The transcription factor LhMYB12 determines anthocyanin pigmentation in the tepals of Asiatic hybrid lilies (Lilium spp.) and regulates pigment quantity

Abstract

A single dominant locus determines anthocyanin biosynthesis in the tepals of Asiatic hybrid lilies (Lilium spp.); however the gene that determines this trait has not been previously reported. Furthermore, anthocyanin colour hue in tepals varies between cultivars, but the mechanisms underlying this variation are not known. Here, we show that LhMYB12, which is homologous to petunia An2, determines anthocyanin pigmentation in tepals and that the level of LhMYB12 transcription affects the quantity of anthocyanin pigments, producing colour hue variation in tepals. The pink-tepal cultivars Montreux and Renoir were heterozygous for the LhMYB12 gene. Their F1 population segregated 3:1 for the presence or absence of anthocyanin in tepals, and LhMYB12 cosegregated perfectly with the presence of anthocyanin, indicating that LhMYB12 determines anthocyanin biosynthesis in tepals. Among seven cultivars, a single anthocyanin cyanidin 3-O-β-rutinoside was detected in tepals displaying light pink, pink–red, dark red, or chocolate brown hues. However, concentrations differed according to the following order of colour hue: light pink < pink–red < dark red < chocolate brown, suggesting that colour hue variation in tepals is strongly related to anthocyanin quantities. The accumulation of LhMYB12 transcripts in tepals varied between seven cultivars in the same order, and transcription levels were positively correlated with pigment quantities. This suggests that the levels of transcription of LhMYB12 vary among the different cultivars and subsequently affect the quantities of pigment in tepals. These results indicate that LhMYB12 determines anthocyanin pigmentation and generates the variation in anthocyanin colour hue in lily tepals.