PPR protein Early Chloroplast Development 2 is essential for chloroplast development at the early stage of Arabidopsis development

•ECD2 is a novel P-type PPR protein located in the chloroplast and essential for chloroplast development.•Down-regulation of ECD2 showed albino cotyledons but with normal true leaves phenotype.•ECD2 is involved in chloroplast gene expression and splicing of several group II introns in cotyledon.•Accumulation of chloroplast ribosomes was seriously affected in cotyledons in ECD2-RNAi line. Chloroplast biogenesis and development regulation have long been a focus of research; however, the underlying mechanisms of these processes have not yet been fully elucidated. Pentatricopeptide repeat (PPR) proteins have been shown to play key roles in chloroplast development. Here, we identified a novel P-type PPR protein, Early Chloroplast Development 2 (ECD2), and the ecd2 mutant resulted in embryo lethality. The RNAi lines of ECD2 showed varying degrees of albino cotyledons and abnormal chloroplast development, but true leaves were similar to the wild-type. Further analysis revealed that ECD2 was responsible for chloroplast gene expression and group II intron splicing of several genes. Transcriptome analysis combined with quantitative real-time PCR showed that ECD2 was associated with the expression of ribosomal genes and accumulation of chloroplast ribosomes. Overall, our results indicate that ECD2 is critically important for early chloroplast development in cotyledon.