Rice Research Institute of Shenyang Agricultural University/Key Laboratory of Northern Japonica Rice Genetics and Breeding, Ministry of Education and Liaoning Province, Shenyang, 110866, China.
State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Hangzhou, 310006, China.
BMC Plant Biol. 2023 Sep 9;23(1):418. doi: 10.1186/s12870-023-04417-2.
Mitochondrion is the key respiratory organ and participate in multiple anabolism and catabolism pathways in eukaryote. However, the underlying mechanism of how mitochondrial membrane proteins regulate leaf and grain development remains to be further elucidated.
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. Moreover, nlg1 also presents abnormal mitochondria structure and was sensitive to the inhibitors of mitochondrial electron transport chain. Map-based cloning and transgenic functional confirmation revealed that NLG1 encodes a mitochondrial import inner membrane translocase containing a subunit Tim21. GUS staining assay and RT-qPCR suggested that NLG1 was mainly expressed in leaves and panicles. The expression level of respiratory function and auxin response related genes were significantly down-regulated in nlg1, which may be responsible for the declination of ATP production and auxin content.
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 into the effects of mitochondria development on leaf and grain morphogenesis in rice.
线粒体是真核生物中关键的呼吸器官，参与多种物质的合成与分解代谢途径。然而，线粒体膜蛋白如何调节叶片和籽粒发育的潜在机制仍有待进一步阐明。
本研究从 EMS 处理的突变体群体中鉴定到一个线粒体缺陷型窄叶和长粒 1（nlg1）突变体，该突变体表现为窄叶和长粒。此外，nlg1 还表现出异常的线粒体结构，并且对线粒体电子传递链抑制剂敏感。基于图谱的克隆和转基因功能验证表明，NLG1 编码一个含有 Tim21 亚基的线粒体输入内膜转运体。GUS 染色和 RT-qPCR 分析表明，NLG1 主要在叶片和穗中表达。nlg1 中呼吸功能和生长素响应相关基因的表达水平显著下调，这可能导致 ATP 生成和生长素含量下降。
这些结果表明，NLG1 通过维持线粒体稳态在叶片和籽粒大小发育的调控中发挥重要作用。本研究结果为线粒体发育对水稻叶片和籽粒形态建成的影响提供了新的认识。
