Gene expression analysis associated with agarwood formation in Aquilaria malaccensis

Aquilaria malaccensis produces exorbitant aromatic wood known as agarwood. The fragrant wood is primarily utilized for its aroma as a retainer of perfume and medicinal values, making it a high-value product suitably called liquid gold. Only infected trees produce agarwood which are exploited for agarwood oil extraction resulting in indiscriminate cutting of trees and its inclusion in Appendix II of the CITES. The current research aims to understand the changes in gene expression during agarwood deposition in A. malaccensis under natural condition. Expression of 25 genes involved in terpenoids biosynthesis was assessed by semi-quantitative PCR followed by qRT-PCR using RNA obtained from infected and non-infected wood. Seven housekeeping genes were also screened of which, GAPDH served as the best potential internal reference gene. Our results showed that, nine of 25 primer pairs tested can differentiate gene expression of agarwood and healthy wood. The genes involved in sesquiterpenoid biosynthesis pathway were up regulated up to 41.59 fold in agarwood as compared to healthy wood which suggests the involvement of these genes in agarwood formation. Sesquiterpene biosynthesis genes were found to be express more in naturally infected Aquilaria plants as compared to artificially induced plants.