Headspace Volatiles and Endogenous Extracts of Prunus mume Cultivars with Different Aroma Types

Abstract

Prunus mume is a traditional ornamental plant, which owed a unique floral scent. However, the diversity of the floral scent in P. mume cultivars with different aroma types was not identified. In this study, the floral scent of eight P. mume cultivars was studied using headspace solid-phase microextraction (HS-SPME) and organic solvent extraction (OSE), combined with gas chromatography-mass spectrometry (GC-MS). In total, 66 headspace volatiles and 74 endogenous extracts were putatively identified, of which phenylpropanoids/benzenoids were the main volatile organic compounds categories. As a result of GC-MS analysis, benzyl acetate (1.55–61.26%), eugenol (0.87–6.03%), benzaldehyde (5.34–46.46%), benzyl alcohol (5.13–57.13%), chavicol (0–5.46%), and cinnamyl alcohol (0–6.49%) were considered to be the main components in most varieties. However, the volatilization rate of these main components was different. Based on the variable importance in projection (VIP) values in the orthogonal partial least-squares discriminate analysis (OPLS-DA), differential components of four aroma types were identified as biomarkers, and 10 volatile and 12 endogenous biomarkers were screened out, respectively. The odor activity value (OAV) revealed that several biomarkers, including (Z)-2-hexen-1-ol, pentyl acetate, (E)-cinnamaldehyde, methyl salicylate, cinnamyl alcohol, and benzoyl cyanide, contributed greatly to the strong-scented, fresh-scented, sweet-scented, and light-scented types of P. mume cultivars. This study provided a theoretical basis for the floral scent evaluation and breeding of P. mume cultivars.

Volatile Metabolome and Aroma Differences of Six Cultivars of Prunus mume Blossoms

“…Contents of benzaldehyde, methyl benzoate, benzyl benzoate, eugenol, 4-allylphenol, and benzyl alcohol in the six cultivars of P. mume blossoms were all far more than in other constituents (the relative content was greater than 1% in all six species), which are the main volatile metabolites of P. mume blossoms and all belong to phenylpropanoids/benzene compounds. This result is partially similar to existing studies [ 4 , 5 , 6 , 7 ] on the volatile metabolites in P. mume blossoms, with a difference in the content of some compounds; the most abundant substance in all six species was methyl benzoate in the present study, other than benzyl acetate, which was closely related to the difference of most of studied cultivars. Comparison of the results of the same cultivar, JM, in the present and a previous study [ 7 ], revealed some differences between both compounds and their contents.…”

“…This result is partially similar to existing studies [ 4 , 5 , 6 , 7 ] on the volatile metabolites in P. mume blossoms, with a difference in the content of some compounds; the most abundant substance in all six species was methyl benzoate in the present study, other than benzyl acetate, which was closely related to the difference of most of studied cultivars. Comparison of the results of the same cultivar, JM, in the present and a previous study [ 7 ], revealed some differences between both compounds and their contents. This may be partially attributed to the origin difference of JM, from Zhejiang, while the previous was from Hubei province, China.…”

“…Deferent sample pretreatment methods have been employed in previous studies; both static headspace adsorption and head space-solid phase microextraction (HS-SPME) were used to collect headspace volatiles emitted from whole blooming flowers [ 4 , 6 , 7 , 9 ], while organic solvent extraction of the ground powder of flowers in liquid nitrogen was applied for endogenous component sampling [ 5 , 7 ]. HS-SPME was selected to collect volatile constituents from the powder of flowers ground in liquid nitrogen for the easy addition of internal standards and preparation of quality control samples.…”

“…Some researchers have studied the scent components of some P. mume blossom cultivars from a better breeding point of view [ 4 , 5 , 6 , 7 ]. Zhao et al [ 4 ] analyzed the volatile constituents of five different cultivars of P. mume blossoms and 45 compounds were tentatively identified; among them benzaldehyde, benzyl alcohol, and benzyl acetate originated from the shikimate pathway and were the main volatiles of the analyzed P. mume , while the common components of hexyl acetate, eugenol, benzyl acetate, and α-pinene were considered the reason for the similar aroma of P. mume blossoms.…”

“…A total of 31 volatile metabolites were identified, in which phenylpropanoids/benzenoids accounted for over 95% of the total amounts, and the emissions of benzyl alcohol, cinnamyl alcohol, benzyl acetate, eugenol, (E)-cinnamyl acetate, and benzyl benzoate could make these intraspecific cultivars distinguishable from each other. Wang et al [ 7 ] investigated the headspace volatiles and endogenous extracts of different aroma types of P. mume blossoms and 66 headspace volatiles and 74 compounds in endogenous extracts were putatively identified, of which phenylpropanoids/benzenoids were the main volatile organic compound categories. Several biomarkers including (Z)-2-hexen-1-ol, amyl acetate, cinnamaldehyde, methyl salicylate, cinnamyl alcohol, and benzoyl cyanide were found to contribute to the differences of strong-, fresh-, sweet-, and light-scented types of P. mume blossoms.…”