多不饱和脂肪酸对植物抗寒具有重要作用。前期我们在牡丹中发现了一个响应低温胁迫关键转录因子bZIP19，直接与多不饱和脂肪酸合成酶基因FAD3-2启动子相结合，而FAD3-2受低温处理显著诱导，其过表达提高了转基因拟南芥中多不饱和脂肪酸含量以及植株抗寒能力。本研究拟通过牡丹病毒诱导基因沉默和拟南芥遗传转化技术，结合qRT-PCR、气质联用检测和低温处理实验，验证bZIP19对多不饱和脂肪酸合成相关基因表达、成分积累及低温胁迫的影响；然后利用酵母双杂交系统，筛选bZIP19的互作蛋白；利用双分子荧光互补实验，确证bZIP19与候选蛋白之间互作关系；在本源沉默和异源表达系统中探究互作蛋白抗寒功能；进一步通过基因表达谱和蛋白表达谱分析，筛选表达变化显著候选基因，构建bZIP19下游完整调控网络。最终阐明bZIP19介导多不饱和脂肪酸调控牡丹耐低温胁迫分子机理，为观赏园艺植物抗寒育种提供理论支持。

Polyunsaturated fatty acids play an essential role in plant resistance to cold. In previous studies, we found that a low temperature-responsive key transcription factor bZIP19 physically bound to the promoter of FAD3-2, which was an enzyme gene in the polyunsaturated fatty acid biosynthesis pathway. FAD3-2 was significantly induced by low temperature treatment, and its constitutive overexpression increased content of polyunsaturated fatty acids and resistance capability of transgenic Arabidopsis plants to cold stress. In this project, we will examine the impact of bZIP19 on polyunsaturated fatty acid biosynthesis-related genes expression, components accumulation, and response to cold threat, using virus-induced gene silencing in tree peony and genetic transformation in Arabidopsis combined with qRT-PCR, GC-MS, and low temperature treatment assays. Next, yeast two-hybrid system will be performed to identify the interacting protein of bZIP19, and bimolecular fluorescence complementation experiment will be carried out to confirm the interaction between bZIP19 and candidate protein. The function of interacting protein in cold resistance will be explored in native silencing and heterologous expression systems. We will further screen candidate genes with remarkable expression changes and construct a downstream complete regulatory network of bZIP19 through gene and protein expression profiles. Ultimately, our results could reveal the molecular mechanism of bZIP19-mediated polyunsaturated fatty acid in tree peony tolerance to low temperature, and provide a theoretical support for cold-resistant breeding of ornamental horticultural plants.