Optimizing a tomato crocin biofactory by fine-tuning plant architecture

Tomato (<i>Solanum lycopersicum</i>) has emerged as a promising platform for the sustainable production of high-value metabolites. In this study, we demonstrate that plant architecture remodeling via genome editing can be exploited as a chassis optimization strategy in plant biofactories. Building on the previously established Tomaffron line, which accumulates saffron apocarotenoids in the fruit, and based on the established knowledge that mutations in <i>SELF-PRUNING</i> (<i>SP</i>) and <i>SP5G</i> genes generate compact, determinate tomato plants, we used CRISPR/Cas9 to edit the <i>SP</i> and <i>SP5G</i> genes in Tomaffron to improve crocin production. The resulting <i>sp</i> sp<i>5g</i> double mutants exhibited a compact growth habit combined with significantly higher fruit yield, total crocin content, and firmer ripe fruits compared with non-mutants. Remarkably, crocin yields per square meter increased nearly fourfold compared to non-mutant Tomaffron plants grown at the same density, representing progress toward achieving the crocin yields of <i>Crocus sativus</i> and offering the advantage of easier cultivation and harvesting in the tomato system. Our results show that genome editing of plant architecture is not only a tool for agronomic improvement but also a powerful strategy to fine-tune our tomato biofactory performance, offering a scalable and sustainable approach for the production of valuable metabolites.