Audran C, Borel C, Frey A, Sotta B, Meyer C, Simonneau T, Marion-Poll A
Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique, Route de St Cyr, 78026 Versailles cedex, France (C.A., A.F., C.M., A.M.-P.).
Plant Physiol. 1998 Nov;118(3):1021-8. doi: 10.1104/pp.118.3.1021.
Abscisic acid (ABA) is a plant hormone involved in the control of a wide range of physiological processes, including adaptation to environmental stress and seed development. In higher plants ABA is a breakdown product of xanthophyll carotenoids (C40) via the C15 intermediate xanthoxin. The ABA2 gene of Nicotiana plumbaginifolia encodes zeaxanthin epoxidase, which catalyzes the conversion of zeaxanthin to violaxanthin. In this study we analyzed steady-state levels of ABA2 mRNA in N. plumbaginifolia. The ABA2 mRNA accumulated in all plant organs, but transcript levels were found to be higher in aerial parts (stems and leaves) than in roots and seeds. In leaves ABA2 mRNA accumulation displayed a day/night cycle; however, the ABA2 protein level remained constant. In roots no diurnal fluctuation in mRNA levels was observed. In seeds the ABA2 mRNA level peaked around the middle of development, when ABA content has been shown to increase in many species. In conditions of drought stress, ABA levels increased in both leaves and roots. A concomitant accumulation of ABA2 mRNA was observed in roots but not in leaves. These results are discussed in relation to the role of zeaxanthin epoxidase both in the xanthophyll cycle and in the synthesis of ABA precursors.
脱落酸（ABA）是一种植物激素，参与调控多种生理过程，包括对环境胁迫的适应和种子发育。在高等植物中，ABA是叶黄素类胡萝卜素（C40）通过C15中间体黄质醛的分解产物。烟草的ABA2基因编码玉米黄质环氧化酶，该酶催化玉米黄质向堇菜黄质的转化。在本研究中，我们分析了烟草中ABA2 mRNA的稳态水平。ABA2 mRNA在所有植物器官中均有积累，但转录水平在地上部分（茎和叶）高于根和种子。在叶片中，ABA2 mRNA的积累呈现昼夜循环；然而，ABA2蛋白水平保持恒定。在根中未观察到mRNA水平的昼夜波动。在种子中，ABA2 mRNA水平在发育中期左右达到峰值，此时许多物种的ABA含量已显示增加。在干旱胁迫条件下，叶片和根中的ABA水平均升高。在根中观察到ABA2 mRNA的伴随积累，但在叶片中未观察到。结合玉米黄质环氧化酶在叶黄素循环和ABA前体合成中的作用对这些结果进行了讨论。
