Molecular and Developmental Studies of a Shootless Mutant of Maize

小行星9318447 Rivin博士已经分离出一种玉米突变体，称为dks 8（缺陷型籽粒无茎-Mu 8），它破坏了功能性茎分生组织的早期建立，但不干扰子叶和主根的正常形态发生和分化。这些特征在玉米的胚突变体中是独特的，并且它们表明由dks 8突变鉴定的基因是胚芽形成中的基本步骤所需的。通过检查该基因在胚胎发育过程中的作用，确定它是否在胚胎后发育中起作用，并确定其序列和产物，可以定义对植物发育至关重要的细胞过程之一。该研究计划具有以下目标：1）从现有的突变体集合中并通过使用EMS诱变的和Mutator转座子储备物的靶向诱变来鉴定dks 8的其他等位基因。2)使用Mutator转座子标签克隆和定位Dks 8基因。dks 8突变似乎是由罗伯逊突变体转座系统的Mu 8元件插入引起的。 将克隆该元件侧翼的序列，并用于绘制dks 8基因座。他们将被分析，以发现这个发育重要基因的产物。3)确定dks 8突变如何以及何时阻止胚芽发育。将使用组织学和分子标准来测试芽顶端分生组织细胞群是否在dks 8突变体中的胚胎发生的第一阶段中被启动和维持。体细胞胚胎发生和胚乳基因型的操作将用于检查dks 8基因的作用是否是发育中的胚胎所固有的，或者它是否作为较大胚珠或种子环境的一部分。4)确定Dks 8基因产物在胚胎发生之外对于茎顶端分生组织的规格或功能是必需的。细胞谱系的克隆分析将用于确定dks 8基因型对已建立的茎顶端分生组织中细胞的发育命运的影响。 ***

9318447 Rivin Dr. Rivin has isolated a maize mutant, termed, dks8 (defective kernel shootless-Mu8), that disrupts the early establishment of a functional shoot meristem, but does not perturb the normal morphogenesis and differentiation of the cotyledon and primary root. These features are unique among the embryo mutants of maize, and they indicate that the gene identified by the dks8 mutation is required for a fundamental step in the formation of the embryonic shoot. By examining the role of this gene during embryonic development, determining if it plays part in post-embryonic development, and identifying its sequence and product, one of the cellular processes critical to plant development may be defined. The research program has the following objectives: 1) Identify other alleles of dks8 from existing mutant collections and by targeted mutagenesis using EMS- mutagenized and Mutator transposon stocks. 2) Clone and map the Dks8 gene using the Mutator transposon tag. The dks8 mutation appears to have been caused by the insertion of a Mu8 element of the Robertson's Mutator transposable system. The sequences flanking this element will be cloned and used to map the dks8 locus. They will be analyzed to discover the product of this developmentally important gene. 3) Determine how and when the dks8 mutation prevents embryonic shoot development. Histological and molecular criteria will be used to test whether the shoot apical meristem cell population is initiated and maintained in the first stages of embryogenesis in dks8 mutants. Somatic embryogenesis and manipulation of endosperm genotype will be used to examine whether dks8 gene action is intrinsic to the developing embryo or whether it acts as part of the larger ovule or seed environment. 4) Determine it the Dks8 gene product is required outside of embryogenesis for the specification or function of the shoot apical meristem. Clonal analysis of cell lineage will be used to determine the effect of the dks8 genotyp e on the developmental fate of cells in an established shoot apical meristem. ***