Department of Plant Bioenergetics, Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland.
Imaging Laboratory, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland.
J Plant Physiol. 2024 Jul;298:154264. doi: 10.1016/j.jplph.2024.154264. Epub 2024 May 7.
Proper plant growth requires balanced nutrient levels. In this study, we analyzed the relationship between ammonium (NH) nutrition and calcium (Ca) homeostasis in the leaf tissues of wild-type and mutant Arabidopsis specimens provided with different nitrogen sources (NH and nitrate, NO). Providing plants with NH as the sole nitrogen source disrupts Ca homeostasis, which is essential for activating signaling pathways and maintaining the cell wall structure. The results revealed that the lower Ca content in Arabidopsis leaves under NH stress might result from reduced transpiration pull, which could impair root-to-shoot Ca transport. Moreover, NH nutrition increased the expression of genes encoding proteins responsible for exporting Ca from the cytosol of leaf cells. Furthermore, overexpression of the Ca/H antiporter 1 (CAX1) gene alleviates the effects of NH syndrome, including stunted growth. The oeCAX1 plants, characterized by a lower apoplastic Ca level, grew better under NH stress than wild-type plants. Evaluation of the mechanical properties of the leaf blades, including stiffness, strength, toughness, and extensibility, showed that the wild-type and oeCAX1 plants responded differently to the nitrogen source, highlighting the role of cell wall metabolism in inhibiting the growth of NH-stressed plants.
植物的正常生长需要营养物质的平衡。在这项研究中，我们分析了在提供不同氮源（铵和硝酸盐）的情况下，野生型和突变型拟南芥叶片组织中铵（NH）营养与钙（Ca）稳态之间的关系。将植物提供 NH 作为唯一氮源会破坏 Ca 稳态，这对于激活信号通路和维持细胞壁结构是必不可少的。结果表明，NH 胁迫下拟南芥叶片中较低的 Ca 含量可能是由于蒸腾拉力降低所致，这可能会损害根到茎的 Ca 运输。此外，NH 营养会增加编码负责将 Ca 从叶细胞质中输出的蛋白质的基因的表达。此外，过表达 Ca/H 反向转运蛋白 1（CAX1）基因可减轻 NH 综合征的影响，包括生长迟缓。oeCAX1 植物具有较低的质外体 Ca 水平，在 NH 胁迫下比野生型植物生长得更好。对叶片叶片力学性能（包括刚度、强度、韧性和伸展性）的评估表明，野生型和 oeCAX1 植物对氮源的反应不同，这突出了细胞壁代谢在抑制 NH 胁迫植物生长中的作用。
