Harnessing mitochondrial genome editing for crop improvement: principles and applications

Plant mitochondria possess a genome that not only encodes genes essential for respiration and energy production but also influences important traits such as cytoplasmic male sterility (CMS). However, the manipulation of mitochondrial DNA (mtDNA) has long been challenging. Recent breakthroughs in protein-based editing tools, beginning with Transcription Activator-Like Effector Nucleases (TALENs) and extending to TALEN gene-drive mutagenesis (TALEN-GDM) and, most recently, TALE-based base editors, have helped overcome some of these barriers. Nevertheless, mitochondrial transformation remains a significant limitation. Promising developments in this field come from nanotechnology and peptide engineering. In this review, we systematically compare these emerging tools, with a focus on the mechanisms responsible for their distinct editing outcomes and inheritance patterns, while critically examining current limitations and proposing potential strategies to overcome them. We assess persistent challenges in plant mitochondrial transformation. Furthermore, we detail how mitochondrial genome editing is advancing research on cytoplasmic male sterility, which has the potential to facilitate crop breeding. Finally, we outline how CRISPR is expected to enrich the editing toolbox and discuss potential uses of mitochondrial genome engineering to expand our understanding of mitochondrial biology and provide novel opportunities for crop improvement.