RXLR effectors are pathogenic factors secreted from oomycetes to manipulate the immunity of the host.Typical RXLR effectors contain an RXLR-dEER motif at the N-terminus,whereas atypical RXLRs show variations on this m...RXLR effectors are pathogenic factors secreted from oomycetes to manipulate the immunity of the host.Typical RXLR effectors contain an RXLR-dEER motif at the N-terminus,whereas atypical RXLRs show variations on this motif.The oomycete Phytophthora cactorum is known to infect over 200 plant species,resulting in significant agricultural economic losses.Although genome-wide identification and functional analyses of typical RXLRs from P.cactorum have been performed,little is known of atypical PcaRXLRs.Here,we identified RXLRs,both typical and atypical,in P.cactorum and compared them with those of other oomycete pathogens.Fewer RXLRs were identified in P.cactorum compared with other Phytophthora species,possibly due to fewer duplication events of RXLRs.In contrast,the percentage of atypical RXLRs was higher in P.cactorum than in other species,suggesting significant roles in P.cactorum pathogenesis.Analysis of RXLR gene expression showed that most were transcribed,suggesting their functionality.Transient expression of two atypical RXLRs in Nicotiana benthamiana showed that they induced necrosis dependent on host SGT1 and HSP90.Furthermore,two additional atypical RXLRs suppressed the defense response in N.benthamiana and promoted P.cactorum infection.These results demonstrate the vital role of atypical RXLRs in P.cactorum and provide valuable information on their evolutionary patterns and interactions with host plants.展开更多
An accurate assessment of host and pathogen gene expression during infection is critical for understanding the molecular aspects of host-pathogen interactions.Often,pathogen-derived transcripts are difficult to ascert...An accurate assessment of host and pathogen gene expression during infection is critical for understanding the molecular aspects of host-pathogen interactions.Often,pathogen-derived transcripts are difficult to ascertain at early infection stages owing to the unfavourable transcript representation compared to the host genes.In this study,we compare two sequencing techniques,RNAseq and enrichment sequencing(RenSeq and PenSeq)of cDNA,to investigate gene expression patterns in the doubled monoploid potato(DM)infected with the late blight pathogen Phytophthora infestans.Our results reveal distinct advantages of cDNA RenSeq and PenSeq over traditional RNAseq in terms of target gene representation and transcriptional quantification at early infection stages.Throughout the infection time course,cDNA enrichment sequencing enables transcriptomic analyses for more targeted host and pathogen genes.For highly expressed genes that were sampled in parallel by both cDNA enrichment and RNAseq,a high level of concordance in expression profiles is observed,indicative of at least semi-quantitative gene expression representation following enrichment.展开更多
Oomycete pathogens secrete hundreds of effectors,including avirulence proteins that trigger host genotypespecific resistance response,to manipulate host immunity and facilitate infection.Sequence and expression variat...Oomycete pathogens secrete hundreds of effectors,including avirulence proteins that trigger host genotypespecific resistance response,to manipulate host immunity and facilitate infection.Sequence and expression variations of avirulence genes in pathogens are well known to be responsible for loss of host genotype-specific disease resistance.However,little is known on the underlying mechanisms associated with virulence variation in the diploid Phytophthora pathogens.We report in this study that the endogenous small RNAs(sRNAs)are involved in the variation of expression of avirulence gene Avr1b in P.sojae.The sRNAs were originated from the natural antisense transcripts of Avr1b.We further showed that the sense and antisense expression of Avr1b were programmed by the 10-base deletions in their promoter regions.Expanded analysis showed that up to 31%of the P.sojae RXLR effector genes were associated with sRNAs.Genome analysis further showed that the 9-bp and 10-bp insertion/deletion variants were significantly enriched in the regulatory regions of RXLR effector genes.These results indicate that the expression of RXLR effector genes are programmed by significantly enriched variations in their regulatory regions that lead to the variations in bidirectional transcription,which likely further affect production of endogenous sRNAs and silencing of homologous RXLR effector genes of Phytophthora pathogens.展开更多
Phytophthora pathogens secrete a large arsenal of effectors that manipulate host processes to create an environment conducive to pathogen colonization. However, the underlying mechanisms by which Phytophthora effector...Phytophthora pathogens secrete a large arsenal of effectors that manipulate host processes to create an environment conducive to pathogen colonization. However, the underlying mechanisms by which Phytophthora effectors manipulate host plant cells still remain largely unclear. In this study, we report that PcAvr3a12, a Phytophthera capsici RXLR effector and a member of the Avr3a effector family, suppresses plant immunity by targeting and inhibiting host plant peptidyl-prolyl cis-trans isomerase （PPlase）. Overexpression of PcAvr3a 12 in Arabidopsis thaliana enhanced plant susceptibility to P. capsici. FKBP15-2, an endoplasmic reticulum （ER）-Iocalized protein, was identified as a host target of PcAvr3a12 during early P. capsici infection. Analyses of A. thaliana T-DNA insertion mutant （fkbp15-2）, RNAi, and overexpression lines consistently showed that FKBP15-2 positively regulates plant immunity in response to Phytophthora infection. FKBP15-2 possesses PPlase activity essential for its contribution to immunity but is directly suppressed by PcAvr3a12. Interestingly, we found that FKBP15-2 is involved in ER stress sensing and is required for ER stress-mediated plant immunity. Taken together, these results suggest that P. capsici deploys an RXLR effector, PcAvr3a12, to facilitate infection by targeting and suppressing a novel ER-Iocalized PPlase, FKBP15-2, which is required for ER stress-mediated plant immunity.展开更多
Local adaptation has been a central theme of eco-evolutionary research for decades.It is generally assumed that plant pathogens are locally adapted due to their standing interactions with biotic and abiotic factors in...Local adaptation has been a central theme of eco-evolutionary research for decades.It is generally assumed that plant pathogens are locally adapted due to their standing interactions with biotic and abiotic factors in the ecosystem.Effectors,secreted small proteins encoded by pathogens,play critical roles in host–pathogen interactions,by activating host genotype-specific resistance,suppressing plant immunity,and playing other functions.In this study,we investigated the potential involvement of RXLR effector genes in ecological adaptation by examining the simple sequence repeat(SSR),virulence,and effector profiles in Phytophthora infestans isolates collected from two geographic regions differing in ecological environments.Genotypic analyses with SSR markers and virulence assays showed that the pathogen from the two regions shared genetic background but differed in virulence spectrums.High-throughput sequencing and expression analysis of 24 selected P.infestans isolates further showed variations in the RXLR effector repertoire,ranging from 536 to 548 for each isolate and the expression of effector genes was highly associated with the accumulation of homologous sRNA.Regional specific alleles were detected at 94 RXLR effector genes,and a specific accumulation of homologous 25–26 nt sRNAs was found at 67 RXLR effector genes.Two of the regional specific RXLR effector genes were confirmed to be virulence factors.Taken together,these results suggest that genomic and epigenetic variations in RXLR effector genes contribute significantly to the ecological adaptation of P.infestans populations and that regional specific effector genes will help to understand the adaptive landscape of pathogens and efficient use of host resistance genes.展开更多
RxLR effectors produced by Phytophthora pathogens have been proposed to bind to phosphatidylinositol 3-phosphate （Ptdlns（3）P） to mediate their translocation into host cells and/or to increase their stability in pl...RxLR effectors produced by Phytophthora pathogens have been proposed to bind to phosphatidylinositol 3-phosphate （Ptdlns（3）P） to mediate their translocation into host cells and/or to increase their stability in planta. Since the levels of Ptdlns（3）P in plants are low, we examined whether Phytophthora species may produce Ptdlns（3）P to pro- mote infection. We observed that Ptdlns（3）P-specific GFP biosensors could bind to P. parasitica and P. sojae hyphae dur- ing infection of Nicotiana benthamiana leaves transiently secreting the biosensors, suggesting that the hyphae exposed Ptdlns（3）P on their plasma membrane and/or secreted Ptdlns（3）R Silencing of the phosphatidylinositol 3-kinases （PI3K） genes, treatment with LY294002, or expression of Ptdlns（3）pobinding proteins by P. sojae reduced the virulence of the pathogen on soybean, indicating that pathogen-synthesized Ptdlns（3）P was required for full virulence. Secretion of Ptdlns（3）P-binding proteins or of a PI3P-5-kinase by N. benthamiana leaves significantly increased the level of resist- ance to infection by P. parasitica and P. capsici. Together, our results support the hypothesis that Phytophthora species produce external Ptdlns（3）P to aid in infection, such as to promote entry of RxLR effectors into host cells. Our results derived from P. sojae RxLR effector Avrlb confirm that both the N-terminus and the C-terminus of this effector can bind Ptdlns（3）P.展开更多
Plant pathogens rely on effector proteins to suppress host innate immune responses and facilitate colonization.Although the Phytophthora sojae RxLR effector Avh241 promotes Phytophthora infection,the molecular basis o...Plant pathogens rely on effector proteins to suppress host innate immune responses and facilitate colonization.Although the Phytophthora sojae RxLR effector Avh241 promotes Phytophthora infection,the molecular basis of Avh241 virulence remains poorly understood.Here we identified non-race specific disease resistance 1(NDR1)-like proteins,the critical components in plant effector-triggered immunity(ETI)responses,as host targets of Avh241.Avh241 interacts with NDR1 in the plasma membrane and suppresses NDR1-participated ETI responses.Silencing of GmNDR1s increases the susceptibility of soybean to P.sojae infection,and overexpression of GmNDR1s reduces infection,which supports its positive role in plant immunity against P.sojae.Furthermore,we demonstrate that GmNDR1 interacts with itself,and Avh241 probably disrupts the self-association of GmNDR1.These data highlight an effective counter-defense mechanism by which a Phytophthora effector suppresses plant immune responses,likely by disturbing the function of NDR1 during infection.展开更多
Phytophthora pathogens lead to numerous economically damaging plant diseases worldwide,including potato late blight caused by P.infestans and soybean root rot caused by P.sojae.Our previous work showed that Phytophtho...Phytophthora pathogens lead to numerous economically damaging plant diseases worldwide,including potato late blight caused by P.infestans and soybean root rot caused by P.sojae.Our previous work showed that Phytophthora pathogens may generate abundant phosphatidylinositol 3-phosphate(PI3P)to promote infection via direct association with RxLR effectors.Here,we designed a disease control strategy for metabolizing pathogen-derived PI3P by expressing secreted Arabidopsis thaliana phosphatidylinositol-4-phosphate 5-kinase 1(AtPIP5K1),which can phosphorylate PI3P to PI(3,4)P2.We fused AtPIP5K1 with the soybean PR1a signal peptide(SP-PIP5K1)to enable its secretion into the plant apoplast.Transgenic soybean and potato plants expressing SP-PIP5K1 showed substantially enhanced resistance to various P.sojae and P.infestans isolates,respectively.SP-PIP5K1 significantly reduced PI3P accumulation during P.sojae and soybean interaction.Knockout or inhibition of PI3 kinases(PI3Ks)in P.sojae compromised the resistance mediated by SP-PIP5K1,indicating that SP-PIP5K1 action requires a supply of pathogen-derived PI3P.Furthermore,we revealed that SP-PIP5K1 can interfere with the action of P.sojae mediated by the RxLR effector Avr1k.This novel disease control strategy has the potential to confer durable broad-spectrum Phytophthora resistance in plants through a clear mechanism in which catabolism of PI3P interferes with RxLR effector actions.展开更多
基金funded by the Liaoning Applied Basic Research Program(2022JH2/101300284)Liaoning Agricultural Science and Technology Innovation Fund(2022XTCX0503 and 2023QN2417).
文摘RXLR effectors are pathogenic factors secreted from oomycetes to manipulate the immunity of the host.Typical RXLR effectors contain an RXLR-dEER motif at the N-terminus,whereas atypical RXLRs show variations on this motif.The oomycete Phytophthora cactorum is known to infect over 200 plant species,resulting in significant agricultural economic losses.Although genome-wide identification and functional analyses of typical RXLRs from P.cactorum have been performed,little is known of atypical PcaRXLRs.Here,we identified RXLRs,both typical and atypical,in P.cactorum and compared them with those of other oomycete pathogens.Fewer RXLRs were identified in P.cactorum compared with other Phytophthora species,possibly due to fewer duplication events of RXLRs.In contrast,the percentage of atypical RXLRs was higher in P.cactorum than in other species,suggesting significant roles in P.cactorum pathogenesis.Analysis of RXLR gene expression showed that most were transcribed,suggesting their functionality.Transient expression of two atypical RXLRs in Nicotiana benthamiana showed that they induced necrosis dependent on host SGT1 and HSP90.Furthermore,two additional atypical RXLRs suppressed the defense response in N.benthamiana and promoted P.cactorum infection.These results demonstrate the vital role of atypical RXLRs in P.cactorum and provide valuable information on their evolutionary patterns and interactions with host plants.
基金supported by the Rural & Environment Science & Analytical Services (RESAS) Division of the Scottish Government through project JHI-B1-1the Biotechnology and Biological Sciences Research Council (BBSRC) through awards BB/ S015663/1+2 种基金BB/X009068/1Research Leaders 2025 fellowship funded by European Union’s Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement no. 754380the Research/Scientific Computing teams at The James Hutton Institute and NIAB for providing computational resources and technical support for the “UK’s Crop Diversity Bioinformatics HPC” (BBSRC grant BB/ S019669/1)。
文摘An accurate assessment of host and pathogen gene expression during infection is critical for understanding the molecular aspects of host-pathogen interactions.Often,pathogen-derived transcripts are difficult to ascertain at early infection stages owing to the unfavourable transcript representation compared to the host genes.In this study,we compare two sequencing techniques,RNAseq and enrichment sequencing(RenSeq and PenSeq)of cDNA,to investigate gene expression patterns in the doubled monoploid potato(DM)infected with the late blight pathogen Phytophthora infestans.Our results reveal distinct advantages of cDNA RenSeq and PenSeq over traditional RNAseq in terms of target gene representation and transcriptional quantification at early infection stages.Throughout the infection time course,cDNA enrichment sequencing enables transcriptomic analyses for more targeted host and pathogen genes.For highly expressed genes that were sampled in parallel by both cDNA enrichment and RNAseq,a high level of concordance in expression profiles is observed,indicative of at least semi-quantitative gene expression representation following enrichment.
基金supported by China Agriculture Research System(CARS-09),National Natural Science Foundation of China(31701747 and 31561143007)the Programme of Introducing Talents of Innovative Discipline to Universities(Project 111)from the State Administration of Foreign Experts Affairs(#B18042)China Postdoctoral Science Foundation(2015M580884,and 2017M623262).
文摘Oomycete pathogens secrete hundreds of effectors,including avirulence proteins that trigger host genotypespecific resistance response,to manipulate host immunity and facilitate infection.Sequence and expression variations of avirulence genes in pathogens are well known to be responsible for loss of host genotype-specific disease resistance.However,little is known on the underlying mechanisms associated with virulence variation in the diploid Phytophthora pathogens.We report in this study that the endogenous small RNAs(sRNAs)are involved in the variation of expression of avirulence gene Avr1b in P.sojae.The sRNAs were originated from the natural antisense transcripts of Avr1b.We further showed that the sense and antisense expression of Avr1b were programmed by the 10-base deletions in their promoter regions.Expanded analysis showed that up to 31%of the P.sojae RXLR effector genes were associated with sRNAs.Genome analysis further showed that the 9-bp and 10-bp insertion/deletion variants were significantly enriched in the regulatory regions of RXLR effector genes.These results indicate that the expression of RXLR effector genes are programmed by significantly enriched variations in their regulatory regions that lead to the variations in bidirectional transcription,which likely further affect production of endogenous sRNAs and silencing of homologous RXLR effector genes of Phytophthora pathogens.
基金This work was supported by the China Agriculture Research System （CARS-09）, the National Natural Science Foundation of China （31125022 and 31561143007）, and the Program of Introducing Talents of Innovative Discipline to Universities （Project 111） from the State Administration of Foreign Experts Affairs （#B18042）.
文摘Phytophthora pathogens secrete a large arsenal of effectors that manipulate host processes to create an environment conducive to pathogen colonization. However, the underlying mechanisms by which Phytophthora effectors manipulate host plant cells still remain largely unclear. In this study, we report that PcAvr3a12, a Phytophthera capsici RXLR effector and a member of the Avr3a effector family, suppresses plant immunity by targeting and inhibiting host plant peptidyl-prolyl cis-trans isomerase （PPlase）. Overexpression of PcAvr3a 12 in Arabidopsis thaliana enhanced plant susceptibility to P. capsici. FKBP15-2, an endoplasmic reticulum （ER）-Iocalized protein, was identified as a host target of PcAvr3a12 during early P. capsici infection. Analyses of A. thaliana T-DNA insertion mutant （fkbp15-2）, RNAi, and overexpression lines consistently showed that FKBP15-2 positively regulates plant immunity in response to Phytophthora infection. FKBP15-2 possesses PPlase activity essential for its contribution to immunity but is directly suppressed by PcAvr3a12. Interestingly, we found that FKBP15-2 is involved in ER stress sensing and is required for ER stress-mediated plant immunity. Taken together, these results suggest that P. capsici deploys an RXLR effector, PcAvr3a12, to facilitate infection by targeting and suppressing a novel ER-Iocalized PPlase, FKBP15-2, which is required for ER stress-mediated plant immunity.
基金supported by China Agriculture Research System(CARS-09)National Natural Science Foundation of China(31561143007)the State Administration for Foreign Experts Affairs,PR China(B18042).
文摘Local adaptation has been a central theme of eco-evolutionary research for decades.It is generally assumed that plant pathogens are locally adapted due to their standing interactions with biotic and abiotic factors in the ecosystem.Effectors,secreted small proteins encoded by pathogens,play critical roles in host–pathogen interactions,by activating host genotype-specific resistance,suppressing plant immunity,and playing other functions.In this study,we investigated the potential involvement of RXLR effector genes in ecological adaptation by examining the simple sequence repeat(SSR),virulence,and effector profiles in Phytophthora infestans isolates collected from two geographic regions differing in ecological environments.Genotypic analyses with SSR markers and virulence assays showed that the pathogen from the two regions shared genetic background but differed in virulence spectrums.High-throughput sequencing and expression analysis of 24 selected P.infestans isolates further showed variations in the RXLR effector repertoire,ranging from 536 to 548 for each isolate and the expression of effector genes was highly associated with the accumulation of homologous sRNA.Regional specific alleles were detected at 94 RXLR effector genes,and a specific accumulation of homologous 25–26 nt sRNAs was found at 67 RXLR effector genes.Two of the regional specific RXLR effector genes were confirmed to be virulence factors.Taken together,these results suggest that genomic and epigenetic variations in RXLR effector genes contribute significantly to the ecological adaptation of P.infestans populations and that regional specific effector genes will help to understand the adaptive landscape of pathogens and efficient use of host resistance genes.
基金This work was supported by grants from the National Natural Science Foundation of China （No. 30971889）, National Science and Technology Major Projects （No. 2009ZX08005-003B）, and the Natural Science Foundation of Jiangsu Province （No. BK2012027）.We appreciate Prof. Brett Tyler （Oregon State） for manuscript preparation, and Yuanming Zhang （Nanjing Agricultural University） for suggestions in data analysis. No conflict of interest declared.
文摘RxLR effectors produced by Phytophthora pathogens have been proposed to bind to phosphatidylinositol 3-phosphate （Ptdlns（3）P） to mediate their translocation into host cells and/or to increase their stability in planta. Since the levels of Ptdlns（3）P in plants are low, we examined whether Phytophthora species may produce Ptdlns（3）P to pro- mote infection. We observed that Ptdlns（3）P-specific GFP biosensors could bind to P. parasitica and P. sojae hyphae dur- ing infection of Nicotiana benthamiana leaves transiently secreting the biosensors, suggesting that the hyphae exposed Ptdlns（3）P on their plasma membrane and/or secreted Ptdlns（3）R Silencing of the phosphatidylinositol 3-kinases （PI3K） genes, treatment with LY294002, or expression of Ptdlns（3）pobinding proteins by P. sojae reduced the virulence of the pathogen on soybean, indicating that pathogen-synthesized Ptdlns（3）P was required for full virulence. Secretion of Ptdlns（3）P-binding proteins or of a PI3P-5-kinase by N. benthamiana leaves significantly increased the level of resist- ance to infection by P. parasitica and P. capsici. Together, our results support the hypothesis that Phytophthora species produce external Ptdlns（3）P to aid in infection, such as to promote entry of RxLR effectors into host cells. Our results derived from P. sojae RxLR effector Avrlb confirm that both the N-terminus and the C-terminus of this effector can bind Ptdlns（3）P.
基金supported by the Natural ScienceFoundation of Jiangsu Province(BK20190520)the NationalNatural Science Foundation of China(31721004,32001882)the National Postdoctoral Program for Innovative Talents(BX20180142)。
文摘Plant pathogens rely on effector proteins to suppress host innate immune responses and facilitate colonization.Although the Phytophthora sojae RxLR effector Avh241 promotes Phytophthora infection,the molecular basis of Avh241 virulence remains poorly understood.Here we identified non-race specific disease resistance 1(NDR1)-like proteins,the critical components in plant effector-triggered immunity(ETI)responses,as host targets of Avh241.Avh241 interacts with NDR1 in the plasma membrane and suppresses NDR1-participated ETI responses.Silencing of GmNDR1s increases the susceptibility of soybean to P.sojae infection,and overexpression of GmNDR1s reduces infection,which supports its positive role in plant immunity against P.sojae.Furthermore,we demonstrate that GmNDR1 interacts with itself,and Avh241 probably disrupts the self-association of GmNDR1.These data highlight an effective counter-defense mechanism by which a Phytophthora effector suppresses plant immune responses,likely by disturbing the function of NDR1 during infection.
基金supported by the National Natural Science Foundation of China,China(32072507,32272495,and 31721004)the Natural Science Foundation of Jiangsu Province,China(BK20220147).
文摘Phytophthora pathogens lead to numerous economically damaging plant diseases worldwide,including potato late blight caused by P.infestans and soybean root rot caused by P.sojae.Our previous work showed that Phytophthora pathogens may generate abundant phosphatidylinositol 3-phosphate(PI3P)to promote infection via direct association with RxLR effectors.Here,we designed a disease control strategy for metabolizing pathogen-derived PI3P by expressing secreted Arabidopsis thaliana phosphatidylinositol-4-phosphate 5-kinase 1(AtPIP5K1),which can phosphorylate PI3P to PI(3,4)P2.We fused AtPIP5K1 with the soybean PR1a signal peptide(SP-PIP5K1)to enable its secretion into the plant apoplast.Transgenic soybean and potato plants expressing SP-PIP5K1 showed substantially enhanced resistance to various P.sojae and P.infestans isolates,respectively.SP-PIP5K1 significantly reduced PI3P accumulation during P.sojae and soybean interaction.Knockout or inhibition of PI3 kinases(PI3Ks)in P.sojae compromised the resistance mediated by SP-PIP5K1,indicating that SP-PIP5K1 action requires a supply of pathogen-derived PI3P.Furthermore,we revealed that SP-PIP5K1 can interfere with the action of P.sojae mediated by the RxLR effector Avr1k.This novel disease control strategy has the potential to confer durable broad-spectrum Phytophthora resistance in plants through a clear mechanism in which catabolism of PI3P interferes with RxLR effector actions.
