Key Laboratory of Forest Tree Genetic Improvement and Biotechnology Ministry of Education, Northeast Forestry University, 26 Hexing Road, Harbin 150040, People's Republic of China.
Mol Biol Rep. 2012 Mar;39(3):2505-13. doi: 10.1007/s11033-011-1002-0. Epub 2011 Jun 17.
Abscisic acid (ABA) is a plant hormone regulating the essential physiological processes of plants and plant responses to various environmental stresses. Recent studies revealed that the key enzymes involved in ABA biosynthesis were zeaxanthin epoxidase (ZEP), 9-cis-epoxycarotenoid dioxygenases (NCED), short-chain dehydrogenase/reductase (SDR), and ABA-aldehyde oxidase (AAO). In this study, we cloned 12 unique genes potentially involved in ABA synthesis, including 5 of BpNCEDs, 1 of BpAAO, and 6 of BpZEPs from birch leaves. We analyzed the time-course expression of these 12 genes during the phase from May to August by real time reverse transcriptase-polymerase chain reaction (RT-PCR). Further, we determined birch endogenous ABA content during this period by liquid chromatography tandem mass spectrometry (LC-MS/MS). The results indicated that ABA level significantly (P < 0.05) increased during the early stages of development and ABA was present in birch leaves throughout the studied period, suggesting that endogenous ABA is necessary for the normal growth and development of plants. The correlation between the expression of above-mentioned genes and ABA levels was analyzed by Pearson correlation analysis. The results revealed that the expression of three genes, namely, BpNCED4, BpNCED5 and BpZE6 significantly (P < 0.05) correlated with the ABA level. Therefore, these three genes may play important roles in ABA biosynthesis.
脱落酸（ABA）是一种植物激素，调节植物的基本生理过程和植物对各种环境胁迫的响应。最近的研究表明，ABA 生物合成中的关键酶有玉米黄质环氧化酶（ZEP）、9-顺式-环氧类胡萝卜素双加氧酶（NCED）、短链脱氢酶/还原酶（SDR）和 ABA-醛氧化酶（AAO）。本研究从桦树叶中克隆了 12 个可能参与 ABA 合成的独特基因，包括 5 个 BpNCEDs、1 个 BpAAO 和 6 个 BpZEPs。我们通过实时逆转录聚合酶链反应（RT-PCR）分析了这些基因在 5 月至 8 月期间的时间表达。此外，我们通过液相色谱串联质谱法（LC-MS/MS）测定了这段时间内桦树的内源 ABA 含量。结果表明，ABA 水平在发育早期显著增加（P < 0.05），并且 ABA 在研究期间存在于桦树叶中，表明内源性 ABA 是植物正常生长和发育所必需的。通过 Pearson 相关分析对上述基因与 ABA 水平的表达关系进行了分析。结果表明，三个基因（BpNCED4、BpNCED5 和 BpZE6）的表达与 ABA 水平显著相关（P < 0.05）。因此，这三个基因可能在 ABA 生物合成中发挥重要作用。
