The fragrant resin comprising agar develops in the tree heartwood after wounding followed by pathological and non-pathological mechanisms (Ng et al. 1997) as a defense reaction of the plant, and is deposited around the wounds over the years following the injury. The accumulation of the various volatile compounds eventually forms agarwood (Subasinghe and Hettiarachchi 2013). Owing to the high value of agarwood and declining wild populations, there has been an increase in the cost of the wood over time as well as increasing efforts to produce agarwood from planted Aquilaria trees. In the commercially cultivated trees, the production of resin is induced by physical penetration of the trunk (wounding) and insertion of a microbial fungal. Aquilaria species require up to a decade to reach maturity and most current harvesting techniques, for both wild and cultivated trees, involve destroying the entire tree.
Agarwood is traded as various products and derivatives, including oil, wood, wood chips, flakes, powder, exhausted powder, carvings, and jewelry (see Chapter 4). High quality wood and oil is primarily used as incense and perfume in Middle Eastern countries (Compton and Ishihara 2004), and agarwood products have been reported as a component of many traditional Ayurvedic remedies in the Indian subcontinent and used in Asian traditional medicines for many ailments including arthritis, infections, fever, and as an analgesic (Barden et al. 2000; Kiet 2003; Lim and Anack 2010). It has also been tested for its anti-carcinogenic properties, including for pancreatic cancer (Dahham et al. 2015). It is clear that the wood has high cultural and medical significance in Asia and the Middle East. Unfortunately, wild populations of all agarwood- producing species have declined considerably over the past 20–30 years (Soehartono and Newton 2001; Chua et al. 2016).