Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling of rice transgenicline carrying the maize resistance gene Rxo1 to Xanthomonas oryzae pv. oryzicola

ABSTRACT: Genome-wide gene responses in a transgenic rice line carrying the maize resistance gene Rxo1 to the rice bacterial streak pathogen, Xanthomonas oryzae pv. oryzicola; Non-host resistance in rice to its bacterial pathogen, Xanthomonas oryzae pv. oryzicola (Xoc), mediated by a maize NBS-LRR type R gene, Rxo1 shows a typical hypersensitive reaction (HR) phenotype, but the molecular mechanism(s) underlying this type of non-host resistance remain largely unknown. Results A microarray experiment was performed to reveal the molecular mechanisms underlying HR of rice to Xoc mediated by Rxo1 using a pair of transgenic and non-transgenic rice lines. Our results indicated that Rxo1 appeared to function in the very early step of the interaction between rice and Xoc, and could specifically activate large numbers of genes involved in signaling pathways leading to HR and some basal defensive pathways such as SA and ET pathways. In the former case, Rxo1 appeared to differ from the typical host R genes in that it could lead to HR without activating NDR1. In the latter cases, Rxo1 was able to induce a unique group of WRKY TF genes and a large set of genes encoding PPR and RRM proteins that share the same G-box in their promoter regions with possible functions in post-transcriptional regulation. In conclusion, Rxo1, like most host R genes, was able to trigger HR against Xoc in the heterologous rice plants by activating multiple defensive pathways related to HR, providing useful information on the evolution of plant resistance genes. Maize non-host resistance gene Rxo1 could trigger the pathogen-specific HR in heterologous rice, and ultimately leading to a localized programmed cell death which exhibits the characteristics consistent with those mediated by host resistance genes, but a number of genes encoding pentatricopeptide repeat and RNA recognition motif protein were found specifically up-regulated in the Rxo1 mediated disease resistance. These results add to our understanding the evolution of plant resistance genes. Experiment Overall Design: All inoculated flag leaves from three plants of 9804-Rxo1 and 9804 were collected two days post-inoculation (dpi), and the flag leaves from three non-inoculated check plants of 9804-Rxo1 and 9804 were also sampled at the same time point as control. The flag leaves from non-inoculated check plants of 9804 were sampled at the same time point as control: 9804-Rxo1 (3-replications), XOC - time: 2 dpi(3-replications); 9804-Rxo1 (3-replications); 9804, XOC - time: 2 dpi(3-replications) 9804. 2 sets of separately normalized data: 9804-Rxo1 and 9804.

ORGANISM(S): Oryza sativa

SUBMITTER: Meirong Xu

PROVIDER: E-GEOD-19239 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Genome-wide gene responses in a transgenic rice line carrying the maize resistance gene Rxo1 to the rice bacterial streak pathogen, Xanthomonas oryzae pv. oryzicola Non-host resistance in rice to its bacterial pathogen, Xanthomonas oryzae pv. oryzicola (Xoc), mediated by a maize NBS-LRR type R gene, Rxo1 shows a typical hypersensitive reaction (HR) phenotype, but the molecular mechanism(s) underlying this type of non-host resistance remain largely unknown. Results A microarray experiment was performed to reveal the molecular mechanisms underlying HR of rice to Xoc mediated by Rxo1 using a pair of transgenic and non-transgenic rice lines. Our results indicated that Rxo1 appeared to function in the very early step of the interaction between rice and Xoc, and could specifically activate large numbers of genes involved in signaling pathways leading to HR and some basal defensive pathways such as SA and ET pathways. In the former case, Rxo1 appeared to differ from the typical host R genes in that it could lead to HR without activating NDR1. In the latter cases, Rxo1 was able to induce a unique group of WRKY TF genes and a large set of genes encoding PPR and RRM proteins that share the same G-box in their promoter regions with possible functions in post-transcriptional regulation. In conclusion, Rxo1, like most host R genes, was able to trigger HR against Xoc in the heterologous rice plants by activating multiple defensive pathways related to HR, providing useful information on the evolution of plant resistance genes. Maize non-host resistance gene Rxo1 could trigger the pathogen-specific HR in heterologous rice, and ultimately leading to a localized programmed cell death which exhibits the characteristics consistent with those mediated by host resistance genes, but a number of genes encoding pentatricopeptide repeat and RNA recognition motif protein were found specifically up-regulated in the Rxo1 mediated disease resistance. These results add to our understanding the evolution of plant resistance genes.

Project description:X. oryzae pv. oryzae (Xoo) is the causal agent of bacterial blight of rice. X. oryzae pv. oryzicola (Xoc) is the causal agent of bacterial streak of rice. Fourteen day old rice leaves were inoculated with one of five strains of Xanthomonas oryzae. Seven strains of Xoo were used; three wild type strains (PXO99A, T7174, and PXO86) and strains PXO99AME7, which has a nonfunctional type III secretion system and is non-pathogenic, , PXO99AME1, a pthXo6 and avrXa27 double mutant, PXO99ME2, a pthXo1 mutant, and PXO99ME5, a reduced virulence strain with uncharacterized mutation in a TAL effector. One strain of Xoc (BLS303) was tested. Controls include an inoculation with water (MOCK) and no inoculation. T7174 is our label for the Japanese isolate MAFF311018. Third leaves are inoculated with a needless syringe at adjacent sites along the upper leaf blade. Six leaves from separate plants are pooled. RNA samples were collected 24 h after treatment. ****[PLEXdb(http://www.plexdb.org) has submitted this series at GEO on behalf of the original contributor, Ginny Antony. The equivalent experiment is OS66 at PLEXdb.] cultivar: Nipponbare - strain: PXO99A(3-replications); cultivar: Nipponbare - strain: PXO99AME7(3-replications); cultivar: Nipponbare - strain: PXO99AME5(3-replications); cultivar: Nipponbare - strain: MOCK(3-replications); cultivar: Nipponbare - strain: NO TREATMENT(2-replications); cultivar: Nipponbare - strain: T7174(3-replications); cultivar: Nipponbare - strain: PXO86(3-replications); cultivar: Nipponbare - strain: BLS303(3-replications); cultivar: Nipponbare - strain: PXO99AME1(3-replications); cultivar: Nipponbare - strain: PXO99AME2(3-replications); cultivar: Nipponbare - strain: PXO99A-2(3-replications); cultivar: IR24 - strain: PXO99A(3-replications); cultivar: IR24 - strain: PXO99AME7(3-replications); cultivar: IR24 - strain: PXO99AME5(3-replications); cultivar: IR24 - strain: MOCK(3-replications); cultivar: IR24 - strain: NO TREATMENT(3-replications); cultivar: IR24 - strain: T7174(3-replications); cultivar: IR24 - strain: PXO86(3-replications); cultivar: IR24 - strain: BLS303(3-replications); cultivar: IR24 - strain: PXO99AME1(3-replications); cultivar: IR24 - strain: PXO99AME2(3-replications); cultivar: IR24 - strain: PXO99A-2(3-replications)

Project description:RESEARCH SUMMARY Bacterial blight and bacterial leaf streak, two of the most serious diseases of rice, are caused by Xanthomonas oryzae pathovar (pv.) oryzae (Xoo) and X. oryzae pv. oryzicola (Xoc) respectively. Xoo is a vascular pathogen that invades the xylem, whereas Xoc is non-vascular and colonizes the mesophyll apoplast. These distinctive types of infection represent the two most common ways plant pathogenic bacteria produce disease. As closely related pathogens of a model plant host, Xoo and Xoc constitute a powerful comparative system. We hypothesize that tissue-specific susceptibility to pathogenic bacteria can be explained partially by differential host responses during infection. To establish the global structure of susceptible responses to infection by Xoo and Xoc, we used the Affymetrix Rice Genome Array to analyze the abundance of transcripts in rice plants over four days after inoculation with virulent strains. MATERIAL AND METHODS - Plant Material: Oryza sativa ssp. japonica cv. Nipponbare plants were grown in pots containing LC-1 soil mixture, and arranged in flats of 20 pots, in growth chambers under a 12-h, 28ºC light and a 12-h, 25ºC dark cycle. To allow inversion of the flats for inoculation (modified dip-inoculation method, Niño-Liu et al, 2005, Journal of Phytopathology) seeds were sown through 1-cm perforations in a fibreglass tray resting on top of the pots. Peters Professional Fertilizer and iron chelate micronutrient were applied with watering every two days at rates of 0.25 and 4.5 g/L, respectively, until the day before inoculation. - Bacterial Strains and preparation of inoculum: Xoo strain PXO99A and Xoc strain BLS256 were used. For each, a single colony from a glucose yeast extract (GYE) agar plate was transferred to 5 ml of GYE liquid medium and incubated for 24 h at 28ºC with constant shaking at 250 rpm. Subsequently, 2 ml of this culture was transferred to 300 ml of fresh GYE liquid medium and incubated as above for an additional 18 h. Cells were pelleted by centrifugation at 4000 rpm. for 10 min, washed twice and resuspended in sterile 10 mm MgCl2 to an OD600 of 0.05, yielding 7 liters of inoculum. Tween-20 was added to a final concentration of 0.5%. - Modified dip-inoculation method: Fourteen days after sowing, and 2 h after the beginning of the light period, seedlings were inverted into inoculum, one flat each for Xoo, Xoc and Mock inoculum consisting of sterile 10 mM MgCl2 with 0.5% Tween-20, and vaccuum infiltrated at 500mm Hg for two minutes, two consecutive times, in a custom-made chamber. Following inoculation, plants were returned to the growth chamber. During growth, plants were cycled weekly in the same order through three growth chambers. In this way all plants could be incubated in the same final chamber following inoculation. For each replicate, position of the flats in the growth chamber (from left to right, used also for the order of inoculation and harvest) was determined by a split-plot design. - Timepoints, tissue collection: Within flats, assignment of pots for the harvest of inoculated tissue at 2, 4, 8, 24 and 96 h was made using a separate randomized complete block design. Tissue was harvested from plants in four pots (approximately 2g fresh weight) for each timepoint per inoculum per replication. Harvested tissue was immediately frozen in liquid nitrogen and stored at -80ºC until processing. - RNA isolation, purification, labeling, hybridizations, scanning: Total RNA was initially isolated from frozen whole plant tissue using the hot TRIzol reagent protocol for barley as described by Caldo et al (Plant Cell, 2004). The RNA was purified using Qiagen RNeasy spin columns, and adjusted to a final concentration of 1 ug/uL. Probe synthesis, labeling, and hybridization were performed at the Iowa State University GeneChip Core facility. ACKNOWLEDGEMENTS This work was supported by a grant (0227357) from the Plant Genome Research Program of the National Science Foundation. ****[PLEXdb(http://www.plexdb.org) has submitted this series at GEO on behalf of the original contributor, David O Niño-Liu. The equivalent experiment is OS3 at PLEXdb.] XOC - time: 2 hai (4-replications) XOC - time: 4 hai (4-replications) XOC - time: 8 hai (4-replications) XOC - time: 24 hai (4-replications) XOC - time: 96 hai (4-replications) XOO - time: 2 hai (4-replications) XOO - time: 4 hai (4-replications) XOO - time: 8 hai (4-replications) XOO - time: 24 hai (4-replications) XOO - time: 96 hai (4-replications) MOCK - time: 2 hai (4-replications) MOCK - time: 4 hai (4-replications) MOCK - time: 8 hai (4-replications) MOCK - time: 24 hai (4-replications) MOCK - time: 96 hai (4-replications)

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Transcription profiling of rice transgenicline carrying the maize resistance gene Rxo1 to Xanthomonas oryzae pv. oryzicola

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