Characterization of dekl: A Maize Embryo-Lethal Mutation

本项目的目的是通过对dek1基因座的分析，更好地了解基因在植物胚胎发生中的作用。谢里丹博士将描述dek1位点的十个突变。所有十个突变等位基因产生隐性胚胎致死和缺陷胚乳表型缺乏花青素和类胡萝卜素。dek1突变体胚胎在原胚状态受阻，不能形成茎尖分生组织，但在发育后期可以扩大并形成根尖分生组织。突变等位基因将通过包括缺失研究在内的剂量分析来分析表型的均匀性和表达水平。在对转座因子Mutator有活性的种群中出现了5个等位基因，其中2个等位基因表现出易变性。通过Southern印迹和Mu1探针杂交对其中一个等位基因进行分离分析，发现了一个共分离的DNA条带。该等位基因将用于初始克隆工作，同时继续寻找新的标记等位基因和DNA共分离带。克隆的突变等位基因将用于鉴定正常等位基因克隆和分离cDNA克隆。后者将用于检查发育中的胚胎的空间和时间表达。x射线诱导区将用于检查dek1形态发生表达的细胞自主性，并评估该位点在花青素基因表达中的作用。新的1S B-A易位将被诱导，这将有助于遗传和结构分析。除了研究dek1突变对茎尖分生组织形成的阻碍外，还将利用x射线和结构方法对正常胚胎茎尖分生组织形成的x射线阻碍以及辐照后正常胚胎调节和产生多胚胎的能力进行有希望的初步观察。

The goal of this project is to obtain a greater understanding of the role of genes in plant embryogenesis by analyzing the dek1 locus. Dr. Sheridan will characterize ten mutations at the dek1 locus. All ten mutant alleles produce a recessive embryo lethal and a defective endosperm phenotype lacking anthocyanin and carotinoids. The dek1 mutant embryo is blocked at the proembryo state and is unable to form a shoot apical meristem but can enlarge and form a root apical meristem late in development. The mutant alleles will be analyzed for uniformity of phenotype and level of expression by dosage analysis including deletion studies. Five of the alleles arose in stocks that were active for the transposable element Mutator and two of these alleles display mutability. Segregation analysis on one of these alleles by Southern blotting and hybridizing with a Mu1 probe has revealed a cosegregating DNA band. This allele will be used for an initial cloning effort while continuing to search for new tagged alleles and DNA cosegregating bands. The cloned mutant allele will be used to identify a normal allele clone and to isolate a cDNA clone. The latter will be used to examine spatial and temporal expression in developing embryos. X-ray induced sectors will be used to examine the cellular autonomy of dek1 morphogenesis expression, and to evaluate the role of this locus in anthocyanin gene expression. New 1S B-A translocation will be induced that will aid in the genetic and structural analysis. In addition to studying the blockage of shoot apical meristem formation by the dek1 mutation, X-ray and structural approaches will be used to follow up promising preliminary observation of x-ray blockage of shoot apical meristem formation of normal embryos and the capacity of irradiated normal embryos to regulate and produce multiple embryos.