Melhorn Vanessa, Matsumi Kunimi, Koiwai Hanae, Ikegami Keiichi, Okamoto Masanori, Nambara Eiji, Bittner Florian, Koshiba Tomokazu
Department of Biological Sciences, Tokyo Metropolitan University, Hachioji 192-0397, Japan.
J Plant Res. 2008 Jan;121(1):125-31. doi: 10.1007/s10265-007-0127-7. Epub 2007 Dec 4.
Abscisic acid (ABA) regulates stomatal closure in response to water loss. Here, we examined the competence of guard cells to synthesize ABA, using two Arabidopsis ABA biosynthetic enzymes. 35S pro::AtNCED3-GFP and AAO3-GFP were introduced into guard cells of broad bean leaves. AtNCED3-GFP expression was detected at the chloroplasts, whereas green fluorescent protein (GFP) and AAO3-GFP were in the cytosol. The stomatal aperture was decreased in AtNCED3-GFP- and AAO3-GFP-transformed guard cells. This indicated that ABA biosynthesis is stimulated by heterologous expression of AtNCED3 and Arabidopsis aldehyde oxidase 3 (AAO3) proteins, which both seem to be regulatory enzymes for ABA biosynthesis in these cells. Furthermore, stomatal closure by the expression of AtNCED3 and AAO3 suggested that the substrates of the enzymes are present and native ABA-biosynthesis enzymes are active in guard cells.
脱落酸（ABA）可响应水分流失调节气孔关闭。在此，我们利用两种拟南芥ABA生物合成酶，检测了保卫细胞合成ABA的能力。将35S pro::AtNCED3-GFP和AAO3-GFP导入蚕豆叶片的保卫细胞中。在叶绿体中检测到AtNCED3-GFP的表达，而绿色荧光蛋白（GFP）和AAO3-GFP位于细胞质中。在AtNCED3-GFP和AAO3-GFP转化的保卫细胞中，气孔孔径减小。这表明AtNCED3和拟南芥醛氧化酶3（AAO3）蛋白的异源表达刺激了ABA生物合成，这两种蛋白似乎都是这些细胞中ABA生物合成的调节酶。此外，AtNCED3和AAO3的表达引起的气孔关闭表明，这些酶的底物存在，并且天然ABA生物合成酶在保卫细胞中具有活性。
