RNA virus-mediated gene editing for tomato trait breeding

Virus-induced genome editing (VIGE) leverages viral vectors to deliver CRISPR-Cas components into plants for robust and flexible trait engineering. We describe here a VIGE approach applying an RNA viral vector based on potato virus X (PVX) for genome editing of tomato, a mayor horticultural crop. Viral delivery of single-guide RNA into Cas9-expressing lines resulted in efficient somatic editing with indel frequencies up to 58%. By proof-of-concept VIGE of PHYTOENE DESATURASE (PDS) and plant regeneration from edited somatic tissue, we recovered loss-of-function pds mutant progeny displaying an albino phenotype. VIGE of STAYGREEN 1 (SGR1), a gene involved in fruit color variation, generated sgr1 mutant lines with recolored red-brown fruits and high chlorophyll levels. The obtained editing events were heritable, overall confirming the successful breeding of fruit color. Altogether, our VIGE approach offers great potential for accelerated functional genomics of tomato variation, as well as for precision breeding of novel tomato traits.