Key Laboratory of Plant-Soil Interactions (Ministry of Education), College of Resources and Environmental Sciences, National Academy of Agriculture Green Development, China Agricultural University, Beijing 100193, China.
Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agricultural and Rural Affairs, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan 430062, China.
Int J Mol Sci. 2022 Apr 15;23(8):4389. doi: 10.3390/ijms23084389.
Stem node has been found to be a hub for controlling mineral nutrient distribution in gramineous plants. However, the characteristics of stem nodes associated with whole-plant carbon partitioning in maize ( L.) and their responses to nitrogen (N) availability remains elusive. Maize plants were grown in greenhouse under low to high N supply. Plant growth, sugar accumulation, and sugar transporters in nodes and leaves, as well as the anatomical structure of nodes, were investigated at vegetative phase. When compared to N-sufficient plants, low-N availability stunted growth and resulted in 49-64% less sugars in leaves, which was attributed to low photosynthesis or the accelerated carbon export, as evidenced by more C detected further below leaf tips. Invariably higher sugar concentrations were found in the stem nodes, rather than in the leaves across N treatments, indicating a crucial role of nodes in facilitating whole-plant carbon partitioning. More and smaller vascular bundles and phloem were observed in stem nodes of N-deficient plants, while higher sugar levels were found in the bottom nodes than in the upper ones. Low-N availability upregulated the gene expressions of sugar transporters, which putatively function in nodes such as and at the bottom stem, but suppressed them in the upper ones, showing a developmental impact on node function. Further, greater activity of sugar transporters in the bottom nodes was associated with less sugars in leaves. Overall, these results highlighted that stem nodes may play an important role in facilitating long-distance sugar transport in maize.
茎节点被发现是禾本科植物控制矿物养分分布的中心。然而，与玉米（L.）整个植株碳分配相关的茎节点特征及其对氮（N）供应的响应仍不清楚。在低氮和高氮供应的温室条件下种植玉米植株。在营养生长期，研究了植株生长、节点和叶片中的糖积累和糖转运体以及节点的解剖结构。与氮充足的植株相比，低氮供应会抑制生长，导致叶片中的糖减少 49-64%，这归因于光合作用降低或碳的加速输出，因为在叶片尖端下方检测到更多的 C。无论氮处理如何，节点中的糖浓度始终高于叶片中的糖浓度，这表明节点在促进整个植株的碳分配中起着至关重要的作用。在氮缺乏的植株中，茎节点中观察到更多和更小的维管束和韧皮部，而下部节点的糖含量高于上部节点。低氮供应上调了糖转运体的基因表达，这些基因在底部茎的节点中可能发挥作用，如 和 ，但在顶部节点中却受到抑制，这表明对节点功能的发育影响。此外，下部节点中糖转运体的活性增加与叶片中的糖含量减少有关。总的来说，这些结果强调了茎节点可能在促进玉米中长距离糖运输中发挥重要作用。
