Analysis of volatile components in tepals of Phalaenopsis lobbii at different flowering stages based on HS-SPME-GC-MS

【Objective】This study aimed to investigate the volatile components in tepals of Phalaenopsis lobbii at different flowering stages and their variation patterns， thereby providing theoretical basis for studying mechanisms of floral aroma and pollination，as well as data support for further developing and utilizing resources of Phalaenopsis lobbii.【Method】Using Phalaenopsis lobbii tepals as materials， headspace solid-phase microextraction （HS-SPME） and gas chromatography-mass spectrometry （GC-MS） were utilized to perform qualitative， quantitative， and principal component analyses of volatile components at the four flowering stages （bud stage， initial flowering stage， full bloom stage， and late flowering stage）， screen differential metabolites at different flowering stages， and identify key aroma components based on odor activity values （OAVs）.【Result】A total of 98 volatile components were identified from tepals at the four flowering stages， and the types and contents of volatile compounds showed an overall trend of first increasing and then decreasing with the process of flowering. The number of volatile compounds in tepals was in the order of full bloom stage （85） > initial flowering stage （71） > bud stage （70） > late flowering stage （68）， with 9， 2， 3， and 3 types of volatile compounds identified， respectively. The volatile compounds were mainly compounds of esters， aldehydes， and alcohols， followed by compounds of hydrocarbons， terpenes， ketones， and aromatics， with ether compounds being the least. The total content of volatile components in tepals was in the order of full bloom stage （412.43 μg/kg） > initial flowering stage （360.15 μg/kg） > bud stage （333.40 μg/kg） > late flowering stage （235.63 μg/kg）. The relative contents of hexaldehyde and ethyl acetate remained high during the whole flowering stages. A total of 31 differential metabolites were screened from the four flowering stages， among which 14 differential metabolites were also the aroma substances of Phalaenopsis lobbii. According to OAV analysis results， ethyl acetate， β-ionone， hexaldehyde， 1-hexanol， and myrcene were key aroma components， among which ethyl acetate and β-ionone were the common aroma components during the whole flowering stages.【Conclusion】Differences are found in types and contents of volatile components at different flowering stages of Phalaenopsis lobbii， and the aroma characteristics are influenced by type， content， and aroma threshold， thus presenting different aromas. The floral aroma is relatively strong at the initial flowering stage and grows weak with the process of flowering.