Amoah Joseph N, Keitel Claudia, Kaiser Brent N
School of Life and Environmental Sciences, University of Sydney, 380 Werombi Road, Brownlow Hill, Camden, NSW 2570 Australia.
Physiol Mol Biol Plants. 2025 Jul;31(7):1089-1103. doi: 10.1007/s12298-025-01631-0. Epub 2025 Aug 6.
Sugars are essential for plant development, with nitrogen (N) availability playing a critical role in their distribution across plant organs, ultimately shaping growth patterns. However, the regulatory mechanisms modulating carbon (C) assimilate allocation and utilization under different N forms are not well understood. This study examined C fixation, utilization, and spatial re-distribution in the roots of hydroponically grown maize seedlings subjected to four N treatments: 1 mM NO (low N; LN), 2 mM NO (medium N; MN), 10 mM NO (high N; HN), and 1 mM NH (low ammonium; LA). LN treatment significantly increased soluble sugar, sucrose, and starch contents while promoting greater root biomass at the expense of shoot biomass, leading to a higher root to shoot assimilate allocation. The activities of sugar and starch metabolism enzymes were more tightly regulated under LN, indicating enhanced C utilization and increased competition for assimilates. Key genes involved in sugar (, , , , , and ) and starch ( and ) metabolism were upregulated under LN, correlating with increased root sucrose and starch accumulation and enhanced enzyme activity. Sucrose and starch accumulated predominantly in the brace and lateral roots. This pattern suggests that excess C accumulation results from inefficient C utilization in sink tissues rather than impaired C assimilation. These findings provide new insights into how LN modulates C partitioning in roots for stress adaptation, highlighting the importance of improving C utilization in sink tissues to mitigate N deficiency and enhance plant growth.
The online version contains supplementary material available at 10.1007/s12298-025-01631-0.
糖类对植物发育至关重要，氮素（N）的可利用性在其在植物器官间的分配中起关键作用，最终塑造生长模式。然而，不同氮形态下调节碳（C）同化产物分配和利用的调控机制尚不清楚。本研究检测了水培玉米幼苗根系在四种氮处理下的碳固定、利用和空间重新分配情况：1 mM NO₃⁻（低氮；LN）、2 mM NO₃⁻（中氮；MN）、10 mM NO₃⁻（高氮；HN）和1 mM NH₄⁺（低铵；LA）。LN处理显著增加了可溶性糖、蔗糖和淀粉含量，同时促进了更大的根生物量，以地上部生物量为代价，导致根对地上部同化产物分配更高。在LN处理下，糖和淀粉代谢酶的活性受到更严格的调控，表明碳利用增强，对同化产物的竞争增加。参与糖（SUS1、SUS2、SUS3、SUS4、SUS5和SUS6）和淀粉（AGPase和GBSS）代谢的关键基因在LN处理下上调，与根中蔗糖和淀粉积累增加以及酶活性增强相关。蔗糖和淀粉主要积累在支持根和侧根中。这种模式表明，过量的碳积累是由于库组织中碳利用效率低下而非碳同化受损所致。这些发现为LN如何调节根系中的碳分配以适应胁迫提供了新见解，突出了提高库组织中碳利用以减轻氮缺乏和促进植物生长的重要性。
在线版本包含可在10.1007/s12298-025-01631-0获取的补充材料。
