Balancing tuber vitamin C improvement with trade-off side effect by fine-tuning regulation of StGGPs.

Potato (Solanum tuberosum L.) is a globally important staple crop. Improving its nutritional quality without compromising yield-a classic manifestation of the growth-defense trade-off-remains a major challenge in modern agriculture. Traditional breeding in potato is hindered by its highly heterozygous genome and tetrasomic inheritance, making it difficult and time-consuming to introduce and fix new traits. To address this, we applied a gene-editing approach to enhance vitamin C (Vc) content in tubers by mutating the upstream open reading frames of two potato GDP-l-galactose phosphorylase genes. New variants, with significantly elevated Vc levels, well-balanced nutrient profiles, and maintained yield, were created. The nutritionally enriched​ tubers retained high Vc content after culinary processing and exhibited substantially increased antioxidant activity. Importantly, we also found that excessive Vc enrichment can disrupt auxin activity, leading to developmental arrest and yield penalties. Thus, our study not only provides an effective strategy for multitrait improvement in potato, but also offers broader insights into the physiological mechanisms governing the balance between yield and nutritional quality in horticultural crops.