桑树MITEs高频转座机制及其在基因组中的作用研究

微型反向重复转座子（MITEs）在植物基因组中广泛存在。MITEs是DNA转座子，却具有高拷贝特征，且高拷贝MITEs常有转座活性，其高频转座机制及在基因组中的作用还需进一步深入研究。我们前期研究表明：1.桑树是迄今已报道MITEs拷贝数及含量最丰富的植物（显著高于代表性植物水稻）；2.桑树进化速度快于蔷薇目已测序物种；3.桑树具有丰富的资源多样性。鲜明特点使桑树成为研究MITEs不可多得的好材料，本研究结合转座子显示、Southern blot、酵母系统、生物信息学、转录组、比较基因组、基因组重测序等方法解析桑树MITEs高频转座机制，并从MITEs推动桑树基因组快速进化及提升桑树遗传变异多样性水平的角度阐释MITEs在基因组中的作用，最终回答MITEs“为什么多”和“有什么用”两个关键科学问题。本研究对理解桑树丰富的资源遗传多样性有重要意义，为桑树功能基因组研究及分子育种提供新思路。

Miniature inverted-repeat transposable elements (MITEs) are widespread in the plant genome. MITEs are DNA transposons, but they have a high copy number in the host genome, and high-copy MITEs often have transposition activity. Further research is needed to interpret the high-frequency transposition mechanism of MITEs and their role in shaping the host genome. Our previous study showed that: 1. Mulberry is the plant with the most abundant MITEs so far (significantly higher than that in the rice genome). 2. Mulberry evolves faster than other Rosales. 3. Mulberry has rich resource diversity. All these distinctive characteristics make mulberry a rare good material for researching MITEs. In this research, some methods, including transposon display, southern blot, yeast system, bioinformatics, transcriptome, comparative genome, and genome resequencing, will be performed to address the high-frequency transposition mechanism of those elements. Besides, we will interpret the role of MITEs in shaping the mulberry genome from the perspective of MITEs' role in promoting genome evolution and improving the level of genetic variation diversity. Finally, we will answer the two critical scientific questions of "why are there so many MITEs" and "What is the significance" of MITEs in the genome. It is of great importance to understand the abundant diversity of mulberry. What is more, this research will provide new ideas in mulberry genomic research and molecular genetics breeding.