Abscisic acid (ABA) is a plant hormone which plays an important role in seed development and dormancy and in plant response to environmental stresses. An ABA-deficient mutant of Nicotiana plumbaginifolia, aba2, was isolated by transposon tagging using the maize Activator transposon. The aba2 mutant exhibits precocious seed germination and a severe wilty phenotype. The mutant is impaired in the first step of the ABA biosynthesis pathway, the zeaxanthin epoxidation reaction. ABA2 cDNA is able to complement N.plumbaginifolia aba2 and Arabidopsis thaliana aba mutations indicating that these mutants are homologous. ABA2 cDNA encodes a chloroplast-imported protein of 72.5 kDa, sharing similarities with different mono-oxigenases and oxidases of bacterial origin and having an ADP-binding fold and an FAD-binding domain. ABA2 protein, produced in Escherichia coli, exhibits in vitro zeaxanthin epoxidase activity. This is the first report of the isolation of a gene of the ABA biosynthetic pathway. The molecular identification of ABA2 opens the possibility to study the regulation of ABA biosynthesis and its cellular location.

中文翻译：

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烟草（Nicotiana plumbaginifolia）的玉米黄质环氧化酶的分子鉴定，该基因与脱落酸的生物合成有关，并且与拟南芥的ABA基因座相对应。

脱落酸（ABA）是一种植物激素，在种子发育和休眠以及植物对环境胁迫的反应中起着重要作用。通过使用玉米激活子转座子进行转座子标记分离了烟草的ABA缺失突变体ABA2。aba2突变体表现出早熟的种子发芽和严重的野生表型。该突变体在ABA生物合成途径的第一步玉米黄质环氧化反应中受损。ABA2 cDNA能够与N.plumbaginifolia aba2和拟南芥aba突变互补，表明这些突变体是同源的。ABA2 cDNA编码72.5 kDa的叶绿体导入蛋白，与细菌来源的不同单-氧化酶和氧化酶具有相似性，并具有ADP结合折叠和FAD结合结构域。ABA2蛋白，在大肠杆菌中产生的产物显示出体外玉米黄质环氧酶活性。这是关于ABA生物合成途径基因分离的首次报道。ABA2的分子鉴定为研究ABA生物合成的调控及其细胞位置提供了可能性。