Peng Wen Ting, Zhang Lu Dan, Zhou Zhi, Fu Chen, Chen Zhi Chang, Liao Hong
College of Resources and Environment, Fujian Agriculture and Forestry University, Fujian, Fuzhou, 350002, China.
Root Biology Center, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Physiol Plant. 2018 Mar 23. doi: 10.1111/ppl.12730.
Magnesium (Mg) is an essential element for the growth of both plants and bacteria. Low availability of Mg in agriculture can limit crop productivity and quality. In addition to direct effects on plant growth, limited Mg supply may also impact biological dinitrogen (N ) fixation in nodules formed from symbiotic interactions between legumes and rhizobial bacteria. To date, the physiological mechanisms involved in Mg-dependent nodulation remains largely unknown. The objectives of this work were to assess how Mg supply affects nodule growth and development in symbiotic systems, and to test if any observed changes in nodule and soybean are correlated with Mg supply. Here, we found that external Mg supply enhanced nodule growth under nitrogen (N) limited conditions, and subsequently improved N fixation and soybean growth. Mg supply altered neither nodule structure nor Mg homeostasis, but remarkably promoted nodule enlargement, resulting in an increase in the number of big nodules. In addition, high Mg supply decreased starch and sucrose accumulation in leaves, and increased their concentrations in roots, which consequently enhanced carbohydrate import into the rhizobia infection zone of nodules. In this study, Mg was shown to promote nodule growth in soybean. This Mg-promoted nodule growth is derived from Mg-facilitated alteration of carbohydrate partitioning and transport into nodules.
镁（Mg）是植物和细菌生长所必需的元素。农业中镁的有效性低会限制作物的生产力和品质。除了对植物生长有直接影响外，镁供应有限还可能影响豆科植物与根瘤菌共生相互作用形成的根瘤中的生物固氮作用。迄今为止，镁依赖型根瘤形成所涉及的生理机制仍 largely unknown。这项工作的目的是评估镁供应如何影响共生系统中根瘤的生长和发育，并测试根瘤和大豆中观察到的任何变化是否与镁供应相关。在这里，我们发现外部镁供应在氮（N）有限的条件下促进了根瘤生长，随后改善了固氮作用和大豆生长。镁供应既没有改变根瘤结构也没有改变镁稳态，但显著促进了根瘤增大，导致大根瘤数量增加。此外，高镁供应降低了叶片中淀粉和蔗糖的积累，并增加了它们在根中的浓度，从而增强了碳水化合物向根瘤根瘤菌感染区的输入。在这项研究中，镁被证明能促进大豆根瘤生长。这种镁促进的根瘤生长源于镁促进的碳水化合物分配和向根瘤运输的改变。
