油菜是我国最重要的油料作物之一，然而很多调节基因对其油脂积累的分子机制仍不清楚。我们前期发现油菜种子油脂积累的重要调节基因BnFUS3-1与DNA拓扑异构酶BnTOP1α-1存在蛋白互作，并首次多角度证实了BnTOP1α-1显著抑制油菜种子油脂的积累。本项目拟从三个方面解析BnTOP1α-1在种子油脂复杂调控网络中的作用机制：一是通过过表达、RNAi、CRISPR/Cas9和转基因等方法分析BnTOP1α-1在油菜种子油脂积累中的作用；二是通过RNA-seq、ChIP-seq、蛋白与靶DNA体内和体外结合、遗传互作以及组蛋白修饰等研究，明确BnTOP1α-1以及它与BnFUS3-1的互作对下游直接调控靶基因的调控机制；三是利用高、低含油量甘蓝型油菜种质将BnTOP1α-1开发成种子含油量的功能性分子标记。本项目的开展不仅具有很好的理论意义，而且能够指导高含油量育种实践并具有潜在的应用价值。

Oilseed rape (Brassica napus L.) is one of the most important oil-producing crops in China. However, the molecular mechanisms of many regulatory genes regarding to seed oil accumulation are largely unknown in B. napus. Our preliminary results indicated that BnFUS3-1 important for seed oil accumulation interacts with BnTOP1α-1 at the protein level. Besides, we first demonstrated BnTOP1α-1 significantly inhibits seed oil accumulation in B.napus. Based on these findings, the regulatory mechanism of BnTOP1α-1 in sophisticated regulatory networks of seed oil accumulation will be investigated on the three following aspects in this proposal: (1) Many techniques that include overexpression, RNAi, CRISPR/Cas9, and transgenic methods will be employed to clarify functions of BnTOP1α-1 on seed oil accumulation. (2) Many experiments will be performed to explore how BnTOP1α-1 and the cross-talk between it and the important regulatory protein (BnFUS3-1) directly regulate the down-stream genes in seed oil biosynthesis. These experiments mainly include RNA-seq, ChIP-seq, binding assay in vitro and in vivo, genetic interaction, and histone methylation. (3) Through the investigation of its DNA sequences in B. napus germplasm with high and low oil content, BnTOP1α-1 will be developed into a useful functional molecular marker of seed oil content. This research project will not only help us understand the molecular mechanisms and the regulatory networks of seed oil accumulation in B. napus, but also guide the high-oil-content breeding practices and has potential application values in oil-producing crops, such as oilseed rape.