DNA甲基化在玉米减数分裂基因重组过程中的调控功能解析

项目名称： DNA甲基化在玉米减数分裂基因重组过程中的调控功能解析

项目编号： No.31471172

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 生物科学

项目作者： 贺岩

作者单位： 中国农业大学

项目金额： 88万元

中文摘要： 减数分裂是真核生物有性生殖过程中的一个重要阶段。在这个过程中，同源染色体发生联会、配对，进而交换重组。在大多数真核生物中，每对同源染色体只发生1-2次交换重组，且主要发生在染色体两端，很少发生在着丝粒和近着丝粒区域。这种重组非均匀分布的形成机理目前还不清楚。最新研究表明，在拟南芥中通过降低DNA甲基化可使基因重组位点分布发生巨大改变。我们最新研究也表明玉米减数分裂最早期起始位点多发生在染色体低甲基化区域。这些前期研究结果为我们探索DNA甲基化在减数分裂基因重组中的重要作用提供了线索。在本项目中，我们将 研究调控玉米DNA甲基化形成的关键基因，包括DDM1、MET1以及CMT3； 利用反向遗传学方法，鉴定这些基因的缺失突变体；结合多种分子生物学手段，解析DNA甲基化在减数分裂基因重组过程中的生物学作用。研究结果将为增加基因重组率、提高育种效率提供理论依据和可行性方法。

中文关键词： 减数分裂；DNA甲基化；DNA双链断裂；交换重组；玉米

英文摘要： Meiotic recombination is an essential process of the life cycles in all sexually reproducing eukaryotes. During this process, homologous pairs of chromosomes closely align up allowing exchange of chromosome segments. In most of eukaryotes, each pair of homologous chromosomes undergoes 1-2 crossovers. In addition, the sites occurring crossovers are not uniformly distributed along chromosomes with the majority located at the distal arm and rarely in centromere or pericentromere regions. Until now, mechanisms determining such non-uniform distribution of chromosomal crossover remain elusive. Recently, it has been demonstrated that the reduction in DNA methylation caused the re-patterning of crossover in Arabidopsis. Meanwhile, our previous study has shown that the initiation sites of recombination more often occur in the chromosomal regions with low levels of methylation, suggesting that DNA methylation could play important roles in regulating meiotic recombination. To reveal the functions of DNA methylation in controlling recombination, in this study, we will identify mutants defective in three key genes mediating methylation biosynthesis in maize, DDM1, MET1 and CMT3; characterize meiotic phenotypes in those mutants, including alterations in chromosomal behavior and the effects in recombination formation and distribution. We anticipate that this research would increase our understanding of meiotic recombination patterning and could provide a plausible method to increase recombination rate and facilitate more efficient breeding.

英文关键词： meiosis;DNA methylation;DNA double-stranded break;crossover;maize