金钗石斛不同开花时期挥发性物质成分与超微结构特征分析

Analysis of volatile components and ultrastructural characteristics of Dendrobium nobile at different flowering stages

关键词:  金钗石斛, 挥发性物质, 超微结构特征, HS-SPME-GC-MS, 扫描电镜

Key words:  Dendrobium nobile, volatile components, ultrastructural characteristics, HS-SPME-GC-MS, scanning electron microscope

摘要:

为探究金钗石斛(Dendrobium nobile)花朵香气生物合成与释放机制,该研究通过整合顶空固相微萃取(HS-SPME)、气相色谱-质谱(GC-MS)联用分析及扫描电子显微镜(SEM)观察技术,系统分析不同开花时期的挥发性成分动态变化与花器官细胞超微结构特征。结果表明:(1)在开花第1天至第14天,对每日定时采集的样本进行挥发性成分的动态监测,共鉴定出26种主要香气成分,以醇类和酯类为主,醛类、萜烯类和酮类次之; 萜烯类化合物的相对含量在第6天达到峰值,此时β-石竹烯(26.80%)、正辛醇(17.00%)和正辛醛(13.01%)为主要组分。(2)不同部位挥发性成分分析显示,唇瓣与蕊柱是主要的挥发性物质释放部位。(3)对花瓣超微结构的观察发现,唇瓣上表皮腺毛长且密集,无气孔分布,腺毛间充满分泌物,表明其表皮毛及细胞的分泌功能显著强于其他部位。因此,金钗石斛花茶原料宜优先选择唇瓣与蕊柱,并于盛花后第6天采收,以最大限度保留关键芳香成分。该研究结果不仅为金钗石斛花茶的精准采收与标准化加工提供了科学依据和量化参考,也为其他兰科芳香药用植物的香气品质调控与高效利用提供了可借鉴的技术范式。

Abstract:

To explore the biosynthesis and emission mechanism of the floral aroma in Dendrobium nobile, this study systematically analyzed the dynamic changes of volatile components and the ultrastructural characteristics of the perianth cells at different flowering stages by integrating headspace solid-phase microextraction(HS-SPME), gas chromatography-mass spectrometry(GC-MS)analysis and scanning electron microscope(SEM)observation techniques. The results were as follows:(1)Through dynamic monitoring of volatile components from samples collected daily from day 1 to day 14 of flowering, a total of 26 main aroma components were detected, mainly alcohols and esters, followed by aldehydes, terpenes, and ketones. Content of terpenes peaked on day 6, with β-caryophyllene(26.80%), 1-octanol(17.00%), and octanal(13.01%)being the dominant components.(2)The analysis of the volatile components of different parts of D. nobile revealed that the labellum and the stamina column were the main sites for the release of volatile substances.(3)Ultrastructural observation showed that the upper epidermis of the labellum had long and dense glandular trichomes without stomata, and the spaces between the glandular trichomes were filled with secretions, further confirming that the secretory function of the epidermal trichomes and cells in labellum was significantly stronger than those in other parts. Therefore, the raw materials for D. nobile flower tea should prioritize the collection of the labellum and the stamina column, and be harvested on day 6 after full bloom to maximize the retention of key aromatic components. The results of this study not only provide a scientific basis and quantitative indicators for the precise harvesting and standardized processing of D. nobile flower tea, but also offer a technical paradigm for the aroma quality regulation and efficient utilization of other fragrant medicinal plants in the Orchidaceae family.