Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 115, Taiwan.
New Phytol. 2023 Aug;239(4):1315-1331. doi: 10.1111/nph.19006. Epub 2023 Jun 10.
We studied Arabidopsis HYPOXIA-RESPONSIVE MODULATOR 1 (HRM1), which belongs to a group of core hypoxia-responsive genes that are conserved among plant species across great evolutionary distance. The hrm1 mutants had lower survival rates and showed more damage than the wild-type (WT) plants under hypoxic stress. Promoter analyses showed that HRM1 is regulated by EIN3 and RAP2.2 during hypoxia. Fluorescence tracing and immunogold labeling assays showed that HRM1 protein was enriched in mitochondria. Co-immunoprecipitation coupled with mass spectrometry and bimolecular fluorescence complementation assays showed that HRM1 associates with the complex-I in mitochondria. Compared with the WT plants, metabolic activities related to the mitochondrial electron transport chain (mETC) were higher in hrm1 mutants during hypoxia. Loss of HRM1 caused de-repression of mETC complex I, II, and IV activities and higher basal and maximum respiration rates under hypoxia. Our results showed that through association with complex-I, HRM1 attenuates mETC activity and modulates the respiratory chain under low oxygen. Compared with the regulatory system in mammalian, adjustment of mitochondrial respiration to low oxygen helps plants decrease reactive oxygen species production and is also critical for the submergence survival.
我们研究了拟南芥缺氧响应调节剂 1（HRM1），它属于一组在不同进化距离的植物物种中保守的核心缺氧响应基因。在缺氧胁迫下，hrm1 突变体的存活率比野生型（WT）植物低，损伤更严重。启动子分析表明，HRM1 在缺氧条件下受 EIN3 和 RAP2.2 调控。荧光示踪和免疫金标记实验表明，HRM1 蛋白在线粒体中富集。免疫共沉淀结合质谱和双分子荧光互补实验表明，HRM1 与线粒体中的复合物 I 相关联。与 WT 植物相比，在缺氧条件下，hrm1 突变体中线粒体电子传递链（mETC）相关的代谢活性更高。失去 HRM1 导致 mETC 复合物 I、II 和 IV 活性去抑制，以及在缺氧下基础呼吸率和最大呼吸率更高。我们的结果表明，通过与复合物 I 结合，HRM1 减弱了 mETC 活性，并在低氧条件下调节呼吸链。与哺乳动物的调控系统相比，植物通过调节线粒体呼吸作用来适应低氧，有助于减少活性氧的产生，这对植物的淹水生存也是至关重要的。
