Maize Dek37 Encodes a P-type PPR Protein That Affects cis -Splicing of Mitochondrial nad2 Intron 1 and Seed Development

Mitochondrial group II introns require the participation of numerous nucleus-encoded general and specific factors to achieve efficient splicing in Pentatricopeptide repeat (PPR) proteins have been implicated in assisting group II intron splicing. Here, we identified and characterized a new maize seed mutant, ( ), which has significantly delayed endosperm and embryo development. encodes a classic P-type PPR protein that targets mitochondria. The mutation causes no detectable DEK37 protein in mutant seeds. Mitochondrial transcripts analysis indicated that mutation decreases splicing efficiency of mitochondrial intron 1, leading to reduced assembly and NADH dehydrogenase activity of complex I. Transmission Electron Microscopy (TEM) revealed severe morphological defects of mitochondria in Transcriptome analysis of endosperm indicated enhanced expression in the alternative respiratory pathway and extensive differentially expressed genes related to mitochondrial function. These results indicated that is involved in -splicing of mitochondrial intron 1 and is required for complex I assembly, mitochondrial function, and seed development in maize.