Marin E, Nussaume L, Quesada A, Gonneau M, Sotta B, Hugueney P, Frey A, Marion-Poll A
INRA, Laboratorie de Biologie Cellulaire, France.
EMBO J. 1996 May 15;15(10):2331-42.
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.
脱落酸（ABA）是一种植物激素，在种子发育与休眠以及植物对环境胁迫的响应中发挥着重要作用。利用玉米激活子转座子通过转座子标签法分离出了烟草（Nicotiana plumbaginifolia）的一个ABA缺陷型突变体aba2。aba2突变体表现出种子早熟萌发和严重的萎蔫表型。该突变体在ABA生物合成途径的第一步，即玉米黄质环氧化反应中存在缺陷。ABA2 cDNA能够互补烟草aba2和拟南芥（Arabidopsis thaliana）aba突变体，表明这些突变体是同源的。ABA2 cDNA编码一种72.5 kDa的叶绿体导入蛋白，与不同的细菌来源的单加氧酶和氧化酶具有相似性，具有ADP结合结构域和FAD结合结构域。在大肠杆菌中产生的ABA2蛋白在体外表现出玉米黄质环氧化酶活性。这是关于ABA生物合成途径中一个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定位提供了可能。
