The remobilization and resorption of plant nutrients is considered as a crucial aspect of the seasonal senescence of plant organs. In leaves, the mechanisms responsible for the relocation of valuable compounds are well understood while the related processes in roots are still being debated. Some research indicates that remobilization in roots occurs, while other studies have not found evidence of this process. Considering that the total biomass of fine roots is equal to or greater than that of leaves, clarifying the conflicting reports and ambiguities may provide critical information on the circulation of chemical elements in forest ecosystems. This study provides new information concerning the basis for remobilization processes in roots by combining physiological data with gene expression and protein levels. We suggest that, as in leaves, molecular mechanisms involved in nitrogen (N) resorption are also activated in senescent roots. An analysis of N concentration indicated that N levels decreased during the senescence of both organs. The decrease was associated with an increase in the expression of a glutamine synthetase (GS) gene and a concomitant elevation in the amount of GS—one of the most important enzymes in N metabolism. In addition, significant accumulation of carbohydrates was observed in fine roots, which may represent an adaptation to unfavorable weather conditions that would allow remobilization to occur rather than a rapid death in response to ground frost or cold. Our results provide new insights into the senescence of plant organs and clarify contentious topics related to the remobilization process in fine roots

中文翻译：

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毛白杨叶和根的季节性衰老-情况是相同还是不同？

植物养分的迁移和吸收被认为是植物器官季节性衰老的关键方面。在叶子中，负责有价值化合物重新定位的机理已广为人知，而有关根的相关过程仍在争论中。一些研究表明发生了根部的迁移，而其他研究尚未发现该过程的证据。考虑到细根的总生物量等于或大于叶片的总生物量，澄清矛盾的报告和歧义可能会提供有关森林生态系统中化学元素循环的关键信息。这项研究通过将生理数据与基因表达和蛋白质水平相结合，提供了有关根部固定过程基础的新信息。我们建议像叶子一样 参与氮（N）吸收的分子机制在衰老根中也被激活。对氮浓度的分析表明，两个器官的衰老过程中氮水平均下降。减少与α表达的增加有关。谷氨酰胺合成酶（GS）基因，伴随着GS含量的增加-GS是N代谢中最重要的酶之一。此外，在细根中观察到大量碳水化合物的积累，这可能是对不利天气条件的适应，这种天气条件将允许发生迁移，而不是因霜冻或寒冷而迅速死亡。我们的结果为植物器官的衰老提供了新的见解，并阐明了与根部修复过程有关的有争议的话题。