Elicitation of Secondary Metabolites in Aquilaria malaccensis Lam. Callus Culture by Crude Mycelial Extract of Fusarium solani and Methyl Jasmonate

Agarwood is a resinous wood of great economic value produced by trees from the Thymelaeaceae family in response to stress. The natural formation of agarwood can take decades after exposure to the stressors. Artificial agarwood induction by inoculating the stem with fungi has been successfully demonstrated, but resin accumulation occurs very slowly. Cell suspension and callus cultures may serve as an alternative solution to provide a fast-growing plant material to produce artificial agarwood in a short period. Here, we induced agarwood formation in callus cultures of Aquilaria malaccensis by application of crude mycelial extracts of Fusarium solani strains GSL1 or GSL2, or methyl jasmonate (MeJA). After 20 days of treatment with elicitors, all treated calluses had less dry weight than the control group. The gas chromatography-mass spectrometry analysis identified 33 different secondary metabolites among all samples, four of which were present in all treatments and control, i.e., 1-docosene and 1-octadecene (alkenes), 4-di-tert-buthylphenol (phenolic), and benzenepropanoic acid (fatty acid). The 6-methoxy-2-(4-methoxyphenethyl)-4H-chromene-4-one, a chromone derivative, was only detected in callus elicited with the F. solani strain GSL2 and MeJA. All treated calli produced more fatty acid derivatives than the control group. We conclude that elicitors used in this study can induce the production of agarwood-related chemicals such as chromone and fatty acid in callus culture.

Automated summary

This study induced the production of agarwood-related chemicals in callus cultures through the application of fungal extracts or methyl jasmonate. The results showed that all treated calluses had a lower dry weight compared to the control group, and gas chromatography-mass spectrometry analysis identified four common secondary metabolites among all samples. Additionally, a new substance was only detected in callus cultures induced by F. solani strains or methyl jasmonate. Therefore, the conclusion is that the elicitors used in this study can induce the production of agarwood-related chemicals in callus cultures.