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
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.
