Isolation and characterization of a novel Lilium flower ‘LC-4–1’ provides insights into flower color changes coregulated by anthocyanin and carotenoid biosynthesis

• This is the first report of a colchicine-induced larger, light yellowish pink Lilium flower ‘LC-4–1’ derived from the smaller, vivid reddish orange flower of L. callosum . • ‘LC-4–1’ contained high carotenoid contents but low anthocyanin contents in the flower petals related to L. callosum . • ‘LC-4–1’ was identified as diploid through genetic variation at a rate of 20.72 % by flow cytometry and ISSR marker. • A hypothetical gene model of anthocyanin and carotenoid biosynthesis regulated by key transcription factors was proposed in Lilium flower. Lilium callosum Sieb. et Zucc. is known as a ‘mini’ flower but characterized by the single reddish orange color. Herein, a novel flower designated ‘LC-4–1’, was isolated from colchicine-induced chimeric L. callosum plants. Compared with L. callosum , ‘LC-4–1’ seedlings and flowering plants displayed wider leaves and slightly thicker stems. Intrestingly, ‘LC-4–1’ showed a larger, light yellowish pink flower, and contained lower anthocyanin but higher carotenoid contents in the petals, which was associated with downregulation of anthocyanin biosynthesis-related genes, upregulation of carotenoid biosynthesis-related genes, and differential expression of key transcription factors including MYB, ERF and WRKY by RNA sequencing. ‘LC-4–1’ possessed inwardly hollow sterile pollen and much embryo-free seeds. In addition, it was identified as diploid through genetic variation at a rate of 20.72 % via flow cytometry and ISSR markers. In combination with qRT-PCR, a potential gene regulatory model for flower color changes between L. callosum and ‘LC-4–1’ was proposed. These results provide new evidence of the colchicine-induced color variation in Lilium flower and increase our understanding of flower color formation by anthocyanins and carotenoids.