NLG1, a novel mitochondrial membrane protein, control leaf and grain development in rice

Abstract Background Mitochondrion is the key respiratory organ and participates in various anabolic and catabolic metabolic pathways in eukaryote. However, the underlying mechanism of how mitochondrial membrane proteins regulate leaf and grain development remains to be further elucidated. Results Here, a mitochondria-defective mutant narrow leaf and slender grain 1 ( nlg1 ) was identified from an EMS-treated mutant population, which exhibits narrow leaves and slender grains. Map-based cloning and transgenic functional confirmation revealed that NLG1 encodes a mitochondrial import inner membrane translocase containing a subunit Tim21 domain. NLG1 was identified as a mitochondria-localized translocase protein, which is mainly transcribed in leaves and panicles. Further analysis showed that the expression level of respiratory function and auxin response related genes were significantly down-regulated, resulting in ATP production and auxin content declined remarkably in nlg1 . Moreover, nlg1 also exhibited abnormal mitochondria structure and was sensitive to the inhibitors of mitochondrial electron transport chain. Conclusions These results suggested that NLG1 plays an important role in the regulation of leaf and grain size development by maintaining mitochondrial homeostasis. Our finding provides a novel insight for exploring the relationship between mitochondria development and plant growth in rice.