Aquilaria sinensis (Lour.) Spreng. - syn.Agallochum sinense (Lour.) Kuntze; Aquilaria grandiflora Bentham; A. ophispermum Poiret. - Thymelaeaceae
土沉香 tu chen xiang (chin.), Chinese agarwood, Chinesisches Adlerholz

Tree, up to 15m high, native zo China; bark dark grey; leaves orbicular or elliptic to oblong, sometimes obovate, dark or purple-green, glossy adaxially, light green abaxially; inflorescence a terminal, loose panicle of umbels, many flowered; flowers fragrant at night, calyx yellowish green, tube narrowly campanulate; fruit capsule ovoid, 2-3cm long, densely yellow pubescent.
„Aquilaria sinensis has been very heavily exploited and is listed as vulnerable by the IUCN. The bark is used to make paper; the heart wood is prized for its fragrance.“
http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200014506

„The species is considered vulnerable in mainland China due to over exploitation there and, therefore has been listed as a Wild Plant under State Protection (Category II) in China owing to the decline in its distribution. In Hong Kong the species is common in lowland forests and fung shui woodlands.“ http://www.greening.gov.hk/en/e_news/Aquilaria_sinensis.pdf There are enforcement actions against illegal logging as well as increased production and planting of seedlings of A. sinensis in country parks of Hong Kong. http://www.epd.gov.hk/epd/sites/default/files/epd/english/boards/advisory_council/files/ncsc_paper03_2013.pdf

„To identify the primary genes that maybe related to agarwood formation, we sequenced 2 cDNA libraries generated from healthy and wounded A. sinensis (Lour.) Gilg. A total of 89,137 unigenes with an average length of 678.65 bp were obtained, and they were annotated in detail at bioinformatics levels. Of those associated with agarwood formation, 30 putatively encoded enzymes in the sesquiterpene biosynthesis pathway, and a handful of transcription factors and protein kinases were related to wound signal transduction. Three full-length cDNAs of sesquiterpene synthases (ASS1-3) were cloned and expressed in Escherichia coli, and enzyme assays revealed that they are active enzymes, with the major products being δ-guaiene. A methyl jasmonate (MJ) induction experiment revealed that the expression of ASS was significantly induced by MJ, and the production of sesquiterpenes was elevated accordingly.“
Products formed by sesquiterpene synthases with farnesyl diphosphate as substrat were mainly δ-guaiene with some β-elemene and α-guaiene.
[Identification of genes related to agarwood formation: transcriptome analysis of healthy and wounded tissues of Aquilaria sinensis., Xu, Y., Zhang, Z., Wang, M., Wei, J., Chen, H., Gao, Z., Li, W., BMC genomics, 14(1), 2013, 227] http://www.biomedcentral.com/1471-2164/14/227

A novel technique used to induce agarwood production in cultivated Aquilaria sinensis trees is based on transpiration pull of water to transport the agarwood inducer to the trunks, roots and lateral branches of the whole tree, causing wounds within the whole tree. The defense response lead to the production of resin infused wood, and after 20 months the agarwood closely resembled wild agarwood. Sesquiterpene content of the essential oil obtained was 47.4-52.7%, lesser than in two wild agarwood samples (62.3-71.4%), but benzylacetone content (6.4-10.0%) was higher than in wild agarwood (2.3%).
[Liu, Yangyang, et al. „Whole-tree agarwood-inducing technique: an efficient novel technique for producing high-quality agarwood in cultivated Aquilaria sinensis trees.“ Molecules 18.3 (2013): 3086-3106] http://www.mdpi.com/1420-3049/18/3/3086/htm

Dongguan agarwood (Aquilaria sinensis) CO2 supercritical fluid extract (SFE) was investigated by GC-MS/FID. Main components were 2-(2-phenylethyl)chromone (11.0%), methoxy-2-(2-phenylethyl)chromone (4.0%), and 2-(methoxyphenylethyl)chromone (3.6%). Olfactory interesting minor components were e.g. benzaldehyde (0.12%), salicylaldehyde (0.03%), 4-phenyl-butan-2-one (0.2%), and vanillin (0.02%). Neopetasane (0.72%), another classical component of agarwood, which easily isomerizes to dihydrokaranone, and dihydrokaranone (0.8%) were also identified and are highly important odorant constituents of agarwood.
[Mladenović, M. Z., Huang, O., Wang, B., Ginestet, A., Desbiaux, D., & Baldovini, N. (2024). Chemical Investigation on the Volatile Part of the CO2 Supercritical Fluid Extract of Infected Aquilaria sinensis (Chinese Agarwood). Molecules, 29(10), 2297]

Aquilaria sinensis, Author: Chong Fat, wikimedia CC BY-SA 3.0