Hossain Mohammad Anowar, Munemasa Shintaro, Uraji Misugi, Nakamura Yoshimasa, Mori Izumi C, Murata Yoshiyuki
Graduate School of Natural Science and Technology, Okayama University, Tsushima-Naka, Okayama 700-8530, Japan.
Plant Physiol. 2011 May;156(1):430-8. doi: 10.1104/pp.111.172254. Epub 2011 Mar 14.
In this study, we examined the involvement of endogenous abscisic acid (ABA) in methyl jasmonate (MeJA)-induced stomatal closure using an inhibitor of ABA biosynthesis, fluridon (FLU), and an ABA-deficient Arabidopsis (Arabidopsis thaliana) mutant, aba2-2. We found that pretreatment with FLU inhibited MeJA-induced stomatal closure but not ABA-induced stomatal closure in wild-type plants. The aba2-2 mutation impaired MeJA-induced stomatal closure but not ABA-induced stomatal closure. We also investigated the effects of FLU and the aba2-2 mutation on cytosolic free calcium concentration (Ca(2+)) in guard cells using a Ca(2+)-reporter fluorescent protein, Yellow Cameleon 3.6. In wild-type guard cells, FLU inhibited MeJA-induced Ca(2+) elevation but not ABA-induced Ca(2+) elevation. The aba2-2 mutation did not affect ABA-elicited Ca(2+) elevation but suppressed MeJA-induced Ca(2+) elevation. We also tested the effects of the aba2-2 mutation and FLU on the expression of MeJA-inducible VEGETATIVE STORAGE PROTEIN1 (VSP1). In the aba2-2 mutant, MeJA did not induce VSP1 expression. In wild-type leaves, FLU inhibited MeJA-induced VSP1 expression. Pretreatment with ABA at 0.1 μm, which is not enough concentration to evoke ABA responses in the wild type, rescued the observed phenotypes of the aba2-2 mutant. Finally, we found that in wild-type leaves, MeJA stimulates the expression of 9-CIS-EPOXYCAROTENOID DIOXYGENASE3, which encodes a crucial enzyme in ABA biosynthesis. These results suggest that endogenous ABA could be involved in MeJA signal transduction and lead to stomatal closure in Arabidopsis guard cells.
在本研究中，我们使用脱落酸（ABA）生物合成抑制剂氟啶酮（FLU）和ABA缺陷型拟南芥（Arabidopsis thaliana）突变体aba2-2，研究了内源性ABA在茉莉酸甲酯（MeJA）诱导的气孔关闭中的作用。我们发现，用FLU预处理可抑制野生型植物中MeJA诱导的气孔关闭，但不影响ABA诱导的气孔关闭。aba2-2突变损害了MeJA诱导的气孔关闭，但不影响ABA诱导的气孔关闭。我们还使用Ca(2+)报告荧光蛋白Yellow Cameleon 3.6研究了FLU和aba2-2突变对保卫细胞胞质游离钙浓度（Ca(2+)）的影响。在野生型保卫细胞中，FLU抑制MeJA诱导的Ca(2+)升高，但不影响ABA诱导的Ca(2+)升高。aba2-2突变不影响ABA引发的Ca(2+)升高，但抑制MeJA诱导的Ca(2+)升高。我们还测试了aba2-2突变和FLU对MeJA诱导的营养贮藏蛋白1（VSP1）表达的影响。在aba2-2突变体中，MeJA不诱导VSP1表达。在野生型叶片中，FLU抑制MeJA诱导的VSP1表达。用0.1μm的ABA预处理，该浓度不足以在野生型中引发ABA反应，挽救了aba2-2突变体观察到的表型。最后，我们发现，在野生型叶片中，MeJA刺激9-顺式环氧类胡萝卜素双加氧酶3的表达，该酶编码ABA生物合成中的关键酶。这些结果表明，内源性ABA可能参与MeJA信号转导，并导致拟南芥保卫细胞气孔关闭。
