Environmental and intrinsic regulation of phosphorus acquisition, partitioning, storage, and mobilization in beech and poplar trees

磷是植物生长和发育所必需的大量营养素，这是由于其在DNA和RNA中用于遗传、在游离核苷酸中用于能量转移、在磷脂中作为膜组分以及在糖磷酸盐中用于碳代谢（包括信号传导和调节）的功能。由于其在许多森林土壤中的可用性低，因此需要在植物和生态系统中有效吸收、使用和循环。此外，这些过程必须适应整个年度生长周期中不断变化的磷需求和环境变化，如增加氮沉积到生态系统中。本项目的目的是（一）的N-沉积对P-循环在山毛榉树的影响，（二）确定驱动程序和过程，控制P-循环在整个树，特别强调N-沉积，（三）检测内在因素，控制P-收购在不同的N-营养。氮沉降到温带森林生态系统强烈影响树木的氮循环，并影响N：P比。在本项目中，将在受控条件下和在SPP的两个对比核心田间点的田间调查氮沉降对白杨和山毛榉树中磷循环的影响;即土壤磷含量低的Lüss，因此预计将成为一个循环生态系统，而Bad Brückenau则是一个具有高植物有效磷的获取生态系统的例子。（在SPP的第一阶段期间进行的田间实验）将用于在受控条件下的实验中，以通过N-施肥诱导P-缺乏。白杨将被调查作为一个模式树种，允许分子分析，以确定内在因素控制磷循环在每年的生长周期，以及后N-沉积诱导的磷缺乏。此外，白杨将用于控制P-采集的系统信号。在所有实验中，将确定Pi和Porg（ATP和葡萄糖-6-P）的P采集和P池，即Ptot和Pi。两年后，开始N-，P-和NxP施肥实验，成年山毛榉树从现场Lüss和Bad Brückenau的施肥地块将进行分析，关于P-收购和P-循环在年度生长周期。

Phosphorus is an essential macronutrient for growth and development of plants due to its function in DNA and RNA for inheritance, in free nucleotides for energy transfer, in phospholipids as membranes components as well as in sugar phosphates for carbon metabolism including signalling and regulation. Because of its low availability in many forest soils, efficient uptake, use and cycling in plants and ecosystems are required. Furthermore, these processes have to be adapted to the changing phosphorus demand throughout the annual growth cycle and to environmental changes like increasing N-deposition into ecosystems. The present project aims (i) to characterize the influence of N-deposition on P-cycling in beech trees, (ii) to identify drivers and processes that control P-cycling within the whole tree with special emphasis on N-deposition and, (iii) to detect intrinsic factors that control P-acquisition at varying N-nutrition. N-deposition into temperate forest ecosystems strongly influences nitrogen cycling in trees und affects N:P ratios. In the present project the effects of N-deposition on P-cycling in poplar and beech trees will be investigated under controlled conditions and in the field at two contrasting core field sites of the SPP; namely Lüss with low soil P and thus expected to be a recycling ecosystem and Bad Brückenau as an example for an acquiring ecosystem with high plant available P. Beech seedlings from the Conventwald which were found to be P-acquiring (field experiments performed during the first phase of the SPP) will be used in experiments under controlled conditions to induce P-deficiency by N-fertilization. Poplar will be investigated as a model tree species that allows for molecular analyses to identify intrinsic factors controlling P-cycling during the annual growth cycle as well as after N-deposition induced P-deficiency. Furthermore, poplar will be used to work on systemic signals that control P-acquisition. In all experiments P-acquisition of Pi and Porg (ATP and glucose-6-P) and P-pools, i.e. Ptot and Pi, will be determined. Two years after starting N-, P- and NxP-fertilization experiments, adult beech trees from the fertilization plots of the field sites Lüss and Bad Brückenau will be analysed regarding P-acquisition and P-cycling during the annual growth cycle.