Involvement of carotenoid cleavage dioxygenase 4 gene in tepal color change in Lilium brownii var. colchesteri

Lilium brownii (F. E. Brown) Miellez var. colchesteri E. H. Wilson has a unique characteristic in its flower color, which changes from yellowish-cream to white one day after anthesis. To elucidate the mechanism of flower color change in this species, the content and composition of carotenoids were analyzed during two days of anthesis. The major carotenoids that contributed to the yellowish-cream color of the tepals were lutein, zeaxanthin, and β-carotene. Analysis showed an obvious decrease in total carotenoid content of the tepal, indicating that the flower color change is caused by the reduction of the total carotenoid content after anthesis. To reveal the factor that controls carotenoid content in the tepals, we isolated carotenoid cleavage dioxygenase 4 (LbCCD4) gene and analyzed the number of LbCCD4 messages by quantitative real-time PCR. The transcription level of LbCCD4 gene increased and reached the maximum level 12 hours after anthesis. The results suggest that the carotenoids in yellow tepals of L. brownii var. colchesteri degraded into colorless compounds by carotenoid cleavage dioxygenase and subsequently resulted in white flowers.