A PPR Protein RFCD1 Affects Chloroplast Gene Expression and Chloroplast Development in Arabidopsis.

Chloroplast development is a highly complex process, involving many regulatory mechanisms that remain poorly understood. This study reports a novel PPR protein, RFCD1 (Regulation Factor of Chloroplast Development 1). Fluorescence localization analysis reveals that the N-terminal 60 amino acids of RFCD1 fused with GFP protein specifically direct the protein to the chloroplast. The knockout mutant of RFCD1 is embryo-lethal. RFCD1 RNA interference (RNAi) transgenic lines display chlorosis phenotypes and abnormal chloroplast development. Quantitative real-time PCR (qRT-PCR) showed that the expression levels of the plastid-encoded RNA polymerase (PEP) genes were significantly decreased in the RNAi lines. Furthermore, RNA blotting results and RNA-seq data showed that the processing of plastid rRNA was also affected in the RNAi lines. Taken together, these results indicate that RFCD1 might be involved in chloroplast gene expression and rRNA processing, which is essential for chloroplast development in Arabidopsis.