Wendel J F, Goodman M M, Stuber C W, Beckett J B
Department of Botany, Iowa State University, Ames 50011.
Biochem Genet. 1988 Jun;26(5-6):421-45. doi: 10.1007/BF02401795.
Electrophoretic variation and inheritance of four novel enzyme systems were studied in maize (Zea mays L.). A minimum of 10 genetic loci collectively encodes isozymes of aconitate hydratase (ACO; EC 4.2.1.3.), adenylate kinase (ADK; EC 2.7.4.3), NADH dehydrogenase (DIA; EC 1.6.99.-), and shikimate dehydrogenase (SAD; EC 1.1.1.25). At least four loci are responsible for the genetic control of ACO. Genetic data for two of the encoding loci, Aco1 and Aco4, demonstrated that at least two maize ACOs are active as monomers. Analysis of organellar preparations suggests that ACO1 and ACO4 are localized in the cytosolic and mitochondrial subcellular fractions, respectively. Maize ADK is encoded by a single nuclear locus, Adk1, governing monomeric enzymes that are located in the chloroplasts. Two cytosolic and two mitochondrial forms of DIA were electrophoretically resolved. Segregation analyses demonstrated that the two cytosolic isozymes are controlled by separate loci, Dia1 and Dia2, coding for products that are functional as monomers (DIA1) and dimers (DIA2). The major isozyme of SAD is apparently cytosolic, although an additional faintly staining plastid form may be present. Alleles at Sad1 are each associated with two bands that cosegregate in controlled crosses. Linkage analyses and crosses with B-A translocation stocks were effective in determining the map locations of six loci, including the previously described but unmapped locus Acp4. Several of these loci were localized to sparsely mapped regions of the genome. Dia2 and Acp4 were placed on the distal portion of the long arm of chromosome 1, 12.6 map units apart. Dia1 was localized to chromosome 2, 22.2 centimorgans (cM) from B1. Aco1 was mapped to chromosome 4, 6.2 cM from su1. Adk1 was placed on the poorly marked short arm of chromosome 6, 8.1 map units from rgd1. Less than 1% recombination was observed between Glu1 (on chromosome 10) and Sad1. In contrast to many other maize isozyme systems, there was little evidence of gene duplication or of parallel linkage relationships for these allozyme loci.
对玉米（Zea mays L.）中四种新型酶系统的电泳变异和遗传进行了研究。至少10个基因座共同编码乌头酸水合酶（ACO；EC 4.2.1.3.）、腺苷酸激酶（ADK；EC 2.7.4.3）、NADH脱氢酶（DIA；EC 1.6.99.-）和莽草酸脱氢酶（SAD；EC 1.1.1.25）的同工酶。至少有四个基因座负责ACO的遗传控制。两个编码基因座Aco1和Aco4的遗传数据表明，至少两种玉米ACO以单体形式具有活性。细胞器制备物的分析表明，ACO1和ACO4分别定位于胞质和线粒体亚细胞组分中。玉米ADK由单个核基因座Adk1编码，该基因座控制位于叶绿体中的单体酶。电泳分离出两种胞质形式和两种线粒体形式的DIA。分离分析表明，两种胞质同工酶由不同的基因座Dia1和Dia2控制，它们编码的产物分别作为单体（DIA1）和二聚体（DIA2）发挥功能。SAD的主要同工酶显然位于胞质中，不过可能还存在一种染色较浅的质体形式。Sad1位点的等位基因各自与两条带相关联，在受控杂交中这些带共分离。连锁分析以及与B-A易位系的杂交有效地确定了六个基因座的图谱位置，包括先前描述但未定位的Acp4基因座。其中几个基因座定位于基因组中图谱绘制稀疏的区域。Dia2和Acp4位于第1号染色体长臂的远端，相距12.6个图谱单位。Dia1定位于第2号染色体，距离B1为22.2厘摩（cM）。Aco1定位于第4号染色体，距离su1为6.2 cM。Adk1位于第6号染色体标记较少的短臂上，距离rgd1为
