Transcriptional Characteristics of Xa21-mediated Defense Responses in Rice
Ontology highlight
ABSTRACT: Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is the most destructive bacterial disease of rice. The cloned rice gene Xa21 confers resistance to a broad spectrum of Xoo races. To identify other genes involved in Xa21-mediated immunity, a whole-genome oligonucleotide microarray of rice was used to profile the expression of rice genes between incompatible interactions and mock treatments at 0, 4, 8, 24, 72 and 120 hours post inoculation (hpi) or between incompatible and compatible interactions at 4 hpi, respectively. A total of 441 differentially expressed genes, designated as XDGs (Xa21 mediated Differentially expressed Genes), were identified. Based on their functional annotations, the XDGs were assigned to 14 categories some of which encode resistance/defense related proteins and signaling regulators. Interestingly, most signaling-related genes were down-regulated at 4 and 8 hpi, suggesting that negative regulation of cellular signaling may play a role in the Xa21-mediated defense response. Moreover, a number of pathogenesis-related genes were induced at 72 and 120 hpi. Comparison of expression profiles mediated by other resistance genes revealed an interesting common responses in the plant immune system. Comparison analyses also suggest possible overlaps with hormone signaling pathways and with defense systems including basal defense and hypersensitive responses.
Project description:Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is the most destructive bacterial disease of rice. The cloned rice gene Xa21 confers resistance to a broad spectrum of Xoo races. To identify other genes involved in Xa21-mediated immunity, a whole-genome oligonucleotide microarray of rice was used to profile the expression of rice genes between incompatible interactions and mock treatments at 0, 4, 8, 24, 72 and 120 hours post inoculation (hpi) or between incompatible and compatible interactions at 4 hpi, respectively. A total of 441 differentially expressed genes, designated as XDGs (Xa21 mediated Differentially expressed Genes), were identified. Based on their functional annotations, the XDGs were assigned to 14 categories some of which encode resistance/defense related proteins and signaling regulators. Interestingly, most signaling-related genes were down-regulated at 4 and 8 hpi, suggesting that negative regulation of cellular signaling may play a role in the Xa21-mediated defense response. Moreover, a number of pathogenesis-related genes were induced at 72 and 120 hpi. Comparison of expression profiles mediated by other resistance genes revealed an interesting common responses in the plant immune system. Comparison analyses also suggest possible overlaps with hormone signaling pathways and with defense systems including basal defense and hypersensitive responses. We investigated the transcriptional characteristics of Xa21-mediated defense responses in rice using whole-genome oligonucleotide microarray, by comparing the expression profiles between incompatible interactions and mock treatments at five time-points and between incompatible and compatible interactions at 4 hours post inoculation. Microarray hybridization at each time point was carried out in three replications including two biological replications and one technological replication. To detect the genes that are significantly regulated and to eliminate those that have inconsistent expression data among replicated experiments, a cutoff of 1.5 fold change and 1.96 for intensity-dependent Z-scores were required in at least two experimental samples.
Project description:Rice Xa21 resistance gene, which encodes a protein with predicted leucine-rich repeat (LRR), transmembrane, juxtamembrane, and intracellular kinase domains, conferred immunity to diverse strains of Xanthomonas oryzae pv. oryzae (Xoo). We generated Xa21 plant on TP309 background (Oryza Sativa Japonica). Systemic Acquired Resistance (SAR) in plants confers durable broad-spectrum resistance to pathogens and requires a phytohormone, salicylic acid (SA). Arabidopsis NPR1/NIM1 is a key regulator of the SAR response. Recently, we found that rice NPR1 homolog 1 (NH1) mediated enhanced resistance responses for Xoo (Chern et al., 2005b). We further investigated relating pathways in rice by identifying proteins that interact with NH1. One of them, constitutive over-expression of NH1 mediated negative regulator of resistance (NRR) gene caused enhanced susceptibility to Xoo , indicating that this gene product negatively affects to basal resistance response (Chern et al., 2005a). To dissect defense responses for rice bacterial blight pathogen, we planed microarray using two resistant mutant named with Xa21-TP309, NH1ox and one super-susceptible mutant (NRRox) before pathogen inoculation and one day post pathogen inoculation. Keywords: Biotic stress response
Project description:Rice Xa21 resistance gene, which encodes a protein with predicted leucine-rich repeat (LRR), transmembrane, juxtamembrane, and intracellular kinase domains, conferred immunity to diverse strains of Xanthomonas oryzae pv. oryzae (Xoo). We generated Xa21 plant on TP309 background (Oryza Sativa Japonica). Systemic Acquired Resistance (SAR) in plants confers durable broad-spectrum resistance to pathogens and requires a phytohormone, salicylic acid (SA). Arabidopsis NPR1/NIM1 is a key regulator of the SAR response. Recently, we found that rice NPR1 homolog 1 (NH1) mediated enhanced resistance responses for Xoo (Chern et al., 2005b). We further investigated relating pathways in rice by identifying proteins that interact with NH1. One of them, constitutive over-expression of NH1 mediated negative regulator of resistance (NRR) gene caused enhanced susceptibility to Xoo , indicating that this gene product negatively affects to basal resistance response (Chern et al., 2005a). To dissect defense responses for rice bacterial blight pathogen, we planed microarray using two resistant mutant named with Xa21-TP309, NH1ox and one super-susceptible mutant (NRRox) before pathogen inoculation and one day post pathogen inoculation. Keywords: Biotic stress response Two or Three-condition experiment, NH1ox vs wild type control (LG) at two durations of Xoo inoculation (0d and 1d); NRRox vs wild type control (LG) at two durations of Xoo inoculation (0d and 1d); and Xa21vs wild type control (TP309) at three durations of Xoo inoculation (0d,1d and 2d);. Biological replicates: 2 or 4, independently grown and harvested.
Project description:TITLE: Transcriptional profiling of Rgene-mediated responses in rice PROJECT DESCRIPTION: The dominant gene Xa7 and the recessive gene xa5 of rice confer resistance to several races of the bacterial blight pathogen Xanthomonas oryzae pv. oryzae (Xoo). To reveal the modes of action and the defense responses these genes initiate, we decided to obtain the global transcriptional profiles of the rice cultivars IRBB7, IRBB5 (which harbor Xa7 and xa5, respectively) and IR24 undergoing early infection by the Xoo Race 2 strain PXO86. Both IRBB7 and IRBB5 are resistant to PXO86 (which carry the corresponding avirulence genes avrXa7 and avrxa5), whereas IR24 is susceptible. We inoculated by vacuum infiltration the three rice cultivars ten days after seed germination (or 2 weeks after sowing) and collected inoculated tissue at 5 different timepoints within the first day after inoculation. The transcriptional profiles obtained will provide valuable insight into the similarities and differences between incompatible interactions mediated by a dominant and a recessive Rgene, in comparison to a compatible interaction. ****[PLEXdb(http://www.plexdb.org) has submitted this series at GEO on behalf of the original contributor, David O Nino-Liu. The equivalent experiment is OS4 at PLEXdb.]
Project description:Xanthomonas oryzae pv. oryzae strain PXO99A, so called Xoo, is disable to infect in rice cultivar carrying Xa21 gene. Disrupted mutant of raxR gene, response regulator of two-component regulatory system (TCS), in Xoo was previously shown to partially retrieve back the bacterial capability to establish in Xa21 rice. RaxR was shown to mediate the expression of other rax gene operon members and also its expression is changed dependent on cell population density. In this study, we investigated the regulatory mechanisms mediated by RaxR using whole-genome transcriptional profiling analysis in comparison of (i) PXO99R (PXO99 strain lacking RaxR) vs. PXO99, (ii) PXO99Rox (PXO99 strain overexpressing RaxR) vs. PXO99, and (iii) PXO99Rox vs. PXO99R. As a result of array analysis, we revealed that RaxR is not only required for AvrXa21 activitiy, it also plays roles in regulatory functions, for example, pathogenicity, motility, and stress tolerance. Then, we generated knock out mutants of RaxR regulon members to validate regulatory functions of RaxR and to extend other biological impacts of RaxR beyond the Xoo AvrXa21 activity. The combined interpretation from array analysis and mutant functional validation presents the complexity of regulatory pathways between AvrXa21 activity and other biological activities in Xoo. Keywords: Comparative transcription profiling between modified genetic mutant and wild type
Project description:Xanthomonas oryzae pv. oryzae (Xoo), the causative agent of bacterial blight disease, is one of the major threats to rice productivity. Yet, the molecular mechanism of rice-Xoo interaction is elusive. Here, we report comparative proteome profiles of Xoo susceptible (Dongjin) and resistant (Hwayeong) cultivars of rice in response to two-time points (3 and 6 days) of Xoo infection. Low-abundance proteins were enriched using a protamine sulfate (PS) precipitation method and isolated proteins were quantified by a label-free quantitative analysis, leading to the identification of 3846 protein groups. Of these, 1128 proteins were significantly changed between mock and Xoo infected plants of Dongjin and Hwayeong cultivars. Based on the abundance pattern and functions of the identified proteins, a total of 23 candidate proteins were shortlisted that potentially participate in plant defense against Xoo in the resistant cultivar. Of these candidate proteins, a mitochondrial arginase-1 showed Hwayeong specific abundance and was significantly accumulated following Xoo inoculation. Overexpression of arginase-1 in susceptible rice cultivar (Dongjin) resulted in enhanced tolerance against Xoo as compared to the wild-type (WT). In addition, expression analysis of defense-related genes encoding PR1, glucanase I, and chitinase II by qRT-PCR showed their enhanced expression in the overexpression lines as compared to WT. Mitochondrial localization of the selected arginase was further confirmed by fluorescent microscopy using GFP-tagged arginase. Taken together, our results uncover the proteome changes in the rice cultivars and highlight the functions of arginase in plant defense against Xoo.
Project description:Bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae (Xoo), gives rise to devastating crop losses in rice. Disease resistant rice cultivars are the most economical way to combat the disease. The TP309 cultivar is susceptible to infection by Xoo strain PXO99. A transgenic variety, TP309_Xa21, expresses the pattern recognition receptor Xa21, and is resistant. PXO99?raxST, a strain lacking the raxST gene, is able to overcome Xa21-mediated immunity. We used a single extraction solvent to demonstrate comprehensive metabolomics and transcriptomics profiling under sample limited conditions, and analyze the molecular responses of two rice lines challenged with either PXO99 or PXO99?raxST. LCTOF raw data file filtering resulted in better within group reproducibility of replicate samples for statistical analyses. Accurate mass match compound identification with molecular formula generation (MFG) ranking of 355 masses was achieved with the METLIN database. GCTOF analysis yielded an additional 441 compounds after BinBase database processing, of which 154 were structurally identified by retention index/MS library matching. Multivariate statistics revealed that the susceptible and resistant genotypes possess distinct profiles. Although few mRNA and metabolite differences were detected in PXO99 challenged TP309 compared to mock, many differential changes occurred in the Xa21-mediated response to PXO99 and PXO99?raxST. Acetophenone, xanthophylls, fatty acids, alkaloids, glutathione, carbohydrate and lipid biosynthetic pathways were affected. Significant transcriptional induction of several pathogenesis related genes in Xa21 challenged strains, as well as differential changes to GAD, PAL, ICL1 and Glutathione-S-transferase transcripts indicated limited correlation with metabolite changes under single time point global profiling conditions.
Project description:The plant cell wall degrading enzyme LipA (Lipase/Esterase A) is a Type II secretion system secreted protein of Xanthomonas oryzae pv. oryzae (Xoo; the casual of bacterial leaf blight of rice). LipA is an Xoo virulence factor. However, LipA is a double edged sword for Xoo as it induces rice defense responses such as programmed cell death/hypersensitive response like reaction (HR) and callose deposition. Prior treatment with LipA enhances resistance against subseqent Xoo infection. In order to understand the molecular events associated with Esterase (LipA) induced innate immune responsein rice , whole genome transcriptional profiling was performed using Affymetrix Rice GeneChips
Project description:Xanthomonas oryzae pv. oryzae (Xoo) is a rice pathogen causing bacterial blight, which outbreaks in most rice cultivating countries and reduces yield up to 50% due to no effective pesticide. Urgent responses of Xoo upon the initial contacts with rice at infection site are essential for pathogenesis. We studied the time-resolved gene expression of both transcriptome and proteome in the pathogenicity-activated Xoo cells with an in vitro assay system. Genes related to cell mobility, inorganic ion transport and effectors are early response genes to help Xoo cells invade into damaged rice leaf tissues, obtain rare cofactors, and evade rice immune responses. Although the time-resolved gene expression pattern of Xoo is conserved in both mRNA and protein, there are varied time gaps in genes between the expression peaks of mRNA and protein, which implies there is an additional translational selection step of specific mRNAs for rapid translation. The expression pattern of genes from a polycistronic mRNA in the same gene cluster is strictly conserved. The time-resolved gene expression study of Xoo in both transcriptome and proteome provides a valuable information about the pathogenic responses of Xoo at the initial stage of Xoo-rice interaction.
Project description:Previously, we successfully introduce the bacterial blight resistance trait from Oryza meyeriana into O. sativa using asymmetric somatic hybridization with O. meyeriana as the donor species. After years of breeding, a progeny named Y73 was generated with recurrent parent O. sativa L. ssp. japonica cv. Dalixiang, and it shows high resistance to broad-spectrum of bacterial blight pathogens Xanthomonas oryzae pv. Oryzae (Xoo). However, the resistance mechanism of Y73 is remain undiscovered. To provide insights into the high resistance phenotype of these plants, we examined the transcriptome response in leaves of Y73 to the bacterial blight infection in this study. Xoo inoculated and mock inoculated rice plants were grown in growth room and the global analysis of gene expression events in rice leaves at 24 hours post inoculation (hpi) were analyzed using Affymetrix Rice GeneChip microarrays. We used microarrays to detail the global programme of gene expression underlying Xoo infection in rice Y73. To find out pathways and genes involved in its high and board-spectrum resistance, microanalysis were carried out on Y73 after Xoo infection at 24 hours post inoculation (hpi). Three independant replicates were perfomed for each treatments.