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Interxylary phloem and xylem rays are the structural foundation of agarwood resin formation in the stems of Aquilaria sinensis

  • Peiwei Liu
  • Xingli Zhang
  • Yun Yang
  • Chun Sui
  • Yanhong Xu
  • Jianhe WeiEmail author
Original Article


Key message

The formation of resin in the wood of A. sinensis was observed, and the results showed that the interxylary phloem, together with xylem rays, provided a structural foundation for the formation of agarwood resin.


Agarwood is a costly resinous wood harvested from wounded Aquilaria trees and has been widely used in medicine, incense, and perfumery. A defensive response of Aquilaria to various wounds has been shown to be the key reason for agarwood formation; however, our understanding of the anatomical basis of agarwood formation is still fragmentary. In this study, we examined the structural characteristics of A. sinensis wood and its relationship with agarwood formation. The results showed that interxylary phloem together with xylem rays is the main tissue that contains living parenchyma cells in the wood of healthy A. sinensis and that the main reserve substance in these parenchyma cells is in the form of starch grains. After Agar-Wit treatment, these starch grains undergo a series of changes and are eventually converted into agarwood resin; the non-starch polysaccharides and phenols are some of the intermediate products in the process of agarwood resin formation. The resin initially forms and mainly accumulates in the parenchyma cells of the interxylary phloem and xylem rays. The results indicated that the interxylary phloem and xylem rays in the wood are not only the primary location of agarwood resin formation but also the main accumulation site. The stored starch grains might be the material underlying the formation of the resin.


Aquilaria sinensis Agar-Wit Interxylary phloem Xylem ray Agarwood resin 



This work was supported by the funding from the Hainan province Key Scientific and Technological Research and Development Special Project (ZDKJ2016004), the National Natural Science Foundation of China (81673549, 81703651), the Ten Thousand Talent Program (99950534),the CAMS Innovation Fund for Medical Sciences (2016-I2M-2-003,2016-I2M-1-012).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interests.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Key Laboratory of State Administration of Traditional Chinese Medicine for Agarwood Sustainable Utilization, Hainan Branch of the Institute of Medicinal Plant DevelopmentChinese Academy of Medical Sciences and Peking Union Medical CollegeHaikouChina
  2. 2.Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education & National Engineering Laboratory for Breeding of Endangered Medicinal Materials, Institute of Medicinal Plant DevelopmentChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina
  3. 3.Qilu University of Technology (Shandong Academy of Sciences)JinanChina

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