澳大利亚乐卓博大学Dugald Reid等研究人员合作发现，锌通过转录因子丝状化介导固氮控制。该项研究成果于2024年6月26日在线发表在《自然》杂志上。

研究人员发现了一种转录调节因子——FIXATION UNDER NITRATE（FUN），它起着传感器的作用，锌控制着非活性丝状结构与活性转录调节因子之间的转换。研究表明，当土壤硝酸盐含量较高时，根瘤中的锌浓度较低，会使丝状体解离并激活FUN。然后，FUN直接以多种途径为靶标，启动根瘤的分解。因此，锌依赖性丝状化机制建立了一个浓度读数，使根瘤功能适应环境氮条件。从更广阔的角度来看，这些结果对于理解金属离子在环境信号与植物发育的整合中的作用以及优化豆科作物固定氮的输送具有重要意义。

据介绍，植物通过调整新陈代谢和基因表达来适应不断变化的环境条件，从而保持健康。在豆科植物中，氮平衡是通过平衡从土壤资源中获取的氮和根瘤中共生细菌的固氮作用来维持的。研究人员发现锌是植物必需的微量营养元素，它是细胞内的第二信使，将环境变化与根瘤中代谢活动的转录因子控制联系起来。

附：英文原文

Title: Zinc mediates control of nitrogen fixation via transcription factor filamentation

Author: Lin, Jieshun, Bjrk, Peter K., Kolte, Marie V., Poulsen, Emil, Dedic, Emil, Drace, Taner, Andersen, Stig U., Nadzieja, Marcin, Liu, Huijun, Castillo-Michel, Hiram, Escudero, Viviana, Gonzlez-Guerrero, Manuel, Boesen, Thomas, Pedersen, Jan Skov, Stougaard, Jens, Andersen, Kasper R., Reid, Dugald

Issue&Volume: 2024-06-26

Abstract: Plants adapt to fluctuating environmental conditions by adjusting their metabolism and gene expression to maintain fitness1. In legumes, nitrogen homeostasis is maintained by balancing nitrogen acquired from soil resources with nitrogen fixation by symbiotic bacteria in root nodules2,3,4,5,6,7,8. Here we show that zinc, an essential plant micronutrient, acts as an intracellular second messenger that connects environmental changes to transcription factor control of metabolic activity in root nodules. We identify a transcriptional regulator, FIXATION UNDER NITRATE (FUN), which acts as a sensor, with zinc controlling the transition between an inactive filamentous megastructure and an active transcriptional regulator. Lower zinc concentrations in the nodule, which we show occur in response to higher levels of soil nitrate, dissociates the filament and activates FUN. FUN then directly targets multiple pathways to initiate breakdown of the nodule. The zinc-dependent filamentation mechanism thus establishes a concentration readout to adapt nodule function to the environmental nitrogen conditions. In a wider perspective, these results have implications for understanding the roles of metal ions in integration of environmental signals with plant development and optimizing delivery of fixed nitrogen in legume crops.

DOI: 10.1038/s41586-024-07607-6

Source: https://www.nature.com/articles/s41586-024-07607-6