Evaluation of biotic and abiotic stressors to artificially induce agarwood production in Gyrinops versteegii (Gilg.) Domke seedlings

Gyrinops versteegii is a tropical, agarwood-producing tree. Agarwood is valued for its fragrant resin, which has resulted in over-harvesting of agarwood trees and their protection as endangered species. Agarwood is produced in response to physical, chemical, or biological stress, and considerable research has been devoted to identifying effective methods for artificial induction of agarwood. Among the known agarwood-forming species, most research has been carried out on species in the genus Aquilaria. In the present study, we report results of a preliminary study on the potential of Gyrinops versteegii for agarwood production using seedlings. Agarwood production in the stem of Gyrinops versteegii seedlings was evaluated in response to bark removal (wounding treatment), or inoculation with bacteria (Bacillus sp. or Alcaligenes sp.) or fungi (Fusarium solani or Paecilomyces variotii), or treatment with salicylic acid. Healthy unwounded seedlings were included in the analyses as negative controls. We found that terpene was formed in response to all treatments and mainly accumulated in the interxylary phloem and xylem rays. Analysis for volatile chemicals using gas chromatography-mass spectrometry revealed that sesquiterpenes were only detected in stems treated with the fungus, Fusarium solani, and that chromones were present in stems inoculated with bacteria or fungi. Our results demonstrate that both biological and chemical agents have the potential to induce the biosynthesis of agarwood resin components in Gyrinops versteegii seedlings. Among these, Fusarium solani was the most effective agent. We anticipate that this study will lead to a more elaborate study of agarwood formation in the genus Gyrinops.