Asparagine metabolism and function in nitrogen signalling

种子蛋白质的积累依赖于对发育中的胚胎的氮素供应，这影响了碳在不同贮藏产品中的分配。天冬酰胺是氮素的一种主要形式，通常被输送到下沉组织。在叶片中，天冬酰胺也在夜间短暂积累，在没有光合作用的情况下，有机酸水平不足以进行氮同化。这项建议的目标是实现对天冬酰胺代谢的详细了解，以及天冬酰胺在植物中作为代谢物信号的功能和认知。这项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诱导的基因表达变化的信号网络。天冬酰胺生物合成酶天冬酰胺合成酶的磷酸化对天冬酰胺生物合成昼夜循环的控制也将被研究。将使用包括细胞生物学、分子遗传学、代谢物分析、酶学和翻译后修饰的表征在内的综合方法来解决这些目标。拟议的研究将提高我们对植物氮代谢的理解，并可能导致生物技术策略来操纵谷物中的储藏产品水平或提高作物的氮素利用效率。

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.