College of Pharmacy, Guangxi University of Chinese Medicine, Nanning, 530200, China.
Key Laboratory of Protection and Utilization of Traditional Chinese Medicine and Ethnic Medicine Resources, Education Department of Guangxi Zhuang Autonomous Region, Nanning, 530200, China.
BMC Plant Biol. 2024 Feb 2;24(1):84. doi: 10.1186/s12870-024-04754-w.
Cinnamomum cassia Presl, classified in the Lauraceae family, is widely used as a spice, but also in medicine, cosmetics, and food. Aroma is an important factor affecting the medicinal and flavoring properties of C. cassia, and is mainly determined by volatile organic compounds (VOCs); however, little is known about the composition of aromatic VOCs in C. cassia and their potential molecular regulatory mechanisms. Here, integrated transcriptomic and volatile metabolomic analyses were employed to provide insights into the formation regularity of aromatic VOCs in C. cassia bark at five different harvesting times.
The bark thickness and volatile oil content were significantly increased along with the development of the bark. A total of 724 differentially accumulated volatiles (DAVs) were identified in the bark samples, most of which were terpenoids. Venn analysis of the top 100 VOCs in each period showed that twenty-eight aromatic VOCs were significantly accumulated in different harvesting times. The most abundant VOC, cinnamaldehyde, peaked at 120 months after planting (MAP) and dominated the aroma qualities. Five terpenoids, α-copaene, β-bourbonene, α-cubebene, α-funebrene, and δ-cadinene, that peaked at 240 MAP could also be important in creating C. cassia's characteristic aroma. A list of 43,412 differentially expressed genes (DEGs) involved in the biosynthetic pathways of aromatic VOCs were identified, including phenylpropanoids, mevalonic acid (MVA) and methylerythritol phosphate (MEP). A gene-metabolite regulatory network for terpenoid and phenylpropanoid metabolism was constructed to show the key candidate structural genes and transcription factors involved in the biosynthesis of terpenoids and phenylpropanoids.
The results of our research revealed the composition and changes of aromatic VOCs in C. cassia bark at different harvesting stages, differentiated the characteristic aroma components of cinnamon, and illuminated the molecular mechanism of aroma formation. These foundational results will provide technical guidance for the quality breeding of C. cassia.
肉桂（Cinnamomum cassia Presl），樟科植物，广泛用作香料，也应用于医学、化妆品和食品行业。香气是影响肉桂药用和调味特性的重要因素，主要由挥发性有机化合物（VOCs）决定；然而，肉桂皮中芳香 VOC 的组成及其潜在的分子调控机制还知之甚少。本研究采用整合转录组学和挥发性代谢组学分析方法，研究了肉桂皮在五个不同收获时间的芳香 VOC 形成规律。
随着树皮的发育，树皮厚度和挥发油含量显著增加。在树皮样品中鉴定出 724 种差异积累挥发物（DAVs），其中大部分为萜类化合物。每个时期前 100 种 VOC 的 Venn 分析表明，28 种芳香 VOC 在不同的收获时间显著积累。最丰富的挥发性化合物肉桂醛在种植后 120 个月（MAP）达到峰值，主导着香气品质。五种萜类化合物，α-罗勒烯、β-蒎烯、α-古巴烯、α-扶郎烯和 δ-杜松烯，在 240 MAP 时达到峰值，也可能对肉桂的特有香气有重要作用。鉴定出涉及芳香 VOC 生物合成途径的 43412 个差异表达基因（DEGs），包括苯丙素、甲羟戊酸（MVA）和甲基赤藓醇磷酸（MEP）途径。构建了萜类和苯丙素代谢的基因-代谢物调控网络，展示了萜类和苯丙素生物合成中关键候选结构基因和转录因子。
本研究揭示了不同收获阶段肉桂皮中芳香 VOC 的组成和变化，区分了肉桂的特征香气成分，阐明了香气形成的分子机制。这些基础研究结果将为肉桂的质量育种提供技术指导。
