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
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.
