Anatomical and biochemical analyses reveal the mechanism of double-color formation in Paeonia suffruticosa ‘Shima Nishiki’

Abstract

Paeonia suffruticosa 'Shima Nishiki' is a very precious double-color cultivar because of its distinctive and colorful flowers. However, our understanding of the underlying mechanisms of its double-color formation is limited. The present study investigated the soluble sugar content, cell sap pH value and anatomical structure, anthocyanin composition and content and expression patterns of genes related to anthocyanin biosynthesis in the red and pink petals of the 'Shima Nishiki' cultivar. Here, we found that soluble sugar content, cell sap pH and the shape of outer epidermal cells were not the key factors that determine double-color formation. Five different anthocyanins were detected in both the red and pink petals, and the pelargonidin-3,5-di-O-glucoside (Pg3G5G) and pelargonidin-3-O-glucoside (Pg3G) contents in the red petals were significantly higher than those in the pink petals at every developmental stage. In addition, these gene expression patterns suggested that the significant differential expression of the dihydroflavonol 4-reductase gene (PsDFR) gene might play a key role in double-color formation. These results will provide a valuable resource for further studies unraveling the underlying genetic mechanisms of double-color formation in P. suffruticosa 'Shima Nishiki'.

Role of core structural genes for flavonoid biosynthesis and transcriptional factors in flower color of plants

“…L. longiflorum with a yellow anther lacks anthocyanin in its petals and anther due to DFR mutation [74]. Research on the two-color Chinese herbaceous peony has demonstrated that the significant differential expression of PsDFR might play an important role in the development of the two colors in this plant [75].…”

Integrated metabolic profiling and transcriptome analysis of pigment accumulation in diverse petal tissues in the lily cultivar ‘Vivian’

“…The expression patterns of some flower-color variation in plants were similar with 'Vivian'. Differences in LBG expression caused color differences in bicolor peony "Shima Nishiki" [75], pink camellia [76], and yellow/orange variation in Gentiana [77]. Therefore, the expression of LBGs can affect the pigmentation in these plants.…”

Advances on the Coloring Mechanism of Double-color Flowers in Plants

“…Flavonoids are very important pigments that extensively affect flower color. Among them, anthocyanins contribute the most (Davies et al, 2012;Grotewold, 2006;Nishihara and Nakatsuka, 2011;Wang et al, 2021;Zhang et al, 2018aZhang et al, , 2018b. In addition to anthocyanins, many physiological factors, such as vacuolar pH value (Quattrocchio et al, 2006;Yoshida et al, 2005), metal element content (Schreiber et al, 2011;Shoji et al, 2010), upper epidermal cell shape (Baumann et al, 2007;Deng et al, 2022;Noda et al, 1994;Zhang et al, 2018b), and soluble sugar content (Zhang et al, 2015;Zheng et al, 2009), can also affect the presentation of flower color to a certain extent.…”