Blue flowers, which are rare, have long been a focus for researchers engaged in colored flower breeding. In this study, Plumbago auriculata, a plant with blue flowers, and its white flower forma Plumbago auriculata f. alba were used as research materials. Flower color quantification, environmental scanning electron microscopy (ESEM) observation of petal epidermal cells, and determination of the cell sap pH were carried out; moreover, metabolomic analysis was used to analyze the flavonoid metabolites of both types of petals. The results showed that the flower color of P. auriculata was bluish violet, and there was no significant difference in the epidermal cell distribution of the white and blue petals. The key substance that determined the bluish violet flower color was cyanidin-3-O-(6″-p-coumaroylglucoside) (Cy3-pC·G). Compared to the white petal cells, the blue petal cells exhibited up to 40 upregulated flavonoid compounds that were copigments. Together with the significantly increased pH (5.92 ± 0.12) of the petal cell sap, these copigments affected the color presentation of Cy3-pC·G, causing the final petal color of P. auriculata to be bluish violet. The results of this study indicate that cyanidin is an important anthocyanidin in blue flowers, which provides new insights into the breeding of blue flowers.

稀有的蓝色花朵长期以来一直是从事有色花朵育种研究的人们的关注重点。在这项研究中，蓝雪花，蓝花植物，它的白色花朵备考蓝雪花F。alba被用作研究材料。进行花色定量，花瓣表皮细胞的环境扫描电子显微镜（ESEM）观察以及细胞液pH的测定。此外，用代谢组学分析法分析了两种花瓣的类黄酮代谢产物。结果表明，紫锥菊的花色呈蓝紫色，白色和蓝色花瓣的表皮细胞分布无明显差异。决定蓝紫色花色的关键物质是花青素3- O-（6″ -p-香豆酰葡萄糖苷）（Cy3-pC·G）。与白色花瓣细胞相比，蓝色花瓣细胞显示出多达40种上调的类黄酮化合物。这些色素与花瓣细胞汁液的pH值显着增加（5.92±0.12）一起，影响了Cy3-pC·G的颜色表现，导致最终的P. auriculata花瓣呈蓝紫色。这项研究的结果表明，花青素是蓝色花中重要的花色苷，为蓝色花的育种提供了新的见识。