Generation of Ornamental Tomatoes with Orange Flowers via Heterologous Expression of LdCCS

The flower color of ornamental tomatoes is predominantly yellow. Developing cultivars with diverse flower colors is critical for enhancing their ornamental value and broadening their application potential. In this study, we cloned the genomic sequence of LdCCS from Lilium davidii var. willmottiae; this sequence spanned 1971 bp and included the promoter and 5′ UTR. The construct was transformed into tomato (Solanum lycopersicum L.) cultivar Micro-Tom, and the resulting transgenic lines exhibited orange pigmentation across the entire flower. No significant difference in total carotenoid content was observed in the flowers of transgenic plants relative to the wild type (WT). Notably, capsanthin and capsorubin were specifically synthesized de novo and accumulated in transgenic flowers, whereas lutein and β-carotene contents were reduced compared with the WT. Collectively, this study provides new genetic resources and a viable strategy for targeted molecular modification of flower color in ornamental tomato, offering new insights for flower color innovation and molecular breeding of ornamental plants.