biostudies-literatureShimoda YJST-Mirai ProgramJapan Society for the Promotion of Science27578https://www.ebi.ac.uk/biostudies/studies/S-EPMC11554776biostudies-literatureUnknown14(1)Symbiotic nitrogen fixation is a highly coordinated process involving legume plants and nitrogen-fixing bacteria known as rhizobia. In this study, we investigated a novel Fix^- mutant of the model legume Lotus japonicus that develops root nodules with endosymbiotic rhizobia but fails in nitrogen fixation. Map-based cloning identified the causal gene encoding the filamentation temperature-sensitive H (FtsH) protein, designated as LjFtsH4. The LjFtsH4 gene was expressed in all plant organs without increased levels during nodulation. Subcellular localization revealed that LjFtsH4, fused with a fluorescent protein, localized in mitochondria. The Ljftsh4 mutant nodules showed signs of premature senescence, including symbiosome membrane collapse and bacteroid disintegration. AdditionalScientific reportsA mitochondrial metalloprotease FtsH4 is required for symbiotic nitrogen fixation in Lotus japonicus nodules.PMC1155477621K0533517570044JPMJMI20E4Kawaguchi MSuganuma NSato SShibata SHakoyama TUmehara YKouchi HYamaya-Ito HKaneko THayashi MShimoda YfalseA mitochondrial metalloprotease FtsH4 is required for symbiotic nitrogen fixation in Lotus japonicus nodules.Symbiotic nitrogen fixation is a highly coordinated process involving legume plants and nitrogen-fixing bacteria known as rhizobia. In this study, we investigated a novel Fix^- mutant of the model legume Lotus japonicus that develops root nodules with endosymbiotic rhizobia but fails in nitrogen fixation. Map-based cloning identified the causal gene encoding the filamentation temperature-sensitive H (FtsH) protein, designated as LjFtsH4. The LjFtsH4 gene was expressed in all plant organs without increased levels during nodulation. Subcellular localization revealed that LjFtsH4, fused with a fluorescent protein, localized in mitochondria. The Ljftsh4 mutant nodules showed signs of premature senescence, including symbiosome membrane collapse and bacteroid disintegration. Additional2024-01-01T00:00:00Z2024 Nov2026-07-15T08:08:18.41Z2025-04-04T12:01:14.602ZS-EPMC115547763952855110.1038/s41598-024-78295-5