Interxylary phloem and xylem rays are the structural foundation of agarwood resin formation in the stems of Aquilaria sinensis
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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.
KeywordsAquilaria 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.
- Adams SJ, Manohara TN, Krishnamurthy KV, Kumar TS (2016) Hitochemical studies on fungal-induced agarwood. Indian J Plant Sci 5(1):102–110Google Scholar
- Chong SP, Abdul-rahim K, Awang MR (2014) Histology study of Aquilaria malaccensis and the agarwood resin formation under light microscope. J Agrobiotechnol 5:77–83Google Scholar
- Cites (2004) Amendments to appendices I and II of cites. In: Proceedings of thirteenth meeting o the conference of the parties, Bangkok, Thailand.Google Scholar
- Elias MF, Ibrahim H, Wan RM (2017) A review on the malaysian Aquilaria species in karas plantation and agarwood production. Int J Acad Res BUSI 7(4):1021–1029Google Scholar
- Gao ZH, Wei JH (2016) Molecular mechanism studies of terpenoid biosynthesis in agarwood. In: Mohanmed R (eds) Agarwod science behind the fragrance. Springer Singapore Press Inc., Singapore, pp 73–87Google Scholar
- Gao ZH, Zhao WT, Sun PW et al (2017) Species and conservation status of the endangered agarwood-producing genus Aquilaria. Mod Chin Med 19(8):1057–1063Google Scholar
- Guangdong Institute of Plant Research (1976) Uncovering the secret of agarwood formation. Acta Bot Sin 18(4):287–291Google Scholar
- InsideWood (2004) http://insidewood.lib.ncsu.edu. Accessed 21 May 2018
- Li ZL (1996) Plant tissue anatomy. Peking University press, BeijingGoogle Scholar
- Mohamed R, Wong MT, Halis R (2013) Microscopic observation of ‘Gaharu’ Wood from Aquilaria malaccensis. Pertanika J Trop Agric Sci 36:(1):43–50Google Scholar
- Nobuchi T, Siripatanadilok S (1991) Preliminary observation of Aquilaria crassna wood associated with the formation of aloeswood bult. Kyoto Univ For 63:226–235Google Scholar
- Zhang XL (2013) Studies on relationships between wound-induced defense response and Agarwood formation in Aquilaria sinensis. Beijing Forestry University, BeijingGoogle Scholar
- Zhang Z, Yun Y, Wei JH, Hui M et al (2010) Advances in studies on mechanism of agarwood formation in Aquilaria sinensis and its hypothesis of agarwood formation induced by defense response. Chin Tradit Herb Drugs 41(1):156–159Google Scholar
- Zhang XL, Liu YY, Chen HJ et al (2012b) Study on xylem structure and histochemistry in Aquilaria sinensis. J Shandong Univ 47(1):1–5Google Scholar