The pentatricopeptide repeat protein TCD6 functions RNA editing and cleavage of ndhA and is required for chloroplast development in early rice seedlings

Pentatricopeptide repeat (PPR) proteins compose one of the largest protein families in higher plants and play a role in regulating organellar gene expression. In this study, we discovered that a new rice mutant tcd6 exhibited albino phenotype and aberrant chloroplast before the three-leaf (autotrophic) seedling stage. Through Map-based cloning and complementation tests, it was shown that TCD6 encodes a chloroplast-located PPR protein, with 14 PPR motifs and an atypical DYW-like motif. In addition, the disruption of TCD6 hindered the nuclear-encoded polymerase (NEP)-dependent transcript levels for plastid genes and led to defects in the cleavage and editing of ndhA (encoding NDH subunit) in early tcd6 mutant seedlings. Taken together, our results indicate that TCD6 is indispensable for chloroplast development and involves in RNA editing and cleavage of ndhA during early seedling (autotrophic) growth of rice.