The rice PPR756 coordinates with MORFs for multiple RNA editing in mitochondria

In land plants, the pentatricopeptide repeat (PPR) proteins form a large family accounting for post-transcriptional process in mitochondria and chloroplasts. Although studies showed a number of PPR proteins generally influence the editing of organellar genes acting as a member of editing complex, few of them were characterized detailed in rice. Here, we reported a PLS-E subclass PPR protein in rice, PPR756, loss function of which lead to the abolishment of RNA editing events among three sites in mitochondrial genes including atp6 (ATP synthase F0 subunit 6), ccmC (cytochrome c biogenesis C) and nad7 (NADH dehydrogenase subunit 7). The defective C- to-U transformation of atp6-368, ccmC-236 and nad7-83 resulted in the retention of proline, proline and serine codon respectively to the right leucine in rice. Furthermore, PPR756 could bind to the three target genes directly and interacted with three OsMORFs (multiple organellar RNA editing factors), OsMORF1, OsMORF8-1 and OsMORF8-2. The knock-out plants of PPR756 exhibited retarded growth and greener leaves during the early stages, accompanied with sterile pollens at reproductive stage. These results established a role for PPR756 in the RNA editing of three various transcripts, cooperating with MORFs via editosome manner in rice.