Gene expression and physiological roles of post-transcriptional editing in plant organellar systems

The genomes of the two endosymbiotic organelles in plants, mitochondria and chloroplasts, have maintained their independence by possessing their own transcriptional and post-transcriptional machinery. In fact, the normal functioning of organellar genes highly depends on post-transcriptional RNA editing events. The most important and prevalent form of these events is C-to-U substitutions. RNA editing has gained remarkable attention in new studies due to its critical contributions to plant development, growth, and adaptation to environmental stresses. The nuclear-encoded pentatricopeptide repeat (PPR) proteins are at the heart of organellar gene expression (OGE) and work with other accessory proteins to edit specific sequences. In this review, we focus on main findings that govern OGE in plants. Furthermore, we discuss the role of RNA editing in plant organelles besides highlighting involved factors, knowledge gaps, and future prospects.