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TC-11

Transcriptomic Evidence for Sesquiterpene-Dominated Aroma Biosynthesis

in Aquilaria crassna

1
2
1
Yen-Chun Li, #,1 Cheng Tsai-Ying Hu, Hsin-Chun Chen, Meng-Shiou Lee, Ming-Kuem
Lin* ,1

1 Department of Chinese Pharmaceutical Sciences and Chinese Medicine Resources, College
of Chinese Medicine, China Medical University, 91 Hsueh-Shih Road, Taichung 40402,
Taiwan R.O.C.
2 Department of Cosmeceutics, College of Pharmacy, China Medical University, 100, Sec. 1,
Jingmao Rd., Beitun Dist., Taichung 406040, Taiwan R.O.C.
* E-mail: linmk@mail.cmu.edu.tw

Abstract
Agarwood (Aquilaria spp.), a member of the Thymelaeaceae family, is highly valued in
traditional medicine, incense, and perfumery for its unique aromatic compounds. Among its
species, Aquilaria crassna and Aquilaria sinensis are the most common and economically
important. A. crassna is endangered and relies mainly on plant tissue culture for propagation,
while Aquilaria sinensis is more abundant. This study induced callus tissues from leaf explants
and cultured them for one month, followed by transcriptome sequencing to investigate aroma-
related gene expression. Agarwood’s major components are sesquiterpenes such as α-humulene,
β-caryophyllene synthase, synthesized primarily via the mevalonate and methylerythritol
phosphate pathways. Gene expression levels were quantified using Fragments per Kilobase of
Transcript per Million Mapped Reads, which normalizes transcript abundance to allow accurate
comparison between A. crassna and A. sinensis, and differentially expressed genes were
subsequently identified. Analysis revealed that several upstream metabolic pathways associated
with acetyl-CoA synthesis in the MVA pathway may indirectly enhance downstream
sesquiterpene production. Furthermore, genes in the Sesquiterpenoid and triterpenoid
biosynthesis pathway were more highly expressed in A. crassna than in A. sinensis, which may
contribute to A. crassna’s stronger aroma. These findings confirm that the agarwood’s major
aromatic compounds are largely derived from sesquiterpene and related pathways, providing
molecular insights into quality differences and the regulation of secondary metabolism in
Aquilaria species.

Keywords: Aquilaria crassna; Aquilaria sinensis; Sesquiterpene biosynthesis; Transcriptome

analysis; Secondary metabolism