共查询到20条相似文献,搜索用时 15 毫秒
1.
A. Jahoor A. Jacobi Christine M. E. Schüller G. Fischbeck 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1993,85(6-7):713-718
Summary The complex structure of the multigene family at the Mla locus conferring powdery mildew resistance in barley was studied by making diallel crosses between several near-isogenic lines carrying different Mla alleles. The mode of inheritance of the Mla alleles investigated was determined to be dominant for Mla1, Mla6, Mla7 and Mla13 and semidominant for Mla3, Mla12 and Mla20. F1 plants were backcrossed to the susceptible recurrent parent in order to identify susceptible and double-resistant recombinants in the BC1F1 generation. Out of 17605 progenies tested in the BC1F1 generation, two susceptible recombinants, one between Mla1 and Mla12 and one between Mla13 and Mla20 were confirmed. The former was also verified by RFLP analysis. 相似文献
2.
3.
McCue KF Allen PV Shepherd LV Blake A Whitworth J Maccree MM Rockhold DR Stewart D Davies HV Belknap WR 《Phytochemistry》2006,67(15):1590-1597
To provide tools for breeders to control the steroidal glycoalkaloid (SGA) pathway in potato, we have investigated the steroidal alkaloid glycosyltransferase (Sgt) gene family. The committed step in the SGA pathway is the glycosylation of solanidine by either UDP-glucose or UDP-galactose leading to α-chaconine or α-solanine, respectively. The Sgt2 gene was identified by deduced protein sequence homology to the previously identified Sgt1 gene. SGT1 has glucosyltransferase activity in vitro, but in vivo serves as the UDP-galactose:solanidine galactosyltransferase. Two alleles of the Sgt2 gene were isolated and its function was established with antisense transgenic lines and in vitro assays of recombinant protein. In tubers of transgenic potato (Solanum tuberosum) cvs. Lenape and Desirée expressing an antisense Sgt2 gene construct, accumulation of α-solanine was increased and α-chaconine was reduced. Studies with recombinant SGT2 protein purified from yeast show that SGT2 glycosylation activity is highly specific for UDP-glucose as a sugar donor. This data establishes the function of the gene product (SGT2), as the primary UDP-glucose:solanidine glucosyltransferase in vivo. 相似文献
4.
Sgt1p contributes to cyclic AMP pathway activity and physically interacts with the adenylyl cyclase Cyr1p/Cdc35p in budding yeast 总被引:5,自引:0,他引:5
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Sgt1p is a highly conserved eucaryotic protein that is required for both SCF (Skp1p/Cdc53p-Cullin-F-box)-mediated ubiquitination and kinetochore function in yeast. We show here that Sgt1p is also involved in the cyclic AMP (cAMP) pathway in Saccharomyces cerevisiae. SGT1 is an allele-specific suppressor of cdc35-1, a thermosensitive mutation in the leucine-rich repeat domain of the adenylyl cyclase Cyr1p/Cdc35p. We demonstrate that Sgt1p and Cyr1p/Cdc35p physically interact and that the activity of the cAMP pathway is affected in an sgt1 conditional mutant. Sequence analysis suggests that Sgt1p has features of a cochaperone. Thus, Sgt1p is a novel activator of adenylyl cyclase in S. cerevisiae and may function in the assembly or the conformational activation of specific multiprotein complexes. 相似文献
5.
Structural and functional analysis of SGT1-HSP90 core complex required for innate immunity in plants
Kadota Y Amigues B Ducassou L Madaoui H Ochsenbein F Guerois R Shirasu K 《EMBO reports》2008,9(12):1209-1215
SGT1 (Suppressor of G2 allele of skp1), a co-chaperone of HSP90 (Heat-shock protein 90), is required for innate immunity in plants and animals. Unveiling the cross talks between SGT1 and other co-chaperones such as p23, AHA1 (Activator of HSP90 ATPase 1) or RAR1 (Required for Mla12 resistance) is an important step towards understanding the HSP90 machinery. Nuclear magnetic resonance spectroscopy and mutational analyses of HSP90 revealed the nature of its binding with the CS domain of SGT1. Although CS is structurally similar to p23, these domains were found to non-competitively bind to various regions of HSP90; yet, unexpectedly, full-length SGT1 could displace p23 from HSP90. RAR1 partly shares the same binding site with HSP90 as the CS domain, whereas AHA1 does not. This analysis allowed us to build a structural model of the HSP90–SGT1 complex and to obtain a compensatory mutant pair between both partners that is able to restore virus resistance in vivo through Rx (Resistance to potato virus X) immune sensor stabilization. 相似文献
6.
A single-amino acid substitution in the sixth leucine-rich repeat of barley MLA6 and MLA13 alleviates dependence on RAR1 for disease resistance signaling 总被引:11,自引:0,他引:11
Interactions between barley and the powdery mildew pathogen, Blumeria graminis f. sp. hordei, (Bgh) are determined by unique combinations of host resistance genes, designated Mildew-resistance locus (Ml), and cognate pathogen avirulence genes. These interactions occur both dependent and independent of Rar1 (required for Mla12 resistance) and Sgt1 (Suppressor of G-two allele of skp1), which are differentially required for diverse plant disease-resistance pathways. We have isolated two new functional Mla alleles, Rar1-independent Mla7 and Rar1-dependent Mla10, as well as the Mla paralogs, Mla6-2 and Mla13-2. Utilizing the inherent diversity amongst Mla-encoded proteins, we identified the only two amino acids exclusively conserved in RAR1-dependent MLA6, MLA10, MLA12, and MLA13 that differ at the corresponding position in RAR1-independent MLA1 and MLA7. Two- and three-dimensional modeling places these residues on a predicted surface of the sixth leucine-rich repeat (LRR) domain at positions distinct from those within the beta-sheets hypothesized to determine resistance specificity. Site-directed mutagenesis of these residues indicates that RAR1 independence requires the presence of an aspartate at position 721, as mutation of this residue to a structurally similar, but uncharged, asparagine did not alter RAR1 dependence. These results demonstrate that a single-amino acid substitution in the sixth MLA LRR can alter host signaling but not resistance specificity to B. graminis. 相似文献
7.
SGT1 encodes an essential component of the yeast kinetochore assembly pathway and a novel subunit of the SCF ubiquitin ligase complex. 总被引:13,自引:0,他引:13
We have identified SGT1 as a dosage suppressor of skp1-4, a mutation causing defects in yeast kinetochore function. Sgt1p physically associates with Skp1p in vivo and in vitro. SGT1 is an essential gene, and different sgt1 conditional mutants arrest with either a G1 or G2 DNA content. Genetic and phenotypic analyses of sgt1-3 (G2 allele) mutants support an essential role in kinetochore function. Sgt1p is required for assembling the yeast kinetochore complex, CBF3, via activation of Ctf13p. Sgt1p also associates with SCF (Skp1p/Cdc53p/F box protein) ubiquitin ligase. sgt1-5 (G1 allele) mutants are defective in Sic1p turnover in vivo and Cln1p ubiquitination in vitro. Human SGT1 rescues an sgt1 null mutation, suggesting that the function of SGT1 is conserved in evolution. 相似文献
8.
The tomato (Solanum lycopersicum) Mi-1 gene encodes a protein with putative coiled-coil nucleotide-binding site and leucine-rich repeat motifs. Mi-1 confers resistance to root-knot nematodes (Meloidogyne spp.), potato aphids (Macrosiphum euphorbiae), and sweet potato whitefly (Bemisia tabaci). To identify genes required in the Mi-1-mediated resistance to nematodes and aphids, we used tobacco rattle virus (TRV)-based virus-induced gene silencing (VIGS) to repress candidate genes and assay for nematode and aphid resistance. We targeted Sgt1 (suppressor of G-two allele of Skp1), Rar1 (required for Mla12 resistance), and Hsp90 (heat shock protein 90), which are known to participate early in resistance gene signaling pathways. Two Arabidopsis (Arabidopsis thaliana) Sgt1 genes exist and one has been implicated in disease resistance. Thus far the sequence of only one Sgt1 ortholog is known in tomato. To design gene-specific VIGS constructs, we cloned a second tomato Sgt1 gene, Sgt1-2. The gene-specific VIGS construct TRV-SlSgt1-1 resulted in lethality, while silencing Sgt1-2 using TRV-SlSgt1-2 did not result in lethal phenotype. Aphid and root-knot nematode assays of Sgt1-2-silenced plants indicated no role for Sgt1-2 in Mi-1-mediated resistance. A Nicotiana benthamiana Sgt1 VIGS construct silencing both Sgt1-1 and Sgt1-2 yielded live plants and identified a role for Sgt1 in Mi-1-mediated aphid resistance. Silencing of Rar1 did not affect Mi-1-mediated nematode and aphid resistance and demonstrated that Rar1 is not required for Mi-1 resistance. Silencing Hsp90-1 resulted in attenuation of Mi-1-mediated aphid and nematode resistance and indicated a role for Hsp90-1. The requirement for Sgt1 and Hsp90-1 in Mi-1-mediated resistance provides further evidence for common components in early resistance gene defense signaling against diverse pathogens and pests. 相似文献
9.
G. Schwarz W. Michalek V. Mohler G. Wenzel A. Jahoor 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(3-4):521-530
The complex Mla locus of barley determines resistance to the powdery mildew pathogen Erysiphe graminis f. sp. hordei. With a view towards gene isolation, a population consisting of 950 F2 individuals derived from a cross between the near-isogenic lines ‘P01’ (Mla1) and ‘P10’ (Mla12) was used to construct a high-resolution map of the Mla region. A fluorescence-based AFLP technique and bulked segregant analysis were applied to screen for polymorphic, tightly
linked AFLP markers. Three AFLP markers were selected as suitable for a chromosome-landing strategy. One of these AFLP markers
and a closely linked RFLP marker were converted into sequence-specific PCR markers. PCR-based screening of approximately 70 000
yeast artificial chromosome (YAC) clones revealed three identical YACs harbouring the Mla locus. Terminal insert sequences were obtained using inverse PCR. The derived STS marker from the right YAC end-clone was
mapped distal to the Mla locus.
Received: 17 July 1998 / Accepted: 9 August 1998 相似文献
10.
Plant defense responses need to be tightly regulated to prevent auto-immunity, which is detrimental to growth and development. To identify negative regulators of Resistance (R) protein-mediated resistance, we screened for mutants with constitutive defense responses in the npr1-1 background. Map-based cloning revealed that one of the mutant genes encodes a conserved TPR domain-containing protein previously known as SRFR1 (SUPPRESSOR OF rps4-RLD). The constitutive defense responses in the srfr1 mutants in Col-0 background are suppressed by mutations in SNC1, which encodes a TIR-NB-LRR (Toll Interleukin1 Receptor-Nucleotide Binding-Leu-Rich Repeat) R protein. Yeast two-hybrid screens identified SGT1a and SGT1b as interacting proteins of SRFR1. The interactions between SGT1 and SRFR1 were further confirmed by co-immunoprecipitation analysis. In srfr1 mutants, levels of multiple NB-LRR R proteins including SNC1, RPS2 and RPS4 are increased. Increased accumulation of SNC1 is also observed in the sgt1b mutant. Our data suggest that SRFR1 functions together with SGT1 to negatively regulate R protein accumulation, which is required for preventing auto-activation of plant immunity. 相似文献
11.
Recognition specificity and RAR1/SGT1 dependence in barley Mla disease resistance genes to the powdery mildew fungus 总被引:9,自引:0,他引:9
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A large number of resistance specificities to the powdery mildew fungus Blumeria graminis f. sp. hordei map to the barley Mla locus. This complex locus harbors multiple members of three distantly related gene families that encode proteins that contain an N-terminal coiled-coil (CC) structure, a central nucleotide binding (NB) site, a Leu-rich repeat (LRR) region, and a C-terminal non-LRR (CT) region. We identified Mla12, which encodes a CC-NB-LRR-CT protein that shares 89 and 92% identical residues with the known proteins MLA1 and MLA6. Slow Mla12-triggered resistance was altered dramatically to a rapid response by overexpression of Mla12. A series of reciprocal domains swaps between MLA1 and MLA6 identified in each protein recognition domain for cognate powdery mildew fungus avirulence genes (AvrMla1 and AvrMla6). These domains were within different but overlapping LRR regions and the CT part. Unexpectedly, MLA chimeras that confer AvrMla6 recognition exhibited markedly different dependence on Rar1, a gene required for the function of some but not all Mla resistance specificities. Furthermore, uncoupling of MLA6-specific function from RAR1 also uncoupled the response from SGT1, a protein known to associate physically with RAR1. Our findings suggest that differences in the degree of RAR1 dependence of different MLA immunity responses are determined by intrinsic properties of MLA variants and place RAR1/SGT1 activity downstream of and/or coincident with the action of resistance protein-containing recognition complexes. 相似文献
12.
Botër M Amigues B Peart J Breuer C Kadota Y Casais C Moore G Kleanthous C Ochsenbein F Shirasu K Guerois R 《The Plant cell》2007,19(11):3791-3804
SGT1 (for suppressor of G2 allele of skp1) and RAR1 (for required for Mla12 resistance) are highly conserved eukaryotic proteins that interact with the molecular chaperone HSP90 (for heat shock protein90). In plants, SGT1, RAR1, and HSP90 are essential for disease resistance triggered by a number of resistance (R) proteins. Here, we present structural and functional characterization of plant SGT1 proteins. Random mutagenesis of Arabidopsis thaliana SGT1b revealed that its CS (for CHORD-SGT1) and SGS (for SGT1 specific) domains are essential for disease resistance. NMR-based interaction surface mapping and mutational analyses of the CS domain showed that the CHORD II domain of RAR1 and the N-terminal domain of HSP90 interact with opposite sides of the CS domain. Functional analysis of the CS mutations indicated that the interaction between SGT1 and HSP90 is required for the accumulation of Rx, a potato (Solanum tuberosum) R protein. Biochemical reconstitution experiments suggest that RAR1 may function to enhance the SGT1-HSP90 interaction by promoting ternary complex formation. 相似文献
13.
14.
Yumei Du Jinping Zhao Tianyuan Chen Qi Liu Haili Zhang Yan Wang Yiguo Hong Fangming Xiao Ling Zhang Qianhua Shen Yule Liu 《PLoS pathogens》2013,9(10)
Tm-22 is a coiled coil-nucleotide binding-leucine rich repeat resistance protein that confers durable extreme resistance against Tomato mosaic virus (ToMV) and Tobacco mosaic virus (TMV) by recognizing the viral movement protein (MP). Here we report that the Nicotiana benthamiana J-domain MIP1 proteins (NbMIP1s) associate with tobamovirus MP, Tm-22 and SGT1. Silencing of NbMIP1s reduced TMV movement and compromised Tm-22-mediated resistance against TMV and ToMV. Furthermore, silencing of NbMIP1s reduced the steady-state protein levels of ToMV MP and Tm-22. Moreover, NbMIP1s are required for plant resistance induced by other R genes and the nonhost pathogen Pseudomonas syringae pv. tomato (Pst) DC3000. In addition, we found that SGT1 associates with Tm-22 and is required for Tm-22-mediated resistance against TMV. These results suggest that NbMIP1s function as co-chaperones during virus infection and plant immunity. 相似文献
15.
Kana Maeda Yasunari Houjyou Takuma Komatsu Hiroki Hori Takahiro Kodaira Atsushi Ishikawa 《Plant signaling & behavior》2010,5(6):755-756
Rice blast, caused by Magnaporthe oryzae, is a devastating disease of rice (Oryza sativa). The mechanisms involved in resistance of rice to blast have been studied extensively and the rice—M. oryzae pathosystem has become a model for plant—microbe interaction studies. However, the mechanisms involved in nonhost resistance (NHR) of other plants to rice blast are still poorly understood. We have recently demonstrated that AGB1 and PMR5 contribute to PEN2-mediated preinvasion resistance to M. oryzae in Arabidopsis thaliana, suggesting a complex genetic network regulating the resistance. To determine whether other defense factors: RAR1, SGT1 and NHO1, affected the A. thaliana-M. oryzae interactions, double mutants were generated between pen2 and these defense-related mutants. All these double mutants exhibited a level of penetration resistance similar to that of the pen2 mutant, suggesting that none of these mutants significantly compromised resistance to M. oryzae in a pen2 background.Key words: nonhost resistance, PEN2, RAR1, SGT1, NHO1Plants face microbial attacks and have evolved innate immunity systems to defend against these threats. The initial step of the immunity signaling pathway is recognition of intra- or extracellular pathogen-derived molecules. Externally oriented transmembrane-type proteins containing leucine-rich repeat (LRR) domains detect extracellular molecules, whereas cytoplasmic sensors possess nucleotide-binding (NB) and LRR domains (NLR).1,2 The LRR domain serves as a pattern-recognition receptor to detect pathogen-derived molecules or host proteins that are targeted by pathogen peptides that have entered the cell, effectors.3 NLR-type sensors are the substrates of a structurally and functionally conserved chaperone complex that consists of HEAT SHOCK PROTEIN 90 (HSP90) and its cochaperone SUPPRESSOR OF THE G2 ALLELE OF SKP1 (SGT1). REQUIRED FOR MLA12 RESISTANCE 1 (RAR1) regulated the HSP90-SGT1 complex, resulting in the stabilization of NLR proteins. Thus, SGT1 and RAR1 are required for the function of multiple and distinct R genes that encode NLR immune sensors in plants.4 Experiments in RAR1-silenced transgenic rice lines showed that RAR1 is not essential for Pib, which encodes an NLR against rice blast fungus.5 In contrast, basal resistance to normally virulent races of rice blast fungus or bacterial blight is significantly reduced in RAR1-silenced lines. This result is consistent with earlier reports that RAR1 is involved in basal resistance to virulent Pseudomonas bacteria in Arabidopsis or blast fungus in barley.6,7 The requirement of SGT1 for immunity in plants is shown mostly by transient silencing of a number of NLR proteins.8,9 In addition, SGT1 is also required for immune responses triggered by non-NLR-type sensors.10 This requirement indicates that either SGT1 function is not limited to the NLR sensors, or some unknown SGT1-dependent NLR proteins also operate downstream of non NLR-type sensors. Furthermore, SGT1 is involved in nonhost resistance, indicating that SGT1 may be a general factor of disease resistance.10 An Arabidopsis mutant, nho1 (nonhost resistance 1), has been isolated on which Pseudomonas syringae pv. phaseolicola grows and causes disease symptoms.11,12 It is significant that this mutant is also compromised in R-gene-mediated resistance to P. syringae.11 Although NHO1 is the flagellin-induced glycerol kinase, whose exact function in NHR remains elusive.12,13 A possible explanation might be that altered plant glycerol pools either directly or indirectly affect nutrient availability for P. syringae. NHO1 is also required for resistance to the fungal pathogen Botrytis cinerea, indicating that NHO1 is not limited to bacterial resistance.12 However, these contributions to NHR to M. oryzae in A. thaliana have not been understood.To determine whether these factors were necessary for the resistance to M. oryzae in A. thaliana, the following A. thaliana mutants were inoculated with M. oryzae and monitored by microscopy: rar1-21;14 edm1-1;15 nho1-1,11 (all Col-0 background). All these mutants exhibited a level of penetration resistance similar to that of the wild-type plants (data not shown), suggesting that none of these mutants significantly compromised resistance to M. oryzae. We have recently shown that among the penetration (pen) mutants, only the pen2,16 mutant allowed increased penetration into epidermal cells by M. oryzae.17 Thus, double mutants were generated between pen2 and these mutants to determine whether these factors were necessary for the resistance to M. oryzae in a pen2 background: pen2 rar1-21; pen2 edm1-1; pen2 nho1-1. All these double mutants exhibited a level of penetration resistance similar to that of the pen2 mutant (Fig. 1), suggesting that none of these mutants significantly compromised resistance to M. oryzae in a pen2 background. This might indicate that NHR against M. oryzae may not be conferred by RAR1- and SGT1-dependent NLR immune sensors. Alternatively, since there has been no report that RAR1 is required for any known transmembrane sensors, such as FLS2, EFR or Xa21, RAR1- and SGT1-independent transmembrane-type immune sensors may be required for NHR against M. oryzae. Future studies will be required to reveal the genetic and mechanistic requirements for NHR in A. thaliana-M. oryzae interactions.Open in a separate windowFigure 1Double mutant analysis to evaluate the role of the defense related genes on resistance to Magnaporthe oryzae in Arabidopsis thaliana. The frequency of M. oryzae penetration on double mutants at 3 days post-inoculation was expressed as a percentage of total appressoria. Data were collected from six independent plants per line. A minimum of 100 infection sites was inspected per leaf. Results represent mean ± standard error of three independent experiments. 相似文献
16.
Young-Su Seo Sang-Kyu Lee Min-Young Song Jung-Pil Suh Tae-Ryong Hahn Pamela Ronald Jong-Seong Jeon 《Journal of Plant Biology》2008,51(1):1-10
The HSP90 (heat shock protein 90), SGT1 (suppressor of G-two allele ofSkp1), and RAR1 (required forMla12 resistance) proteins in plants form a molecular chaperone complex which is involved in diverse biological signaling including
development and disease resistance. The three components of this complex interact via specific protein binding motifs and
recruit client proteins to initiate a specific signaling cascade in response to cellular or environmental cues. Although the
functions of this chaperone complex during development/growth have not been well characterized, the HSP90 chaperone and SGT1
and RAR1 co-chaperones have been demonstrated to be essential signaling components of plant immune responses. These three
proteins also play important roles in activation of the mammalian Nod genes, which possess a structurally conserved plant
resistance (R) protein motif, NB-LRR (nucleotide binding site-leucine rich repeat). In this review, we summarize the structures
and functions of these molecular chaperones, and discuss their putative modes of action in plant immune responses. 相似文献
17.
The Rpi-blb2 recognizes the presence of the Phytophthora infestans AVRblb2 and initiates effector-triggered immunity (ETI). We performed gain-of-function and loss-of-function studies in Nicotiana benthamiana to elucidate Rpi-blb2-mediated resistance to P. infestans. Rpi-blb2 triggered a hypersensitive response through SGT1-mediated, but not RAR-mediated or HSP90-mediated, pathways. NbSGT1 was also required for basal and ETI-mediated by Rpi-blb2 in N. benthamiana. Moreover, salicylic acid (SA) affected basal defense and Rpi-blb2-mediated resistance against P. infestans. The increased susceptibility of Rpi-blb2-transgenic plants in the NahG-background correlated with reduced levels of SA. These findings provide evidence for the roles of SGT1- and SA-signaling in Rpi-blb2-mediated resistance against P. infestans. 相似文献
18.
Mammalian CHORD-containing protein 1 is a novel heat shock protein 90-interacting protein 总被引:4,自引:0,他引:4
With two tandem repeated cysteine- and histidine-rich domains (designated as CHORD), CHORD-containing proteins (CHPs) are a novel family of highly conserved proteins that play important roles in plant disease resistance and animal development. Through interacting with suppressor of the G2 allele of Skp1 (SGT1) and Hsp90, plant CHORD-containing protein RAR1 (required for Mla resistance 1) plays a critical role in disease resistance mediated by multiple R genes. Yet, the physiological function of vertebrate CHORD-containing protein-1 (Chp-1) has been poorly investigated. In this study, we provide the first biochemical evidence demonstrating that mammalian Chp-1 is a novel Hsp90-interacting protein. Mammalian Chp-1 contains two CHORD domains (I and II) and one CS domain (a domain shared by CHORD-containing proteins and SGT1). With sequence and structural similarity to Hsp90 co-chaperones p23 and SGT1, Chp-1 binds to the ATPase domain of Hsp90, but the biochemical property of the interaction is unique. The Chp-1-Hsp90 interaction is independent of ATP and ATPase-coupled conformational change of Hsp90, a feature that distinguishes Chp-1 from p23. Furthermore, it appears that multiple domains of Chp-1 are required for stable Chp-1-Hsp90 interaction. Unlike SGT1 whose CS domain is sufficient for Hsp90 binding, the CS domain of Chp-1 is essential but not sufficient for Hsp90 binding. While the CHORD-I domain of Chp-1 is dispensable for Hsp90 binding, the CHORD-II domain and the linker region are essential. Interestingly, the CHORD-I domain of plant RAR1 protein is solely responsible for Hsp90 binding. The unique Chp-1-Hsp90 interaction may be indicative of a distinct biological activity of Chp-1 and functional diversification of CHORD-containing proteins during evolution. 相似文献
19.
Plants utilize proteins containing nucleotide binding site (NB) and leucine-rich repeat (LRR) domains as intracellular innate immune receptors to recognize pathogens and initiate defense responses. Since mis-activation of defense responses can lead to tissue damage and even developmental arrest, proper regulation of NB–LRR protein signaling is critical. RAR1, SGT1, and HSP90 act as regulatory chaperones of pre-activation NB–LRR steady-state proteins. We extended our analysis of mutants derived from a rar1 suppressor screen and present two allelic rar1 suppressor (rsp) mutations of Arabidopsis COI1. Like all other coi1 mutations, coi1rsp missense mutations impair Jasmonic Acid (JA) signaling resulting in JA–insensitivity. However, unlike previously identified coi1 alleles, both coi1rsp alleles lack a male sterile phenotype. The coi1rsp mutants express two sets of disease resistance phenotypes. The first, also observed in coi1-1 null allele, includes enhanced basal defense against the virulent bacterial pathogen Pto DC3000 and enhanced effector-triggered immunity (ETI) mediated by the NB–LRR RPM1 protein in both rar1 and wild-type backgrounds. These enhanced disease resistance phenotypes depend on the JA signaling function of COI1. Additionally, the coi1rsp mutants showed a unique inability to properly regulate RPM1 accumulation and HR, exhibited increased RPM1 levels in rar1, and weakened RPM1-mediated HR in RAR1. Importantly, there was no change in the steady-state levels or HR function of RPM1 in coi1-1. These results suggest that the coi1rsp proteins regulate NB–LRR protein accumulation independent of JA signaling. Based on the phenotypic similarities and genetic interactions among coi1rsp, sgt1b, and hsp90.2rsp mutants, our data suggest that COI1 affects NB–LRR accumulation via two NB–LRR co-chaperones, SGT1b and HSP90. Together, our data demonstrate a role for COI1 in disease resistance independent of JA signaling and provide a molecular link between the JA and NB–LRR signaling pathways. 相似文献
20.
Min-Young Song Chi-Yeol Kim Muho Han Hak-Seung Ryu Sang-Kyu Lee Li Sun Zuhua He Young-Su Seo Patrick Canal Pamela C. Ronald Jong-Seong Jeon 《Molecules and cells》2013,35(4):327-334
The required for Mla12 resistance (RAR1) protein is essential for the plant immune response. In rice, a model monocot species, the function of Oryza sativa RAR1 (OsRAR1) has been little explored. In our current study, we characterized the response of a rice osrar1 T-DNA insertion mutant to infection by Magnaporthe oryzae, the causal agent of rice blast disease. osrar1 mutants displayed reduced resistance compared with wild type rice when inoculated with the normally virulent M. oryzae isolate PO6-6, indicating that OsRAR1 is required for an immune response to this pathogen. We also investigated the function of OsRAR1 in the resistance mechanism mediated by the immune receptor genes Pib and Pi5 that encode nucleotide binding-leucine rich repeat (NB-LRR) proteins. We inoculated progeny from Pib/osrar1 and Pi5/osrar1 heterozygous plants with the avirulent M. oryzae isolates, race 007 and PO6-6, respectively. We found that only Pib-mediated resistance was compromised by the osrar1 mutation and that the introduction of the OsRAR1 cDNA into Pib/osrar1 rescued Pib-mediated resistance. These results indicate that OsRAR1 is required for Pib-mediated resistance but not Pi5-mediated resistance to M. oryzae. 相似文献