褪黑素在动物中是一种重要的吲哚胺类激素，具有调节活性氧、促进睡眠、抗衰老、调节免疫等多项生理功能。相对于动物中褪黑素合成分解及信号途径研究得很清楚，植物里的相关研究则刚刚起步，还有很多问题不清楚。比如植物褪黑素水平如何受到严密的调控？褪黑素合成代谢中有哪些主要或限速步骤？褪黑素如何调控植物抗病反应的分子机制？等等。申请人将围绕以上问题，以木薯为研究对象，以褪黑素合成基因为着眼点，通过筛选并验证互作蛋白和上游转录因子，系统分析其所形成的蛋白复合体及调节的抗细菌性枯萎病反应。由于褪黑素和生长素的合成共用相同的前体-色氨酸，且褪黑素与生长素均调节植物抗病反应，我们还将探讨褪黑素合成基因对生长素含量的影响，从蛋白互作及激素互作等方面阐明这些基因介导生长素与褪黑素信号互作调控植物抗病反应的分子机理，构建新遗传网络。通过以上研究，既解决相关科学问题，又探索褪黑素及其合成基因在木薯抗病分子育种中的应用。

Melatonin (N-acetyl-5-methoxytryptamine) is a tryptophan-derived indole molecule that is very important in animals. Melatonin involved in antioxidative activity through its interaction with reactive oxygen species, sleep physiology, senescence, innate and special immunity, etc. Compared with the melatonin synthesis and signal transduction pathway in animals, the related research in plants is just started. However, there are a lot of questions remain clear. For example, how the endogenous melatonin level is strictly regulated in plants? What are the main or the rate limiting steps in melatonin synthesis? How melatonin regulates plant stress resistance and what is the underlying mechanism? Based on the above issues in cassava, we will focus on melatonin synthesis genes in cassava. Through screening the interacting proteins and upstream transcription factors of melatonin synthesis genes, we will investigate these genes-formed protein complex-mediated defense responses to cassava bacterial blight. Because melatonin and auxin synthesis shared the same precursor-tryptophan, and they are involved in plant immune response, we will discuss the effect of melatonin biosynthesis genes on auxin content. We will also reveal the molecular mechanism of these genes-formed protein complex involved the crosstalk between auxin and melatonin signalings and mediated plant biotic and abiotic stress responses, from the aspects of protein interaction and phytohormone crosstalk. Based on above studies, we will solve the related scientific questions, and explore the possible application of melatonin as well as melatonin synthesis genes in cassava molecular breeding of disease resistance.