Key Laboratory of Plant-Soil Interaction, MOE, Center for Resources, Environment and Food Security, College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China.
Plant Cell Environ. 2015 Apr;38(4):740-50. doi: 10.1111/pce.12439. Epub 2014 Oct 7.
The plasticity of root architecture is crucial for plants to acclimate to unfavourable environments including low nitrogen (LN) stress. How maize roots coordinate the growth of axile roots and lateral roots (LRs), as well as longitudinal and radial cell behaviours in response to LN stress, remains unclear. Maize plants were cultivated hydroponically under control (4 mm nitrate) and LN (40 μm) conditions. Temporal and spatial samples were taken to analyse changes in the morphology, anatomical structure and carbon/nitrogen (C/N) ratio in the axile root and LRs. LN stress increased axile root elongation, reduced the number of crown roots and decreased LR density and length. LN stress extended cell elongation zones and increased the mature cell length in the roots. LN stress reduced the cell diameter and total area of vessels and increased the amount of aerenchyma, but the number of cell layers in the crown root cortex was unchanged. The C/N ratio was higher in the axile roots than in the LRs. Maize roots acclimate to LN stress by optimizing the anatomical structure and N allocation. As a result, axile root elongation is favoured to efficiently find available N in the soil.
根系结构的可塑性对于植物适应不利环境（包括低氮胁迫）至关重要。然而，玉米根系如何协调轴向根和侧根（LRs）的生长，以及轴向和径向细胞行为对低氮胁迫的响应，目前尚不清楚。本研究采用水培方法，在对照（4mm 硝酸盐）和低氮（40μm）条件下培养玉米植株。采集时间和空间样本，分析轴向根和侧根形态、解剖结构和碳/氮（C/N）比的变化。低氮胁迫增加了轴向根的伸长，减少了冠根的数量，降低了侧根的密度和长度。低氮胁迫延长了根中细胞伸长区的长度，增加了成熟细胞的长度。低氮胁迫降低了导管的细胞直径和总面积，增加了通气组织的数量，但冠根皮层的细胞层数没有变化。轴向根的 C/N 比高于侧根。玉米根通过优化解剖结构和氮分配来适应低氮胁迫。因此，轴向根的伸长有利于在土壤中有效地寻找可用的氮。
