【摘要】 基因组中转座子的插入和剪切都会使插入位点的序列发生改变，包括基因突变，进而导致表型变异或基因组进化。Mrh/rMrh是玉米Mutator超家族中首个经遗传学鉴定的双元转座子系统，其中仅有非自主性转座子rMrh完成了基因克隆及序列测定。通过遗传杂交后代的表型分离比确定Mrh活性系中仅有一个自主性转座子Mrh调控报告基因a1位点的rMrh发生转座。为了明确rMrh转座子在玉米体细胞中的转座剪切修复对宿主a1基因功能的影响，以及分处两个遗传位点的自主性Mrh转座子对同一a1位点rMrh剪切转座后序列修复类型的影响，对转座修复位点的PCR扩增产物进行了分子克隆及测序。结果显示，rMrh在玉米体细胞中a1位点转座后产生两种足迹类型，一种是精确修复，另一种是末端反向重复序列（terminal inverted repeat,TIR）残留。同时，在不同遗传位点的自主性转座子Mrh的调控下，rMrh在玉米体细胞中原初位点发生转座剪切时的修复类型相对单一，既能通过精确修复恢复宿主基因功能，也会因为残留碱基导致宿主基因功能的突变，但是不同遗传位点的自主性转座子Mrh的修复产物序列不尽相同。研究结果明确了经典Mrh/rMrh双元转座子系统中rMrh的转座剪切修复特性，在丰富对Mutator转座子遗传特性认识的同时，也为进一步应用这一转座子系统创制玉米新种质资源和功能基因组学遗传材料奠定了理论基础。更多还原

【Abstract】 Transposable element insertions and excisions are prevalent forces in driving phenotypic variations, gene mutations and genome evolution. Mrh/rMrh transposons are the components of the first genetically characterized two-element transposon system from Mutator superfamily in maize, wherein rMrh transposon, the nonautonomous component has been cloned for sequence characterization. Through phenotypic analysis on the segregation ratio of progeny segregants from genetic cross population, we verified the existence of a single copy autonomous Mrh transposon to catalyse the excision of rMrh from the reporter a1 allele in the maize genome. To elucidate the effects of somatic excision and repairing pattern of rMrh on the function of host a1 gene, and the effects of two autonomous Mrh elements from distinct genetic loci on the somatic excision and repairing pattern of rMrh element at the identical a1 locus, PCR amplification and cloning were applied to recover the simple somatic excision products for sequencing. Results suggested two types of major somatic transposition footprints upon the somatic excision of rMrh transposon in maize, one is precise excision repairing, and another is partial retentions of TIRs from rMrh. Meanwhile, under the regulation of Mrh elements from different genetic loci, the repairing patterns of rMrh somatic excision are rather simple at the primary insertion site in maize, and lead to recovery of the function of host gene through precise excision repairing or host gene mutation due to extra basepair retentions, but the sequences of repairing products are varied between autonomous Mrh elements from different genetic loci regardless. Our results elucidated the excision repairing features of rMrh from the classic Mrh/rMrh two-element transposon system, enriched the knowledge of genetics characteristics of Mutator transposons, and provided theoretical bases for further exploration of Mrh/rMrh transposon system for generating novel maize germplasms and genetic materials for functional genomics.更多还原