Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, National Forestry and Grassland Administration Key Laboratory of Forest Resource Conservation and Ecological Safety on the Upper Reaches of the Yangtze River, Rainy Area of West China Plantation Ecosystem Permanent Scientific Research Base, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China.
Sichuan Academy of Forestry, Sichuan Key Laboratory of Ecological Restoration and Conservation for Forest and Wetland, Chengdu 610081, China.
Molecules. 2023 Oct 12;28(20):7047. doi: 10.3390/molecules28207047.
Nanmu () has a unique fragrance and is a high-quality tree species for forest conservation. The types and contents of volatile compounds in different tissues of nanmu wood are different, and the study of its volatile metabolites can help us to understand the source of its fragrance and functions. In order to explore the metabolites related to the wood fragrance of nanmu and to find out the unique volatile substances in the heartwood, gas chromatography-mass spectrometry (GC-MS) was performed to analyze the non-targeted metabolomics in five radial tissues from the sapwood to the heartwood of nanmu. A total of 53 volatile metabolites belonging to 11 classes were detected in all tissues, including terpenes, aromatic hydrocarbons, organoheterocyclics, phenols, esters, organic acids, alcohols, alkaloids, alkane, indoles derivatives, and others. And most of the volatile metabolites were identified for the first time in nanmu wood. Among them, terpenes and aromatic hydrocarbons were the main volatile components. In addition, 22 differential metabolites were screened from HW and SW, HW, and TZ via metabolomic analysis. Among these DAMs, three volatile metabolites (cadinene, a sesquiterpenoid; -cymene, a monoterpenoid; 1,3,5-triisopropylbenzene, an aromatic hydrocarbon) contributed heavily to the characteristic fragrance of the heartwood. Additionally, the expression of transcripts showed that the unigenes in the terpenoid biosynthesis pathway were especially up-regulated in the SW. Therefore, we speculated that fragrance-related metabolites were synthesized in SW and then deposited in heartwood during sapwood transformed to heartwood. The expression levels of transcription factors (e.g., WRKY, C2H2, NAC) acted as the major regulatory factors in the synthesis of terpenoid. The results lay the foundations for further studies on the formation mechanism of fragrance components in nanmu wood and also provide a reference for the further development and utilization of nanmu wood.
楠木（）具有独特的香气，是森林保护的优质树种。不同组织楠木木材挥发性化合物的类型和含量不同，研究其挥发性代谢产物有助于我们了解其香气和功能的来源。为了探讨楠木木香相关的代谢物，找出心材中独特的挥发性物质，采用气相色谱-质谱联用（GC-MS）对楠木从边材到心材的 5 个径向组织进行非靶向代谢组学分析。在所有组织中均检测到 53 种属于 11 类的挥发性代谢物，包括萜类、芳烃、有机杂环、酚类、酯类、有机酸、醇类、生物碱、烷烃、吲哚衍生物等。而且大多数挥发性代谢物在楠木木材中首次被鉴定出来。其中，萜类和芳烃是主要的挥发性成分。此外，通过代谢组学分析从 HW 和 SW、HW 和 TZ 中筛选出 22 种差异代谢物。在这些 DAM 中，三种挥发性代谢物（倍半萜类化合物杜松烯；单萜类化合物-蒎烯；芳烃类化合物 1,3,5-三异丙基苯）对心材的特征香气贡献较大。此外，转录本的表达表明，萜类生物合成途径中的基因在边材中表达上调。因此，我们推测与香气相关的代谢物在边材中合成，然后在心材形成过程中沉积在心材中。转录因子（如 WRKY、C2H2、NAC）的表达水平作为萜类合成的主要调控因子。这些结果为进一步研究楠木木香成分的形成机制奠定了基础，也为楠木木材的进一步开发利用提供了参考。
