Keeping immune responses in an off state in the absence of a threat is essential to avoid the deleterious consequences of autoimmunity,while their timely activation upon perception of non-self determines the capacity ...Keeping immune responses in an off state in the absence of a threat is essential to avoid the deleterious consequences of autoimmunity,while their timely activation upon perception of non-self determines the capacity of an organism to defend against potential pathogens.In plants,constitutive or untimely activation of immune responses dramatically limits growth and reproduction,highlighting the essential role of negative regulators of immunity for plant fitness.While a number of such regulators have been identified in the past couple of decades,the full complexity of the molecular mechanisms deployed by plants to ensure an appropriately controlled activation of immune responses,as well as their coordination with growth and development,are still largely elusive.展开更多
Jasmonates(JAs) are phytohormones that finely regulate critical biological processes, including plant development and defense. JASMONATE ZIM-DOMAIN(JAZ) proteins are crucial transcriptional regulators that keep JA-res...Jasmonates(JAs) are phytohormones that finely regulate critical biological processes, including plant development and defense. JASMONATE ZIM-DOMAIN(JAZ) proteins are crucial transcriptional regulators that keep JA-responsive genes in a repressed state. In the presence of JA-Ile, JAZ repressors are ubiquitinated and targeted for degradation by the ubiquitin/proteasome system,allowing the activation of downstream transcription factors and, consequently, the induction of JA-responsive genes. A growing body of evidence has shown that JA signaling is crucial in defending against plant viruses and their insect vectors. Here, we describe the interaction of C2proteins from two tomato-infecting geminiviruses from the genus Begomovirus, tomato yellow leaf curl virus(TYLCV) and tomato yellow curl Sardinia virus(TYLCSaV), with the transcriptional repressor JAZ8 from Arabidopsis thaliana and its closest orthologue in tomato, SlJAZ9. Both JAZ and C2proteins colocalize in the nucleus, forming discrete nuclear speckles. Overexpression of JAZ8did not lead to altered responses to TYLCV infection in Arabidopsis;however, knock-down of JAZ8 favors geminiviral infection. Low levels of JAZ8 likely affect the viral infection specifically,since JAZ8-silenced plants neither display obvious developmental phenotypes nor present differences in their interaction with the viral insect vector. In summary, our results show that the geminivirus-encoded C2 interacts with JAZ8 in the nucleus, and suggest that this plant protein exerts an anti-geminiviral effect.展开更多
Bacterial wilt disease caused by several Ralstonia species is one of the most destructive diseases in Solanaceae crops.Only a few functional resistance genes against bacterial wilt have been cloned to date.Here,we sho...Bacterial wilt disease caused by several Ralstonia species is one of the most destructive diseases in Solanaceae crops.Only a few functional resistance genes against bacterial wilt have been cloned to date.Here,we showthat the broadly conserved typeⅢsecreted effector RipY is recognized by the Nicotiana benthamiana immune system,leading to cell death induction,induction of defense-related gene expression,and restriction of bacterial pathogen growth.Using a multiplexed virus-induced gene-silencing-based N.benthamiana nucleotide-binding and leucine-rich repeat receptor(NbNLR)library,we identified a coiled-coil(CC)nucleotide-binding and leucine-rich repeat receptor(CNL)required for recognition of RipY,which we named RESISTANCE TO RALSTONIA SOLANACEARUM RIPY(RRS-Y).Genetic complementation assays in RRS-Y-silenced plants and stable rrs-y knockout mutants demonstrated that RRS-Y is sufficient to activate RipY-induced cell death andRipY-induced immunity to Ralstonia pseudosolanacearum.RRS-Y function is dependent on the phosphate-binding loop motif of the nucleotide-binding domain but independent of the characterized signaling components ENHANCED DISEASE SUSCEPTIBILITY 1,ACTIVATED DISEASE RESISTANCE 1,and N REQUIREMENT GENE 1 and the NLR helpers NB-LRR REQUIRED FOR HR-ASSOCIATED CELL DEATH-2,-3,and-4 in N.benthamiana.We further show that RRS-Y localization at the plasma membrane is mediated by two cysteine residues in the CC domain and is required for RipY recognition.RRSY also broadly recognizes RipY homologs across Ralstonia species.Lastly,we show that the C-terminal region of RipY is indispensable for RRS-Y activation.Together,our findings provide an additional effector/receptor pair system to deepen our understanding of CNL activation in plants.展开更多
Quantitative disease resistance(QDR)remains the most prevalent form of plant resistance in crop fields and wild habitats.Genome-wide association studies(GWAS)have proved to be successful in deciphering the quantitativ...Quantitative disease resistance(QDR)remains the most prevalent form of plant resistance in crop fields and wild habitats.Genome-wide association studies(GWAS)have proved to be successful in deciphering the quantitative genetic basis of complex traits such as QDR.To unravel the genetics of QDR to the devastating worldwide bacterial pathogen Ralstonia solanacearum,we performed a GWAS by challenging a highly polymorphic local mapping population of Arabidopsis thaliana with four R.solanacearum type III effector(T3E)mutants,identified as key pathogenicity determinants after a first screen on an A.thaliana core collection of 25 accessions.Although most quantitative trait loci(QTLs)were highly specific to the identity of the T3E mutant(ripAC,ripAG,ripAQ,and ripU),we finely mapped a common QTL located on a cluster of nucleotide-binding domain and leucine-rich repeat(NLR)genes that exhibited structural variation.We functionally validated one of these NLRs as a susceptibility factor in response to R.solanacearum,named it Bacterial Wilt Susceptibility 1(BWS1),and cloned two alleles that conferred contrasting levels of QDR.Further characterization indicated that expression of BWS1 leads to suppression of immunity triggered by different R.solanacearum effectors.In addition,we showed a direct interaction between BWS1 and RipAC T3E,and BWS1 and SUPPRESSOR OF G2 ALLELE OF skp1(SGT1b),the latter interaction being suppressed by RipAC.Together,our results highlight a putative role for BWS1 as a quantitative susceptibility factor directly targeted by the T3E RipAC,mediating negative regulation of the SGT1-dependent immune response.展开更多
The extensive phenotypic diversity within natural populations of Arabidopsis is associated with differences in gene expression.Transcript levels can be considered as in-heritable quantitative traits,and used to map ex...The extensive phenotypic diversity within natural populations of Arabidopsis is associated with differences in gene expression.Transcript levels can be considered as in-heritable quantitative traits,and used to map expression quantitative trait loci(eQTL)in genome-wide association studies(GWASs).In order to identify putative genetic de-terminants for variations in gene expression,we used pub-licly available genomic and transcript variation data from 665 Arabidopsis accessions and applied the single nucleotide polymorphism-set(Sequence)Kernel Association Test(SKAT)method for the identification of eQTL.Moreover,we used the penalized orthogonal-components regression(POCRE)method to increase the power of statistical tests.Then,gene annotations were used as test units to identify genes that are associated with natural variations in transcript accumulation,which correspond to candidate regulators,some of which may have a broad impact on gene ex-pression.Besides increasing the chances to identify real as-sociations,the analysis using POCRE and SKAT significantly reduced the computational cost required to analyze large datasets.As a proof of concept,we used this approach to identify eQTL that represent novel candidate regulators of immune responses.The versatility of this approach allows its application to any process that is subjected to natural var-iation among Arabidopsis accessions.展开更多
文摘Keeping immune responses in an off state in the absence of a threat is essential to avoid the deleterious consequences of autoimmunity,while their timely activation upon perception of non-self determines the capacity of an organism to defend against potential pathogens.In plants,constitutive or untimely activation of immune responses dramatically limits growth and reproduction,highlighting the essential role of negative regulators of immunity for plant fitness.While a number of such regulators have been identified in the past couple of decades,the full complexity of the molecular mechanisms deployed by plants to ensure an appropriately controlled activation of immune responses,as well as their coordination with growth and development,are still largely elusive.
基金supported by a President's International Fellowship Initiative (PIFI) postdoctoral fel owship (No. 2016PB042) from the Chinese Academy of Sciencesthe “Programa Juan de la Cierva” (IJCI-2017-33367) from the MCIN and FEDER program UMA20-FEDERJA-132 by AEI and by “ERDF A way of making Europe,” by the “European Union”Funding for Open Access charge: Universidad de Málaga / CBUA。
文摘Jasmonates(JAs) are phytohormones that finely regulate critical biological processes, including plant development and defense. JASMONATE ZIM-DOMAIN(JAZ) proteins are crucial transcriptional regulators that keep JA-responsive genes in a repressed state. In the presence of JA-Ile, JAZ repressors are ubiquitinated and targeted for degradation by the ubiquitin/proteasome system,allowing the activation of downstream transcription factors and, consequently, the induction of JA-responsive genes. A growing body of evidence has shown that JA signaling is crucial in defending against plant viruses and their insect vectors. Here, we describe the interaction of C2proteins from two tomato-infecting geminiviruses from the genus Begomovirus, tomato yellow leaf curl virus(TYLCV) and tomato yellow curl Sardinia virus(TYLCSaV), with the transcriptional repressor JAZ8 from Arabidopsis thaliana and its closest orthologue in tomato, SlJAZ9. Both JAZ and C2proteins colocalize in the nucleus, forming discrete nuclear speckles. Overexpression of JAZ8did not lead to altered responses to TYLCV infection in Arabidopsis;however, knock-down of JAZ8 favors geminiviral infection. Low levels of JAZ8 likely affect the viral infection specifically,since JAZ8-silenced plants neither display obvious developmental phenotypes nor present differences in their interaction with the viral insect vector. In summary, our results show that the geminivirus-encoded C2 interacts with JAZ8 in the nucleus, and suggest that this plant protein exerts an anti-geminiviral effect.
基金supported by the National Research Foundation of Korea(NRF)funded by the Korean Ministry of Education(Global PhD Fellowship Program Project 500–20190213)by the Ministry of Sciences and ICT(Projects 2018R1A5A1023599,2020R1A2C1101419).
文摘Bacterial wilt disease caused by several Ralstonia species is one of the most destructive diseases in Solanaceae crops.Only a few functional resistance genes against bacterial wilt have been cloned to date.Here,we showthat the broadly conserved typeⅢsecreted effector RipY is recognized by the Nicotiana benthamiana immune system,leading to cell death induction,induction of defense-related gene expression,and restriction of bacterial pathogen growth.Using a multiplexed virus-induced gene-silencing-based N.benthamiana nucleotide-binding and leucine-rich repeat receptor(NbNLR)library,we identified a coiled-coil(CC)nucleotide-binding and leucine-rich repeat receptor(CNL)required for recognition of RipY,which we named RESISTANCE TO RALSTONIA SOLANACEARUM RIPY(RRS-Y).Genetic complementation assays in RRS-Y-silenced plants and stable rrs-y knockout mutants demonstrated that RRS-Y is sufficient to activate RipY-induced cell death andRipY-induced immunity to Ralstonia pseudosolanacearum.RRS-Y function is dependent on the phosphate-binding loop motif of the nucleotide-binding domain but independent of the characterized signaling components ENHANCED DISEASE SUSCEPTIBILITY 1,ACTIVATED DISEASE RESISTANCE 1,and N REQUIREMENT GENE 1 and the NLR helpers NB-LRR REQUIRED FOR HR-ASSOCIATED CELL DEATH-2,-3,and-4 in N.benthamiana.We further show that RRS-Y localization at the plasma membrane is mediated by two cysteine residues in the CC domain and is required for RipY recognition.RRSY also broadly recognizes RipY homologs across Ralstonia species.Lastly,we show that the C-terminal region of RipY is indispensable for RRS-Y activation.Together,our findings provide an additional effector/receptor pair system to deepen our understanding of CNL activation in plants.
基金supported by the Laboratoire d’Excellence(LABEX)TULIP(ANR-10-LABX-41)funded by a grant from the Lebanese University+4 种基金INRAE,Campus France,and the INRAE Plant Health and Environment division(SPE)for their support and fundinga PhD grant co-financed by the Occitanie Regional Council and the INRAE Plant Health and Environment division(SPE)funded by a grant from the French Ministry of National Education and Researchsupported by France Genomique National infrastructurefunded as part of the Investissement d’avenir program managed by Agence Nationale de la Recherche(contract ANR-10-INBS-09).
文摘Quantitative disease resistance(QDR)remains the most prevalent form of plant resistance in crop fields and wild habitats.Genome-wide association studies(GWAS)have proved to be successful in deciphering the quantitative genetic basis of complex traits such as QDR.To unravel the genetics of QDR to the devastating worldwide bacterial pathogen Ralstonia solanacearum,we performed a GWAS by challenging a highly polymorphic local mapping population of Arabidopsis thaliana with four R.solanacearum type III effector(T3E)mutants,identified as key pathogenicity determinants after a first screen on an A.thaliana core collection of 25 accessions.Although most quantitative trait loci(QTLs)were highly specific to the identity of the T3E mutant(ripAC,ripAG,ripAQ,and ripU),we finely mapped a common QTL located on a cluster of nucleotide-binding domain and leucine-rich repeat(NLR)genes that exhibited structural variation.We functionally validated one of these NLRs as a susceptibility factor in response to R.solanacearum,named it Bacterial Wilt Susceptibility 1(BWS1),and cloned two alleles that conferred contrasting levels of QDR.Further characterization indicated that expression of BWS1 leads to suppression of immunity triggered by different R.solanacearum effectors.In addition,we showed a direct interaction between BWS1 and RipAC T3E,and BWS1 and SUPPRESSOR OF G2 ALLELE OF skp1(SGT1b),the latter interaction being suppressed by RipAC.Together,our results highlight a putative role for BWS1 as a quantitative susceptibility factor directly targeted by the T3E RipAC,mediating negative regulation of the SGT1-dependent immune response.
基金we thank Shaojun Xie and Kai Tang for discussionsand technical assistance.This work was supported byfunds from the Chinese Academy of Sciences and Purdue UniversityThe authors acknowledge thesupport of NIH(R03CA235363,R03CA211831)the Purdue University Center for Cancer Research SupportGrant(P30CA023168).
文摘The extensive phenotypic diversity within natural populations of Arabidopsis is associated with differences in gene expression.Transcript levels can be considered as in-heritable quantitative traits,and used to map expression quantitative trait loci(eQTL)in genome-wide association studies(GWASs).In order to identify putative genetic de-terminants for variations in gene expression,we used pub-licly available genomic and transcript variation data from 665 Arabidopsis accessions and applied the single nucleotide polymorphism-set(Sequence)Kernel Association Test(SKAT)method for the identification of eQTL.Moreover,we used the penalized orthogonal-components regression(POCRE)method to increase the power of statistical tests.Then,gene annotations were used as test units to identify genes that are associated with natural variations in transcript accumulation,which correspond to candidate regulators,some of which may have a broad impact on gene ex-pression.Besides increasing the chances to identify real as-sociations,the analysis using POCRE and SKAT significantly reduced the computational cost required to analyze large datasets.As a proof of concept,we used this approach to identify eQTL that represent novel candidate regulators of immune responses.The versatility of this approach allows its application to any process that is subjected to natural var-iation among Arabidopsis accessions.
