Optimizing plant size for vertical farming by editing stem length regulators

Summary Vertical farming offers the advantage of providing a stable environment for plant cultivation, shielding them from adverse conditions such as climate change. For fruit‐harvesting plants like tomato, vertical farming necessitates the optimization of plant growth and architecture. The gibberellin 3‐oxidase ( GA3ox ) genes encode gibberellin 3‐oxidases responsible for activating GA within the pathway and modulating stem length. Among the five SlGA3ox genes, we targeted the coding regions of three SlGA3ox genes (named SlGA3ox3 , SlGA3ox4 and SlGA3ox5 ) using multiplex CRISPR genome editing. The slga3ox4 single mutants exhibited a slight reduction in primary shoot length, leading to a smaller stature. In contrast, the slga3ox3 and slga3ox5 single mutants showed subtle phenotypic changes. Notably, the slga3ox3 slga3ox4 double mutants developed a more compact shoot architecture with minor physiological differences, potentially making them suitable for vertical farming applications. We observed a correlation between total yield and plant size across all genotypes through multiple yield trials. Observations from vertical farm cultivation revealed that slga3ox3 slga3ox4 plants possess a markedly compact plant size, offering potential benefits for space‐efficient cultivation. Our research suggests that targeted manipulation of hormone biosynthetic genes can effectively tailor plant architecture for vertical farming.