Suhita Dontamala, Raghavendra Agepati S, Kwak June M, Vavasseur Alain
CEA/Cadarache-DSV-DEVM, Laboratoire des Echanges Membranaires et Signalisation, UMR 163 CNRS-CEA, Université de la Méditerranée, 13108 St Paul lez Durance cedex, France.
Plant Physiol. 2004 Apr;134(4):1536-45. doi: 10.1104/pp.103.032250. Epub 2004 Apr 2.
Signaling events during abscisic acid (ABA) or methyl jasmonate (MJ)-induced stomatal closure were examined in Arabidopsis wild type, ABA-insensitive (ost1-2), and MJ-insensitive mutants (jar1-1) in order to examine a crosstalk between ABA and MJ signal transduction. Some of the experiments were performed on epidermal strips of Pisum sativum. Stomata of jar1-1 mutant plants are insensitive to MJ but are able to close in response to ABA. However, their sensitivity to ABA is less than that of wild-type plants. Reciprocally, the stomata of ost1-2 are insensitive to ABA but are able to close in response to MJ to a lesser extent compared to wild-type plants. Both MJ and ABA promote H(2)O(2) production in wild-type guard cells, while exogenous application of diphenylene iodonium (DPI) chloride, an inhibitor of NAD(P)H oxidases, results in the suppression of ABA- and MJ-induced stomatal closure. ABA elevates H(2)O(2) production in wild-type and jar1-1 guard cells but not in ost1-2, whereas MJ induces H(2)O(2) production in both wild-type and ost1-2 guard cells, but not in jar1-1. MJ-induced stomatal closing is suppressed in the NAD(P)H oxidase double mutant atrbohD/F and in the outward potassium channel mutant gork1. Furthermore, MJ induces alkalization in guard cell cytosol, and MJ-induced stomatal closing is inhibited by butyrate. Analyses of the kinetics of cytosolic pH changes and reactive oxygen species (ROS) production show that the alkalization of cytoplasm precedes ROS production during the stomatal response to both ABA and MJ. Our results further indicate that JAR1, as OST1, functions upstream of ROS produced by NAD(P)H oxidases and that the cytoplasmic alkalization precedes ROS production during MJ or ABA signal transduction in guard cells.
为了研究脱落酸（ABA）和茉莉酸甲酯（MJ）信号转导之间的相互作用，我们检测了拟南芥野生型、ABA不敏感突变体（ost1-2）和MJ不敏感突变体（jar1-1）在ABA或MJ诱导气孔关闭过程中的信号事件。部分实验在豌豆的表皮条上进行。jar1-1突变体植株的气孔对MJ不敏感，但能对ABA作出反应而关闭。然而，它们对ABA的敏感性低于野生型植株。相反，ost1-2的气孔对ABA不敏感，但与野生型植株相比，能对MJ作出较小程度的反应而关闭。MJ和ABA都能促进野生型保卫细胞中H₂O₂的产生，而外源施加NAD(P)H氧化酶抑制剂氯化二苯基碘鎓（DPI）会抑制ABA和MJ诱导的气孔关闭。ABA能提高野生型和jar1-1保卫细胞中H₂O₂的产生，但不能提高ost1-2保卫细胞中H₂O₂的产生，而MJ能诱导野生型和ost1-2保卫细胞中H₂O₂的产生，但不能诱导jar1-1保卫细胞中H₂O₂的产生。在NAD(P)H氧化酶双突变体atrbohD/F和外向钾通道突变体gork1中，MJ诱导的气孔关闭受到抑制。此外，MJ能诱导保卫细胞胞质碱化，且MJ诱导的气孔关闭受到丁酸盐的抑制。对胞质pH变化和活性氧（ROS）产生动力学的分析表明，在气孔对ABA和MJ的反应过程中，细胞质碱化先于ROS产生。我们的结果进一步表明，JAR1与OST1一样，在NAD(P)H氧化酶产生的ROS上游发挥作用，并且在保卫细胞中MJ或ABA信号转导过程中，细胞质碱化先于ROS产生。
