Table_2_Seasonal Alterations in Organic Phosphorus Metabolism Drive the Phosphorus Economy of Annual Growth in F. sylvatica Trees on P-Impoverished Soil.XLSX

Phosphorus (P) is one of the most important macronutrients limiting plant growth and development, particularly in forest ecosystems such as temperate beech (Fagus sylvatica) forests in Central Europe. Efficient tree internal P cycling during annual growth is an important strategy of beech trees to adapt to low soil-P. Organic P (Porg) is thought to play a decisive role in P cycling, but the significance of individual compounds and processes has not been elucidated. To identify processes and metabolites involved in P cycling of beech trees, polar-metabolome and lipidome profiling was performed during annual growth with twig tissues from a sufficient (Conventwald, Con) and a low-soil-P (Tuttlingen, Tut) forest. Autumnal phospholipid degradation in leaves and P export from senescent leaves, accumulation of phospholipids and glucosamine-6-phosphate (GlcN6P) in the bark, storage of N-acetyl-D-glucosamine-6-phosphate (GlcNAc6P) in the wood, and establishing of a phospholipid “start-up capital” in buds constitute main processes involved in P cycling that were enhanced in beech trees on low-P soil of the Tut forest. In spring, mobilization of P from storage pools in the bark contributed to an effective P cycling. Due to the higher phospholipid “start-up capital” in buds of Tut beeches, the P metabolite profile in developing leaves in spring was similar in beech trees of both forests. During summer, leaves of Tut beeches meet their phosphate (Pi) needs by replacing phospholipids by galacto- and sulfolipids. Thus, several processes contribute to adequate Pi supply on P impoverished soil thereby mediating similar growth of beech at low and sufficient soil-P availability.

磷（Phosphorus, P）是限制植物生长发育的关键大量营养元素之一，在中欧温带山毛榉（Fagus sylvatica）林等森林生态系统中，其养分限制作用尤为突出。山毛榉在年度生长周期内高效开展体内磷循环，是其适应低磷土壤环境的重要适应性策略。有机磷（Organic P, Porg）被认为在磷循环中扮演决定性角色，但目前尚未明确单一磷化合物及相关过程的具体贡献。为解析山毛榉磷循环所涉及的过程与代谢物，本研究以磷充足（康特瓦尔德，Conventwald, Con）与低磷土壤（图特林根，Tuttlingen, Tut）两处林分的嫩枝组织为材料，在年度生长周期内开展了极性代谢组（polar-metabolome）与脂质组（lipidome）谱分析。叶片秋季磷脂降解与衰老叶片的磷输出、树皮中磷脂及葡萄糖胺-6-磷酸（Glucosamine-6-phosphate, GlcN6P）的积累、木材中N-乙酰-D-葡萄糖胺-6-磷酸（N-acetyl-D-glucosamine-6-phosphate, GlcNAc6P）的储存，以及芽中磷脂“启动储备”的建立，构成了磷循环的核心过程，且在图特林根林分的低磷土壤山毛榉中这些过程显著增强。春季时，树皮储存库中的磷被动员利用，进一步推动高效磷循环的运转。由于图特林根山毛榉芽中的磷脂“启动储备”水平更高，两处林分山毛榉春季新生叶片的磷代谢物谱并无显著差异。夏季期间，图特林根山毛榉的叶片通过半乳糖脂与硫脂替代磷脂的方式，满足自身对磷酸根（Phosphate, Pi）的需求。综上，多种过程共同保障了低磷土壤中充足的磷酸根供应，从而使得山毛榉在低磷与磷充足两种土壤条件下的生长表现基本一致。