Repackaging the Corn Genome for Molecular Mapping

这项研究的目标是开发一种产生染色体缺失的有序集的方法。植物染色体臂将通过Cre-lox定点重组转移到培养细胞系的基因组中。由此产生的杂交染色体将被称为RAC。将产生携带植物染色体臂缺失衍生品的亚克隆细胞系。这些缺失将通过同源依赖的基因靶向易位断裂点下游的新的lox位点，然后删除两个lox位点之间的干涉DNA来实现。通过插入一系列下游lox位点，可以产生每个植物染色体臂的有序缺失集。对于玉米基因组的RAC缺失文库，目标是在相距~2.5×107bp的位置插入新的LOX位点，产生~200个RAC，每个RAC包含一个25-250 Mbp的玉米染色体片段，在玉米染色体图谱上有明确的终点。RAC缺失文库可用于酵母或细菌人工染色体(YAC或BAC)或单个cDNA的物理定位。本项目的具体目标是：第一，开发在培养细胞中产生RAC的方法；第二，在每条染色体臂上靠近着丝点的地方产生玉米植株。该研究结果将为玉米基因组和其他大型基因组的物理图谱提供有价值的工具。这样的工具将允许以一种以前不可能实现的方式对大型植物基因组进行详细分析。

The goal of the research is to develop a method to generate ordered sets of chromosome deletions. Plant chromosome arms will be translocatcd into the genome of cultured cell lines via Cre-lox site-specific recombination. The resulting hybrid chromosomes will be referred to as RACs. Subclone cell lines will be generated carrying deletion derivatives of the plant chromosome arm. The deletions will be made through homology-dependent gene targeting of new lox sites downstream of the translocation breakpoint, followed by the deletion of intervening DNA between the two lox sites. An ordered set of deletions for each plant chromosome arm can be generated with the insertion of a series of downstream lox sites. For a RAC deletion library of the maize genome, the goal will be to insert new lox sites at ~2.5 x 107 bp apart, resulting in ~200 RACs, each containing a maize chromosome fragment of 25 to 250 Mbp with defined endpoints on the maize chromosome map. The RAC deletion library can be used for physical mapping of Yeast or Bacterial Artificial Chromosome (YAC or BAC), or individual cDNAs. The specific objectives of the current project are first, to develop the method of generating RACs in cultured cells, and second, to generate maize plants with a lox site on each chromosome arm near the centromere.Results from this research will provide a valuable tool for the physical mapping of the maize genome and other large genomes. Such a tool will allow detailed analysis of large plant genomes in a way that has not been possible before.