Abscisic acid （ABA） regulates ion channel activity and stomatal movements in response to drought and other stresses. Here, we show that the Arabidopsis thaliana gene NRGA1 is a putative mitochondrial pyruvate carrie...Abscisic acid （ABA） regulates ion channel activity and stomatal movements in response to drought and other stresses. Here, we show that the Arabidopsis thaliana gene NRGA1 is a putative mitochondrial pyruvate carrier which negatively regulates ABA-induced guard cell signaling. NRGA1 transcript was abundant in the A. thaliana leaf and par- ticularly in the guard cells, and its product was directed to the mitochondria. The heterologous co-expression of NRGA1 and AtMPC1 in yeast complemented a loss-of-function mitochondrial pyruvate carrier （MPC） mutant. The nrgal loss-of- function mutant was very sensitive to the presence of ABA in the context of stomatal movements, and exhibited a height- ened tolerance to drought stress. Disruption of NRGA1 gene resulted in increased ABA inhibition of inward K＋ currents and ABA activation of slow anion currents in guard cells. The nrgal/NRGA1 functional complementation lines restored the mutant＇s phenotypes. Furthermore, transgenic lines of constitutively overexpressing NRGA1 showed opposite stomatal responses, reduced drought tolerance, and ABA sensitivity of guard cell inward K＋ channel inhibition and anion channel activation. Our findings highlight a putative role for the mitochondrial pyruvate carrier in guard cell ABA signaling in response to drought.展开更多
文摘Abscisic acid （ABA） regulates ion channel activity and stomatal movements in response to drought and other stresses. Here, we show that the Arabidopsis thaliana gene NRGA1 is a putative mitochondrial pyruvate carrier which negatively regulates ABA-induced guard cell signaling. NRGA1 transcript was abundant in the A. thaliana leaf and par- ticularly in the guard cells, and its product was directed to the mitochondria. The heterologous co-expression of NRGA1 and AtMPC1 in yeast complemented a loss-of-function mitochondrial pyruvate carrier （MPC） mutant. The nrgal loss-of- function mutant was very sensitive to the presence of ABA in the context of stomatal movements, and exhibited a height- ened tolerance to drought stress. Disruption of NRGA1 gene resulted in increased ABA inhibition of inward K＋ currents and ABA activation of slow anion currents in guard cells. The nrgal/NRGA1 functional complementation lines restored the mutant＇s phenotypes. Furthermore, transgenic lines of constitutively overexpressing NRGA1 showed opposite stomatal responses, reduced drought tolerance, and ABA sensitivity of guard cell inward K＋ channel inhibition and anion channel activation. Our findings highlight a putative role for the mitochondrial pyruvate carrier in guard cell ABA signaling in response to drought.
