## 3 Discussion
The sesquiterpene synthetase 1 (ASS1) is a prototypical wound-induced enzyme that facilitates the synthesis of various sesquiterpene compounds, including \(\delta\)-guaiene, \(\alpha\)-guaiene, and \(\alpha\)-humulene, in vitro [62]. Its promoter harbors a core sequence that responds to signals associated with tissue injury, while its key transcription factor, AsWRKY44, exerts inhibitory effects on ASS1 promoter activity [63]. Recent studies have revealed that RING3, a C3 HC4-type E3 ubiquitin ligase, plays a crucial role in the degradation of AsWRKY44. This process effectively alleviates the inhibitory effect of AsWRKY44 on ASS1 and activates the expression of ASS1. Consequently, it positively regulates sesquiterpene biosynthesis in response to wound stimulation [62]. The metabolic pattern of the callus exhibited similarities to those of roots, stems, and seeds, whereas its transcriptional pattern showed the highest resemblance to husk, followed by roots and stems. This illustration implies that significant alterations in leaf metabolic and transcriptional profiles transpire subsequent to callus formation. In addition, both metabolic and transcriptional patterns displayed similarities between roots and stems. The pathway analysis revealed that the differentially expressed genes (DEGs) and differential accumulation metabolites (DAMs) were predominantly co-enriched in key metabolic pathways, including \"Biosynthesis of various plant secondary metabolites\", \"Phenylpropanol biosynthesis\", and \"Glycolysis/Gluconeogenesis\". Among them, the differential metabolites between leaf callus and other tissues were also enriched in the \"Biosynthesis of cofactors\", and \"Sesquirepenoid and triterpenoid biosynthesis\". Additionally, the differentially expressed genes showed enrichment in \"ABC transporters\" and \"MAPK signaling pathway-plant\". The ATP Binding Cassette-Type Transporters play an essential role in the transportation process of endogenous secondary metabolites [64], terpenoids [65], and plant defense against fungal pathogens [66]. Reversible protein phosphorylation plays a crucial regulatory role in wound signaling pathways. The MAPK signaling cascade has been demonstrated to participate in abiotic stress-induced signaling pathways across various species, including Arabidopsis [67]. The results of this study demonstrate the activation of defense signaling pathways during wound signaling and callus formation, facilitating an effective response to external stress through differential accumulation of sesquiterpenes and other secondary metabolites, as well as modulation of gene expression related to metabolism. It is plausible that there might be a mechanistic similarity with agarwood formation. In addition, it has been reported [4] that there is a potential correlation between the formation of agarwood and the metabolism of starch and sugar. The utilization of sugar is essential for the promotion of plant growth and development. The presence of soluble sugars serves as an osmotic regulator, enabling the modulation of internal and external permeability in plant cells. This facilitates the maintenance of a relative equilibrium with the surrounding environment and enhances plant resilience to stress [68]. Healthy wood exhibited a substantial presence of starch particles, whereas damaged wood displayed degradation of starch particles accompanied by an increase in agarwood resin content. The differentially expressed genes involved in the \"Starch and sucrose metabolism\" pathway exhibited significant up-regulation in roots, leaves, and stems compared to calluses, suggesting a decrease in starch content following callus formation. This finding implies that calluses and alaceae may share similar regulatory patterns within this metabolic pathway. The metabolite and transcriptome data in this study provide a comprehensive analysis of metabolic and transcriptional expression patterns across different tissues of _A.