Polymorphic microsatellites for forensic identification of agarwood (Aquilaria crassna)

Tropical agarwood (Aquilaria) is in danger of extinction in the wild due to illegal logging. Its resin (Gaharu) is used for the production of highly valued incense throughout Asia. We have isolated and characterized microsatellite loci of Aquilaria crassna to detect the geographic origin of agarwood for forensic applications using a modified enrichment procedure based on the capture of repetitive sequences from restricted genomic DNA. We assessed the polymorphisms of five microsatellites amplified from fresh leaves of 22 trees from seven plantations in Vietnam and Thailand and dried leaves of a herbarium specimen of one wild tree. Cross specificity of these markers was confirmed on two related Aquilaria species occurring in China and Vietnam and one microsatellite locus was successfully amplified from wood and incense samples. Four of the loci were polymorphic and the number of alleles ranged from 3 to 15. The loci characterized here can provide a starting point for forensic identification of traded material and certification of sustainably produced agarwood.