Pathogens generate and secrete effector proteins to the host plant cells during pathogenesis to promote virulence and colonization.If the plant carries resistance(R)proteins that recognize pathogen effectors,effector-...Pathogens generate and secrete effector proteins to the host plant cells during pathogenesis to promote virulence and colonization.If the plant carries resistance(R)proteins that recognize pathogen effectors,effector-triggered immunity(ETI)is activated,resulting in a robust immune response and hypersensitive response(HR).The bipartite effector AvrRps4 from Pseudomonas syringae pv.pisi has been well studied in terms of avirulence function.In planta,AvrRps4 is processed into two parts.The Cterminal fragment of AvrRps4(AvrRps4^(C))induces HR in turnip and is recognized by the paired resistance proteins AtRRS1/AtRPS4 in Arabidopsis.Here,we show that AvrRps4^(C)targets a group of Arabidopsis WRKY,including WRKY46,WRKY53,WRKY54,and WRKY70,to induce its virulence function.Indeed,AvrRps4^(C)suppresses the general binding and transcriptional activities of immune-positive regulator WRKY54 and WRKY54-mediated resistance.AvrRps4^(C)interferes with WRKY54's binding activity to target gene SARD1 in vitro,suggesting WRKY54 is sequestered from the SARD1 promoter by AvrRps4^(C).Through the interaction of Avr Rps4^(C)with four WRKYs,AvrRps4 enhances the formation of homo-/heterotypic complexes of four WRKYs and sequesters them in the cytoplasm,thus inhibiting their function in plant immunity.Together,our results provide a detailed virulence mechanism of AvrRps4 through its C-terminus.展开更多
Callose,aβ-1,3-glucan plant cell wall polymer,regulates symplasmic channel size at plasmodesmata(PD)and plays a crucial role in a variety of plant processes.However,elucidating the molecular mechanism of PD callose h...Callose,aβ-1,3-glucan plant cell wall polymer,regulates symplasmic channel size at plasmodesmata(PD)and plays a crucial role in a variety of plant processes.However,elucidating the molecular mechanism of PD callose homeostasis is limited.We screened and identified an Arabidopsis mutant plant with excessive callose deposition at PD and found that the mutated gene wasα1-COP,a member of the coat protein I(COPI)coatomer complex.We report that loss of function ofα1-COP elevates the callose accumulation at PD by affecting subcellular protein localization of callose degradation enzyme Pd BG2.This process is linked to the functions of ERH1,an inositol phosphoryl ceramide synthase,and glucosylceramide synthase through physical interactions with theα1-COP protein.Additionally,the loss of function ofα1-COP alters the subcellular localization of ERH1 and GCS proteins,resulting in a reduction of Glc Cers and Glc HCers molecules,which are key sphingolipid(SL)species for lipid raft formation.Our findings suggest thatα1-COP protein,together with SL modifiers controlling lipid raft compositions,regulates the subcellular localization of GPI-anchored PDBG2 proteins,and hence the callose turnover at PD and symplasmic movement of biomolecules.Our findings provide the first key clue to link the COPI-mediated intracellular trafficking pathway to the callose-mediated intercellular signaling pathway through PD.展开更多
基金supported by Basic Science Research Program and LAMP Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2021R1I1A3054417,2022R1I1A1A01063394,RS-2023-00301974)the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.2021M3A9I5023695,2022R1A5A1031361)grants from the New Breeding Technologies Development Program(RS-2024-00322125),Rural Development Administration,Republic of Korea。
文摘Pathogens generate and secrete effector proteins to the host plant cells during pathogenesis to promote virulence and colonization.If the plant carries resistance(R)proteins that recognize pathogen effectors,effector-triggered immunity(ETI)is activated,resulting in a robust immune response and hypersensitive response(HR).The bipartite effector AvrRps4 from Pseudomonas syringae pv.pisi has been well studied in terms of avirulence function.In planta,AvrRps4 is processed into two parts.The Cterminal fragment of AvrRps4(AvrRps4^(C))induces HR in turnip and is recognized by the paired resistance proteins AtRRS1/AtRPS4 in Arabidopsis.Here,we show that AvrRps4^(C)targets a group of Arabidopsis WRKY,including WRKY46,WRKY53,WRKY54,and WRKY70,to induce its virulence function.Indeed,AvrRps4^(C)suppresses the general binding and transcriptional activities of immune-positive regulator WRKY54 and WRKY54-mediated resistance.AvrRps4^(C)interferes with WRKY54's binding activity to target gene SARD1 in vitro,suggesting WRKY54 is sequestered from the SARD1 promoter by AvrRps4^(C).Through the interaction of Avr Rps4^(C)with four WRKYs,AvrRps4 enhances the formation of homo-/heterotypic complexes of four WRKYs and sequesters them in the cytoplasm,thus inhibiting their function in plant immunity.Together,our results provide a detailed virulence mechanism of AvrRps4 through its C-terminus.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea Government(MSIT)(Grant Nos.NRF 2018R1A2A1A05077295,2020M3A9I4038352,2022R1A2C3010331,2020R1A6A1A03044344,and 2022R1A 5A1031361)a grant from the New Breeding Technologies Development Program(Grant No.PJ01653202),Rural Development Administration(RDA),Republic of Korea。
文摘Callose,aβ-1,3-glucan plant cell wall polymer,regulates symplasmic channel size at plasmodesmata(PD)and plays a crucial role in a variety of plant processes.However,elucidating the molecular mechanism of PD callose homeostasis is limited.We screened and identified an Arabidopsis mutant plant with excessive callose deposition at PD and found that the mutated gene wasα1-COP,a member of the coat protein I(COPI)coatomer complex.We report that loss of function ofα1-COP elevates the callose accumulation at PD by affecting subcellular protein localization of callose degradation enzyme Pd BG2.This process is linked to the functions of ERH1,an inositol phosphoryl ceramide synthase,and glucosylceramide synthase through physical interactions with theα1-COP protein.Additionally,the loss of function ofα1-COP alters the subcellular localization of ERH1 and GCS proteins,resulting in a reduction of Glc Cers and Glc HCers molecules,which are key sphingolipid(SL)species for lipid raft formation.Our findings suggest thatα1-COP protein,together with SL modifiers controlling lipid raft compositions,regulates the subcellular localization of GPI-anchored PDBG2 proteins,and hence the callose turnover at PD and symplasmic movement of biomolecules.Our findings provide the first key clue to link the COPI-mediated intracellular trafficking pathway to the callose-mediated intercellular signaling pathway through PD.
