The βC1 protein encoded by the Tomato yellow leaf curl China virus-associated betasatellite functions as a pathogenicity determinant. To better understand the molecular basis whereby βC1 functions in pathogenicity, ...The βC1 protein encoded by the Tomato yellow leaf curl China virus-associated betasatellite functions as a pathogenicity determinant. To better understand the molecular basis whereby βC1 functions in pathogenicity, a yeast two-hybrid screen of a tobacco cDNA library was carried out using βC1 as the bait. The screen revealed that βC1 interacts with a tobacco RING-finger protein designated NtRFP1, which was further confirmed by the bimolecular fluorescence complementation and co-immunoprecipitation assays in Nicotiana benthamiana cells. Expression of NtRFP1 was induced by βC1, and in vitro ubiquiti- nation assays showed that NtRFP1 is a functional E3 ubiquiUn ligase that mediates βC1 ubiquitination. In addition, βC1 was shown to be ubiquitinated in vivo and degraded by the plant 26S proteasome. After viral infection, plants overexpressing NtRFP1 developed attenuated symptoms, whereas plants with silenced expression of NtRFP1 showed severe symptoms. Other lines of evidence showed that NtRFP1 attenuates βC1-induced symptoms through promoting its degradation by the 26S proteasome. Taken together, our results suggest that tobacco RING E3 ligase NtRFP1 attenuates disease symptoms by interacting with βC1 to mediate its ubiquitination and degradation via the ubiquitin/26S proteasome system.展开更多
Geminiviruses are a family of plant viruses that cause devastating diseases in many economically important crops worldwide. These pathogens encapsidate circular,single-stranded DNAs (ssDNAs)of 2.5-3.0 kb that replicat...Geminiviruses are a family of plant viruses that cause devastating diseases in many economically important crops worldwide. These pathogens encapsidate circular,single-stranded DNAs (ssDNAs)of 2.5-3.0 kb that replicate through double-stranded DNA (dsDNA)intermediates.Members of the genus Begomovirus,which comprises by far the largest number of species in the family,are transmitted by whiteflies and have genomes consisting of one or two DNAs.展开更多
UPR is a conserved response in eukaryotes and can alleviate endoplasmic reticulum(ER)stresses induced by abiotic and biotic stresses.The interactions between UPR and plant RNA viruses have been documented,while the in...UPR is a conserved response in eukaryotes and can alleviate endoplasmic reticulum(ER)stresses induced by abiotic and biotic stresses.The interactions between UPR and plant RNA viruses have been documented,while the interplays between UPR and plant DNA viruses remain unknown.Using tomato yellow leaf curl China virus(TYLCCNV)and its associated betasatellite(TYLCCNB)as a model,we indicate that TYLCCNBβC1 is a major inducer of UPR and can upregulate the expression of b ZIP60,a transcription factor in Nicotiana benthamiana plants.Treatment using ER stress inducers or overexpression of Nbb ZIP60 increasesβC1 accumulation and benefits TYLCCNV/TYLCCNB infection in N.benthamiana plants,and vice versa.In the TYLCCNV/TYLCCNB-infected or theβC1-expressing cells,Nbb ZIP60 is exported from the nucleus to the nuclear periphery via the XPO1 pathway,and blocking the XPO1 pathway inhibited TYLCCNV/TYLCCNB infection.We have found that the Nbb ZIP60-regulated pro-survival genes could promote virus infection,and the pro-death gene plays a contrasting role in virus infection.This study reveals that geminivirus infection activates UPR and utilizes the up-regulated molecular chaperons to promote viral infection,and then induces the nuclear export of Nbb ZIP60 to evade plant defense response,which is a distinct virulence strategy exploited by plant pathogens.展开更多
Transcription factors(TFs)play crucial roles in plant development and pathogen defense.However,plant viruses can exploit TFs to facilitate their infection or transmission.In this study,we confirmed theβC1 proteins,en...Transcription factors(TFs)play crucial roles in plant development and pathogen defense.However,plant viruses can exploit TFs to facilitate their infection or transmission.In this study,we confirmed theβC1 proteins,encoded by tobacco curly shoot virus(TbCSV)-and tomato yellow leaf curl China virus(TYLCCNV)-associated betasatellites,interacted with GLABROUS1 enhancer binding protein(GeBP)TFs from solanaceous plants including Nicotiana benthamiana,Solanum lycopersicum,S.tuberosum,and Capsicum annuum.Further analysis verified the nuclear localization,homodimerization,and DNA-binding ability of the GeBP TFs,along with its interaction withβC1 in the nucleus.PVX-mediated overexpression of NbGeBP showed no effect on the accumulation of viral and betasatellite DNAs in N.benthamiana plants after infection with TbCSV and its heterologous betasatellite,malvastrum yellow vein virus associated betasatellite(MaYVB),or its homologous betasatellite,TbCSB.However,both TbCSV and MaYVV caused a decrease in NbGeBP expression during the early stages of infection,regardless of the presence of homologous or heterologous betasatellites,implying that NbGeBP might play a role in virus infection.TbCSV/TbCSB and TYLCCNV/TYLCCNB infect many solanaceous plants,and solanaceous GeBP proteins interact withβC1 proteins from TbCSB and TYLCCNB.The yeast two-hybrid and bimoleccular fluorescence complementation assays showed that AtGeBP from Arabidopsis thaliana could not interact with TbCSBβC1,revealing that the GeBP-βC1 interactions might only exist in GeBP proteins from solanaceous plants.Importantly,theβC1 protein from MaYVB,which was almost not reported on natural infection in solanaceous plants,could not interact with GeBP,suggesting the potential roles of GeBP in monopartite begomovirus infection of solanaceous plants.展开更多
Chloroplasts are central to plant immunity,with the chloroplast-localized protein AGD2-LIKE DEFENSE RESPONSE PROTEIN 1(ALD1)playing a critical role in producing pipecolic acid(Pip),a key immune signal.However,the regu...Chloroplasts are central to plant immunity,with the chloroplast-localized protein AGD2-LIKE DEFENSE RESPONSE PROTEIN 1(ALD1)playing a critical role in producing pipecolic acid(Pip),a key immune signal.However,the regulation of ALD1 and how pathogens evade ALD1-mediated defenses remain poorly understood.Using the geminivirus tomato yellow leaf curl China virus and its associated betasatellite(TYLCCNV/TYLCCNB)as a model,we uncovered a defense mechanism involving organellar single-stranded DNA-binding protein 1(OSB1),which stabilizes ALD1 and promotes Pip biosynthesis to strengthen immunity.Crucially,the viralβC1 effector encoded by TYLCCNB disrupts this pathway by binding OSB1 and sequestering it away from chloroplasts,thereby blocking OSB1-ALD1 interaction,destabilizing ALD1,and suppressing Pip-dependent defenses.Strikingly,βC1 mutants defective in OSB1 binding fail to interfere with the OSB1-ALD1 stability,and TYLCCNV infections carrying these mutants induce attenuated symptoms in Nicotiana benthamiana.Our study not only reveals how ALD1-OSB1 cooperates in chloroplast immunity but also demonstrates how geminiviruses,as a tractable model,can dissect pathogen counter-defense strategies.展开更多
文摘The βC1 protein encoded by the Tomato yellow leaf curl China virus-associated betasatellite functions as a pathogenicity determinant. To better understand the molecular basis whereby βC1 functions in pathogenicity, a yeast two-hybrid screen of a tobacco cDNA library was carried out using βC1 as the bait. The screen revealed that βC1 interacts with a tobacco RING-finger protein designated NtRFP1, which was further confirmed by the bimolecular fluorescence complementation and co-immunoprecipitation assays in Nicotiana benthamiana cells. Expression of NtRFP1 was induced by βC1, and in vitro ubiquiti- nation assays showed that NtRFP1 is a functional E3 ubiquiUn ligase that mediates βC1 ubiquitination. In addition, βC1 was shown to be ubiquitinated in vivo and degraded by the plant 26S proteasome. After viral infection, plants overexpressing NtRFP1 developed attenuated symptoms, whereas plants with silenced expression of NtRFP1 showed severe symptoms. Other lines of evidence showed that NtRFP1 attenuates βC1-induced symptoms through promoting its degradation by the 26S proteasome. Taken together, our results suggest that tobacco RING E3 ligase NtRFP1 attenuates disease symptoms by interacting with βC1 to mediate its ubiquitination and degradation via the ubiquitin/26S proteasome system.
基金The National Natural Science Foundation of China (31390422 and 31720103914)The Bisaro laboratory is supported by grants from the US National Science Foundation (NSF IOS-1354636)the US Department of Agriculture and National Institute of Food and Agriculture (USDA/NIFA 2015-6703-22999).
文摘Geminiviruses are a family of plant viruses that cause devastating diseases in many economically important crops worldwide. These pathogens encapsidate circular,single-stranded DNAs (ssDNAs)of 2.5-3.0 kb that replicate through double-stranded DNA (dsDNA)intermediates.Members of the genus Begomovirus,which comprises by far the largest number of species in the family,are transmitted by whiteflies and have genomes consisting of one or two DNAs.
基金supported by the National Key Research and Development Program of China (2021YFD1400400)the National Natural Science Foundation of China (32172385,31930089)。
文摘UPR is a conserved response in eukaryotes and can alleviate endoplasmic reticulum(ER)stresses induced by abiotic and biotic stresses.The interactions between UPR and plant RNA viruses have been documented,while the interplays between UPR and plant DNA viruses remain unknown.Using tomato yellow leaf curl China virus(TYLCCNV)and its associated betasatellite(TYLCCNB)as a model,we indicate that TYLCCNBβC1 is a major inducer of UPR and can upregulate the expression of b ZIP60,a transcription factor in Nicotiana benthamiana plants.Treatment using ER stress inducers or overexpression of Nbb ZIP60 increasesβC1 accumulation and benefits TYLCCNV/TYLCCNB infection in N.benthamiana plants,and vice versa.In the TYLCCNV/TYLCCNB-infected or theβC1-expressing cells,Nbb ZIP60 is exported from the nucleus to the nuclear periphery via the XPO1 pathway,and blocking the XPO1 pathway inhibited TYLCCNV/TYLCCNB infection.We have found that the Nbb ZIP60-regulated pro-survival genes could promote virus infection,and the pro-death gene plays a contrasting role in virus infection.This study reveals that geminivirus infection activates UPR and utilizes the up-regulated molecular chaperons to promote viral infection,and then induces the nuclear export of Nbb ZIP60 to evade plant defense response,which is a distinct virulence strategy exploited by plant pathogens.
基金supported by the National Natural Science Foundation of China(32072380)Fundamental Research Funds for the Central Universities(SWUKT22058)+1 种基金Chongqing Postgraduate Research Innovation Project(CYB22140)Chongqing Municipal Training Program of Innovation and Entrepreneurship for Undergraduates(S202310635211 and X202310635107).
文摘Transcription factors(TFs)play crucial roles in plant development and pathogen defense.However,plant viruses can exploit TFs to facilitate their infection or transmission.In this study,we confirmed theβC1 proteins,encoded by tobacco curly shoot virus(TbCSV)-and tomato yellow leaf curl China virus(TYLCCNV)-associated betasatellites,interacted with GLABROUS1 enhancer binding protein(GeBP)TFs from solanaceous plants including Nicotiana benthamiana,Solanum lycopersicum,S.tuberosum,and Capsicum annuum.Further analysis verified the nuclear localization,homodimerization,and DNA-binding ability of the GeBP TFs,along with its interaction withβC1 in the nucleus.PVX-mediated overexpression of NbGeBP showed no effect on the accumulation of viral and betasatellite DNAs in N.benthamiana plants after infection with TbCSV and its heterologous betasatellite,malvastrum yellow vein virus associated betasatellite(MaYVB),or its homologous betasatellite,TbCSB.However,both TbCSV and MaYVV caused a decrease in NbGeBP expression during the early stages of infection,regardless of the presence of homologous or heterologous betasatellites,implying that NbGeBP might play a role in virus infection.TbCSV/TbCSB and TYLCCNV/TYLCCNB infect many solanaceous plants,and solanaceous GeBP proteins interact withβC1 proteins from TbCSB and TYLCCNB.The yeast two-hybrid and bimoleccular fluorescence complementation assays showed that AtGeBP from Arabidopsis thaliana could not interact with TbCSBβC1,revealing that the GeBP-βC1 interactions might only exist in GeBP proteins from solanaceous plants.Importantly,theβC1 protein from MaYVB,which was almost not reported on natural infection in solanaceous plants,could not interact with GeBP,suggesting the potential roles of GeBP in monopartite begomovirus infection of solanaceous plants.
基金supported by the National Key Research and Development Program of China(2021YFD1400400)to Fangfang Lithe National Natural Science Foundation of China(W2411024)to Xueping Zhou,respectively.
文摘Chloroplasts are central to plant immunity,with the chloroplast-localized protein AGD2-LIKE DEFENSE RESPONSE PROTEIN 1(ALD1)playing a critical role in producing pipecolic acid(Pip),a key immune signal.However,the regulation of ALD1 and how pathogens evade ALD1-mediated defenses remain poorly understood.Using the geminivirus tomato yellow leaf curl China virus and its associated betasatellite(TYLCCNV/TYLCCNB)as a model,we uncovered a defense mechanism involving organellar single-stranded DNA-binding protein 1(OSB1),which stabilizes ALD1 and promotes Pip biosynthesis to strengthen immunity.Crucially,the viralβC1 effector encoded by TYLCCNB disrupts this pathway by binding OSB1 and sequestering it away from chloroplasts,thereby blocking OSB1-ALD1 interaction,destabilizing ALD1,and suppressing Pip-dependent defenses.Strikingly,βC1 mutants defective in OSB1 binding fail to interfere with the OSB1-ALD1 stability,and TYLCCNV infections carrying these mutants induce attenuated symptoms in Nicotiana benthamiana.Our study not only reveals how ALD1-OSB1 cooperates in chloroplast immunity but also demonstrates how geminiviruses,as a tractable model,can dissect pathogen counter-defense strategies.
