Anatomical and biochemical studies of bicolored flower development in Muscari latifolium

Abstract

The inflorescence of the broad-leafed grape hyacinth, Muscari latifolium, shows an interesting, two-tone appearance with the upper flowers being pale blue and the lower ones purple. To elucidate the mechanism of the differential color development, anatomical research was carried out and a cytological study of the colored protoplasts in which the shapes of the cells accumulating anthocyanin were observed by scanning electron microscopy. Next, vacuolar pH was recorded using a pH meter with a micro combination pH electrode, and the sap's metal-ion content was measured by inductively coupled plasma mass spectrometry. The anthocyanin and co-pigment composition was determined by high-performance liquid chromatography (HPLC). Chemical analyses reveal that the difference in metal-ion content of the two parts was not great. The vacuolar pHs of the upper and lower flowers were 5.91 and 5.84, respectively, with the difference being nonsignificant. HPLC results indicate that the dihydroflavonol and flavonol contents are also very similar in the two sorts of flower. However, the upper flowers contained only delphinidin, whereas the lower flowers also contained cyanidin. The total anthocyanin content in the lower flowers was 4.36 mg g(-1), which is approximately seven times higher than in the upper flowers, while the delphinidin content is four times higher. Quantitative real-time PCR analysis established that the two-tone flower was a result of different expressions of the F3'5'H, F3'H and DFR genes, and these lead to different amounts of anthocyanin.

Transcriptome sequencing and metabolite analysis reveals the role of delphinidin metabolism in flower colour in grape hyacinth

“…The anthocyanins were determined using high-performance liquid chromatography (HPLC) as previously described (Qi et al , 2013). For extraction of other flavonoids, freeze-dried flowers were finely ground and 50mg was extracted in 500 μl of MeOH for 48h at 4 °C in darkness.…”

“…After samples were centrifuged, the supernatants were transferred to fresh tubes and the pellet was resuspended and incubated in 500 μl of 1% MeOH at 4 °C for 24h, and then the supernatant was combined for further HPLC analysis. HPLC was performed as previously described (Qi et al , 2013). Cyanidin, cyanidin-galactoside, dihydroquercetin, dihydrokaempferol, (+)-catechin, (–)-epicatechin, luteolin, naringenin, and quercetin were obtained from Sigma-Aldrich China (Shanghai).…”

“…Grape hyacinth ( Muscari ) is an important ornamental bulbous plant with a unique flower shape, extraordinary blue colour, and sweet fragrance (Qi et al , 2013). These quality traits are largely determined by the metabolic composition of the flower.…”

“…For example, anthocyanins are the principal flower pigments in Muscari flowers (Mori et al , 2002). It is reported that the varying shades found in the blue flowers are attributable to delphinidin (Del), while the reddish hues are attributable to cyanidin (Cy) (Qi et al , 2013). Anthocyanins are among the most studied and best understood compounds in plant science, and their metabolic pathway has been extensively described (Grotewold, 2006; Tanaka et al , 2008).…”

Activity in space

“…The third contribution by Qi et al (2013) in the current issue investigated the molecular events underlying the characteristic flower pattern of the broad-leafed grape hyacinth (Muscari latifolium). The inflorescence of this flower is pale blue in the upper and purple in the lower domain.…”