TnpB: A miniature genome editor for plant engineering

Plant engineering is an effective means of conferring beneficial traits for increased food production and pathogen resistance. CRISPR-Cas technology was revolutionary for plant engineering advancements, but large coding sequences of Cas proteins limit effective delivery. Through the search for minimally encoded Cas proteins, the OMEGA (obligate mobile element-guided activity) systems were discovered to be comprised of RNA guided nucleases originating from insertion sequence (IS) elements. The compact coding sequence of OMEGA proteins is highly appealing to the gene therapy field and plant genetic engineering for delivery via viral vectors with limited cargo capacities. The smallest of the OMEGA systems, TnpB, has become the focus of many studies and demonstrates potential as a potent genome editor through its capabilities in target programmability, genome editing in vitro and in vivo, and successful delivery by viral vectors. This review highlights the discovery of the TnpB system, validated optimizations, and its utilization within plant genetic engineering.