The DYW-type pentatricopeptide repeat protein DEK618 interacts with ZmMORFs to modulate mitochondrial RNA editing and kernel development in maize.

C-to-U editing is a critical post-transcriptional modification process in plant mitochondrial RNAs, involving the conversion of specific cytidine (C) residues to uridine (U). Pentatricopeptide repeat (PPR) proteins serve as site-specific recognition factors in this process. Although certain DYW-type PPR proteins (DYW-PPR) are known to participate in the post-transcriptional processing of mitochondrial RNAs, the functions of more than 60 DYW-PPR proteins in maize remain uncharacterized. In this study, we identify a novel DYW-PPR protein, DEK618, which is associated with defective kernel development and dwarfism in maize. A 254 bp insertion in the Dek618 gene disrupted protein expression and resulted in abnormal mitochondrial morphology. Loss of DEK618 function altered the editing efficiency at 88 C-to-U sites. Notably, editing at cob-298, ccmC-184, ccmB-428, and ccmFC-1219 was completely abolished in the dek618 mutant, likely due to impaired mitochondrial function affecting the assembly and activity of mitochondrial complex III. Furthermore, DEK618 was found to physically interact with ZmMORF1 and ZmMORF8, suggesting that these proteins collaborate to facilitate C-to-U RNA editing as part of a complex within mitochondria.