Arabidopsis thaliana H+-ATPases(AHAs)are key plasma membrane enzymes that drive nutrient uptake and ion transport across the membrane.RAPID ALKALINIZATION FACTOR 1(RALF1)induces phosphorylation of AHA2 and inhibits it...Arabidopsis thaliana H+-ATPases(AHAs)are key plasma membrane enzymes that drive nutrient uptake and ion transport across the membrane.RAPID ALKALINIZATION FACTOR 1(RALF1)induces phosphorylation of AHA2 and inhibits its activity.While the phosphorylation of AHA2 induced by RALF1 has been well described,the ultimate fate of AHA2 following phosphorylation remains unclear.Here,we analyzed the diffusion dynamics of GFP-AHA2 in Arabidopsis thaliana using single-particle tracking combined with variable-angle total internal reflection fluorescence microscopy.Treatment with RALF1,which causes extracellular alkalinization,markedly inhibited AHA2 activity and reduced the velocity of GFP-AHA2.RALF1 promotes the internalization and degradation of GFP-AHA2 through both clathrin-mediated and clathrin-independent endocytosis.In addition,single-particle tracking showed that phosphorylation influences the spatiotemporal dynamics of AHA2.These findings reveal a previously unreported role for RALF1 in promoting AHA2 internalization and degradation via synergistic endocytosis,offering new insights into plant signaling,environmental responses,and protein endocytosis.展开更多
In higher plants,stomatal movements represent a critical physiological process that matains cellular water homestasis while enabling photosynthetic gas exchange.Open stomata 1(OST1),a key protein kinase in the abscisi...In higher plants,stomatal movements represent a critical physiological process that matains cellular water homestasis while enabling photosynthetic gas exchange.Open stomata 1(OST1),a key protein kinase in the abscisic acid(ABA)signaling cascade,has been established as a central regulator of stomatal dynamics.This study reveals that two highly conserved mitogen-activated protein kinase 1(MAP4K1)and MAP4K2 are positive regulators in ABA promoted stomatal closure,and ABA-activated OST1 potentiates MAP4K1/2 through phosphorylation at conserved serine and threonine residues(S166,T170,and S479/S488).The activated MAP4K1,in turn,phosphorylates two critical downstream targets:plasma membrane H+-ATPase 2(AHA2)at residues T858,T881,and Y946,and slow anion channel-associated 1(SLAC1)at T114 and S116.Functional analysis demonstrates that the phosphomimetic(3D:S166D/T170D/S479D)MAP4K1,but not non-phosphorylatable(3A:S166A/T170A/S479A)MAP4K1,could fully restore drought tolerance and reduced water loss in detached leaves of map4k1map4k2 double mutant.Our findings delineate a previously unrecognized signaling module comprising OST1-MAP4K1/2-AHA2/SLAC1,which crucially modulates ABA-mediated stomatal regulation.This work advances our mechanistic understanding of phosphorylation cascades governing plant water relations and stress responses.展开更多
Arabidopsis plants adapt to warm temperatures by promoting hypocotyl growth primarily through the basic helix-loop-helix transcription factor PIF4 and its downstream genes involved in auxin responses,which enhance cel...Arabidopsis plants adapt to warm temperatures by promoting hypocotyl growth primarily through the basic helix-loop-helix transcription factor PIF4 and its downstream genes involved in auxin responses,which enhance cell division.In the current study,we discovered that cell wall-related calcium-binding protein 2(CCaP2)and its paralogs CCaP1 and CCaP3 function as positive regulators of thermo-responsive hypocotyl growth by promoting cell elongation in Arabidopsis.Interestingly,mutations in CCaP1/CCaP2/CCaP3 do not affect the expression of PIF4-regulated classic downstream genes.However,they do noticeably reduce the expression of xyloglucan endotransglucosylase/hydrolase genes,which are involved in cell wall modification.We also found that CCaP1/CCaP2/CCaP3 are predominantly localized to the plasma membrane,where they interact with the plasma membrane H^(+)-ATPases AHA1/AHA2.Furthermore,we observed that vanadate-sensitive H^(+)-ATPase activity and cell wall pectin and hemicellulose contents are significantly increased in wild-type plants grown at warm temperatures compared with those grown at normal growth temperatures,but these changes are not evident in the ccap1-1 ccap2-1 ccap3-1 triple mutant.Overall,our findings demonstrate that CCaP1/CCaP2/CCaP3 play an important role in controlling thermo-responsive hypocotyl growth and provide new insights into the alternative pathway regulating hypocotyl growth at warm temperatures through cell wall modification mediated by CCaP1/CCaP2/CCaP3.展开更多
基金supported by the National Key R&D Program of China during the 14th Five-Year Plan period(2023YFD2200101)the National Natural Science Foundation of China(32470434,91954202,and 32370740)+3 种基金the Fundamental Research Funds for the Central Universities(QNTD202502)the Third Xinjiang Scientific Expedition Program(grant no.2022xjkk1200)the Beijing Nova Program(20230484251)the Introducing Talents of Discipline to University Program(111 Project,B13007).
文摘Arabidopsis thaliana H+-ATPases(AHAs)are key plasma membrane enzymes that drive nutrient uptake and ion transport across the membrane.RAPID ALKALINIZATION FACTOR 1(RALF1)induces phosphorylation of AHA2 and inhibits its activity.While the phosphorylation of AHA2 induced by RALF1 has been well described,the ultimate fate of AHA2 following phosphorylation remains unclear.Here,we analyzed the diffusion dynamics of GFP-AHA2 in Arabidopsis thaliana using single-particle tracking combined with variable-angle total internal reflection fluorescence microscopy.Treatment with RALF1,which causes extracellular alkalinization,markedly inhibited AHA2 activity and reduced the velocity of GFP-AHA2.RALF1 promotes the internalization and degradation of GFP-AHA2 through both clathrin-mediated and clathrin-independent endocytosis.In addition,single-particle tracking showed that phosphorylation influences the spatiotemporal dynamics of AHA2.These findings reveal a previously unreported role for RALF1 in promoting AHA2 internalization and degradation via synergistic endocytosis,offering new insights into plant signaling,environmental responses,and protein endocytosis.
基金supported by grants from the National Science Foundation of China(31921001)the Beijing Outstanding University Discipline。
文摘In higher plants,stomatal movements represent a critical physiological process that matains cellular water homestasis while enabling photosynthetic gas exchange.Open stomata 1(OST1),a key protein kinase in the abscisic acid(ABA)signaling cascade,has been established as a central regulator of stomatal dynamics.This study reveals that two highly conserved mitogen-activated protein kinase 1(MAP4K1)and MAP4K2 are positive regulators in ABA promoted stomatal closure,and ABA-activated OST1 potentiates MAP4K1/2 through phosphorylation at conserved serine and threonine residues(S166,T170,and S479/S488).The activated MAP4K1,in turn,phosphorylates two critical downstream targets:plasma membrane H+-ATPase 2(AHA2)at residues T858,T881,and Y946,and slow anion channel-associated 1(SLAC1)at T114 and S116.Functional analysis demonstrates that the phosphomimetic(3D:S166D/T170D/S479D)MAP4K1,but not non-phosphorylatable(3A:S166A/T170A/S479A)MAP4K1,could fully restore drought tolerance and reduced water loss in detached leaves of map4k1map4k2 double mutant.Our findings delineate a previously unrecognized signaling module comprising OST1-MAP4K1/2-AHA2/SLAC1,which crucially modulates ABA-mediated stomatal regulation.This work advances our mechanistic understanding of phosphorylation cascades governing plant water relations and stress responses.
基金supported by a grant from the National Natural Science Foundation of China(31872653).
文摘Arabidopsis plants adapt to warm temperatures by promoting hypocotyl growth primarily through the basic helix-loop-helix transcription factor PIF4 and its downstream genes involved in auxin responses,which enhance cell division.In the current study,we discovered that cell wall-related calcium-binding protein 2(CCaP2)and its paralogs CCaP1 and CCaP3 function as positive regulators of thermo-responsive hypocotyl growth by promoting cell elongation in Arabidopsis.Interestingly,mutations in CCaP1/CCaP2/CCaP3 do not affect the expression of PIF4-regulated classic downstream genes.However,they do noticeably reduce the expression of xyloglucan endotransglucosylase/hydrolase genes,which are involved in cell wall modification.We also found that CCaP1/CCaP2/CCaP3 are predominantly localized to the plasma membrane,where they interact with the plasma membrane H^(+)-ATPases AHA1/AHA2.Furthermore,we observed that vanadate-sensitive H^(+)-ATPase activity and cell wall pectin and hemicellulose contents are significantly increased in wild-type plants grown at warm temperatures compared with those grown at normal growth temperatures,but these changes are not evident in the ccap1-1 ccap2-1 ccap3-1 triple mutant.Overall,our findings demonstrate that CCaP1/CCaP2/CCaP3 play an important role in controlling thermo-responsive hypocotyl growth and provide new insights into the alternative pathway regulating hypocotyl growth at warm temperatures through cell wall modification mediated by CCaP1/CCaP2/CCaP3.
