ABA-mediated stress response with focus on salt-stress and trunk development

硝酸还原酶（NR）是草本植物中研究最多的酶之一。然而，很少有人知道木本植物中的硝酸盐同化。白杨作为具有所有已知益处的树木的模式植物将使我们能够更详细地研究这一途径。我们将利用我们现有的知识，在烟草中的器官特异性表达的硝酸盐在木本植物的硝酸盐同化的复杂的调节。我们将分析根和地上部之间的串扰，这些器官之间的硝酸盐和还原氮化合物的分配，仅在根中的N-同化的阈值和N-化合物的储存能力。我们的工作将集中在不同的水平上，通过（i）分析已经存在的稳定转化的杨树品系含有不同的基因构建体，包括NR和钼辅因子生物合成途径的基因，（ii）产生一组新的转化白杨建立RNAi技术，和（iii）分析NR的启动子。通过与研究小组其他小组的密切合作，这些研究将在以下领域为白杨提供见解：氮同化和分配，不同组织对硝酸盐还原的重要性，硝酸盐还原酶与氮同化途径后续酶之间的相关性，与其他生物的相互作用（菌根）、植物激素对硝酸盐吸收的重要性、温度和氧气短缺对根系N同化的重要性（季节效应）、盐胁迫对N同化的影响。

Nitrate reductase [NR] is one of the best studied enzymes in herbaceous plants. However, little is known about nitrate assimilation in woody plants. Poplar as the model plant for trees with all of the known benefits will allow us to investigate this pathway in more detail. We will investigate the complex regulation of nitrate assimilation in woody plants by making use of our already existing knowledge of organ-specific expression of NR in tobacco. We will analyze the cross-talk between roots and shoot, the allocation of nitrate and reduced N-compounds between these organs, the threshold of N-assimilation exclusively in the roots and the storage capacity of N-compounds. Our work will be focused on different levels by (i) analyzing the already existing stably transformed poplar-lines containing different gene constructs including genes of NR and of the molybdenum cofactor biosynthetic pathway, (ii) producing a new set of transformed poplar plants be establishing the RNAi technique, and (iii) analyzing the promoter of NR. In tight collaboration with other groups of the Forschergruppe, these studies will give insights for poplar in the following areas: N-assimilation and allocation, importance of the different tissues for nitrate reduction, correlation between NR and the subsequent enzymes of the N-assimilation pathway, interaction with other organisms (mycorrhiza), importance of phytohormones for nitrate-uptake, importance of temperature and oxygen shortage for root N-assimilation (seasonal effects), influence of N-assimilation by salt stress.