How genes paint lily flowers: Regulation of colouration and pigmentation patterning

• Large variation in tepal colours observed in Asiatic and Oriental hybrid lilies.
• Varieties of colour patterning (spots and bicolours) seen in lily flowers.
• New advances in molecular regulation of flower colours and pigmentation patterning.
• Spatially regulated anthocyanin biosyntheses are key for colour variation.
• Biosynthesis and cleavage of carotenoids are important for carotenoid accumulation.

Flower colour and pigmentation patterning are key traits for floricultural crops. Large variation in tepal colours is observed among lily cultivars, including pink, red, yellow, orange, and white. In addition, large variation in the patterning of these colours are found in lily flowers, including raised spots, splatter spots, and bicolours, which are caused by spatially and temporally discrete anthocyanin deposition. Many Oriental and Asiatic hybrid lily cultivars accumulate pigments such as anthocyanins, whose biosynthesis is co-ordinately regulated by R2R3-MYB and basic helix–loop–helix transcription factors. Lilies have several R2R3-MYB genes regulating anthocyanin biosynthesis, which are key determinants of pigmentation intensity and patterning in flowers. Additional pigments include xanthophylls and capsanthin (carotenoids), which accumulate in yellow and orange lily flowers, respectively. Biosynthesis and cleavage of carotenoids should be important factors that determine carotenoid accumulation. Therefore, this review article discusses the molecular determination of flower colouring, colour intensity, and the mechanisms involved in the pigmentation patterning of lily flowers.