CLONING AND CHARACTERIZATION OF THE MAIZE AN1 GENE
CLONING AND CHARACTERIZATION OF THE MAIZE AN1 GENE
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DOI：
10.1105/tpc.7.1.75
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发表时间：
1995-01-01
期刊：
影响因子：
11.6
通讯作者：
BRIGGS, SP
中科院分区：
文献类型：
--
作者：
BENSEN, RJ;JOHAL, GS;BRIGGS, SP
花药耳1（An 1）基因产物参与赤霉素（GA）生物合成途径中的第一个四环中间体对映贝壳杉烯的合成。导致Anl功能丧失的突变导致GA响应表型，其包括降低的植物高度、延迟成熟和在正常雌蕊穗上发育完美的花。anl：：Mu 2 891339等位基因从Mutator（Mu）F-2家族回收。以Mu元件为分子探针，鉴定并克隆了一个含An 1的限制性片段。克隆基因作为An 1的身份通过使用含有插入克隆基因的Mu元件的玉米家族的反向遗传学筛选，然后通过证明插入导致An 1表型来确认。An 1 cDNA的预测氨基酸序列与植物环化酶具有同源性，并且含有一个基本的N-末端序列，该序列可能将An 1基因产物靶向叶绿体。该序列是一致的预测AN 1在叶绿体中的亚细胞定位和其生化作用的香叶基香叶基焦磷酸，20-碳类异戊二烯，对映贝壳杉烯环化。an 1突变体的半矮小身材与玉米中其他位点的GA响应突变体的更严重的矮小身材相反，并且可能是由GA生物合成途径的这一步骤中的冗余引起的。DNA凝胶印迹分析表明，An 1是一个单拷贝基因，完全位于an 1-bz 2 -6923突变体的缺失。然而，纯合缺失突变体积累的对映贝壳杉烯的野生型水平的20%，这表明的An 1的功能是由一个额外的活动补充。
The Anther ear1 (An1) gene product is involved in the synthesis of ent-kaurene, the first tetracyclic intermediate in the gibberellin (GA) biosynthetic pathway. Mutations causing the loss of An1 function result in a GA-responsive phenotype that includes reduced plant height, delayed maturity, and development of perfect flowers on normally pistillate ears, The an1::Mu2 891339 allele was recovered from a Mutator (Mu) F-2 family. Using Mu elements as molecular probes, an An1-containing restriction fragment was identified and cloned. The identity of the cloned gene as An1 was confirmed by using a reverse genetics screen for maize families that contain a Mu element inserted into the cloned gene and then by demonstrating that the insertion causes an an1 phenotype. The predicted amino acid sequence of the An1 cDNA shares homology with plant cyclases and contains a basic N-terminal sequence that may target the An1 gene product to the chloroplast. The sequence is consistent with the predicted subcellular localization of AN1 in the chloroplast and with its biochemical role in the cyclization of geranylgeranyl pyrophosphate, a 20-carbon isoprenoid, to ent-kaurene. The semidwarfed stature of an1 mutants is in contrast with the more severely dwarfed stature of GA-responsive mutants at other loci in maize and may be caused by redundancy in this step of the GA biosynthetic pathway. DNA gel blot analysis indicated that An1 is a single-copy gene that lies entirely within the deletion of the an1-bz2-6923 mutant. However, homozygous deletion mutants accumulated ent-kaurene to 20% of the wild-type level, suggesting that the function of An1 is supplemented by an additional activity.