Peptide-mediated gene and protein delivery systems to plant mitochondria for modifying mitochondrial functions

Plant mitochondria are essential for energy production and male sterility. The genetic transformation of plant mitochondria has attracted attention due to its potential to improve the mitochondrial function and agricultural productivity of energy crops. However, mitochondrial genome editing has been challenging because the delivery of the macromolecules needed for genome engineering to mitochondria has not been established until now. In addition, the genome editing efficiency in mitochondria needs to be improved as much as possible due to the lack of a selection marker for mitochondria. To achieve mitochondrial modification, the proteins and/or DNA/RNA needed for genome editing should be delivered to mitochondria precisely and efficiently. Peptides have been utilized to improve delivery efficiency to plant mitochondria. Thus, we herein review advances in delivery technologies related to plant mitochondrial genome engineering using various functional peptides. There are many barriers to gene and protein delivery to plant mitochondria, such as cell walls, cell membranes, and cytosolic localization. Functional peptides have been used to overcome these barriers. Peptides have a characteristic function depending on their sequence and high-order structure. The cytotoxicity of these peptides is also low. Therefore, functional peptides have attracted attention for their ability to improve gene and protein delivery efficiency to plant mitochondria.