Asparagine metabolism and function in nitrogen signalling

种子蛋白质的积累依赖于发育中的胚的氮供应，这影响了碳在不同贮藏产物中的分配。天冬酰胺是氮的一种主要形式，通常被运送到汇组织。在叶片中，天冬酰胺也会在夜间短暂积累，因为在没有光合作用的情况下，有机酸的水平不足以同化氮。本研究的目的是详细了解天冬酰胺的代谢，以及天冬酰胺作为植物代谢信号的功能和感知。拟议的项目将试图了解天冬酰胺抑制根伸长的生理和代谢基础，并表征决定天冬酰胺引起的基因表达变化的信号网络。此外，还将研究天冬酰胺合成酶磷酸化对昼夜循环中天冬酰胺生物合成的控制作用。包括细胞生物学、分子遗传学、代谢物分析、酶学和翻译后修饰表征在内的综合方法将用于解决这些目标。该研究将有助于提高我们对植物氮代谢的认识，并可能为控制谷物储存产物水平或提高作物氮利用效率提供生物技术策略。

Seed protein accumulation is dependent on the supply of nitrogen to the developing embryo, which influences the partitioning of carbon into the different storage products. Asparagine is a major form of nitrogen commonly transported to sink tissue. In leaf, asparagine is also transiently accumulated at night when, in the absence of photosynthesis, levels of organic acids are insufficient for nitrogen assimilation. The objectives of this proposal are to achieve a detailed understanding of asparagine metabolism and of the function and perception of asparagine as a metabolite signal in plants. The proposed project will seek to understand the physiological and metabolic basis underlying the inhibition of root elongation by asparagine, and to characterize the signalling network determining changes in gene expression elicited by asparagine. Control of asparagine biosynthesis during the day and night cycle by phosphorylation of the asparagine biosynthetic enzyme asparagine synthetase will also be investigated. An integrated approach including cellular biology, molecular genetics, metabolite profiling, enzymology and characterization of post-translational modifications will be used to address these goals. The proposed research should improve our understanding of plant nitrogen metabolism and may lead to biotechnological strategies to manipulate the levels of storage products in grain or to enhance nitrogen use efficiency in crops.