Regulation of nitrogen storage and mobilization in the annual life cycle of poplar

氮素营养是树木生长的主要限制因素，因此，氮素吸收和同化受到高度调控。最近的研究表明，除了谷氨酰胺等还原氮化合物外，细胞分裂素等植物激素还可以调节硝酸盐的吸收。本项目的中心目的是验证两条相互拮抗的调节通路参与树木对氮素需求的适应：(1)特定氨基酸化合物的丰富是抑制氮素吸收的信号；(2)细胞分裂素的丰富增加了与氮素吸收和同化相关的基因的表达。分子和生理方法与计算机模拟相结合的方法将被用来评估减少的N-化合物和细胞分裂素在杨树体内的N代谢的调节及其在植物内的循环。

Nitrogen nutrition is a major growth limiting factor for trees and, therefore, nitrogen uptake and assimilation are highly regulated. Recently it was shown that beside reduced nitrogen compounds, e.g. glutamine, phytohormones such as cytokinins regulate nitrate uptake. The central aim of this project is to test the hypothesis that two antagonistic regulatory pathways are involved in the adaptation of N uptake by the roots to the N-demand of trees: (1) The enrichment of particular amino compounds serves as signal for the repression of nitrogen uptake and (2) the enrichment of cytokinins increases the expression of genes involved in nitrogen uptake and assimilation. A combination of molecular and physiological methods with computer modelling will be used to assess the regulation of N-metabolism by reduced N-compounds and cytokinins in poplar and their cycling within the plant.