رائحة الإجهاد: أدلة من الرائحة الفريدة للعود

This comprehensive review examines how agarwood produces its distinctive fragrance through Aquilaria plant stress responses. Agarwood is arguably the most expensive wood in the world, with production confined to specific regions in South and Southeast Asia. The fragrant resin formation results from complex biotic, abiotic, and physical stress on Aquilaria trees. The agarwood aroma consists of approximately 150 fragrant molecules, yet the detailed mechanisms remained unclear until recent research. The review aims to provide a comprehensive scientific framework for understanding these biological and chemical processes.

Agarwood is produced by several species within the genus Aquilaria. Primary species include A. malaccensis, A. crassna, and A. sinensis. These species are distributed throughout South and Southeast Asia, including India, China, Vietnam, Malaysia, and Indonesia. Global agarwood trade is valued at approximately US$6-8 billion annually. The qualitative composition of aromatic molecules varies by species and geographic origin, directly affecting market quality and pricing.

Agarwood consists of hundreds of chemical compounds, with approximately 150 aromatic molecules responsible for its distinctive scent. Main chemical groups include sesquiterpenes, hydrocarbons, aldehydes, and ketones. Important compounds include agarospirol, jinkoh-eremol, and chromans. Qualitative composition varies by species and origin.

Agarwood resin formation occurs in response to multiple stress factors. These can be categorized as: (1) Biotic stress - fungal infection and insect attack, (2) Abiotic stress - water deficit, salinity, and temperature, (3) Physical stress - wounding and mechanical damage. When trees experience stress, various signaling pathways are activated. One critical pathway involves jasmonic acid, which plays a central role in regulating defense responses.

Recent studies reveal several molecular pathways involved in triggering agarwood formation. The Jasmonate Pathway (JA) is considered one of the most important mechanisms. Under stress, jasmonic acid concentration increases, activating specific genes responsible for aromatic compound synthesis. The LOX Pathway participates in fatty acid oxidation. Other pathways include ROS responses that activate protective mechanisms.