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🌸 Genetic Transformation Platform for Sweet Cherry: Targeting FT and TFL1 Genes

The application of transformation technologies in Prunus species has remained modest compared to major genetically engineered crops. A key limitation is the absence of efficient biotechnology platforms, which continues to be a bottleneck for genetic improvement in these woody perennials. Additionally, traits such as dormancy and chilling requirements are increasingly relevant for an industry facing seasonal disruptions due to climate change.

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🧪 Micropropagation and Transformation Strategy

We recently developed protocols for massive micropropagation of sweet cherry genotypes and their rootstocks using temporary immersion systems (TIS). These protocols support the establishment of a regeneration and transformation platform, now applied to genotypes including Maxma-14, ‘Bing’, and ‘Rainier’.

Seed-derived explants—hypocotyls, epicotyls, embryo segments, and cotyledons—were evaluated as starting materials. All led to successful generation of transgenic trees, demonstrating the feasibility of transformation in these genotypes.

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🔬 Gene Targets and Constructs

Two transformation plasmids were designed:

• FT-GFP fusion: Combines the Flowering Locus T gene with GFP, previously validated in Arabidopsis, to induce Sch-FT overexpression.

• amiR-TFL1: An artificial microRNA targeting the Terminal Flower 1 gene of sweet cherry, triggering RNA interference against this flowering inhibitor.

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🌱 Observations and Implications

After one cold cycle, no deregulated or accelerated flowering was observed in the transgenic trees, contrary to initial expectations. However, notable architectural changes were recorded, suggesting that FT and TFL1 may influence plant morphology beyond flowering regulation.

These findings imply that the flowering process in sweet cherry is more complex than anticipated, potentially modulated by additional developmental factors such as juvenility. The platform now enables deeper exploration of gene function and supports future breeding efforts targeting climate resilience, flowering control, and tree architecture.