants against the bacterial wilt pathogen Ralstonia solanacearum remains unclear. To assess roles of NtPR1a in tobacco responding to R. solanacearum, we performed overexpression experiments in Yunyan 87 plants (a susceptible tobacco cultivar). The results illuminated that overexpression of NtPR1a contributed to improving resistance to R. solanacearum in tobacco Yunyan 87. Specifically speaking, NtPR1a gene could be induced by exogenous hormones like salicylic acid (SA) and pathogenic bacteria R. Solanacearum. Moreover, NtPR1a-overexpressing tobacco significantly reduced multiple of R. solanacearum and inhibited the development of disease symptoms compared with wild-type plants. Importantly, overexpression of NtPR1a activated a series of defense-related genes expression, including the hypersensitive response (HR)-associated genes NtHSR201 and NtHIN1, SA-, JA- and ET-associated genes NtPR2, NtCHN50, NtPR1b, NtEFE26, and Ntacc oxidase, and detoxification-associated gene NtGST1. In summary, our results suggested that NtPR1a-enhanced tobacco resistance to R. solanacearum may be mainly dependent on activation of the defense-related genes.201930545635
4210.8493Suppression of the rice fatty-acid desaturase gene OsSSI2 enhances resistance to blast and leaf blight diseases in rice. Fatty acids and their derivatives play important signaling roles in plant defense responses. It has been shown that suppressing a gene for stearoyl acyl carrier protein fatty-acid desaturase (SACPD) enhances the resistance of Arabidopsis (SSI2) and soybean to multiple pathogens. In this study, we present functional analyses of a rice homolog of SSI2 (OsSSI2) in disease resistance of rice plants. A transposon insertion mutation (Osssi2-Tos17) and RNAi-mediated knockdown of OsSSI2 (OsSSI2-kd) reduced the oleic acid (18:1) level and increased that of stearic acid (18:0), indicating that OsSSI2 is responsible for fatty-acid desaturase activity. These plants displayed spontaneous lesion formation in leaf blades, retarded growth, slight increase in endogenous free salicylic acid (SA) levels, and SA/benzothiadiazole (BTH)-specific inducible genes, including WRKY45, a key regulator of SA/BTH-induced resistance, in rice. Moreover, the OsSSI2-kd plants showed markedly enhanced resistance to the blast fungus Magnaporthe grisea and leaf-blight bacteria Xanthomonas oryzae pv. oryzae. These results suggest that OsSSI2 is involved in the negative regulation of defense responses in rice, as are its Arabidopsis and soybean counterparts. Microarray analyses identified 406 genes that were differentially expressed (>or=2-fold) in OsSSI2-kd rice plants compared with wild-type rice and, of these, approximately 39% were BTH responsive. Taken together, our results suggest that induction of SA-responsive genes, including WRKY45, is likely responsible for enhanced disease resistance in OsSSI2-kd rice plants.200919522564
5020.8439OsNPR1 Enhances Rice Resistance to Xanthomonas oryzae pv. oryzae by Upregulating Rice Defense Genes and Repressing Bacteria Virulence Genes. The bacteria pathogen Xanthomonas oryzae pv. oryzae (Xoo) infects rice and causes the severe disease of rice bacteria blight. As the central regulator of the salic acid (SA) signaling pathway, NPR1 is responsible for sensing SA and inducing the expression of pathogen-related (PR) genes in plants. Overexpression of OsNPR1 significantly increases rice resistance to Xoo. Although some downstream rice genes were found to be regulated by OsNPR1, how OsNPR1 affects the interaction of rice-Xoo and alters Xoo gene expression remains unknown. In this study, we challenged the wild-type and OsNPR1-OE rice materials with Xoo and performed dual RNA-seq analyses for the rice and Xoo genomes simultaneously. In Xoo-infected OsNPR1-OE plants, rice genes involved in cell wall biosynthesis and SA signaling pathways, as well as PR genes and nucleotide-binding site-leucine-rich repeat (NBS-LRR) genes, were significantly upregulated compared to rice variety TP309. On the other hand, Xoo genes involved in energy metabolism, oxidative phosphorylation, biosynthesis of primary and secondary metabolism, and transportation were repressed. Many virulence genes of Xoo, including genes encoding components of type III and other secretion systems, were downregulated by OsNPR1 overexpression. Our results suggest that OsNPR1 enhances rice resistance to Xoo by bidirectionally regulating gene expression in rice and Xoo.202337240026
1230.8424A Diketopiperazine, Cyclo-(L-Pro-L-Ile), Derived From Bacillus thuringiensis JCK-1233 Controls Pine Wilt Disease by Elicitation of Moderate Hypersensitive Reaction. Pine wilt disease (PWD) caused by the pine wood nematode (PWN) Bursaphelenchus xylophilus is one of the devastating diseases affecting pine forests worldwide. Although effective control measurements are still missing, induction of resistance could represent a possible eco-friendly alternative. In this study, induced resistance-based in vitro and in vivo screening tests were carried out for selection of bacteria with the ability to suppress PWD. Out of 504 isolated bacteria, Bacillus thuringiensis JCK-1233 was selected for its ability to boost pathogenesis-related 1 (PR1) gene expression, a marker of systemic acquired resistance. Moreover, treatment of pine seedlings with B. thuringiensis JCK-1233 resulted in increased expression of other defense-related genes, and significantly inhibited PWD development under greenhouse conditions. However, B. thuringiensis JCK-1233 showed no direct nematicidal activity against B. xylophilus. To identify the effective compound responsible for the induction of resistance in B. thuringiensis JCK-1233, several diketopiperazines (DPKs) including cyclo-(D-Pro-L-Val), cyclo-(L-Pro-L-Ile), cyclo-(L-Pro-L-Phe), and cyclo-(L-Leu-L-Val) were isolated and tested. Foliar treatment of pine seedlings with Cyclo-(L-Pro-L-Ile) resulted in suppression of PWD severity and increased the expression of defense-related genes similarly to B. thuringiensis JCK-1233 treatment. Interestingly, treatment with B. thuringiensis JCK-1233 or cyclo-(L-Pro-L-Ile) showed moderately enhanced expression of PR-1, PR-2, PR-3, PR-4, PR-5, and PR-9 genes following inoculation with PWN compared to that in the untreated control, indicating that they mitigated the burst of hypersensitive reaction in susceptible pine seedlings. In contrast, they significantly increased the expression levels of PR-6 and PR-10 before PWN inoculation. In conclusion, foliar spraying with either B. thuringiensis JCK-1233 culture suspension or DPKs could induce resistance in pine seedlings, thereby alleviating the serious damage by PWD. Taken together, this study supports aerial spraying with eco-friendly biotic or abiotic agents as a valuable strategy that may mark an epoch for the control of PWD in pine forests.202032849672
51640.8410Role of Iron-Containing Alcohol Dehydrogenases in Acinetobacter baumannii ATCC 19606 Stress Resistance and Virulence. Most bacteria possess alcohol dehydrogenase (ADH) genes (Adh genes) to mitigate alcohol toxicity, but these genes have functions beyond alcohol degradation. Previous research has shown that ADH can modulate quorum sensing in Acinetobacter baumannii, a rising opportunistic pathogen. However, the number and nature of Adh genes in A. baumannii have not yet been fully characterized. We identified seven alcohol dehydrogenases (NAD(+)-ADHs) from A. baumannii ATCC 19606, and examined the roles of three iron-containing ADHs, ADH3, ADH4, and ADH6. Marker-less mutation was used to generate Adh3, Adh4, and Adh6 single, double, and triple mutants. Disrupted Adh4 mutants failed to grow in ethanol-, 1-butanol-, or 1-propanol-containing mediums, and recombinant ADH4 exhibited strongest activity against ethanol. Stress resistance assays with inorganic and organic hydroperoxides showed that Adh3 and Adh6 were key to oxidative stress resistance. Virulence assays performed on the Galleria mellonella model organism revealed that Adh4 mutants had comparable virulence to wild-type, while Adh3 and Adh6 mutants had reduced virulence. The results suggest that ADH4 is primarily involved in alcohol metabolism, while ADH3 and ADH6 are key to stress resistance and virulence. Further investigation into the roles of other ADHs in A. baumannii is warranted.202134576087
850.8409The hawthorn CpLRR-RLK1 gene targeted by ACLSV-derived vsiRNA positively regulate resistance to bacteria disease. Virus-derived small interfering RNAs (vsiRNAs) can target not only viruses but also plant genes. Apple chlorotic leaf spot virus (ACLSV) is an RNA virus that infects Rosaceae plants extensively, including apple, pear and hawthorn. Here, we report an ACLSV-derived vsiRNA [vsiR1360(-)] that targets and down-regulates the leucine-rich repeat receptor-like kinase 1 (LRR-RLK1) gene of hawthorn (Crataegus pinnatifida). The targeting and cleavage of the CpLRR-RLK1 gene by vsiR1360(-) were validated by RNA ligase-mediated 5' rapid amplification of cDNA ends and tobacco transient transformation assays. And the CpLRR-RLK1 protein fused to green fluorescent protein localized to the cell membrane. Conserved domain and phylogenetic tree analyses showed that CpLRR-RLK1 is closely related to the proteins of the LRRII-RLK subfamily. The biological function of CpLRR-RLK1 was explored by heterologous overexpression of CpLRR-RLK1 gene in Arabidopsis. The results of inoculation of Pst DC3000 in Arabidopsis leaves showed that the symptoms of CpLRR-RLK1 overexpression plants infected with Pst DC3000 were significantly reduced compared with the wild type. In addition, the detection of reactive oxygen species and callose deposition and the expression analysis of defense-related genes showed that the CpLRR-RLK1 gene can indeed enhance the resistance of Arabidopsis to bacteria disease.202033180701
4660.8404The pepper Bs4C proteins are localized to the endoplasmic reticulum (ER) membrane and confer disease resistance to bacterial blight in transgenic rice. Transcription activator-like effector (TALE)-dependent dominant disease resistance (R) genes in plants, also referred to as executor R genes, are induced on infection by phytopathogenic bacteria of the genus Xanthomonas harbouring the corresponding TALE genes. Unlike the traditional R proteins, the executor R proteins do not determine the resistance specificity and may function broadly in different plant species. The executor R gene Bs4C-R in the resistant genotype PI 235047 of the pepper species Capsicum pubescens (CpBs4C-R) confers disease resistance to Xanthomonas campestris pv. vesicatoria (Xcv) harbouring the TALE genes avrBsP/avrBs4. In this study, the synthetic genes of CpBs4C-R and two other Bs4C-like genes, the susceptible allele in the genotype PI585270 of C. pubescens (CpBs4C-S) and the CaBs4C-R homologue gene in the cultivar 'CM334' of Capsicum annum (CaBs4C), were characterized in tobacco (Nicotiana benthamiana) and rice (Oryza sativa). The Bs4C genes induced cell death in N. benthamiana. The functional Bs4C-eCFP fusion proteins were localized to the endoplasmic reticulum (ER) membrane in the leaf epidermal cells of N. benthamiana. The Xa10 promoter-Bs4C fusion genes in transgenic rice conferred strain-specific disease resistance to Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight in rice, and were specifically induced by the Xa10-incompatible Xoo strain PXO99(A) (pHM1avrXa10). The results indicate that the Bs4C proteins from pepper species function broadly in rice and the Bs4C protein-mediated cell death from the ER is conserved between dicotyledonous and monocotyledonous plants, which can be utilized to engineer novel and enhanced disease resistance in heterologous plants.201829603592
1770.8401Biocontrol Potential of Endophytic Plant-Growth-Promoting Bacteria against Phytopathogenic Viruses: Molecular Interaction with the Host Plant and Comparison with Chitosan. Endophytic plant-growth-promoting bacteria (ePGPB) are interesting tools for pest management strategies. However, the molecular interactions underlying specific biocontrol effects, particularly against phytopathogenic viruses, remain unexplored. Herein, we investigated the antiviral effects and triggers of induced systemic resistance mediated by four ePGPB (Paraburkholderia fungorum strain R8, Paenibacillus pasadenensis strain R16, Pantoea agglomerans strain 255-7, and Pseudomonas syringae strain 260-02) against four viruses (Cymbidium Ring Spot Virus-CymRSV; Cucumber Mosaic Virus-CMV; Potato Virus X-PVX; and Potato Virus Y-PVY) on Nicotiana benthamiana plants under controlled conditions and compared them with a chitosan-based resistance inducer product. Our studies indicated that ePGPB- and chitosan-treated plants presented well-defined biocontrol efficacy against CymRSV and CMV, unlike PVX and PVY. They exhibited significant reductions in symptom severity while promoting plant height compared to nontreated, virus-infected controls. However, these phenotypic traits showed no association with relative virus quantification. Moreover, the tested defense-related genes (Enhanced Disease Susceptibility-1 (EDS1), Non-expressor of Pathogenesis-related genes-1 (NPR1), and Pathogenesis-related protein-2B (PR2B)) implied the involvement of a salicylic-acid-related defense pathway triggered by EDS1 gene upregulation.202235805989
580.8393GmRAR1 and GmSGT1 are required for basal, R gene-mediated and systemic acquired resistance in soybean. RAR1, SGT1, and HSP90 are important components of effector-triggered immunity (ETI) in diverse plants, where RAR1 and SGT1 are thought to serve as HSP90 co-chaperones. We show that ETI in soybean requires RAR1 and SGT1 but not HSP90. Rsv1-mediated extreme resistance to Soybean mosaic virus (SMV) and Rpg-1b-mediated resistance to Pseudomonas syringae were compromised in plants silenced for GmRAR1 and GmSGT1-2 but not GmHSP90. This suggests that RAR1- or SGT1-dependant signaling is not always associated with a dependence on HSP90. Unlike in Arabidopsis, SGT1 in soybean also mediates ETI against the bacterial pathogen P. syringae. Similar to Arabidopsis, soybean RAR1 and SGT1 proteins interact with each other and two related HSP90 proteins. Plants silenced for GmHSP90 genes or GmRAR1 exhibited altered morphology, suggesting that these proteins also contribute to developmental processes. Silencing GmRAR1 and GmSGT1-2 impaired resistance to virulent bacteria and systemic acquired resistance (SAR) in soybean as well. Because the Arabidopsis rar1 mutant also showed a defect in SAR, we conclude that RAR1 and SGT1 serve as a point of convergence for basal resistance, ETI, and SAR. We demonstrate that, although soybean defense signaling pathways recruit structurally conserved components, they have distinct requirements for specific proteins.200919061405
2190.8391miR159a modulates poplar resistance against different fungi and bacteria. Trees are inevitably attacked by different kinds of pathogens in their life. However, little is known about the regulatory factors in poplar response to different pathogen infections. MicroRNA159 (miR159) is a highly conserved microRNA (miRNA) in plants and regulates plant development and stress responses. Here, transgenic poplar overexpressing pto-miR159a (OX-159) showed antagonistic regulation mode to poplar stem disease caused by fungi Cytospora chrysosperma and bacteria Lonsdalea populi. OX-159 lines exhibited a higher susceptibility after inoculation with bacterium L. populi, whereas enhanced disease resistance to necrotrophic fungi C. chrysosperma compared with wild-type (WT) poplars. Intriguingly, further disease assay found that OX159 line rendered the poplar susceptible to hemi-biotrophic fungi Colletotrichum gloeosporioide, exhibiting larger necrosis and lower ROS accumulation than WT lines. Transcriptome analyses revealed that more down-regulated differentially expressed genes with disease-resistant domains in OX-159 line compared with WT line. Moreover, the central mediator NPR1 of salicylic acid (SA) pathway showed a decrease in expression level, while jasmonic acid/ethylene (JA/ET) signal pathway marker genes ERF, as well as PR3, MPK3, and MPK6 genes showed an increase level in OX159-2 and OX159-5 compared with WT lines. Further spatio-temporal expression analysis revealed JA/ET signaling was involved in the dynamic response process to C. gloeosporioides in WT and OX159 lines. These results demonstrate that overexpression of pto-miR159a resulted in the crosstalk changes of the downstream hub genes, thereby controlling the disease resistance of poplars, which provides clues for understanding pto-miR159a role in coordinating poplar-pathogen interactions.202337494825
47100.8380LTP3 contributes to disease susceptibility in Arabidopsis by enhancing abscisic acid (ABA) biosynthesis. Several plant lipid transfer proteins (LTPs) act positively in plant disease resistance. Here, we show that LTP3 (At5g59320), a pathogen and abscisic acid (ABA)-induced gene, negatively regulates plant immunity in Arabidopsis. The overexpression of LTP3 (LTP3-OX) led to an enhanced susceptibility to virulent bacteria and compromised resistance to avirulent bacteria. On infection of LTP3-OX plants with Pseudomonas syringae pv. tomato, genes involved in ABA biosynthesis, NCED3 and AAO3, were highly induced, whereas salicylic acid (SA)-related genes, ICS1 and PR1, were down-regulated. Accordingly, in LTP3-OX plants, we observed increased ABA levels and decreased SA levels relative to the wild-type. We also showed that the LTP3 overexpression-mediated enhanced susceptibility was partially dependent on AAO3. Interestingly, loss of function of LTP3 (ltp3-1) did not affect ABA pathways, but resulted in PR1 gene induction and elevated SA levels, suggesting that LTP3 can negatively regulate SA in an ABA-independent manner. However, a double mutant consisting of ltp3-1 and silent LTP4 (ltp3/ltp4) showed reduced susceptibility to Pseudomonas and down-regulation of ABA biosynthesis genes, suggesting that LTP3 acts in a redundant manner with its closest homologue LTP4 by modulating the ABA pathway. Taken together, our data show that LTP3 is a novel negative regulator of plant immunity which acts through the manipulation of the ABA-SA balance.201626123657
49110.8378Ectopic activation of the rice NLR heteropair RGA4/RGA5 confers resistance to bacterial blight and bacterial leaf streak diseases. Bacterial blight (BB) and bacterial leaf streak (BLS) are important diseases in Oryza sativa caused by Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc), respectively. In both bacteria, transcription activator-like (TAL) effectors are major virulence determinants that act by transactivating host genes downstream of effector-binding elements (EBEs) bound in a sequence-specific manner. Resistance to Xoo is mostly related to the action of TAL effectors, either by polymorphisms that prevent the induction of susceptibility (S) genes or by executor (R) genes with EBEs embedded in their promoter, and that induce cell death and resistance. For Xoc, no resistance sources are known in rice. Here, we investigated whether the recognition of effectors by nucleotide binding and leucine-rich repeat domain immune receptors (NLRs), the most widespread resistance mechanism in plants, is also able to stop BB and BLS. In one instance, transgenic rice lines harboring the AVR1-CO39 effector gene from the rice blast fungus Magnaporthe oryzae, under the control of an inducible promoter, were challenged with transgenic Xoo and Xoc strains carrying a TAL effector designed to transactivate the inducible promoter. This induced AVR1-CO39 expression and triggered BB and BLS resistance when the corresponding Pi-CO39 resistance locus was present. In a second example, the transactivation of an auto-active NLR by Xoo-delivered designer TAL effectors resulted in BB resistance, demonstrating that NLR-triggered immune responses efficiently control Xoo. This forms the foundation for future BB and BLS disease control strategies, whereupon endogenous TAL effectors will target synthetic promoter regions of Avr or NLR executor genes.201627289079
16120.8378A glycoside hydrolase 30 protein BpXynC of Bacillus paralicheniformis NMSW12 recognized as A MAMP triggers plant immunity response. Bacillus spp. has been widely used as a biocontrol agent to control plant diseases. However, little is known about mechanisms of the protein MAMP secreted by Bacillus spp. Herein, our study reported a glycoside hydrolase family 30 (GH30) protein, BpXynC, produced by the biocontrol bacteria Bacillus paralicheniformis NMSW12, that can induce cell death in several plant species. The results revealed that the recombinant protein triggers cell death in Nicotiana benthamiana in a BAK1-dependent manner and elicits an early defense response, including ROS burst, activation of MAPK cascades, and upregulation of plant immunity marker genes. BpXynC was also found to be a glucuronoxylanase that exhibits hydrolysis activity on xlyan. Two mutants of BpXynC which lost the glucuronoxylanase activity still retained the elicitor activity. The qRT-PCR results of defense-related genes showed that BpXynC induces plant immunity responses via an SA-mediated pathway. BpXynC and its mutants could induce resistance in N. benthamiana against infection by Sclerotinia sclerotiorum and tobacco mosaic virus (TMV). Furthermore, BpXynC-treated tomato fruits exhibited strong resistance to the infection of Phytophthora capsica. Overall, our study revealed that GH30 protein BpXynC can induce plant immunity response as MAMP, which can be further applied as a biopesticide to control plant diseases.202438286384
51130.8376A pair of allelic WRKY genes play opposite roles in rice-bacteria interactions. Although allelic diversity of genes has been reported to play important roles in different physiological processes, information on allelic diversity of defense-responsive genes in host-pathogen interactions is limited. Here, we report that a pair of allelic genes, OsWRKY45-1 and OsWRKY45-2, which encode proteins with a 10-amino acid difference, play opposite roles in rice (Oryza sativa) resistance against bacterial pathogens. Bacterial blight caused by Xanthomonas oryzae pv oryzae (Xoo), bacterial streak caused by Xanthomonas oryzae pv oryzicola (Xoc), and fungal blast caused by Magnaporthe grisea are devastating diseases of rice worldwide. OsWRKY45-1-overexpressing plants showed increased susceptibility and OsWRKY45-1-knockout plants showed enhanced resistance to Xoo and Xoc. In contrast, OsWRKY45-2-overexpressing plants showed enhanced resistance and OsWRKY45-2-suppressing plants showed increased susceptibility to Xoo and Xoc. Interestingly, both OsWRKY45-1- and OsWRKY45-2-overexpressing plants showed enhanced resistance to M. grisea. OsWRKY45-1-regulated Xoo resistance was accompanied by increased accumulation of salicylic acid and jasmonic acid and induced expression of a subset of defense-responsive genes, while OsWRKY45-2-regulated Xoo resistance was accompanied by increased accumulation of jasmonic acid but not salicylic acid and induced expression of another subset of defense-responsive genes. These results suggest that both OsWRKY45-1 and OsWRKY45-2 are positive regulators in rice resistance against M. grisea, but the former is a negative regulator and the latter is a positive regulator in rice resistance against Xoo and Xoc. The opposite roles of the two allelic genes in rice-Xoo interaction appear to be due to their mediation of different defense signaling pathways.200919700558
52140.8374NHL25 and NHL3, two NDR1/HIN1-1ike genes in Arabidopsis thaliana with potential role(s) in plant defense. The Arabidopsis genome contains 28 genes with sequence homology to the Arabidopsis NDR1 gene and the tobacco HIN1 gene. Expression analysis of eight of these genes identified two (NHL25 and NHL3 for NDR1/HIN1-like) that show pathogen-dependent mRNA accumulation. Transcripts did not accumulate during infection with virulent Pseudomonas syringae pv. tomato DC3000 but did accumulate specifically when the bacteria carried any of the four avirulence genes avrRpm1, avrRpt2, avrB, or avrRps4. Furthermore, expression of avrRpt2 in plants containing the corresponding resistance gene, RPS2, was sufficient to induce transcript accumulation. However, during infection with an avirulent oomycete, Peronospora parasitica isolate Cala-2, only NHL25 expression was reproducibly induced. Salicylic acid (SA) treatment can induce expression of NHL25 and NHL3. Studies performed on nahG plants showed that, during interaction with avirulent bacteria, only the expression of NHL25 but not that of NHL3 was affected. This suggests involvement of separate SA-dependent and SA-independent pathways, respectively, in the transcriptional activation of these genes. Bacteria-induced gene expression was not abolished in ethylene- (etrl-3 and ein2-1) and jasmonate- (coil-1) insensitive mutants or in mutants impaired in disease resistance (ndr1-1 and pad4-1). Interestingly, NHL3 transcripts accumulated after infiltration with the avirulent hrcC mutant of Pseudomonas syringae pv. tomato DC3000 and nonhost bacteria but not with the virulent Pseudomonas syringae pv. tomato DC3000, suggesting that virulent bacteria may suppress NHL3 expression during pathogenesis. Hence, the expression patterns and sequence homology to NDR1 and HIN1 suggest one or more potential roles for these genes in plant resistance.200212059109
57150.8365Functional analysis of NtMPK2 uncovers its positive role in response to Pseudomonas syringae pv. tomato DC3000 in tobacco. Mitogen-activated protein kinase cascades are highly conserved signaling modules downstream of receptors/sensors and play pivotal roles in signaling plant defense against pathogen attack. Extensive studies on Arabidopsis MPK4 have implicated that the MAP kinase is involved in multilayered plant defense pathways. In this study, we identified tobacco NtMPK2 as an ortholog of AtMPK4. Transgenic tobacco overexpressing NtMPK2 markedly enhances resistance to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) virulent and avirulent strains. Transcriptome analysis of NtMPK2-dependent genes shows that possibly the basal resistance system is activated by NtMPK2 overexpression. In addition to NtMPK2-mediated resistance, multiple pathways are involved in response to the avirulent bacteria based on analysis of Pst-responding genes, including SA and ET pathways. Notably, it is possible that biosynthesis of antibacterial compounds is responsible for inhibition of Pst DC3000 avirulent strain when programmed cell death processes in the host. Our results uncover that NtMPK2 positively regulate tobacco defense response to Pst DC3000 and improve our understanding of plant molecular defense mechanism.201626482478
45160.8364Vitis vinifera VvNPR1.1 is the functional ortholog of AtNPR1 and its overexpression in grapevine triggers constitutive activation of PR genes and enhanced resistance to powdery mildew. Studying grapevine (Vitis vinifera) innate defense mechanisms is a prerequisite to the development of new protection strategies, based on the stimulation of plant signaling pathways to trigger pathogen resistance. Two transcriptional coactivators (VvNPR1.1 and VvNPR1.2) with similarity to Arabidopsis thaliana NPR1 (Non-Expressor of PR genes 1), a well-characterized and key signaling element of the salicylic acid (SA) pathway, were recently isolated in Vitis vinifera. In this study, functional characterization of VvNPR1.1 and VvNPR1.2, including complementation of the Arabidopsis npr1 mutant, revealed that VvNPR1.1 is a functional ortholog of AtNPR1, whereas VvNPR1.2 likely has a different function. Ectopic overexpression of VvNPR1.1 in the Arabidopsis npr1-2 mutant restored plant growth at a high SA concentration, Pathogenesis Related 1 (PR1) gene expression after treatment with SA or bacterial inoculation, and resistance to virulent Pseudomonas syringae pv. maculicola bacteria. Moreover, stable overexpression of VvNPR1.1-GFP in V. vinifera resulted in constitutive nuclear localization of the fusion protein and enhanced PR gene expression in uninfected plants. Furthermore, grapevine plants overexpressing VvNPR1.1-GFP exhibited an enhanced resistance to powdery mildew infection. This work highlights the importance of the conserved SA/NPR1 signaling pathway for resistance to biotrophic pathogens in V. vinifera.201121505863
40170.8359Combinative effects of a bacterial type-III effector and a biocontrol bacterium on rice growth and disease resistance. Expression of HpaG(Xoo), a bacterial type-III effector, in transgenic plants induces disease resistance. Resistance also can be elicited by biocontrol bacteria. In both cases, plant growth is often promoted. Here we address whether biocontrol bacteria and HpaG(Xoo) can act together to provide better results in crop improvement. We studied effects of Pseudomonas cepacia on the rice variety R109 and the hpaG(Xoo)-expressing rice line HER1. Compared to R109, HER1 showed increased growth, grain yield, and defense responses toward diseases and salinity stress. Colonization of roots by P. cepacia caused 20% and 13% increase, in contrast to controls, in root growth of R109 and HER1. Growth of leaves and stems also increased in R109 but that of HER1 was inhibited. When P. cepacia colonization was subsequent to plant inoculation with Rhizoctonia solani, a pathogen that causes sheath blight, the disease was less severe than controls in both R109 and HER1; HER1, nevertheless, was more resistant, suggesting that P. cepacia and HpaG(Xoo) cooperate in inducing disease resistance. Several genes that critically regulate growth and defense behaved differentially in HER1 and R109 while responding to P. cepacia. In R109 leaves, the OsARF1 gene, which regulates plant growth, was expressed in consistence with growth promotion by P. cepacia. Inversely, OsARF1 expression was coincident with inhibition in growth of HER1 leaves. In both plants, the expression of OsEXP1, which encodes an expansin protein involved in plant growth,was concomitant with growth promotion in leaves instead of roots,in response to P. cepacia . We also studied OsMAPK, a gene that encodes a mitogen-activated protein kinase and controls defense responses toward salinity and infection by pathogens in rice. In response to P. cepacia, an early expression of OsMAPK was coincident with R109 resistance to the disease, while HER1 expressed the gene similarly whether P. cepacia was present or not. Evidently, P. cepacia and G(Xoo)-gene mediated resistance may act differently in rice growth and resistance. Whereas combinative effects of P. cepacia and HpaG(Xoo) in disease resistance have a great potential in agricultural use, it is interesting to study mechanisms that underlie interactions involving biocontrol bacteria, type-III effectors and pathogens.200617301500
97180.8358Universal gene co-expression network reveals receptor-like protein genes involved in broad-spectrum resistance in pepper (Capsicum annuum L.). Receptor-like proteins (RLPs) on plant cells have been implicated in immune responses and developmental processes. Although hundreds of RLP genes have been identified in plants, only a few RLPs have been functionally characterized in a limited number of plant species. Here, we identified RLPs in the pepper (Capsicum annuum) genome and performed comparative transcriptomics coupled with the analysis of conserved gene co-expression networks (GCNs) to reveal the role of core RLP regulators in pepper-pathogen interactions. A total of 102 RNA-seq datasets of pepper plants infected with four pathogens were used to construct CaRLP-targeted GCNs (CaRLP-GCNs). Resistance-responsive CaRLP-GCNs were merged to construct a universal GCN. Fourteen hub CaRLPs, tightly connected with defense-related gene clusters, were identified in eight modules. Based on the CaRLP-GCNs, we evaluated whether hub CaRLPs in the universal GCN are involved in the biotic stress response. Of the nine hub CaRLPs tested by virus-induced gene silencing, three genes (CaRLP264, CaRLP277, and CaRLP351) showed defense suppression with less hypersensitive response-like cell death in race-specific and non-host resistance response to viruses and bacteria, respectively, and consistently enhanced susceptibility to Ralstonia solanacearum and/or Phytophthora capsici. These data suggest that key CaRLPs are involved in the defense response to multiple biotic stresses and can be used to engineer a plant with broad-spectrum resistance. Together, our data show that generating a universal GCN using comprehensive transcriptome datasets can provide important clues to uncover genes involved in various biological processes.202235043174
48190.8356Priming of the Arabidopsis pattern-triggered immunity response upon infection by necrotrophic Pectobacterium carotovorum bacteria. Boosted responsiveness of plant cells to stress at the onset of pathogen- or chemically induced resistance is called priming. The chemical β-aminobutyric acid (BABA) enhances Arabidopsis thaliana resistance to hemibiotrophic bacteria through the priming of the salicylic acid (SA) defence response. Whether BABA increases Arabidopsis resistance to the necrotrophic bacterium Pectobacterium carotovorum ssp. carotovorum (Pcc) is not clear. In this work, we show that treatment with BABA protects Arabidopsis against the soft-rot pathogen Pcc. BABA did not prime the expression of the jasmonate/ethylene-responsive gene PLANT DEFENSIN 1.2 (PDF1.2), the up-regulation of which is usually associated with resistance to necrotrophic pathogens. Expression of the SA marker gene PATHOGENESIS RELATED 1 (PR1) on Pcc infection was primed by BABA treatment, but SA-defective mutants demonstrated a wild-type level of BABA-induced resistance against Pcc. BABA primed the expression of the pattern-triggered immunity (PTI)-responsive genes FLG22-INDUCED RECEPTOR-LIKE KINASE 1 (FRK1), ARABIDOPSIS NON-RACE SPECIFIC DISEASE RESISTANCE GENE (NDR1)/HAIRPIN-INDUCED GENE (HIN1)-LIKE 10 (NHL10) and CYTOCHROME P450, FAMILY 81 (CYP81F2) after inoculation with Pcc or after treatment with purified bacterial microbe-associated molecular patterns, such as flg22 or elf26. PTI-mediated callose deposition was also potentiated in BABA-treated Arabidopsis, and BABA boosted Arabidopsis stomatal immunity to Pcc. BABA treatment primed the PTI response in the SA-defective mutants SA induction deficient 2-1 (sid2-1) and phytoalexin deficient 4-1 (pad4-1). In addition, BABA priming was associated with open chromatin configurations in the promoter region of PTI marker genes. Our data indicate that BABA primes the PTI response upon necrotrophic bacterial infection and suggest a role for the PTI response in BABA-induced resistance.201322947164