Late blight pathogen Phytophthora infestans secretes numerous effectors to suppress plant immunity.However,little is known about their underlying biochemical mechanisms.Here we report that,in the host Nicotiana bentha...Late blight pathogen Phytophthora infestans secretes numerous effectors to suppress plant immunity.However,little is known about their underlying biochemical mechanisms.Here we report that,in the host Nicotiana benthamiana,P.infestans core RXLR effector Pi17063 suppresses plant immunity by targeting the host plasma membrane and NbRab-G3 proteins,small GTPases of the Ras-related brain(Rab)family.Pi17063 functions as their specific GTPase-activating protein(GAP),driving them to the cytoplasm-localized guanosine diphosphate(GDP)-bound inactive state.Mutant analysis of the conserved Pi17063 arginine residues showed the essential role of its GAP activity for virulence contribution.All four NbRab-G3 subfamily members are positive immune regulators,and NbRab-G3c mutants lost the ability to switch between active and inactive states and showed compromised immune function.Consistent with this,both silencing and overexpression of an endogenous GAP,NbGYP,inhibited NbRab-G3c-mediated plant immunity.Our results revealed positive immune roles of host NbRab-G3 GTPases,the importance of their state balance,and the biochemical mechanism by which their functions are suppressed by a P.infestans effector,providing insights into understanding eukaryotic effector-mediated plant susceptibility.展开更多
In plants, recognition of small secreted peptides, such as damage/danger-associated molecular patterns(DAMPs), regulates diverse processes,includingstressandimmune responses. Here, we identified an SGPS(Ser-Gly-Pro-Se...In plants, recognition of small secreted peptides, such as damage/danger-associated molecular patterns(DAMPs), regulates diverse processes,includingstressandimmune responses. Here, we identified an SGPS(Ser-Gly-Pro-Ser) motif-containing peptide, Nicotiana tabacum NtPROPPI, and its two homologs in Nicotiana benthamiana, NbPROPPI1 and NbPROPPI2. Phytophthora parasitica infection and salicylic acid(SA) treatment induced NbPROPPI1/2 expression. Moreover, SignalP predicted that the 89-amino acid NtPROPPI includes a 24-amino acid N-terminal signal peptide and NbPROPPI1/2-GFP fusion proteins were mainly localized to the periplasm. Transient expression of NbPROPPI1/2 inhibited P.parasiticacolonization,andNbPROPPI1/2 knockdown rendered plants more susceptible to P. parasitica. An eight-amino-acid segment in the NbPROPPI1 C-terminus was essential for its immune function and a synthetic 20-residue peptide, NbPPI1, derived from the C-terminus of NbPROPPI1 provoked significant immune responses in N. benthamiana. These responses led to enhanced accumulation of reactive oxygen species, activation of mitogen-activated protein kinases, and up-regulation of the defense genes Flg22-induced receptor-like kinase(FRK) and WRKY DNA-binding protein 33(WRKY33). The NbPPI1-induced defense responses require Brassinosteroid insensitive1-associated receptor kinase 1(BAK1). These results suggest that NbPPI1 functions as a DAMP in N. benthamiana;this novel DAMP provides a potentially useful target for improving plant resistance to Pytophthora pathogens.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
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
基金supported by the National Key R&D Program of China(2023YFD2302100)the Agricultural Breeding Program(2019NYYZ01)from the Ningxia Department of Science and Technology,the China Agriculture Research System(CARS-09)the Program of Introducing Talents of Innovative Discipline to Universities(Project 111)from the State Administration for Foreign Experts Affairs,China(B18042).
文摘Late blight pathogen Phytophthora infestans secretes numerous effectors to suppress plant immunity.However,little is known about their underlying biochemical mechanisms.Here we report that,in the host Nicotiana benthamiana,P.infestans core RXLR effector Pi17063 suppresses plant immunity by targeting the host plasma membrane and NbRab-G3 proteins,small GTPases of the Ras-related brain(Rab)family.Pi17063 functions as their specific GTPase-activating protein(GAP),driving them to the cytoplasm-localized guanosine diphosphate(GDP)-bound inactive state.Mutant analysis of the conserved Pi17063 arginine residues showed the essential role of its GAP activity for virulence contribution.All four NbRab-G3 subfamily members are positive immune regulators,and NbRab-G3c mutants lost the ability to switch between active and inactive states and showed compromised immune function.Consistent with this,both silencing and overexpression of an endogenous GAP,NbGYP,inhibited NbRab-G3c-mediated plant immunity.Our results revealed positive immune roles of host NbRab-G3 GTPases,the importance of their state balance,and the biochemical mechanism by which their functions are suppressed by a P.infestans effector,providing insights into understanding eukaryotic effector-mediated plant susceptibility.
基金This work was supported by the National Natural Science Foundation of China(31125022 and 31930094)the China Agriculture Research System(CARS-09)the Program of Introducing Talents of Innovative Discipline to Universities(Project 111)from the State Administration of Foreign Experts Affairs(#B18042)。
文摘In plants, recognition of small secreted peptides, such as damage/danger-associated molecular patterns(DAMPs), regulates diverse processes,includingstressandimmune responses. Here, we identified an SGPS(Ser-Gly-Pro-Ser) motif-containing peptide, Nicotiana tabacum NtPROPPI, and its two homologs in Nicotiana benthamiana, NbPROPPI1 and NbPROPPI2. Phytophthora parasitica infection and salicylic acid(SA) treatment induced NbPROPPI1/2 expression. Moreover, SignalP predicted that the 89-amino acid NtPROPPI includes a 24-amino acid N-terminal signal peptide and NbPROPPI1/2-GFP fusion proteins were mainly localized to the periplasm. Transient expression of NbPROPPI1/2 inhibited P.parasiticacolonization,andNbPROPPI1/2 knockdown rendered plants more susceptible to P. parasitica. An eight-amino-acid segment in the NbPROPPI1 C-terminus was essential for its immune function and a synthetic 20-residue peptide, NbPPI1, derived from the C-terminus of NbPROPPI1 provoked significant immune responses in N. benthamiana. These responses led to enhanced accumulation of reactive oxygen species, activation of mitogen-activated protein kinases, and up-regulation of the defense genes Flg22-induced receptor-like kinase(FRK) and WRKY DNA-binding protein 33(WRKY33). The NbPPI1-induced defense responses require Brassinosteroid insensitive1-associated receptor kinase 1(BAK1). These results suggest that NbPPI1 functions as a DAMP in N. benthamiana;this novel DAMP provides a potentially useful target for improving plant resistance to Pytophthora pathogens.
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.
