Global warming profoundly affects plant communities,but the mechanisms and the identity of sensors con-trolling plant thermosensing remain poorly understood.In this study,we identify the heat-shock factor A1b(HsFA1b)t...Global warming profoundly affects plant communities,but the mechanisms and the identity of sensors con-trolling plant thermosensing remain poorly understood.In this study,we identify the heat-shock factor A1b(HsFA1b)transcription factoras a heat sensor that regulates stomatal responses by inhibiting open sto-mata 1(OsT1)kinase activity in Arabidopsis.OsT1 induces stomatal closure under heat stress indepen-dently of abscisic acid,and its activity is inhibited in the cytosol by the C-terminus of HSFA1b through intrinsic adenylate cyclase(AC)activity.Arabidopsis HSFA1b could complement an AC-deficient bacte-rium,andthe cyclic AMP produced by HSFA1b could bind to and inhibit OST1kinase activity.This inhibition is relieved under heat stress by HSFA1b translocation into the nucleus,coupling OST1 inhibition with the activation of heat-shock protein genes involved in the perception and signaling of high temperature.Collectively,our study demonstrates that HsFA1b functions as a heat sensor,inhibiting heat stress-induced andOsT1-mediated stomatalclosurethrough itsAC activity.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
Plants adapt to their ever-changing environment via positive and negative signals induced by environmental stimuli.Drought stress,for instance,induces accumulation of the plant hormone abscisic acid(ABA),triggering AB...Plants adapt to their ever-changing environment via positive and negative signals induced by environmental stimuli.Drought stress,for instance,induces accumulation of the plant hormone abscisic acid(ABA),triggering ABA signal transduction.However,the molecular mechanisms for switching between plant growth promotion and stress response remain poorly understood.Here we report that RAF(rapidly accelerated fibrosarcoma)-LIKE MITOGEN-ACTIVATED PROTEIN KINASE KINASE KINASE 22(RAF22)in Arabidopsis tha/iana physically interacts with ABA INSENSITIVE 1(ABl1)and phosphorylates ABl1 at Ser416 residue to enhance its phosphatase activity.Interestingly,ABl1 can also enhance the activity of RAF22 through dephosphorylation,reciprocally inhibiting ABA signaling and promoting the maintenance of plant growth under normal conditions.Under drought stress,however,the ASA-activated OPEN STOMATA1(OST1)phosphorylates the Ser81 residue of RAF22 and inhibits its kinase activity,restraining its enhancement of ABl1 activity.Taken together,our study reveals that RAF22,ABl1,and OST1 form a dynamic regulatory network that plays crucial roles in optimizing plant growth and environmental adaptation under drought stress.展开更多
Dehydrating stresses trigger the accumulation of abscisic acid(ABA),a key plant stress-signaling hormone that activates Snf1-Related Kinases(SnRK2s)to mount adaptive responses.However,the regulatory circuits that term...Dehydrating stresses trigger the accumulation of abscisic acid(ABA),a key plant stress-signaling hormone that activates Snf1-Related Kinases(SnRK2s)to mount adaptive responses.However,the regulatory circuits that terminate the SnRK2s signal relay after acclimation or post-stress conditions remain to be defined.Here,we show that the desensitization of the ABA signal is achieved by the regulation of OST1(SnRK2.6)protein stability via the E3-ubiquitin ligase HOS15.Upon ABA signal,HOS15-induced degradation of OST1 is inhibited and stabilized OST1 promotes the stress response.When the ABA signal terminates,protein phosphatases ABI1/2 promote rapid degradation of OST1 via HOS15.Notably,we found that even in the presence of ABA,OST1 levels are also depleted within hours of ABA signal onset.The unexpected dynamics of OST1 abundance are then resolved by systematic mathematical modeling,demonstrating a desensitizing feedback loop by which OST1-induced upregulation of ABI1/2 leads to the degradation of OST1.This model illustrates the complex rheostat dynamics underlying the ABA-induced stress response and desensitization.展开更多
Protein phosphorylation and dephosphorylation have been reported to play important roles in plant cold responses.In addition,phospho-regulatory feedback is a conserved mechanism for biological processes and stress res...Protein phosphorylation and dephosphorylation have been reported to play important roles in plant cold responses.In addition,phospho-regulatory feedback is a conserved mechanism for biological processes and stress responses in animals and plants.However,it is less well known that a regulatory feedback loop is formed by the protein kinase and the protein phosphatase in plant responses to cold stress.Here,we report that OPEN STOMATA 1(OST1)and PROTEIN PHOSPHATASE 2C G GROUP 1(PP2CG1)reciprocally regulate the activity during the cold stress response.The interaction of PP2CG1 and OST1 is inhibited by cold stress,which results in the release of OST1 at the cytoplasm and nucleus from suppression by PP2CG1.Interestingly,cold-activated OST1 phosphorylates PP2CG1 to suppress its phosphatase activity,thereby amplifying cold signaling in plants.Mutations of PP2CG1 and its homolog PP2CG2 enhance freezing tolerance,whereas overexpression of PP2CG1 decreases freezing tolerance.Moreover,PP2CG1 negatively regulates protein levels of C-REPEAT BINDING FACTORs(CBFs)under cold stress.Our results uncover a phosphor/dephosphor-regulatory feedback loop mediated by PP2CG1 phosphatase and OST1 protein kinase in plant cold responses.展开更多
The sucrose non-fermenting 1(SNF1)-related protein kinase 2(SnRK2)family members have been discovered to regulate abiotic stress response via the abscisic acid(ABA)-independent and dependent signaling pathways.SnRK2.6...The sucrose non-fermenting 1(SNF1)-related protein kinase 2(SnRK2)family members have been discovered to regulate abiotic stress response via the abscisic acid(ABA)-independent and dependent signaling pathways.SnRK2.6,also known as Open Stomata 1(OST1),is a serine/threonine protein kinase that plays critical roles in linking ABA receptor complexes and downstream components such as transcription factors and anion channels to regulate stress response.Asides from its well-known regulatory roles in stomatal movement and cold stress response,OST1 has also been demonstrated recently to modulate major developmental roles of flowering and growth in plants.In this review,we will discuss about the various roles of OST1 as well as the‘doors’that OST1 can‘open’to help plants perform stress adaptation.Therefore,we will address how OST1 can regulate stomata apertures,cold stress tolerance as well as other aspects of its emerging roles such as balancing flowering and root growth in response to drought.展开更多
Stomatal movements are critical in regulating gas exchange for photosynthesis and water balance between plant tissues and the atmosphere. The plant hormone abscisic acid （ABA） plays key roles in regulating stomatal ...Stomatal movements are critical in regulating gas exchange for photosynthesis and water balance between plant tissues and the atmosphere. The plant hormone abscisic acid （ABA） plays key roles in regulating stomatal closure under various abiotic stresses. In this study, we revealed a novel role of BAKI in guard cell ABA signaling. We found that the brassinosteroid （BR） signaling mutant bakl lost more water than wild- type plants and showed ABA insensitivity in stomatal closure. ABA-induced OST1 expression and reactive oxygen species （ROS） production were also impaired in bakl. Unlike direct treatment with H202, overex-pression of OST1 did not completely rescue the insensitivity of bakl to ABA. We demonstrated that BAK1 forms a complex with OST1 near the plasma membrane and that the BAKI/OST1 complex is increased in response to ABA in planta. Brassinolide, the most active BR, exerted a negative effect on ABA-induced formation of the BAK1/OST1 complex and OST1 expression. Moreover, we found that BAK1 and ABI1 oppositely regulate OST1 phosphorylation in vitro, and that ABI1 interacts with BAK1 and inhibits the interaction of BAK1 and OST1. Taken together, our results suggest that BAK1 regulates ABA-induced stomatal closure in guard cells.展开更多
基金supported by the National Natural Science Foundation of China(U21A20206 and 32322010)the Education Department of Hainan Province(Hnjg2025ZD-90)the Natural Science Foundation of Henan Province(252300421075).
文摘Global warming profoundly affects plant communities,but the mechanisms and the identity of sensors con-trolling plant thermosensing remain poorly understood.In this study,we identify the heat-shock factor A1b(HsFA1b)transcription factoras a heat sensor that regulates stomatal responses by inhibiting open sto-mata 1(OsT1)kinase activity in Arabidopsis.OsT1 induces stomatal closure under heat stress indepen-dently of abscisic acid,and its activity is inhibited in the cytosol by the C-terminus of HSFA1b through intrinsic adenylate cyclase(AC)activity.Arabidopsis HSFA1b could complement an AC-deficient bacte-rium,andthe cyclic AMP produced by HSFA1b could bind to and inhibit OST1kinase activity.This inhibition is relieved under heat stress by HSFA1b translocation into the nucleus,coupling OST1 inhibition with the activation of heat-shock protein genes involved in the perception and signaling of high temperature.Collectively,our study demonstrates that HsFA1b functions as a heat sensor,inhibiting heat stress-induced andOsT1-mediated stomatalclosurethrough itsAC activity.
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 grants from the National Science Foundation of China(31730007 and 31921001)。
文摘Plants adapt to their ever-changing environment via positive and negative signals induced by environmental stimuli.Drought stress,for instance,induces accumulation of the plant hormone abscisic acid(ABA),triggering ABA signal transduction.However,the molecular mechanisms for switching between plant growth promotion and stress response remain poorly understood.Here we report that RAF(rapidly accelerated fibrosarcoma)-LIKE MITOGEN-ACTIVATED PROTEIN KINASE KINASE KINASE 22(RAF22)in Arabidopsis tha/iana physically interacts with ABA INSENSITIVE 1(ABl1)and phosphorylates ABl1 at Ser416 residue to enhance its phosphatase activity.Interestingly,ABl1 can also enhance the activity of RAF22 through dephosphorylation,reciprocally inhibiting ABA signaling and promoting the maintenance of plant growth under normal conditions.Under drought stress,however,the ASA-activated OPEN STOMATA1(OST1)phosphorylates the Ser81 residue of RAF22 and inhibits its kinase activity,restraining its enhancement of ABl1 activity.Taken together,our study reveals that RAF22,ABl1,and OST1 form a dynamic regulatory network that plays crucial roles in optimizing plant growth and environmental adaptation under drought stress.
文摘Dehydrating stresses trigger the accumulation of abscisic acid(ABA),a key plant stress-signaling hormone that activates Snf1-Related Kinases(SnRK2s)to mount adaptive responses.However,the regulatory circuits that terminate the SnRK2s signal relay after acclimation or post-stress conditions remain to be defined.Here,we show that the desensitization of the ABA signal is achieved by the regulation of OST1(SnRK2.6)protein stability via the E3-ubiquitin ligase HOS15.Upon ABA signal,HOS15-induced degradation of OST1 is inhibited and stabilized OST1 promotes the stress response.When the ABA signal terminates,protein phosphatases ABI1/2 promote rapid degradation of OST1 via HOS15.Notably,we found that even in the presence of ABA,OST1 levels are also depleted within hours of ABA signal onset.The unexpected dynamics of OST1 abundance are then resolved by systematic mathematical modeling,demonstrating a desensitizing feedback loop by which OST1-induced upregulation of ABI1/2 leads to the degradation of OST1.This model illustrates the complex rheostat dynamics underlying the ABA-induced stress response and desensitization.
基金This work was supported by the National Key Research and Development Project(2020YFA0509902)the National Natural Science Foundation of China(31730011,31970295,31921001),and Beijing Outstanding University Discipline Program.
文摘Protein phosphorylation and dephosphorylation have been reported to play important roles in plant cold responses.In addition,phospho-regulatory feedback is a conserved mechanism for biological processes and stress responses in animals and plants.However,it is less well known that a regulatory feedback loop is formed by the protein kinase and the protein phosphatase in plant responses to cold stress.Here,we report that OPEN STOMATA 1(OST1)and PROTEIN PHOSPHATASE 2C G GROUP 1(PP2CG1)reciprocally regulate the activity during the cold stress response.The interaction of PP2CG1 and OST1 is inhibited by cold stress,which results in the release of OST1 at the cytoplasm and nucleus from suppression by PP2CG1.Interestingly,cold-activated OST1 phosphorylates PP2CG1 to suppress its phosphatase activity,thereby amplifying cold signaling in plants.Mutations of PP2CG1 and its homolog PP2CG2 enhance freezing tolerance,whereas overexpression of PP2CG1 decreases freezing tolerance.Moreover,PP2CG1 negatively regulates protein levels of C-REPEAT BINDING FACTORs(CBFs)under cold stress.Our results uncover a phosphor/dephosphor-regulatory feedback loop mediated by PP2CG1 phosphatase and OST1 protein kinase in plant cold responses.
基金supported by the National Natural Science Foundation of China(NSFC 31900238,32070307,32150410345 and 32270308)the Henan Science and Technology Development Plan Project 212300410023 and Scientific and Technological Innovation Talents in Colleges and Universities in Henan,China(23HASTIT036).
文摘The sucrose non-fermenting 1(SNF1)-related protein kinase 2(SnRK2)family members have been discovered to regulate abiotic stress response via the abscisic acid(ABA)-independent and dependent signaling pathways.SnRK2.6,also known as Open Stomata 1(OST1),is a serine/threonine protein kinase that plays critical roles in linking ABA receptor complexes and downstream components such as transcription factors and anion channels to regulate stress response.Asides from its well-known regulatory roles in stomatal movement and cold stress response,OST1 has also been demonstrated recently to modulate major developmental roles of flowering and growth in plants.In this review,we will discuss about the various roles of OST1 as well as the‘doors’that OST1 can‘open’to help plants perform stress adaptation.Therefore,we will address how OST1 can regulate stomata apertures,cold stress tolerance as well as other aspects of its emerging roles such as balancing flowering and root growth in response to drought.
文摘Stomatal movements are critical in regulating gas exchange for photosynthesis and water balance between plant tissues and the atmosphere. The plant hormone abscisic acid （ABA） plays key roles in regulating stomatal closure under various abiotic stresses. In this study, we revealed a novel role of BAKI in guard cell ABA signaling. We found that the brassinosteroid （BR） signaling mutant bakl lost more water than wild- type plants and showed ABA insensitivity in stomatal closure. ABA-induced OST1 expression and reactive oxygen species （ROS） production were also impaired in bakl. Unlike direct treatment with H202, overex-pression of OST1 did not completely rescue the insensitivity of bakl to ABA. We demonstrated that BAK1 forms a complex with OST1 near the plasma membrane and that the BAKI/OST1 complex is increased in response to ABA in planta. Brassinolide, the most active BR, exerted a negative effect on ABA-induced formation of the BAK1/OST1 complex and OST1 expression. Moreover, we found that BAK1 and ABI1 oppositely regulate OST1 phosphorylation in vitro, and that ABI1 interacts with BAK1 and inhibits the interaction of BAK1 and OST1. Taken together, our results suggest that BAK1 regulates ABA-induced stomatal closure in guard cells.
