Physicochemical characteristics and anthocyanin components affecting the color of rose petals

Abstract [Objective] This study aims to explore the mechanism of flower color formation in rose and to provide references and receptor cultivars for flower breeding by quantitative evaluation and correlation analysis of the physicochemical factors affecting coloration of rose petals. There is of great significance for exploring the mechanism of flower color formation and germplasm innovation. [Methods] 8 cultivars of rose with different flower colors were used as experimental materials to measure and compare the physicochemical indexes such as petal color parameter, pH value of petal cells, metal ion content, total anthocyanin content, total flavonoids content, and total chlorophyll content, etc., and the anthocyanin components were quantitatively analyzed. [Results] (1) There were significant differences between the physicochemical factors of different flower color of roses, among which the factors such as pH value of petal cells, Fe3+ , Ca2+ and Al3+ content, total anthocyanin content, and total flavonoid content were closely related to the formation of petal color, but the changes in the content of total flavonoids and total anthocyanin played direct roles, and the factors such as metal ions and pH value of petal cells affected the flower color by changing the structure of anthocyanidin. (2) The components of anthocyanins in petals of different roses were different. Among them, cyanidin-3,5-diglucoside dominated in the roses and mainly regulated the formation of purplish-red flowers; followed by pelargonidin-3,5-diglucoside, which mainly regulated the formation of orange and red flowers. Yellow flowers contained very little anthocyanin and were mainly regulated by carotenoids. Orange flowers were dually regulated by both anthocyanin and carotenoids, while white flowers contained almost no anthocyanin. Rutin was abundant in all 8 rose cultivars, but there was no significant correlation with petal formation. (3) Cluster analysis of anthocyanin components in 8 rose petals revealed that the pink-purple cultivar ‘Lavender Flower Circus’ was always clustered in a separate group with high rutin content and small anthocyanin content. [Conclusion] The type and content of anthocyanins directly affect flower color of rose, and flavonoids assist the formation of anthocyanin. Factors such as pH value of petal cells, Fe3+ , Ca2+ and Al3+ content indirectly affect flower color. Among the 8 selected cultivars of rose, the pink-purple cultivar ‘Lavender Flower Circus’ is the most suitable recipient cultivar for flower color improvement due to its excellent anthocyanin composition and high pH value in petal cells.