A Molecular and Genetic Analysis of Apical Dominance

[507082]植物形态的巨大多样性的一个促成因素是侧芽的生长，以及随后形成的特征枝系统。这个建议是一个更新以前的资助支持腋窝分支和根尖优势的遗传分析。先前的研究表明，通过诱变可以诱导足够的遗传多样性，从而使腋窝分支的遗传研究成为可能。在矮牵牛（Petunia hybrida）中发现了3个控制腋窝分枝程度的遗传位点。隐性等位基因的表型表现为分支潜能增加或顶端显性降低（dad）。研究目标如下：1)继续研究dad1和dad3突变体的发育和生理特征；2)分离dad1和dad3的第二位点抑制基因的遗传学研究，以及抑制突变体的遗传学特征；3)利用dad突变体和增加的顶端显性突变体进行双突变和三突变体分析；4)转座子标记克隆dad1基因。利用玉米元素解离（Ds）技术建立了一种玉米杂交种转座子标记系统。戴维斯收集了159株含有独立的Ds供体位点的植物。在杂交产生的F1后代中，Ds可以高频率地从供体位点被反激活，从而从激活子（Activator, Ac）中提供活性转座酶。Napoli博士分析了51个Ds供体位点，并证明了减数分裂前事件导致生发切除事件的发生。两个供体d位点被定位到dad1基因约2.8cM处。一个测试杂交已经开始标记和克隆dad1基因。* * *

9507082 Napoli A contributing factor to the enormous diversity observed for plant form is the outgrowth of lateral buds, and the subsequent formation of a characteristic shoot system. This proposal is a renewal of previous funding supporting a genetic analysis of axillary branching and apical dominance. Previous work demonstrated that sufficient genetic diversity can be induced through mutagenesis in order to make a genetic study of axillary branching possible. Three genetic loci have been identified in Petunia hybrida that control the degree of axillary branching. The recessive alleles condition the phenotypic expression of increased branching potential or decreased apical dominance (dad). The following objectives will be pursued: 1) continued developmental and physiological characterization of dad1 and dad3 mutants, 2) genetic studies to isolate second site suppressors of dad1 and dad3, along with the genetic characterization of suppressor mutants, 3) double mutant and triple mutant analysis employing dad mutants and increased apical dominance mutants, and 4) transposon tagging to clone the dad1 gene. A transposon tagging system using the maize element Dissociation (Ds) has been developed in this laboratory for an inbred genetic line of P. hybrida. The Davis collection contains 159 plants containing independent Ds donor loci. Ds can be transactivated to excise from donor sites at a high frequency in F1 progeny resulting from a cross to provide active transposase from Activator (Ac). Dr. Napoli has analyzed 51 of the Ds donor loci and have demonstrated the occurrence of pre-meiotic events giving rise to germinal excision events. Two donor Ds loci have been mapped to approximately 2.8cM of the dad1 gene. A test cross has been initiated to tag and clone the dad1 gene. ***