Plant-Microsymbiont Interaction Lab, Division of Molecular Systems Biology, Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria; Research Support Facilities, Mass Spectrometry Unit UBB, University of Vienna, Vienna, Austria.
Research Support Facilities, Mass Spectrometry Unit UBB, University of Vienna, Vienna, Austria.
J Plant Physiol. 2024 Jun;297:154260. doi: 10.1016/j.jplph.2024.154260. Epub 2024 Apr 26.
Sulfur is an essential nutrient for all plants, but also crucial for the nitrogen fixing symbiosis between legumes and rhizobia. Sulfur limitation can hamper nodule development and functioning. Until now, it remained unclear whether sulfate uptake into nodules is local or mainly systemic via the roots, and if long-distance transport from shoots to roots and into nodules occurs. Therefore, this work investigates the systemic regulation of sulfur transportation in the model legume Lotus japonicus by applying stable isotope labeling to a split-root system. Metabolite and protein extraction together with mass spectrometry analyses were conducted to determine the plants molecular phenotype and relative isotope protein abundances. Data show that treatments of varying sulfate concentrations including the absence of sulfate on one side of a nodulated root was not affecting nodule development as long as the other side of the root system was provided with sufficient sulfate. Concentrations of shoot metabolites did not indicate a significant stress response caused by a lack of sulfur. Further, we did not observe any quantitative changes in proteins involved in biological nitrogen fixation in response to the different sulfate treatments. Relative isotope abundance of S confirmed a long-distance transport of sulfur from one side of the roots to the other side and into the nodules. Altogether, these results provide evidence for a systemic long-distance transport of sulfur via the upper part of the plant to the nodules suggesting a demand driven sulfur distribution for the maintenance of symbiotic N-fixation.
硫是所有植物的必需营养物质，但对豆科植物与根瘤菌之间的固氮共生也至关重要。硫素限制会阻碍根瘤的发育和功能。到目前为止，仍不清楚硫酸盐进入根瘤是局部吸收还是主要通过根部进行系统吸收，以及是否存在从地上部分到根部再到根瘤的长距离运输。因此，本研究通过对分根系统进行稳定同位素标记，研究了模式豆科植物百脉根中硫素运输的系统调控。进行了代谢物和蛋白质提取以及质谱分析，以确定植物的分子表型和相对同位素蛋白丰度。数据表明，在根瘤形成的一侧根缺乏硫酸盐的情况下，只要另一侧根系提供足够的硫酸盐，就不会影响根瘤的发育。地上部分代谢物的浓度并没有表明由于缺乏硫而导致明显的应激反应。此外，我们没有观察到任何参与生物固氮的蛋白质对不同硫酸盐处理的定量变化。S 的相对同位素丰度证实了硫从根系一侧向另一侧和根瘤的长距离运输。总的来说，这些结果为硫通过植物的上部进行系统长距离运输到根瘤提供了证据，表明为了维持共生固氮，硫的分配是由需求驱动的。
