绿豆芽萌发过程维生素C积累的代谢调控机制

Mung bean sprouts are the largest demand of vegetables in China because of short production cycle and high nutritional value. Our previously research showed that vitamin C content was dramatically increased in mung bean sprouts during germination (almost 24 folds), and the antioxidant quality of mung bean sprouts was significantly enhanced followed by the rising of vitamin C. However, the regulatory mechanism of vitamin C metabolism was not systemically and deeply studied in mung bean sprouts. The research experiences on vitamin C metabolic regulation in our lab showed that regulation of key-encoding genes in L-galactose pathway was significant effect on vitamin C biosynthesis, and over-expression of ascorbate reductase also improved the regeneration cycle of vitamin C in plant. Our hypothesis is that L-galactose biosynthetic pathway and regeneration cycle for vitamin C accumulation was activated by germination in mung bean sprouts. The proposal aims to study the regulatory mechanism of vitamin C biosynthesis and regeneration in mung bean sprouts during germination. Functional genes screening related to vitamin C metabolism in mung bean sprouts will be analyzed by RNA-seq technique. Gene expression patterns and enzyme activities related to vitamin C metabolism will be analyzed in mung bean sprouts. Upon the comprehensive evaluation of functional gene expression profiles and key enzyme activities in mung bean sprouts, the metabolic regulatory network of vitamin C will be revealed in our study. The expected results will provide theoretical guidance and technical support for production technology optimization and nutrition quality fortification for mung bean sprouts, and will have great social economic value for agricultural processing.

绿豆芽的生产周期短、营养价值高，是我国需求量最大的芽苗菜。研究表明，绿豆在萌芽过程中其维生素C的含量可急剧增高（24倍），维生素C积累明显增强绿豆芽抗氧化品质，但与之相关的机理，未见较系统和深入的研究。本人所在实验室通过对维生素C代谢调控研究发现，植物维生素C的L-半乳糖合成途径功能基因表达调控对维生素C合成有明显影响，增强抗坏血酸还原酶基因的表达能提高维生素C的再生循环。因此，推测萌芽可能通过激活绿豆芽维生素C的L-半乳糖合成途径和再生循环，导致绿豆芽维生素C含量显著提升。本项目拟通过转录组测序筛选绿豆芽维生素C代谢调控相关功能基因，分析功能基因的表达模式，构建绿豆芽维生素C代谢通路，探明影响绿豆芽维生素C增高的主要因素及其过程，为优化绿豆芽生产工艺和强化营养品质提供理论依据。

植物种子萌发是一个涉及很多基因调控的复杂的生物过程。绿豆芽的生产周期短、营养价值高，是我国需求量最大的芽苗菜。研究表明，绿豆在萌芽过程中其维生素C的含量可急剧增高（24倍），维生素C积累明显增强绿豆芽抗氧化品质，但与之相关的机理，未见较系统和深入的研究。本研究针对绿豆芽萌发过程的三个生长阶段，基于二代高通量测序技术获得了不同发育阶段的差异基因30050个，其中上调基因10225个，下调基因7006个；通过KEGG数据库关联分析发现，绿豆芽萌发过程细胞分裂、环境胁迫、遗传信息加工、代谢调控等124个通路受到影响；通过代谢组学技术获得了160个差异代谢物特征峰，其中60个特征峰经标准品检测为已知单体化合物，主要为碳水化合物、氨基酸、有机酸以及植物激素等代谢物；对绿豆芽萌发过程维生素C合成的L-半乳糖途径、L-古洛糖途径、肌醇途径以及糖醛酸途径基因表达情况进行系统研究，并对维生素C分解再生途径以及维生素C-谷胱甘肽氧化还原途径的关键酶基因进行了表达研究，并对维生素C代谢途径的关键酶表达浓度与活性进行了验证，明确了绿豆芽萌发过程维生素C的代谢调控系统，阐明了萌芽动力强化绿豆芽维生素C合成与代谢的调控机制，探明了影响绿豆芽维生素C积累的主要因素及其调控模式，为优化绿豆芽生产工艺和强化营养品质提供了理论依据，也为分子改良农作物种子萌发性状、提高种子发芽率和品质形状提供重要理论依据。