Lettuce is widely grown and consumed but provides lower nutritional value compared to other leafy greens, particularly in the essential vitamins A and C. To address this, major control points in carotenoid and ascorbic acid (AsA) production were targeted using a viral-based CRISPR/Cas9 system in the commercial lettuce cultivar 'Noga'. Knockout of lycopene ε-cyclase (LCY-ε), the enzymatic gatekeeper opposing production of β-branch carotenoids, increased β-carotene (provitamin A) levels up to 2.7-fold and facilitated zeaxanthin accumulation up to 4.3 μg/g fresh weight. Chlorophyll fluorescence measurements revealed that photosystem II efficiency was unaffected in LCY-ε mutants, though their non-photochemical quenching (NPQ) capacity decreased at light intensities above 400 μmol m