倒伏是影响油菜产量、品质和机械化的关键因素。本项目前期发现一个蕾薹末期茎秆弯曲的茎倒突变体stb1；分析表明其受常染色体上的隐性单基因控制，定位于A01染色体的1.995 Mb范围内；RNA-Seq分析表明stb1茎秆中生长素极性运输相关基因显著下调。我们推测stb1的曲茎表型可能与生长素极性运输速率低于新生茎秆伸长速率，导致生长素异常积累和分布有关。本项目将继续构建F2精细定位群体，图位克隆STB1基因；通过qRT-PCR、原位杂交和启动子分析，明确STB1的表达模式；对转基因植株进行深入研究以解析STB1基因功能；RNA-Seq、ChIP-Seq或RIP-Seq鉴定下游调控基因；免疫共沉淀结合质谱分析及酵母双杂交筛选互作蛋白，构建以STB1基因为核心的生长素极性运输速率调控网络。研究结果将为油菜抗倒育种提供分子理论基础，为生长素极性运输速率调控机制研究提供新的研究思路和模型。

Lodging is a key factor in reducing seed yield and quality and limiting the mechanized production of rapeseed (Brassica napus). In previous study, a stem lodging mutant with stem bending phenotype at the end of bud stage has been identified and named stb1. Genetic analysis demonstrated that the mutant was controlled by a single autosomal recessive gene, which has been mapped to a 1.995-Mb region of chromosome A01. RNA-Seq analysis showed that genes involved in polar auxin transport were significantly down-regulated in the stem of stb1 mutant. We proposed that the stem bending phenotype of stb1 mutant was probably caused by the slower velocity of polar auxin transport than the elongation speed of stem, which leading to abnormalities in auxin accumulation and distribution. To validate the hypothesis, the F2 segregating population will be constructed and used for map-based cloning of STB1 gene. Quantitative reverse transcription-PCR (qRT-PCR), in situ hybridization and promoter analysis will be used to reveal the temporal and spatial expression patterns of this gene. The biological function of STB1 will be elucidated by further studies on the complement plants, STB1-silencing and -overexpressing transgenic plants. The downstream genes regulated by STB1 will be screened with RNA-Seq, ChIP-Seq or RIP-Seq analysis. Proteins interacting with STB1 will be fished out by immunoprecipitation combined with mass spectrometry analysis and validated by yeast-two hybrid system. The STB1-centric regulatory network of the velocity of polar auxin transport will be summarized based on abovementioned studies. Our researches not only lay a theoretical foundation for the lodging resistance breeding of rapeseed, but also provide a novel research strategy and model for investigation on the molecular regulatory mechanism of the velocity of polar auxin transport.