基于代谢物流向解析烟草烟碱杂种优势形成的生理与分子机制

烟碱是在烟草的根部合成、通过木质部运输到叶片中积累的次生代谢产物。前期，我们发现烟碱具有明显的杂种优势，利用烟草根转录组分析揭示了超显性在烟叶烟碱杂种优势形成中的关键作用，发现与烟碱质膜转运和叶细胞积累相关的基因在杂交种根部表达水平显著上调，但烟叶烟碱杂种优势与烟碱转运和积累的关系仍有待阐明，特别是杂交种烟碱转运和积累提高的生理与分子机制缺乏了解。为此，本项目将通过分析不同优势杂交组合烟碱合成、转运和积累的规律，从酶组学水平上开展烟碱代谢相关酶基因在根茎叶中的差异表达研究，从代谢组学水平上开展烟碱代谢产物在根茎叶中的流向研究，并进行转录组学、酶组学及代谢组学的关联性分析。以期阐明烟草烟碱杂种优势与烟碱合成、转运和积累的关系，揭示烟碱杂种优势的形成的生理与分子机制。研究结果对于指导烟草生产和高烟碱烟草品种的培育具有重要意义。

Nicotine is a secondary metabolite that is synthesized in the roots of tobacco and accumulated in the leaves through xylem transport. We found in previous research that nicotine accumulation showed obvious heterosis. Analysis of tobacco root transcriptome suggested that overdominance played a key role in the formation of nicotine heterosis in tobacco leaves. We revealed that development of nicotine heterosis was related to higher synthetic efficiency of nicotine in hybrids. On the other hand, the relationship between nicotine heterosis and nicotine transport and accumulation in tobacco leaves remains unclear, and the physiological and molecular mechanisms promoting nicotine transport and accumulation are still poorly understood. In order to clarify the relationship between nicotine heterosis and nicotine synthesis, transport and accumulation in tobacco, and to reveal the physiological and molecular mechanisms of the development of nicotine heterosis, this project will analyze nicotine synthesis, transport, and accumulation in different dominant combinations. Research on the differential expression of genes related to the enzymes of nicotine metabolism in the roots, stems, and leaves at the level of enzymomics will be conducted. Translocation of nicotine related metabolites in the roots, stems, and leaves will be studied at the level of metabolomics. The correlation between transcriptomics, enzymomics and metabolomics will be analyzed. The research results will be of great significance for guiding tobacco production and breeding of tobacco varieties with high-nicotine content.