Breaking the nexus between yield and carotenoid levels in sweet potato: Development of improved cultivars and identification of key improvement genes

Sweet potato ( Ipomoea batatas (L.) Lam) is a globally important staple crop with high nutritional value, yet most commercial cultivars exhibit a trade-off between yield and carotenoid content. To address this limitation, we used a hybrid population of 27 elite varieties to undergo open pollination and identified two novel lines, XZ 8 − 1 and LS 9 − 1 with improved agronomic traits. XZ 8 − 1 showed a 40-fold increase in carotenoid content compared to its maternal line, while LS 9 − 1 maintained the high carotenoid levels of the maternal line but showed significantly improved yield. Molecular analysis revealed that IbGGPPS2 , a geranylgeranyl diphosphate synthase gene, was highly expressed in the high-carotenoid line XZ 8 − 1. Bacterial complementation assays confirmed that IbGGPPS2 encodes a protein with geranylgeranyl diphosphate synthase activity. Functional validation via heterologous expression in Arabidopsis and overexpression in sweet potato confirmed that IbGGPPS2 enhances carotenoid biosynthesis and has a strong positive effect on plant growth. Our findings provide a promising strategy for the simultaneous improvement of nutritional quality and yield in sweet potato breeding programs.