title: Anatomical and biochemical analysis reveal the role of anthocyanins in flower coloration of herbaceous peony.
abstract: Herbaceous peony (Paeonia lactiflora Pall.) is particularly appreciated because of its elegant and gorgeous flower color, but little is known about the underlying mechanisms of flower coloration. In this study, three P. lactiflora cultivars 'Xuefeng', 'Fenyulou' and 'Dahonglou' with white, pink and red flower were selected as the materials. Their anatomical structures, cell sap pH and metal elements were investigated, and the colored pigment mainly distributed in palisade mesophyll was only found in 'Fenyulou' and 'Dahonglou', and their shape of epidermal cells, cell sap pH and metal elements were not the key factors deciding phenotype color. Moreover, the qualitative and quantitative analysis of flavonoids were performed, their total anthocyanin, anthoxanthin and flavonoid contents were decreased during flower development, and only anthocyanin content in 'Dahonglou' was always higher than that in 'Xuefeng' and 'Fenyulou'. Subsequently, three anthocyanin compositions were found, and peonidin 3,5-di-O-glucoside (Pn3G5G) was identified as the main anthocyanin composition. In addition, the full-length of flavonol synthase gene (FLS) was isolated with the GenBank accession number KM259902, and the expression patterns of eight flavonoid biosynthetic genes showed that only PlDFR and PlANS basically had the highest levels in 'Dahonglou' and the lowest levels in 'Xuefeng', and they basically displayed a descended trend during flower development especially PlDFR, suggesting that these two genes might play a key role in the anthocyanin biosynthesis which resulted in the shift from white to pink and red in flowers. These results would contribute to understand the underlying molecular mechanisms of flower coloration in P. lactiflora.
authors.affiliation: Jiangsu Key Laboratory of Crop Genetics and Physiology, College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, PR China; Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement, Nanjing 210014, PR China.
authors.forename: Da-Qiu
authors.initials: DQ
authors.lastname: Zhao
authors.affiliation: Jiangsu Key Laboratory of Crop Genetics and Physiology, College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, PR China; Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement, Nanjing 210014, PR China.
authors.forename: Meng-Ran
authors.initials: MR
authors.lastname: Wei
authors.affiliation: Jiangsu Key Laboratory of Crop Genetics and Physiology, College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, PR China; Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement, Nanjing 210014, PR China.
authors.forename: Ding
authors.initials: D
authors.lastname: Liu
authors.affiliation: Jiangsu Key Laboratory of Crop Genetics and Physiology, College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, PR China; Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement, Nanjing 210014, PR China. Electronic address: taojun@yzu.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Tao
mesh_terms: D000872:Anthocyanins / Q000096:biosynthesis / Q000235:genetics; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D029596:Paeonia / Q000235:genetics / Q000378:metabolism; D010858:Pigmentation / Q000502:physiology*
chemical_list: D000872:Anthocyanins; C473205:peonidin
keywords: Anatomical analysis; Anthocyanins; Herbaceous peony; Red colour