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Score: 11.00
Title: A conserved threonine residue in the juxtamembrane domain of the XA21 pattern recognition receptor is critical for kinase autophosphorylation and XA21-mediated immunity .
Author: Chen X Chern M Canlas PE Jiang C Ruan D Cao P Ronald PC
Journal: J Biol Chem Type: MEDLINE
Literature: oryza Field: abstract Doc ID: pub20118235 Accession (PMID): 20118235
Abstract: Despite the key role that pattern recognition receptors ( PRRs ) play in regulating immunity in plants and animals , the mechanism of activation of the associated non-arginine-aspartate ( non-RD ) kinases is unknown . The rice PRR XA21 recognizes the pathogen-associated molecular pattern , Ax21 ( activator of XA21-mediated immunity ) . Here we show that the XA21 juxtamembrane ( JM ) domain is required for kinase autophosphorylation . Threonine 705 in the XA21 JM domain is essential for XA21 autophosphorylation in vitro and XA21-mediated innate immunity in vivo . The replacement of Thr ( 705 ) by an alanine or glutamic acid abolishes XA21 autophosphorylation and eliminates interactions between XA21 and four XA21-binding proteins in yeast and rice . Although threonine residues analogous to Thr ( 705 ) of XA21 are present in the JM domains of most RD and non-RD plant receptor-like kinases , this residue is not required for autophosphorylation of the Arabidopsis RD RLK BRI1 ( brassinosteroid insensitive 1 ) . The threonine 705 of XA21 is conserved only in the JM domains of plant RLKs but not in those of fly , human , or mouse suggesting distinct regulatory mechanisms . These results contribute to growing knowledge regarding the mechanism by which non-RD RLKs function in plant .
Score: 10.00
Title: Plasma membrane localization and potential endocytosis of constitutively expressed XA21 proteins in transgenic rice .
Author: Chen F Gao MJ Miao YS Yuan YX Wang MY Li Q Mao BZ Jiang LW He ZH
Journal: Mol Plant Type: MEDLINE
Literature: oryza Field: abstract Doc ID: pub20616165 Accession (PMID): 20616165
Abstract: The rice pattern recognition receptor ( PRR ) XA21 confers race-specific resistance in leaf infection by bacterial blight Xathomonas oryzae pv . oryzae ( Xoo ) , and was shown to be primarily localized to the endoplasmic reticulum ( ER ) when expressed with its native promoter or overexpressed in the protoplast However , whether the protein is still ER-localization in the intact cell when overexpressed remains to be identified . Here , we showed that XA21 , its kinase-dead mutant XA21P ( K736EP ) , and the triple autophosphorylation mutant XA21P ( S686A/T688A/S699A ) GFP fusions were primarily localized to the plasma membrane ( PM ) when overexpressed in the intact transgenic rice cell , and also localized to the ER in the transgenic protoplast The transgenic plants constitutively expressing the wild-type XA21 or its GFP fusion displayed race-specific resistance to Xoo at the adult and seedling stages . XA21 and XA21P ( K736EP ) could be internalized probably via the SCAMP-positive early endosomal compartment in the protoplast , suggesting that XA21 might be endocytosed to initiate resistance responses during pathogen infection . We also established a root infection system and demonstrated that XA21 also mediated race-specific resistance responses to Xoo in the root . Our current study provides an insight into the nature of the XA21-mediated resistance and a practical approach using the root cell system to further dissect the cellular signaling of the PRR during the rice-Xoo interaction .
Score: 10.00
Title: Adaptive evolution of Xa21 homologs in Gramineae .
Author: Tan S Wang D Ding J Tian D Zhang X Yang S
Journal: Genetica Type: In-Process
Literature: oryza Field: abstract Doc ID: pub22451352 Accession (PMID): 22451352
Abstract: The XA21 protein has broad spectrum resistance against Xanthomonas oryzae pv . oryzae . Although Xa21-mediated immunity is well characterized , little is known about the origin and evolutionary history of this gene in grasses . Therefore , we analyzed all Xa21 gene homologs in eight whole-genome sequenced rice lines , as well as in four gramineous genomes , rice , Brachypodium , sorghum and maize ; using Arabidopsis Xa21 homologs as outgroups , 17 , 7 , 7 and 3 Xa21 homologs were detected in these four grasses , respectively . Synteny and phylogenetic analysis showed that frequent gene translocation , duplication and/or loss , have occurred at Xa21 homologous loci , suggesting that they have undergone or are undergoing rapid generation of copy number variations . Within the rice species , the high level of nucleotide diversity between Xa21-like orthologs showed a strong association with the presence/absence haplotypes , suggesting that the genetic structure of rice lines plays an important role in the variations between these Xa21-like orthologs . Strongly positive selection was detected in the core region of the leucine-rich repeat domains of the Xa21 subclade among the rice lines , indicating that the rapid gene diversification of Xa21 homologs may be a strategy for a given species to adapt to the changing spectrum of species-specific pathogens .
Score: 9.00
Title: Biochemical characterization of the kinase domain of the rice disease resistance receptor-like kinase XA21 .
Author: Liu GZ Pi LY Walker JC Ronald PC Song WY .
Journal: J Biol . Chem . Type: ARTICLE
Literature: oryza Field: abstract Doc ID: pub11927577 Accession (PMID): 11927577
Abstract: The rice disease resistance gene , Xa21 , encodes a receptor kinase-like protein consisting of leucine-rich repeats in the putative extracellular domain and a serine/threonine kinase in the putative intracellular domain . The putative XA21 kinase domain was expressed as maltose-binding and glutathione S-transferase fusion proteins in Escherichia coli . The fusion proteins are capable of autophosphorylation . Phosphoamino acid analysis of the glutathione S-transferase fusion protein indicates that only serine and threonine residues are phosphorylated . The relative phosphorylation rate of the XA21 kinase against increasing enzyme concentrations follows a first-order rather than second-order kinetics , indicating an intramolecular phosphorylation mechanism . Moreover , the active XA21 kinase can not phosphorylate a kinase-deficient mutant of XA21 kinase . The enzymatic activity of the XA21 kinase in a buffer containing Mn ( 2+ ) is at least 15 times higher than that with Mg ( 2+ ) . The K ( m ) and V ( max ) of XA21 kinase for ATP are 0 . 3 microm and 8 . 4 nmol/mg/min , respectively . Tryptic phosphopeptide mapping reveals that multiple sites on the XA21 kinase are phosphorylated . Finally , our data suggest that the region of XA21 kinase corresponding to the RD kinase activation domain is not phosphorylated , revealing a distinct mode of action compared with the tomato Pto serine/threonine kinase conferring disease resistance .
Score: 9.00
Title: Rice XA21 Binding Protein 3 Is a Ubiquitin Ligase Required for Full Xa21-Mediated Disease Resistance .
Author: Wang YS Pi LY Chen X Chakrabarty PK Jiang J De Leon AL Liu GZ Li L Benny U Oard J Ronald PC Song WY .
Journal: Type: ARTICLE
Literature: oryza Field: abstract Doc ID: pub17172358 Accession (PMID): 17172358
Abstract: XA21 is a receptor-like kinase protein in rice ( Oryza sativa ) that confers gene-for-gene resistance to specific races of the causal agent of bacterial blight disease , Xanthomonas oryzae pv oryzae . We identified XA21 binding protein 3 ( XB3 ) , an E3 ubiquitin ligase , as a substrate for the XA21 Ser and Thr kinase . The interaction between XB3 and the kinase domain of XA21 has been shown in yeast and in vitro , and the physical association between XB3 and XA21 in vivo has also been confirmed by coimmunoprecipitation assays . XB3 contains an ankyrin repeat domain and a RING finger motif that is sufficient for its interaction with the kinase domain of XA21 and for its E3 ubiquitin ligase activity , respectively . Transgenic plants with reduced expression of the Xb3 gene are compromised in resistance to the avirulent race of X oryzae pv oryzae . Furthermore , reduced levels of Xb3 lead to decreased levels of the XA21 protein . These results indicate that Xb3 is necessary for full accumulation of the XA21 protein and for Xa21-mediated resistance .
Score: 9.00
Title: Rice XB15 , a protein phosphatase 2C , negatively regulates cell death and XA21-mediated innate immunity .
Author: Park CJ Peng Y Chen X Dardick C Ruan D Bart R Canlas PE Ronald PC
Journal: PLoS Biol Type: MEDLINE
Literature: oryza Field: abstract Doc ID: pub18817453 Accession (PMID): 18817453
Abstract: Perception of extracellular signals by cell surface receptors is of central importance to eukaryotic development and immunity . Kinases that are associated with the receptors or are part of the receptors themselves modulate signaling through phosphorylation events . The rice ( Oryza sativa L ) XA21 receptor kinase is a key recognition and signaling determinant in the innate immune response . A yeast two-hybrid screen using the intracellular portion of XA21 , including the juxtamembrane ( JM ) and kinase domain as bait , identified a protein phosphatase 2C ( PP2C ) , called XA21 binding protein 15 ( XB15 ) . The interaction of XA21 and XB15 was confirmed in vitro and in vivo by glutathione-S-transferase ( GST ) pull-down and co-immunoprecipitation assays , respectively . XB15 fusion proteins purified from Escherichia coli and from transgenic rice carry PP2C activity . Autophosphorylated XA21 can be dephosphorylated by XB15 in a temporal and dosage-dependent manner . A serine residue in the XA21 JM domain is required for XB15 binding . Xb15 mutants display a severe cell death phenotype , induction of pathogenesis-related genes , and enhanced XA21-mediated resistance . Overexpression of Xb15 in an XA21 rice line compromises resistance to the bacterial pathogen Xanthomonas oryzae pv . oryzae . These results demonstrate that Xb15 encodes a PP2C that negatively regulates the XA21-mediated innate immune response .
Score: 9.00
Title: Xa21D encodes a receptor-like molecule with a leucine-rich repeat domain that determines race-specific recognition and is subject to adaptive evolution .
Author: Wang GL Ruan DL Song WY Sideris S Chen L Pi LY Zhang S Zhang Z Fauquet C Gaut BS Whalen MC Ronald PC .
Journal: Plant Cell Type: ARTICLE
Literature: oryza Field: abstract Doc ID: pub9596635 Accession (PMID): 9596635
Abstract: The rice Xa21 gene confers resistance to Xanthomonas oryzae pv oryzae in a race-specific manner . Analysis of the inheritance patterns and resistance spectra of transgenic plants carrying six Xa21 gene family members indicated that one member , designated Xa21D , displayed a resistance spectrum identical to that observed for Xa21 but conferred only partial resistance . Xa21D encodes a receptor-like protein carrying leucine-rich repeat ( LRR ) motifs in the presumed extracellular domain . The Xa21D transcript terminates shortly after the stop codon introduced by the retrotransposon Retrofit . Comparison of nucleotide substitutions in the LRR coding regions of Xa21 and Xa21D provided evidence of adaptive selection . Both functional and evolutionary evidence indicates that the Xa21D LRR domain controls race-specific pathogen recognition .
Score: 8.00
Title: Genetic and physical analysis of the rice bacterial blight disease resistance locus , Xa21 .
Author: Ronald PC Albano B Tabien R Abenes L Wu KS McCouch S Tanksley SD .
Journal: Mol . Gen . Genet . Type: ARTICLE
Literature: oryza Field: abstract Doc ID: pub1362973 Accession (PMID): 1362973
Abstract: Nearly isogenic lines ( NILs ) of rice ( Oryza sativa ) differing at a locus conferring resistance to the pathogen Xanthomonas oryzae pv . oryzae were surveyed with 123 DNA markers and 985 random primers using restriction fragment length plymorphism ( RFLP ) and random amplified polymorphic DNA ( RAPD ) analysis . One chromosome 11 marker ( RG103 ) detected polymorphism between the NILs that cosegregated with Xa21 . All other chromosome 11 DNA markers tested were monomorphic between the NILs , localizing the Xa21 introgressed region to an 8 . 3 cM interval on chromosome 11 . Furthermore , we identified two polymerase chain reaction ( PCR ) products ( RAPD2148 and RAPD818 ) that detected polymorphisms between the NILs . Genomic sequences hybridizing with RAPD818 , RAPD248 and RG103 were duplicated specifically in the Xa21 NIL . All three markers cosegregated with the resistance locus , Xa21 , in a F2 population of 386 progeny . Based on the frequency with which we recovered polymorphic Xa21-linked markers , we estimated the physical size of the introgressed region to be approximately 800 kb . This estimation was supported by physical mapping ( using pulsed field gel electrophoresis ) of the sequences hybridizing with the three Xa21-linked DNA markers . The results showed that the three Xa21-linked markers are physically close to each other , with one copy of the RAPD818 sequences located within 60 kb of RAPD248 and the other copy within 270 kb of RG103 . None of the enzymes tested generated a DNA fragment that hybridized with all three of the markers indicating that the introgressed region containing the resistance locus Xa21 is probably larger than 270 kb .
Score: 8.00
Title: Isolation and characterization of rice mutants compromised in Xa21-mediated resistance to X oryzae pv . oryzae .
Author: Wang GL Wu C Zeng L He C Baraoidan M de Assis Goes da Silva F Williams CE Ronald PC Leung H
Journal: Theor . Appl . Genet . Type: ARTICLE
Literature: oryza Field: abstract Doc ID: pub14523518 Accession (PMID): 14523518
Abstract: The rice gene , Xa21 , confers resistance to diverse races of Xanthomonas oryzae pv . oryzae ( Xoo ) and encodes a receptor-like kinase with leucine-rich repeats in the extra-cellular domain . To identify genes essential for the function of the Xa21 gene , 4 , 500 IRBB21 ( Xa21 isogenic line in IR24 background ) mutants , induced by diepoxybutane and fast neutrons , were screened against Philippine race six ( PR6 ) Xoo for a change from resistance to susceptibility . From two greenhouse screens , 23 mutants were identified that had changed from resistant to fully ( 6 ) or partially ( 17 ) susceptible to PR6 . All fully susceptible mutants carried rearrangements at the Xa21 locus as detected by PCR and Southern hybridization . For the partially susceptible mutants , no changes were detected at the Xa21 locus based on Southern and PCR analyses . However , two of these mutants were confirmed via genetic analysis to have mutations at the Xa21 locus . Partially susceptible mutants exhibited variation in level of susceptibility to different Xoo strains , suggesting that they may carry different mutations required for the Xa21-mediated resistance . The mutants identified in this study provide useful materials for dissecting the Xa21-mediated resistance pathway in rice .
Score: 8.00
Title: Analysis of T-DNA Xa21 loci and bacterial blight resistance effects of the transgene Xa21 in transgenic rice .
Author: Zhai W Chen C Zhu X Chen X Zhang D Li X Zhu L
Journal: Theor . Appl . Genet . Type: ARTICLE
Literature: oryza Field: abstract Doc ID: pub15088086 Accession (PMID): 15088086
Abstract: The genetic loci and phenotypic effects of the transgene Xa21 , a bacterial blight ( BB ) resistance gene cloned from rice , were investigated in transgenic rice produced through an Agrobacterium-mediated transformation system . The flanking sequences of integrated T-DNAs were isolated from Xa21 transgenic rice lines using thermal asymmetric interlaced PCR . Based on the analysis of 24 T-DNA Xa21 flanking sequences , T-DNA loci in rice could be classified into three types : the typical T-DNA integration with the definite left and right borders , the T-DNA integration linked with the adjacent vector backbone sequences and the T-DNA integration involved in a complicated recombination in the flanking sequences . The T-DNA integration in rice was similar to that in dicotyledonous genomes but was significantly different from the integration produced through direct DNA transformation approaches . All three types of integrated transgene Xa21 could be stably inherited and expressed the BB resistance through derived generations in their respective transgenic lines . The flanking sequences of the typical T-DNA integration consisted of actual rice genomic DNA and could be used as probes to locate the transgene on the rice genetic map . A total of 15 different rice T-DNA flanking sequences were identified . They displayed restriction fragment length polymorphisms ( RFLPs ) between two rice varieties , ZYQ8 and JX17 , and were mapped on rice chromosomes 1 , 3 , 4 , 5 , 7 , 9 , 10 , 11 and 12 , respectively , by using a double haploid population derived from a cross between ZYQ8 and JX17 . The blast search and homology comparison of the rice T-DNA flanking sequences with the rice chromosome-anchored sequence database confirmed the RFLP mapping results . On the basis of genetic mapping of the T-DNA Xa21 loci , the BB resistance effects of the transgene Xa21 at different chromosome locations were investigated using homozygous transgenic lines with only one copy of the transgene . Among the transgenic lines , no obvious position effects of the transgene Xa21 were observed . In addition , the BB resistance levels of the Xa21 transgenic plants with different transgene copy numbers and on different genetic backgrounds were also investigated . It was observed that genetic background ( or genome ) effects were more obvious than dosage effects and position effects on the BB resistance level of the transgenic plants .
Score: 8.00
Title: Elucidation of XA21-mediated innate immunity .
Author: Park CJ Han SW Chen X Ronald PC
Journal: Cell Microbiol Type: MEDLINE
Literature: oryza Field: abstract Doc ID: pub20590657 Accession (PMID): 20590657
Abstract: In the early 1970s , the Xa21 gene from the wild rice species Oryza longistaminata drew attention of rice breeders because of its broad-spectrum resistance to diverse strains of a serious bacterial disease of rice in Asia and Africa , called bacterial blight disease , caused by the Gram-negative bacterium , Xanthomonas oryzae pv . oryzae ( Xoo ) . In 1995 , we isolated the gene controlling this resistance and in 2009 demonstrated that XA21 recognizes a highly conserved peptide , called Ax21 ( activator of XA21-mediated immunity ) . Tyrosine sulfation of Ax21 is required for recognition by rice XA21 . A decade of genetic , molecular and biochemical studies have uncovered key components of the XA21-mediated signalling cascade . Ax21 recognition by XA21 at the cell surface induces phosphorylation-mediated events , which are predicted to alter subcellular localization and/or DNA-binding activity of a WRKY family of transcription factors . Because XA21 is representative of the large number of predicted pattern recognition receptors ( PRRs ) in rice ( n = 328 ) , Arabidopsis ( n = 35 ) and other plant species , further characterization of XA21-mediated signalling pathways will contribute to elucidation of these important defence responses .
Score: 7.00
Title: Short communication : developmental control of Xa21-mediated disease resistance in rice .
Author: Century KS Lagman RA Adkisson M Morlan J Tobias R Schwartz K Smith A Love J Ronald PC Whalen MC .
Journal: Plant J Type: ARTICLE
Literature: oryza Field: abstract Doc ID: pub10571882 Accession (PMID): 10571882
Abstract: The rice resistance gene Xa21 confers resistance against the bacterial pathogen Xanthomonas oryzae pv . oryzae ( Xoo ) . The molecular genetic mechanism controlling the integration of the Xa21-mediated disease resistance response with the developmental program in rice is under study in this model system . Reproducible means of infecting plants at certain developmental stages were designed based on the timing of full expansion of the leaf . Xa21-resistance progressively increases from the susceptible juvenile leaf 2 stage through later stages , with 100% resistance at the adult leaf 9/10 stage . We found that Xa21 expression is independent of plant developmental stage , infection with Xoo , or wounding . Expression of the Xa21 gene transcript is not correlated with expression of Xa21 disease resistance indicating that the developmental regulation of Xa21-resistance is either controlled post-transcriptionally or by other factors .
Score: 7.00
Title: The autophosphorylated Ser686 , Thr688 , and Ser689 residues in the intracellular juxtamembrane domain of XA21 are implicated in stability control of rice receptor-like kinase .
Author: Xu WH Wang YS Liu GZ Chen X Tinjuangjun P Pi LY Song WY .
Journal: Plant J Type: ARTICLE
Literature: oryza Field: abstract Doc ID: pub16460508 Accession (PMID): 16460508
Abstract: The rice gene Xa21 confers resistance against Xanthomonas oryzae pv . oryzae ( Xoo ) . Xa21 encodes a receptor-like kinase ( XA21 ) . We demonstrate that XA21 autophosphorylates residues Ser686 , Thr688 and Ser689 in vitro . Substitution of these residues with alanines did not affect the autophosphorylation function of this kinase , but specifically destabilized the resistance protein in vitro and in vivo . Plants carrying these same substitutions in XA21 were compromised in their resistance to the normally avirulent Xoo Philippine race 6 . Additionally , we show that wild-type XA21 and the kinase-dead mutant with the invariable Lys736 residue mutated to glutamic acid were also proteolytically degraded in protein extracts . Finally , we show a correlation between the in vitro degradation and in vivo instability of the proteins . We propose that autophosphorylation of Ser686 , Thr688 and Ser689 functions to stabilize XA21 against the developmentally controlled proteolytic activity .
Score: 7.00
Title: Ectopic expression of rice Xa21 overcomes developmentally controlled resistance to Xanthomonas oryzae pv . oryzae .
Author: Park CJ Lee SW Chern M Sharma R Canlas PE Song MY Jeon JS Ronald PC
Journal: Plant Sci Type: In-Data-Review
Literature: oryza Field: abstract Doc ID: pub21076626 Accession (PMID): 21076626
Abstract: Recognition of pathogen-associated molecular patterns ( PAMPs ) by pattern recognition receptors ( PRRs ) activates the innate immune response . The rice PRR , XA21 , confers robust resistance at adult stages to most strains of the bacterial pathogen Xanthomonas oryzae pv . oryzae ( Xoo ) . Seedlings are still easily infected by Xoo , causing severe yield losses . Here we report that Xa21 is induced by Xoo infection and that ectopic expression of Xa21 confers resistance at three leaf stage ( three-week-old ) , overcoming the developmental limitation of XA21-mediated resistance . Ectopic expression of Xa21 also up-regulates a larger set of defense-related genes as compared to Xa21 driven by the native promoter . These results indicate that altered regulation of Xa21 expression is useful for developing enhanced resistance to Xoo at multiple developmental stages .
Score: 6.00
Title: [ Accelerated improvement of bacterial blight resistance of Shuhui527 using molecular marker-assisted selection ]
Author: Huang TY Li SG Wang YP Li HY .
Journal: Sheng Wu Gong Cheng Xue Bao Type: ARTICLE
Literature: oryza Field: abstract Doc ID: pub15966313 Accession (PMID): 15966313
Abstract: Shuhui527 is a promising restorer line bred by Rice Research Institute of Sichuan Agricultural University in recent years . However , this line is susceptible to Bacterial Blight ( BB ) , which limits its use . The IRBB60 , from the International Rice Research Institute ( IRRI ) , contains dominant genes Xa21 and Xa4 conferring resistance to BB . The objective of this study is to improve the BB resistance of Shuhui527 by introgressing Xa21 and Xa4 , the two broad-spectrum BB resistance genes , into Shuhui527 with IRBB60 as the donor , pTA248 and MP12 , linking tightly with Xa21 and Xa4 respectively as DNA markers . BC1 F1 progenies of ( Shuhui527 x IRBB60 ) , containing Xa21 and Xa4 identified using PCR screening and with agronomic traits including plant type , grain type and days to heading etc similar to those of Shuhui527 , were subsequently backcrossed to Shuhui527 and self-pollinated to generate BC2 F1 and BC1 F2 . The BC3 F1 and BC3 F2 were subsequently developed using the same approach . Among the 20 BC3 F2 plants , homozygous Xa21 and Xa4 , 10 plants were the most similar to Shuhui527 in the agronomic traits , and were screened using 120 pairs SSR and 100 pairs RAPD markers . Based on the results of the background screening and the performance of the agronomic traits , 5 plants were identified as improved-Shuhui527 and designated as 527R-5 , 527R-6 , 527R-8 , 527R-9 and 527R-10 . The improved- Shuhui527 lines expressed high resistance to Xanthomonas oryzae pv . oryzae ( Xoo ) stains C I - C VII , P1 and P6 . The evaluation of the polymorphisms and selection accuracies of pTA248 and MP12 demonstrated that the polymorphisms of the two markers were obvious and co-dominant and the accuracies were more than 97% and 83% respectively , indicating the two markers are good for Xa21 and Xa4 in Molecular Marker-assisted Selection .
Score: 6.00
Title: Epigenetic inheritance in rice plants .
Author: Akimoto K Katakami H Kim HJ Ogawa E Sano CM Wada Y Sano H
Journal: Ann Bot ( Lond ) Type: MEDLINE
Literature: oryza Field: abstract Doc ID: pub17576658 Accession (PMID): 17576658
Abstract: BACKGROUND AND AIMS : Epigenetics is defined as mechanisms that regulate gene expression without base sequence alteration . One molecular basis is considered to be DNA cytosine methylation , which reversibly modifies DNA or chromatin structures . Although its correlation with epigenetic inheritance over generations has been circumstantially shown , evidence at the gene level has been limited . The present study aims to find genes whose methylation status directly correlates with inheritance of phenotypic changes . METHODS : DNA methylation in vivo was artificially reduced by treating rice ( Oryza sativa ssp . japonica ) seeds with 5-azadeoxycytidine , and the progeny were cultivated in the field for > 10 years . Genomic regions with changed methylation status were screened by the methylation-sensitive amplified polymorphysm ( MSAP ) method , and cytosine methylation was directly scanned by the bisulfite mapping method . Pathogen infection with Xanthomonas oryzae pv . oryzae , race PR2 was performed by the scissors-dip method on mature leaf blades . KEY RESULTS : The majority of seedlings were lethal , but some survived to maturity . One line designated as Line-2 showed a clear marker phenotype of dwarfism , which was stably inherited by the progeny over nine generations . MSAP screening identified six fragments , among which two were further characterized by DNA blot hybridization and direct methylation mapping . One clone encoding a retrotransposon gag-pol polyprotein showed a complete erasure of 5-methylcytosines in Line-2 , but neither translocation nor expression of this region was detectable . The other clone encoded an Xa21-like protein , Xa21G . In wild-type plants , all cytosines were methylated within the promoter region , whereas in Line-2 , corresponding methylation was completely erased throughout generations . Expression of Xa21G was not detectable in wild type but was constitutive in Line-2 . When infected with X oryzae pv . oryzae , against which Xa21 confers resistance in a gene-for-gene manner , the progeny of Line-2 were apparently resistant while the wild type was highly susceptible without Xa21G expression . CONCLUSIONS : These results indicated that demethylation was selective in Line-2 , and that promoter demethylation abolished the constitutive silencing of Xa21G due to hypermethylation , resulting in acquisition of disease resistance . Both hypomethylation and resistant trait were stably inherited . This is a clear example of epigenetic inheritance , and supports the idea of Lamarckian inheritance which suggested acquired traits to be heritable .
Score: 6.00
Title: [ Expression and autophosphorylation analysis of XA21 and PI-D2 protein kinases in Saccharomyces cerevisiae ]
Author: Wang SL Li LY Shang JJ Wang J Liu GZ
Journal: Wei Sheng Wu Xue Bao Type: In-Process
Literature: oryza Field: abstract Doc ID: pub18271255 Accession (PMID): 18271255
Abstract: Rice bacterial blight and blast are the most crucial rice disease . Xa21 confers resistance to bacterial blight , while Pi-d2 confers resistance to rice blast Both Xa21 and Pi-d2 encode receptor kinase-like proteins . Biochemical properties of XA21 kinase expressed in bacterial were characterized in our previous report . In this study , both XA21 and PI-D2 kinase domain were PCR amplified and cloned into yeast expression vector pEGH via recombinational cloning strategy , kinase proteins expressed in eukaryotic yeast system was purified and autophosphorylation assay was carried out . The results indicated that XA21 and PI-D2 protein can be detected by SDS-PAGE and showed expected molecular weight . Autophosphorylation assay indicated that yeast expressed XA21 and PI-D2 were active when incubated with P32 labelled ATP . The experiment provided basic materials for biochemical prosperity analysis , protein-protein interaction and substrate screening research .
Score: 6.00
Title: Dissection of the factors affecting development-controlled and race-specific disease resistance conferred by leucine-rich repeat receptor kinase-type R genes in rice .
Author: Zhao J Fu J Li X Xu C Wang S
Journal: Theor Appl Genet Type: Publisher
Literature: oryza Field: abstract Doc ID: pub19390838 Accession (PMID): 19390838
Abstract: Development-controlled resistance and resistance specificity frequently restrict the application of a disease resistance ( R ) gene in crop breeding programs . Xa3/Xa26 and Xa21 , encoding leucine-rich repeat ( LRR ) -kinase type plasma membrane proteins , mediate race-specific resistance to Xanthomonas oryzae pv . oryzae ( Xoo ) , which causes bacterial blight , one of the most devastating rice diseases . Plants carrying Xa3/Xa26 and plants carrying Xa21 have different resistance spectra and the functions of the two R genes are regulated by developmental stage . Four chimeric genes encoding proteins consisting of different parts of XA3/XA26 and XA21 were constructed by domain swapping and transformed into a susceptible rice variety . The resistance spectra and development-regulated resistance of the transgenic plants carrying Xa3/Xa26 , Xa21 , or chimeric gene to different Xoo strains were analyzed in the same genetic background . The results suggest that the gradually increased expression of Xa3/Xa26 and Xa21 plays an important role in the progressively enhanced Xoo resistance during rice development . In addition , the LRR domains of XA3/XA26 and XA21 are important determinants of race-specific recognition during rice-Xoo interaction , but juxtamembrane regions of the two R proteins also appear to contribute to resistance specificity .
Score: 6.00
Title: Overexpression of the endoplasmic reticulum chaperone BiP3 regulates XA21-mediated innate immunity in rice .
Author: Park CJ Bart R Chern M Canlas PE Bai W Ronald PC
Journal: PLoS One Type: MEDLINE
Literature: oryza Field: abstract Doc ID: pub20174657 Accession (PMID): 20174657
Abstract: Recognition of pathogen-associated molecular patterns by pattern recognition receptors ( PRRs ) activates the innate immune response . Although PRR-mediated signaling events are critical to the survival of plants and animals , secretion and localization of PRRs have not yet been clearly elucidated . Here we report the in vivo interaction of the endoplasmic reticulum ( ER ) chaperone BiP3 with the rice XA21 PRR , which confers resistance to the Gram negative bacterium , Xanthomonas oryzae pv . oryzae ( Xoo ) . We show that XA21 is glycosylated and is primarily localized to the ER and also to the plasma membrane ( PM ) . In BiP3-overexpressing rice plants , XA21-mediated immunity is compromised , XA21 stability is significantly decreased , and XA21 proteolytic cleavage is inhibited . BiP3 overexpression does not affect the general rice defense response , cell death or brassinolide-induced responses . These results indicate that BiP3 regulates XA21 protein stability and processing and that this regulation is critical for resistance to Xoo .
Score: 5.00
Title: [ Generation of selectable marker-free and vector backbone sequence-free Xa21 transgenic rice ]
Author: Xia ZH Li XB Chen CY Fan HK Jiang GH Zhu LH Zhai WX .
Journal: Sheng Wu Gong Cheng Xue Bao Type: ARTICLE
Literature: oryza Field: abstract Doc ID: pub16607944 Accession (PMID): 16607944
Abstract: The dominant gene Xa21 with broad-spectrum and high resistance to Xanthomonas oryzae pv . oryzae ( Xoo ) was transferred into C418 , an important restorer line of japonica hybrid rice in China using double right-border ( DRB ) T-DNA binary vector through Agrobacterium-mediated transformation . 17 transgenic lines were Xa21-positive with high resistance to the race P6 of Xoo through PCR analysis and resistance identification , among the total 27 independent primary transformants ( T0 ) obtained . The subsequent analysis of the T1 progenies of these 17 T0 lines through PCR-assisted selection and resistance investigation showed that four Xa21 transgenic T0 lines could produce selectable marker-free ( SMF ) progenies . The frequency of primary transformants producing SMF progenies was 15% . In addition , PCR analysis also revealed these SMF progenies did not contain vector backbone sequence , and they were named as SMF and vector backbone sequence-free ( SMF-VBSF ) Xa21 transgenic plants . The further molecular and phenotypic analysis of the T2 and T3 progenies testified the homozygous SMF-VBSF Xa21 transgenic plants were obtained with high resistance to Xoo .

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