From Screening to Rescue of Recalcitrant Genotypes: Identifying Lettuce Cultivars with Reliable Regeneration Capacity for Downstream Genetic Engineering

The efficiency of plant regeneration varies not only across species, but also across cultivars or genotypes within a species. In our study, a standard lettuce ( Lactuca sativa ) regeneration protocol was used to compare six lettuce cultivars—Kordaat, Valmaine, Salinas, Ninja, Cobham Green, and PI251246)—in regeneration parameters. Our results show that ‘PI251246’ and ‘Valmaine’ outperformed the other cultivars, including the commonly used cultivars Cobham Green and Salinas, in terms of highest regeneration capacity in the shortest time. Callus browning affected shoot elongation and growth in ‘Kordaat’ and ‘Ninja’. The addition of activated charcoal proved highly effective in reducing callus browning and in enhancing the regeneration capacity of both cultivars. Our results show that baseline regeneration efficiency and timeline vary significantly among cultivars and provide effective cultivar-specific regeneration protocols for lettuce.