Mitochondria, the main energy transducers in plant cells, require the proper assembly of respiratory chain complexes Ⅰ–Ⅴ for their function. The NADH dehydrogenase4(nad4) gene encodes mitochondrial respiratory chai...Mitochondria, the main energy transducers in plant cells, require the proper assembly of respiratory chain complexes Ⅰ–Ⅴ for their function. The NADH dehydrogenase4(nad4) gene encodes mitochondrial respiratory chain complex Ⅰ subunit Ⅳ, but the mechanism underlying nad4 transcript splicing is unclear. Here, we report that the P-type pentatricopeptide repeat(PPR) protein DEFECTIVE KERNEL 43(DEK43) is responsible for cis-splicing of the nad4 transcript in maize. We demonstrate that DEK43 localizes to both the nucleus and mitochondria. The mutation of Dek43 resulted in embryo-lethal and light-colored defective kernels. Among the 22 mitochondrial group Ⅱ introns, the splicing efficiency of nad4 introns 1 and 3 was reduced by up to 50% compared to the wild type. The levels of complex Ⅰ and supercomplex Ⅰ+Ⅲ2 were also reduced in dek43. Furthermore, in-gel NADH dehydrogenase assays indicated that the activities of these complexes were significantly reduced in dek43. Further, the mitochondrial ultrastructure was altered in the mutant. Together, our findings indicate that DEK43, a dual-localized PPR protein,plays an important role in maintaining mitochondrial function and maize kernel development.展开更多
基金funded by the National Natural Science Foundation of China(91735301 and 91535109)the National Plant Transgenic Program(2016ZX08003-003)+2 种基金Taishan Scholars Project(ts201712024)Funds of Shandong“Double Tops”Program(SYL2017YSTD03)a project(dxkt201707)from the State Key Laboratory of Crop Biology。
文摘Mitochondria, the main energy transducers in plant cells, require the proper assembly of respiratory chain complexes Ⅰ–Ⅴ for their function. The NADH dehydrogenase4(nad4) gene encodes mitochondrial respiratory chain complex Ⅰ subunit Ⅳ, but the mechanism underlying nad4 transcript splicing is unclear. Here, we report that the P-type pentatricopeptide repeat(PPR) protein DEFECTIVE KERNEL 43(DEK43) is responsible for cis-splicing of the nad4 transcript in maize. We demonstrate that DEK43 localizes to both the nucleus and mitochondria. The mutation of Dek43 resulted in embryo-lethal and light-colored defective kernels. Among the 22 mitochondrial group Ⅱ introns, the splicing efficiency of nad4 introns 1 and 3 was reduced by up to 50% compared to the wild type. The levels of complex Ⅰ and supercomplex Ⅰ+Ⅲ2 were also reduced in dek43. Furthermore, in-gel NADH dehydrogenase assays indicated that the activities of these complexes were significantly reduced in dek43. Further, the mitochondrial ultrastructure was altered in the mutant. Together, our findings indicate that DEK43, a dual-localized PPR protein,plays an important role in maintaining mitochondrial function and maize kernel development.
