# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 25 | 0 | 1.0000 | Ectopic expression of Tsi1 in transgenic hot pepper plants enhances host resistance to viral, bacterial, and oomycete pathogens. In many plants, including hot pepper plants, productivity is greatly affected by pathogen attack. We reported previously that tobacco stress-induced gene 1 (Tsi1) may play an important role in regulating stress responsive genes and pathogenesis-related (PR) genes. In this study, we demonstrated that overexpression of Tsi1 gene in transgenic hot pepper plants induced constitutive expression of several PR genes in the absence of stress or pathogen treatment. The transgenic hot pepper plants expressing Tsi1 exhibited resistance to Pepper mild mottle virus (PMMV) and Cucumber mosaic virus (CMV). Furthermore, these transgenic plants showed increased resistance to a bacterial pathogen, Xanthomonas campestris pv. vesicatoria and also an oomycete pathogen, Phytophthora capsici. These results suggested that ectopic expression of Tsi1 in transgenic hot pepper plants enhanced the resistance of the plants to various pathogens, including viruses, bacteria, and oomycete. These results suggest that using transcriptional regulatory protein genes may contribute to developing broad-spectrum resistance in crop plants. | 2002 | 12437295 |
| 88 | 1 | 0.9995 | Constitutive expression of mammalian nitric oxide synthase in tobacco plants triggers disease resistance to pathogens. Nitric oxide (NO) is known for its role in the activation of plant defense responses. To examine the involvement and mode of action of NO in plant defense responses, we introduced calmodulin-dependent mammalian neuronal nitric oxide synthase (nNOS), which controls the CaMV35S promoter, into wild-type and NahG tobacco plants. Constitutive expression of nNOS led to NO production and triggered spontaneous induction of leaf lesions. Transgenic plants accumulated high amounts of H(2)O(2), with catalase activity lower than that in the wild type. nNOS transgenic plants contained high levels of salicylic acid (SA), and they induced an array of SA-, jasmonic acid (JA)-, and/or ethylene (ET)-related genes. Consequently, NahG co-expression blocked the induction of systemic acquired resistance (SAR)-associated genes in transgenic plants, implying SA is involved in NO-mediated induction of SAR genes. The transgenic plants exhibited enhanced resistance to a spectrum of pathogens, including bacteria, fungi, and viruses. Our results suggest a highly ranked regulatory role for NO in SA-, JA-, and/or ET-dependent pathways that lead to disease resistance. | 2012 | 23124383 |
| 8777 | 2 | 0.9994 | Systemic resistance in Arabidopsis induced by biocontrol bacteria is independent of salicylic acid accumulation and pathogenesis-related gene expression. Systemic acquired resistance is a pathogen-inducible defense mechanism in plants. The resistant state is dependent on endogenous accumulation of salicylic acid (SA) and is characterized by the activation of genes encoding pathogenesis-related (PR) proteins. Recently, selected nonpathogenic, root-colonizing biocontrol bacteria have been shown to trigger a systemic resistance response as well. To study the molecular basis underlying this type of systemic resistance, we developed an Arabidopsis-based model system using Fusarium oxysporum f sp raphani and Pseudomonas syringae pv tomato as challenging pathogens. Colonization of the rhizosphere by the biological control strain WCS417r of P. fluorescens resulted in a plant-mediated resistance response that significantly reduced symptoms elicited by both challenging pathogens. Moreover, growth of P. syringae in infected leaves was strongly inhibited in P. fluorescens WCS417r-treated plants. Transgenic Arabidopsis NahG plants, unable to accumulate SA, and wild-type plants were equally responsive to P. fluorescens WCS417r-mediated induction of resistance. Furthermore, P. fluorescens WCS417r-mediated systemic resistance did not coincide with the accumulation of PR mRNAs before challenge inoculation. These results indicate that P. fluorescens WCS417r induces a pathway different from the one that controls classic systemic acquired resistance and that this pathway leads to a form of systemic resistance independent of SA accumulation and PR gene expression. | 1996 | 8776893 |
| 8778 | 3 | 0.9994 | The transcriptome of rhizobacteria-induced systemic resistance in arabidopsis. Plants develop an enhanced defensive capacity against a broad spectrum of plant pathogens after colonization of the roots by selected strains of nonpathogenic, fluorescent Pseudomonas spp. In Arabidopsis thaliana, this rhizobacteria-induced systemic resistance (ISR) functions independently of salicylic acid but requires responsiveness to the plant hormones jasmonic acid and ethylene. In contrast to pathogen-induced systemic acquired resistance, rhizobacteria-mediated ISR is not associated with changes in the expression of genes encoding pathogenesis-related proteins. To identify ISR-related genes, we surveyed the transcriptional response of over 8,000 Arabidopsis genes during rhizobacteria-mediated ISR. Locally in the roots, ISR-inducing Pseudomonas fluorescens WCS417r bacteria elicited a substantial change in the expression of 97 genes. However, systemically in the leaves, none of the approximately 8,000 genes tested showed a consistent change in expression in response to effective colonization of the roots by WCS417r, indicating that the onset of ISR in the leaves is not associated with detectable changes in gene expression. After challenge inoculation of WCS417r-induced plants with the bacterial leaf pathogen P. syringae pv. tomato DC3000, 81 genes showed an augmented expression pattern in ISR-expressing leaves, suggesting that these genes were primed to respond faster or more strongly upon pathogen attack. The majority of the primed genes was predicted to be regulated by jasmonic acid or ethylene signaling. Priming of pathogen-induced genes allows the plant to react more effectively to the invader encountered, which might explain the broad-spectrum action of rhizobacteria-mediated ISR. | 2004 | 15305611 |
| 90 | 4 | 0.9994 | Non-host defense response in a novel Arabidopsis-Xanthomonas citri subsp. citri pathosystem. Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc), is one of the most destructive diseases of citrus. Progress of breeding citrus canker-resistant varieties is modest due to limited resistant germplasm resources and lack of candidate genes for genetic manipulation. The objective of this study is to establish a novel heterologous pathosystem between Xcc and the well-established model plant Arabidopsis thaliana for defense mechanism dissection and resistance gene identification. Our results indicate that Xcc bacteria neither grow nor decline in Arabidopsis, but induce multiple defense responses including callose deposition, reactive oxygen species and salicylic aicd (SA) production, and defense gene expression, indicating that Xcc activates non-host resistance in Arabidopsis. Moreover, Xcc-induced defense gene expression is suppressed or attenuated in several well-characterized SA signaling mutants including eds1, pad4, eds5, sid2, and npr1. Interestingly, resistance to Xcc is compromised only in eds1, pad4, and eds5, but not in sid2 and npr1. However, combining sid2 and npr1 in the sid2npr1 double mutant compromises resistance to Xcc, suggesting genetic interactions likely exist between SID2 and NPR1 in the non-host resistance against Xcc in Arabidopsis. These results demonstrate that the SA signaling pathway plays a critical role in regulating non-host defense against Xcc in Arabidopsis and suggest that the SA signaling pathway genes may hold great potential for breeding citrus canker-resistant varieties through modern gene transfer technology. | 2012 | 22299054 |
| 8776 | 5 | 0.9994 | Systemic resistance induced by rhizosphere bacteria. Nonpathogenic rhizobacteria can induce a systemic resistance in plants that is phenotypically similar to pathogen-induced systemic acquired resistance (SAR). Rhizobacteria-mediated induced systemic resistance (ISR) has been demonstrated against fungi, bacteria, and viruses in Arabidopsis, bean, carnation, cucumber, radish, tobacco, and tomato under conditions in which the inducing bacteria and the challenging pathogen remained spatially separated. Bacterial strains differ in their ability to induce resistance in different plant species, and plants show variation in the expression of ISR upon induction by specific bacterial strains. Bacterial determinants of ISR include lipopolysaccharides, siderophores, and salicylic acid (SA). Whereas some of the rhizobacteria induce resistance through the SA-dependent SAR pathway, others do not and require jasmonic acid and ethylene perception by the plant for ISR to develop. No consistent host plant alterations are associated with the induced state, but upon challenge inoculation, resistance responses are accelerated and enhanced. ISR is effective under field conditions and offers a natural mechanism for biological control of plant disease. | 1998 | 15012509 |
| 24 | 6 | 0.9993 | Environmental History Modulates Arabidopsis Pattern-Triggered Immunity in a HISTONE ACETYLTRANSFERASE1-Dependent Manner. In nature, plants are exposed to a fluctuating environment, and individuals exposed to contrasting environmental factors develop different environmental histories. Whether different environmental histories alter plant responses to a current stress remains elusive. Here, we show that environmental history modulates the plant response to microbial pathogens. Arabidopsis thaliana plants exposed to repetitive heat, cold, or salt stress were more resistant to virulent bacteria than Arabidopsis grown in a more stable environment. By contrast, long-term exposure to heat, cold, or exposure to high concentrations of NaCl did not provide enhanced protection against bacteria. Enhanced resistance occurred with priming of Arabidopsis pattern-triggered immunity (PTI)-responsive genes and the potentiation of PTI-mediated callose deposition. In repetitively stress-challenged Arabidopsis, PTI-responsive genes showed enrichment for epigenetic marks associated with transcriptional activation. Upon bacterial infection, enrichment of RNA polymerase II at primed PTI marker genes was observed in environmentally challenged Arabidopsis. Finally, repetitively stress-challenged histone acetyltransferase1-1 (hac1-1) mutants failed to demonstrate enhanced resistance to bacteria, priming of PTI, and increased open chromatin states. These findings reveal that environmental history shapes the plant response to bacteria through the development of a HAC1-dependent epigenetic mark characteristic of a primed PTI response, demonstrating a mechanistic link between the primed state in plants and epigenetics. | 2014 | 24963055 |
| 85 | 7 | 0.9993 | Bacterial disease resistance in Arabidopsis through flagellin perception. Plants and animals recognize microbial invaders by detecting pathogen-associated molecular patterns (PAMPs) such as flagellin. However, the importance of flagellin perception for disease resistance has, until now, not been demonstrated. Here we show that treatment of plants with flg22, a peptide representing the elicitor-active epitope of flagellin, induces the expression of numerous defence-related genes and triggers resistance to pathogenic bacteria in wild-type plants, but not in plants carrying mutations in the flagellin receptor gene FLS2. This induced resistance seems to be independent of salicylic acid, jasmonic acid and ethylene signalling. Wild-type and fls2 mutants both display enhanced resistance when treated with crude bacterial extracts, even devoid of elicitor-active flagellin, indicating the existence of functional perception systems for PAMPs other than flagellin. Although fls2 mutant plants are as susceptible as the wild type when bacteria are infiltrated into leaves, they are more susceptible to the pathogen Pseudomonas syringae pv. tomato DC3000 when it is sprayed on the leaf surface. Thus, flagellin perception restricts bacterial invasion, probably at an early step, and contributes to the plant's disease resistance. | 2004 | 15085136 |
| 8774 | 8 | 0.9993 | Effects of colonization of a bacterial endophyte, Azospirillum sp. B510, on disease resistance in rice. Agriculturally important grasses contain numerous diazotrophic bacteria, the interactions of which are speculated to have some other benefits to the host plants. In this study, we analyzed the effects of a bacterial endophyte, Azospirillum sp. B510, on disease resistance in host rice plants. Rice plants (Oryza sativa cv. Nipponbare) were inoculated with B510 exhibited enhanced resistance against diseases caused by the virulent rice blast fungus Magnaporthe oryzae and by the virulent bacterial pathogen Xanthomonas oryzae. In the rice plants, neither salicylic acid (SA) accumulation nor expression of pathogenesis-related (PR) genes was induced by interaction with this bacterium, except for slight induction of PBZ1. These results indicate the possibility that strain B510 is able to induce disease resistance in rice by activating a novel type of resistance mechanism independent of SA-mediated defense signaling. | 2009 | 19966496 |
| 84 | 9 | 0.9993 | Two pathways act in an additive rather than obligatorily synergistic fashion to induce systemic acquired resistance and PR gene expression. BACKGROUND: Local infection with necrotizing pathogens induces whole plant immunity to secondary challenge. Pathogenesis-related genes are induced in parallel with this systemic acquired resistance response and thought to be co-regulated. The hypothesis of co-regulation has been challenged by induction of Arabidopsis PR-1 but not systemic acquired resistance in npr1 mutant plants responding to Pseudomonas syringae carrying the avirulence gene avrRpt2. However, experiments with ndr1 mutant plants have revealed major differences between avirulence genes. The ndr1-1 mutation prevents hypersensitive cell death, systemic acquired resistance and PR-1 induction elicited by bacteria carrying avrRpt2. This mutation does not prevent these responses to bacteria carrying avrB. RESULTS: Systemic acquired resistance, PR-1 induction and PR-5 induction were assessed in comparisons of npr1-2 and ndr1-1 mutant plants, double mutant plants, and wild-type plants. Systemic acquired resistance was displayed by all four plant lines in response to Pseudomonas syringae bacteria carrying avrB. PR-1 induction was partially impaired by either single mutation in response to either bacterial strain, but only fully impaired in the double mutant in response to avrRpt2. PR-5 induction was not fully impaired in any of the mutants in response to either avirulence gene. CONCLUSION: Two pathways act additively, rather than in an obligatorily synergistic fashion, to induce systemic acquired resistance, PR-1 and PR-5. One of these pathways is NPR1-independent and depends on signals associated with hypersensitive cell death. The other pathway is dependent on salicylic acid accumulation and acts through NPR1. At least two other pathways also contribute additively to PR-5 induction. | 2002 | 12381270 |
| 86 | 10 | 0.9993 | Decreased abundance of type III secretion system-inducing signals in Arabidopsis mkp1 enhances resistance against Pseudomonas syringae. Genes encoding the virulence-promoting type III secretion system (T3SS) in phytopathogenic bacteria are induced at the start of infection, indicating that recognition of signals from the host plant initiates this response. However, the precise nature of these signals and whether their concentrations can be altered to affect the biological outcome of host-pathogen interactions remain speculative. Here we use a metabolomic comparison of resistant and susceptible genotypes to identify plant-derived metabolites that induce T3SS genes in Pseudomonas syringae pv tomato DC3000 and report that mapk phosphatase 1 (mkp1), an Arabidopsis mutant that is more resistant to bacterial infection, produces decreased levels of these bioactive compounds. Consistent with these observations, T3SS effector expression and delivery by DC3000 was impaired when infecting the mkp1 mutant. The addition of bioactive metabolites fully restored T3SS effector delivery and suppressed the enhanced resistance in the mkp1 mutant. Pretreatment of plants with pathogen-associated molecular patterns (PAMPs) to induce PAMP-triggered immunity (PTI) also restricts T3SS effector delivery and enhances resistance by unknown mechanisms, and the addition of the bioactive metabolites similarly suppressed both aspects of PTI. Together, these results demonstrate that DC3000 perceives multiple signals derived from plants to initiate its T3SS and that the level of these host-derived signals impacts bacterial pathogenesis. | 2014 | 24753604 |
| 87 | 11 | 0.9993 | Involvement of specific calmodulin isoforms in salicylic acid-independent activation of plant disease resistance responses. The Ca2+ signal is essential for the activation of plant defense responses, but downstream components of the signaling pathway are still poorly defined. Here we demonstrate that specific calmodulin (CaM) isoforms are activated by infection or pathogen-derived elicitors and participate in Ca2+-mediated induction of plant disease resistance responses. Soybean CaM (SCaM)-4 and SCaM-5 genes, which encode for divergent CaM isoforms, were induced within 30 min by a fungal elicitor or pathogen, whereas other SCaM genes encoding highly conserved CaM isoforms did not show such response. This pathogen-triggered induction of these genes specifically depended on the increase of intracellular Ca2+ level. Constitutive expression of SCaM-4 and SCaM-5 in transgenic tobacco plants triggered spontaneous induction of lesions and induces an array of systemic acquired resistance (SAR)-associated genes. Surprisingly, these transgenic plants have normal levels of endogenous salicylic acid (SA). Furthermore, coexpression of nahG gene did not block the induction of SAR-associated genes in these transgenic plants, indicating that SA is not involved in the SAR gene induction mediated by SCaM-4 or SCaM-5. The transgenic plants exhibit enhanced resistance to a wide spectrum of virulent and avirulent pathogens, including bacteria, fungi, and virus. These results suggest that specific CaM isoforms are components of a SA-independent signal transduction chain leading to disease resistance. | 1999 | 9892708 |
| 23 | 12 | 0.9992 | Ectopic expression of Hrf1 enhances bacterial resistance via regulation of diterpene phytoalexins, silicon and reactive oxygen species burst in rice. Harpin proteins as elicitor derived from plant gram negative bacteria such as Xanthomonas oryzae pv. oryzae (Xoo), Erwinia amylovora induce disease resistance in plants by activating multiple defense responses. However, it is unclear whether phytoalexin production and ROS burst are involved in the disease resistance conferred by the expression of the harpin(Xoo) protein in rice. In this article, ectopic expression of hrf1 in rice enhanced resistance to bacterial blight. Accompanying with the activation of genes related to the phytoalexin biosynthesis pathway in hrf1-transformed rice, phytoalexins quickly and consistently accumulated concurrent with the limitation of bacterial growth rate. Moreover, the hrf1-transformed rice showed an increased ability for ROS scavenging and decreased hydrogen peroxide (H(2)O(2)) concentration. Furthermore, the localization and relative quantification of silicon deposition in rice leaves was detected by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometer (EDS). Finally, the transcript levels of defense response genes increased in transformed rice. These results show a correlation between Xoo resistance and phytoalexin production, H(2)O(2), silicon deposition and defense gene expression in hrf1-transformed rice. These data are significant because they provide evidence for a better understanding the role of defense responses in the incompatible interaction between bacterial disease and hrf1-transformed plants. These data also supply an opportunity for generating nonspecific resistance to pathogens. | 2012 | 22970151 |
| 70 | 13 | 0.9992 | A host basal transcription factor is a key component for infection of rice by TALE-carrying bacteria. Transcription activator-like effectors (TALEs) are sequence-specific DNA binding proteins found in a range of plant pathogenic bacteria, where they play important roles in host-pathogen interactions. However, it has been unclear how TALEs, after they have been injected into the host cells, activate transcription of host genes required for infection success. Here, we show that the basal transcription factor IIA gamma subunit TFIIAγ5 from rice is a key component for infection by the TALE-carrying bacterium Xanthomonas oryzae pv. oryzae, the causal agent for bacterial blight. Direct interaction of several TALEs with TFIIAγ5 is required for activation of disease susceptibility genes. Conversely, reduced expression of the TFIIAγ5 host gene limits the induction of susceptibility genes and thus decreases bacterial blight symptoms. Suppression or mutation of TFIIAγ5 can also reduce bacterial streak, another devastating disease of rice caused by TALE-carrying X. oryzae pv. oryzicola. These results have important implications for formulating a widely applicable strategy with which to improve resistance of plants to TALE-carrying pathogens. | 2016 | 27472897 |
| 80 | 14 | 0.9992 | Virus infection induces resistance to Pseudomonas syringae and to drought in both compatible and incompatible bacteria-host interactions, which are compromised under conditions of elevated temperature and CO(2) levels. Plants are simultaneously exposed to a variety of biotic and abiotic stresses, such as infections by viruses and bacteria, or drought. This study aimed to improve our understanding of interactions between viral and bacterial pathogens and the environment in the incompatible host Nicotiana benthamiana and the susceptible host Arabidopsis thaliana, and the contribution of viral virulence proteins to these responses. Infection by the Potato virus X (PVX)/Plum pox virus (PPV) pathosystem induced resistance to Pseudomonas syringae (Pst) and to drought in both compatible and incompatible bacteria-host interactions, once a threshold level of defence responses was triggered by the virulence proteins P25 of PVX and the helper component proteinase of PPV. Virus-induced resistance to Pst was compromised in salicylic acid and jasmonic acid signalling-deficient Arabidopsis but not in N. benthamiana lines. Elevated temperature and CO(2) levels, parameters associated with climate change, negatively affected resistance to Pst and to drought induced by virus infection, and this correlated with diminished H(2)O(2) production, decreased expression of defence genes and a drop in virus titres. Thus, diminished virulence should be considered as a potential factor limiting the outcome of beneficial trade-offs in the response of virus-infected plants to drought or bacterial pathogens under a climate change scenario. | 2020 | 31730035 |
| 83 | 15 | 0.9992 | Transcriptional responses of Arabidopsis thaliana to the bacteria-derived PAMPs harpin and lipopolysaccharide. Many plant-pathogen interactions are controlled by specific interactions between pathogen avirulence (avr) gene loci and the corresponding plant resistance R locus (gene-for-gene-hypothesis). Very often, this type of interaction culminates in a hypersensitive reaction (HR). However, recently pathogen-associated molecular patterns (PAMPs) such as flagellin or lipopolysaccharides (LPS) that are common to all bacteria have been shown to act as general elicitors of basal or innate immune responses in several plant species. Here, we summarize the genetic programs in Arabidopsis thaliana behind the LPS-induced basal response and the HR induced by harpin, respectively. Using Agilent Arabidopsis cDNA microarrays consisting of approximately 15,000 oligomers, changes in transcript accumulation of treated cells were monitored over a period of 24h after elicitor treatment. Analysis of the array data revealed significant responses to LPS (309 genes), harpin (951 genes) or both (313 genes). Concentrating our analysis on the genes encoding transcription factors, defence genes, cell wall biogenesis-related genes and signal transduction components we monitored interesting parallels, but also remarkably different expression patterns. Harpin and LPS induced an overlapping set of genes involved in cell wall biogenesis, cellular communication and signalling. The pattern of induced genes associated with cell rescue and general stress responses such as small heat-shock proteins was highly similar. In contrast, there is a striking difference regarding some of the most prominent, central components of plant defence such as WRKY transcription factors and oxidative burst-associated genes like NADPH oxidases, whose expression became apparent only after treatment with harpin. While both harpin and LPS can stimulate plant immunity in Arabidopsis, the PAMP LPS induces much more subtle host reactions at the transcriptome scale. The defence machinery induced by harpin resembles the known HR-type host responses leading to cell death after treatment with this elicitor. LPS is a weak inducer of basal resistance and induces a different pattern of genes. Strikingly the biggest overlap (40) of responding genes was found between the early harpin response (30min) and the late LPS response (24h). | 2008 | 18406364 |
| 590 | 16 | 0.9992 | Recent advances in functional assays of WRKY transcription factors in plant immunity against pathogens. WRKY transcription factors (TFs) are one of the largest transcription factor families in plants and play important roles in plant processes, most notably in responding to diverse biotic and abiotic stresses. This article reviews the recent research progresses on WRKY TFs in regulating plant immunity, which includes both positive and negative regulation. WRKY TFs were shown to regulate plant defense against pathogens including fungi, bacteria, oomycetes, and viruses by modulating downstream pathogen resistance genes or interacting with other regulators. Plant signaling pathways or components involved in the regulatory network of WRKY-mediated plant immunity mainly involve the action of phytohormones, MAPKs (Mitogen-activated protein kinases), and other transcription factors. The interaction of WRKY TFs with these factors during pathogen resistance was discussed in this article, which may contribute to understanding the mechanisms of WRKY transcription factors in plant immunity. | 2024 | 39917597 |
| 79 | 17 | 0.9992 | A novel link between tomato GRAS genes, plant disease resistance and mechanical stress response. SUMMARY Members of the GRAS family of transcriptional regulators have been implicated in the control of plant growth and development, and in the interaction of plants with symbiotic bacteria. Here we examine the complexity of the GRAS gene family in tomato (Solanum lycopersicum) and investigate its role in disease resistance and mechanical stress. A large number of tomato ESTs corresponding to GRAS transcripts were retrieved from the public database and assembled in 17 contigs of putative genes. Expression analysis of these genes by real-time RT-PCR revealed that six SlGRAS transcripts accumulate during the onset of disease resistance to Pseudomonas syringae pv. tomato. Further analysis of two selected family members showed that their transcripts preferentially accumulate in tomato plants in response to different avirulent bacteria or to the fungal elicitor EIX, and their expression kinetics correlate with the appearance of the hypersensitive response. In addition, transcript levels of eight SlGRAS genes, including all the Pseudomonas-inducible family members, increased in response to mechanical stress much earlier than upon pathogen attack. Accumulation of SlGRAS transcripts following mechanical stress was in part dependent on the signalling molecule jasmonic acid. Remarkably, suppression of SlGRAS6 gene expression by virus-induced gene silencing impaired tomato resistance to P. syringae pv. tomato. These results support a function for GRAS transcriptional regulators in the plant response to biotic and abiotic stress. | 2006 | 20507472 |
| 89 | 18 | 0.9992 | The Arabidopsis flavin-dependent monooxygenase FMO1 is an essential component of biologically induced systemic acquired resistance. Upon localized attack by necrotizing pathogens, plants gradually develop increased resistance against subsequent infections at the whole-plant level, a phenomenon known as systemic acquired resistance (SAR). To identify genes involved in the establishment of SAR, we pursued a strategy that combined gene expression information from microarray data with pathological characterization of selected Arabidopsis (Arabidopsis thaliana) T-DNA insertion lines. A gene that is up-regulated in Arabidopsis leaves inoculated with avirulent or virulent strains of the bacterial pathogen Pseudomonas syringae pv maculicola (Psm) showed homology to flavin-dependent monooxygenases (FMO) and was designated as FMO1. An Arabidopsis knockout line of FMO1 proved to be fully impaired in the establishment of SAR triggered by avirulent (Psm avrRpm1) or virulent (Psm) bacteria. Loss of SAR in the fmo1 mutants was accompanied by the inability to initiate systemic accumulation of salicylic acid (SA) and systemic expression of diverse defense-related genes. In contrast, responses at the site of pathogen attack, including increases in the levels of the defense signals SA and jasmonic acid, camalexin accumulation, and expression of various defense genes, were induced in a similar manner in both fmo1 mutant and wild-type plants. Consistently, the fmo1 mutation did not significantly affect local disease resistance toward virulent or avirulent bacteria in naive plants. Induction of FMO1 expression at the site of pathogen inoculation is independent of SA signaling, but attenuated in the Arabidopsis eds1 and pad4 defense mutants. Importantly, FMO1 expression is also systemically induced upon localized P. syringae infection. This systemic up-regulation is missing in the SAR-defective SA pathway mutants sid2 and npr1, as well as in the defense mutant ndr1, indicating a close correlation between systemic FMO1 expression and SAR establishment. Our findings suggest that the presence of the FMO1 gene product in systemic tissue is critical for the development of SAR, possibly by synthesis of a metabolite required for the transduction or amplification of a signal during the early phases of SAR establishment in systemic leaves. | 2006 | 16778014 |
| 8762 | 19 | 0.9991 | Resistance Genes and their Interactions with Bacterial Blight/Leaf Streak Pathogens (Xanthomonas oryzae) in Rice (Oryza sativa L.)-an Updated Review. Rice (Oryza sativa L.) is a staple food crop, feeding more than 50% of the world's population. Diseases caused by bacterial, fungal, and viral pathogens constantly threaten the rice production and lead to enormous yield losses. Bacterial blight (BB) and bacterial leaf streak (BLS), caused respectively by gram-negative bacteria Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc), are two important diseases affecting rice production worldwide. Due to the economic importance, extensive genetic and genomic studies have been conducted to elucidate the molecular mechanism of rice response to Xoo and Xoc in the last two decades. A series of resistance (R) genes and their cognate avirulence and virulence effector genes have been characterized. Here, we summarize the recent advances in studies on interactions between rice and the two pathogens through these R genes or their products and effectors. Breeding strategies to develop varieties with durable and broad-spectrum resistance to Xanthomonas oryzae based on the published studies are also discussed. | 2020 | 31915945 |