Temporal characteristics of agarwood formation in Aquilaria sinensis after applying whole-tree agarwood-inducing technique

Objective: Agarwood-a resinous wood produced by Aquilaria plants in response to injury or artificial induction-is a valuable medicinal and fragrance resource. Whole-Tree Agarwood-Inducing Technique (Agar-WIT) has been widely used to produce agarwood. However, the time-dependent characteristics of agarwood formation induced by Agar-WIT are yet to be clarified. To promote technologically efficient utilization and upgradation of Agar-WIT, the dynamic process and mechanism of agarwood formation were analyzed for one year. Methods: Agarwood formation percentage, barrier layer microscopic properties, extract levels, compound level, and characteristic chromatograms of agarwood were examined by referring to the Chinese Pharmacopeia (2020 version).Results: Agar-WIT could maintain a high percentage of agarwood formation over one year compared with that of healthy plants. Alcohol-soluble extract and agarotetrol levels showed fluctuating cyclic changes with peaks occurring first during the fifth and sixth months, and subsequently in the 11th month. Aquilaria trees subjected to Agar-WIT treatment for 1-12 months showed significant characteristics of a dynamic agarwood formation process. The barrier layer began to appear in the fourth month after treat-ment. Alcohol-soluble extractive levels in agarwood formed in the second month, and thereafter, exceeded 10.0%, and agarotetrol in agarwood produced after four months or later, exceeded 0.10%.Conclusion: According to the Chinese Pharmacopoeia, alcohol-soluble extractive levels in agarwood should not be less than 10.0% and agarotetrol level should exceed 0.10%. After four months of Agar-WIT treat-ment, the formed agarwood theoretically met these standards and was suitable for developed and utiliza-tion. However, the optimal harvest time was found to be the 11th month, followed by the sixth month after Agar-WIT treatment. Therefore, Agar-WIT resulted in swift agarwood formation and stable accumu-lation of alcohol-soluble extracts and agarotetrol. Thus, this method is efficient for large-scale cultivation of Aquilaria sinensis to produce agarwood and provide raw materials for the agarwood medicinal industry.(c) 2022 Tianjin Press of Chinese Herbal Medicines. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).