Biochemical insights into Agarwood resin formation: comparative analysis of microbial induced via insect-infested and artificially induced Aquilaria malaccensis tissues

Agarwood is a highly valuable, fragrant resinous wood produced by Aquilaria trees in response to infection or injury. Agarwood obtained through the infestation by the insect Neurozerra conferta generally is in higher demand. It receives higher prices than artificially induced agarwood and is usually preferred by farmers and traders. Although different grades of insects infested and artificially induced wood are available in the market, no study exists that compared them to recognize the underlying reasons. Therefore, the present study, for the first time examines the difference between the insect-infested and artificially induced agarwood. Insect-infested and artificially induced resinous agarwood tissues were firstly segregated visually into grades and after that studied biochemically. The findings revealed significant differences in their phytochemical and polysaccharide constituent. GC-MS profiling with Principal Component Analysis (PCA), and Heatmap analysis not only validated the visual grading of agarwood but also the existence of key biochemical variations (mainly cellulose, and lignin) between the two types of wood. Furthermore, the findings indicate the possibility of repression of the defense mechanism in Aquilaria malaccensis trees by the insect N. conferta and thereby regulates the synthesis of other compounds which could be the possible reason that makes it better in its quality. Although the selective infestation of the A. malaccensis trees by the insect in contrast to blanket artificial induction creates limitations on the extent of commercial agarwood resin induction, yet the same selectivity helps in selecting suitable trees that can confer a clear qualitative advantage in agarwood resin development.