Characterization of MYB genes regulating anthocyanin biosynthesis in Asiatic hybrid lily

一个显性基因座决定了亚洲杂交百合花青素的生物合成。然而，决定这一特征的基因此前并未被报道过。此外，花青素在不同品种的花被片中有不同的颜色，但这种变化的机制尚不清楚。在这里，我们发现与矮牵牛An2同源的LhMYB12决定花青素在花被片中的色素沉着，并且LhMYB12的转录水平影响花青素色素的数量，从而产生花被片的色调变化。粉红色花被品种‘蒙特勒’和‘雷诺阿’是LhMYB12基因的杂合品种。他们的F_1群体在花青素存在或不存在的情况下的分离率为3:1，LhMYB12与花青素存在的共分离很好，说明LhMYB12决定了花青素在花被片中的生物合成。在7个品种的花青素中，花青素3-0-0-芦丁苷被检出单一的花青素，花青素被检出浅粉红色、粉红色、暗红色和巧克力棕色。然而，花青素的浓度根据颜色色调的顺序不同：浅粉色<粉红色<深红色<巧克力棕色，这表明花青素的颜色色调变化与花青素的含量密切相关。7个品种被片中LhMYB12转录本的积累顺序不同，转录水平与色素含量呈正相关。这表明LhMYB12的转录水平在不同的品种之间有所不同，并随后影响花被中色素的数量。这些结果表明，LhMYB12决定了百合花青素的色素沉着，并引起花青素色相的变化。

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 among 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 F_1 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 7 cultivars, a single anthocyanin cyanidin 3-0-0-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 among 7 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.