Abstract:

【Objective】This study aimed to investigate and analyze the volatile components of three wild tree peony species and identify the key volatile components and aroma-releasing sites. This was done to provide a reference for future research, such as on the breeding and genetic regulation of the floral fragrance of tree peony, and for the development of related products. 【Method】The volatile components in different parts of flower organs (whole flower, petals and stamens) of Paeonia ludlowii, P. lutea and P. ostii were analyzed using headspace-gas chromatography-mass spectrometry, and based on the identified volatile components, three tree peony species were analyzed by principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). 【Result】 A total of 147 volatile compounds were detected in the flowers of three species of tree peony. The main volatile components in P. ludlowii were ketones, alcohols, olefins and aldehydes. The main compounds in the whole flower of P. ludlowii were acetophenone, 6,6-dimethyl-bicyclo[3.1.1]heptane-2-carboxaldehyde and linalool, while β-copaene, acetophenone and linalool were the main compounds of petals, and acetophenone and linalool were the main compounds of stamens. The main components of P. lutea were olefins, alkanes and alcohols. α-pinene, β-copaene and linalool were the main compounds of the whole flower and petals in P. lutea, while 1-octane, β-copaene, and α-pinene were the main compounds of stamens. The main components of P. ostii were olefins and alkanes. The main compounds in the whole flower of P. ostii were α-pinene, ocimene and pentadecane; ocimene was the main compound of petals and its relative content was as high as 81.58%; and ocimene and pentadecane were the main compounds of stamens. These three tree peony species were effectively classified by the PCA and PLS-DA models based on their volatile components, and 15 differential components of the three peony species were identified using the PLS-DA model (V_VIP > 1, P < 0.05). 【Conclusion】 There were significant differences among the types and relative contents of compounds among the three tree peony species and among different parts of the same tree peony species. The main aromatic components of P. ludlowii were acetophenone and linalool. The main aroma components of P. lutea were α-pinene, β-copaene and linalool. The main aroma components of P. ostii were ocimene, α-pinene and pentadecane. The relative alkane contents in the stamens of the three tree peony species were much higher than those in whole flowers and petals, suggesting that the stamen may be an important alkane synthesis site. Different volatile components formed the unique aroma characteristics of the three tree peony species, P. ludlowii and P. lutea showed intense floral attributes, whereas P. ostii had herbal and waxy attributes.

Key words: Paeonia ludlowii, P. lutea, P. ostii, volatile compound, principle component analysis(PCA), partial least squares discriminant analysis(PLS-DA)