Agarwood is the fragrant resin-infused wood derived from the wounded trees of Aquilaria species. It is a valuable non-timber forest product used in fragrances and as medicine. Reforestation for Aquilaria trees in combination with artificial agarwood-inducing methods serves as a way to supply agarwood and conserve of wild Aquilaria stock. However, the existing agarwood-inducing methods produce poor-quality agarwood at low yield. Our study evaluated a novel technique for producing agarwood in cultivated Aquilaria trees, called the whole-tree agarwood-inducing technique (Agar-Wit). Ten different agarwood inducers were used for comparison of Agar-Wit with three existing agarwood-inducing methods. For Aquilaria trees treated with these ten inducers, agarwood formed and spread throughout the entire tree from the transfusion point in the trunk to the roots and branches of the whole tree. Agarwood yield per tree reached 2,444.83 to 5,860.74 g, which is 4 to 28 times higher than that by the existing agarwood-inducing methods. Furthermore, this agarwood derived from Agar-Wit induction was found to have a higher quality compared with the existing methods, and similar to that of wild agarwood. This indicates Agar-Wit may have commercial potential. Induction of cultivated agarwood using this method could satisfy the significant demand for agarwood, while conserving and protecting the remaining wild Aquilaria trees.

Background: Agarwood is an expensive resinous heartwood derived fromAquilariaplants that is widely used in traditional medicines, incense and perfume. Only wounded trees can produce agarwood, and the huge demand for the agarwood products has led allAquilariaspp. being endangered and listed in the Appendix II of the CITES (http://www.cites.org). The major components of agarwood are sesquiterpenes and phenylethyl chromones. Owing to a lack of genomic information, the molecular basis of wound-induced sesquiterpenes biosynthesis and agarwood formation remains unknown.Results: To identify the primary genes that maybe related to agarwood formation, we sequenced 2 cDNA libraries generated from healthy and woundedA. sinensis(Lour.) Gilg. A total of 89,137 unigenes with an average length of 678.65 bp were obtained, and they were annotated in detail at bioinformatics levels. Of those associated with agarwood formation, 30 putatively encoded enzymes in the sesquiterpene biosynthesis pathway, and a handful of transcription factors and protein kinases were related to wound signal transduction. Three full-length cDNAs of sesquiterpene synthases (ASS1-3) were cloned and expressed inEscherichia coli, and enzyme assays revealed that they are active enzymes, with the major products being δ-guaiene. A methyl jasmonate (MJ) induction experiment revealed that the expression ofASSwas significantly induced by MJ, and the production of sesquiterpenes was elevated accordingly. The expression of some transcription factors and protein kinases, especiallyMYB4,WRKY4,MPKK2andMAPK2, was also induced by MJ and coordinated withASSexpression, suggesting they maybe positive regulators ofASS.Conclusions: This study provides extensive transcriptome information forAquilariaspp.and valuable clues for elucidating the mechanism of wound-induced agarwood sesquiterpenes biosynthesis and their regulation.

As widely recognized, agarwood formation in Aquilaria trees is induced by external wounding. Because agarwood usually harbors specific microbes, the function of microbes in agarwood formation has been debated for almost a century. In this study, two wounding methods, the burning-chisel-drilling method (BCD) and the whole-tree agarwood-inducing method (Agar-Wit), were used under the non-contamination of environmental microorganisms. After pyrosequencing the small rRNA subunits of the wounds induced by the BCD and Agar-Wit, no substantial variation was observed either in fungal and bacterial enrichment and diversity or in the relative abundances of taxa. By contrast, significant variations in fungal and bacterial communities were detected following the partial tree pruning (PTP)-wounding. The wound-induced sesquiterpene biosynthesis and vessel-occlusion formation, however, were found to be similar in all types of wounded trunks. We thus infer that wounding in the absence of variations in microbial communities may induce agarwood formation. This result does not support the long-standing notion that agarwood formation depends on microbes.

Dalbergia odorifera, a critically endangered tree species, produces heartwood containing a vast variety of flavonoids. This heartwood, also known as Chinese rosewood, has high economic and medicinal value, but its formation takes several decades. In this study, we showed that discolored wood induced by pruning displays similar color, structure, and flavonoids content to those of natural heartwood, suggesting that wounding is an efficient method for inducing flavonoid production in D. odorifera. Transcriptome analysis was performed to investigate the mechanism underlying wounding-induced flavonoids production in D. odorifera heartwood. Wounding upregulated the expression of 90 unigenes, which covered 19 gene families of the phenylpropanoid and flavonoid pathways, including PAL, C4H, 4CL, CHS, CHI, 6DCS, F3’5’H, F3H, FMO, GT, PMAT, CHOMT, IFS, HI4’OMT, HID, IOMT, I2’H, IFR, and I3’H. Furthermore, 47 upregulated unigenes were mapped to the biosynthesis pathways for five signal molecules (ET, JA, ABA, ROS, and SA). Exogenous application of these signal molecules resulted in the accumulation of flavonoids in cell suspensions of D. odorifera, supporting their role in wounding-induced flavonoid production. Insights from this study will help develop new methods for rapidly inducing the formation of heartwood with enhanced medicinal value.

Introduction: Dalbergia odorifera T. Chen, known as fragrant rosewood, is a rare and endangered tree species. Studies have shown that plant growth regulators can effectively promote heartwood formation. This study aimed to investigate the effects of ethephon (ETH) on heartwood formation and the influence of ethephon and hydrogen peroxide (H₂O₂) on the physiological characteristics in D. odorifera.Methods: D. odorifera branches underwent treatment with 2.5% plant growth regulators, including ETH, jasmonic acid (JA), salicylic acid (SA), abscisic acid (ABA), H₂O₂, and inhibitors such as ascorbic acid (AsA) to inhibit H₂O₂ synthesis, and (S) -trans 2-amino-4 - (2-aminoethoxy) -3-butene (AVG) to inhibit ethylene synthesis. After a 14-day period, we conducted an analysis to evaluate the impact of these plant growth regulators on elongation distance, vessel occlusion percentage, and trans-nerol content. Additionally, the effects of ETH and H₂O₂ on endogenous plant hormones, H₂O₂ content, soluble protein content, and enzyme activity were investigated within 0-48 h of treatment.Results: After treatment with ETH for 14 days, the extension distance of the heartwood material was 15 cm, while the trans-nerolol content was 15 times that of the ABA group. ETH and H₂O₂ promoted endogenous ethylene synthesis; Ethylene content peaked at 6 and 18 h. The peak ethylene content in the ETH group was 68.07%, 12.89%, and 20.87% higher than the initial value of the H₂O₂ group and ddH₂O group, respectively, and 29.64% higher than that in the AVG group. The soluble protein content and activity of related enzymes were significantly increased following ETH treatment.Discussion: ETH exhibited the most impact on heartwood formation while not hindering tree growth. This treatment effectively triggered the production of endogenous ethylene in plants and enhanced the activity of essential enzymes involved in heartwood formation. These findings serve as a valuable reference for future investigations into heartwood formation.

Dalbergia odorifera is widely used to treat cardiovascular diseases. Our research group found that Dalbergia odorifera volatile oil has a good anti-myocardial ischemic effect, and its main pharmacodynamic components are trans-nerolol and its oxides. However, the exact mechanisms underlying this effect have not yet been elucidated. This study aimed to explore the potential myocardial protective effects of trans-nerolol and its underlying molecular mechanisms. Molecular docking was used to predict and visualize the possible mechanism of the anti-apoptotic myocardial protection by trans-nerolol. The myocardial protective effect of trans-nerolol was evaluated by observing pathological injury, myocardial enzyme levels, oxidation, antioxidant levels, and the expression of related proteins. Molecular docking results showed that trans-nerolol binds closely to cytochrome C (Cytc) and apoptosis-related proteins, suggesting that it may play a role in interacting with these target proteins. The results showed that pre-treatment with dose-dependent trans-nerolol significantly mitigated the myocardial histological damage; decreased lactate dehydrogenase (LDH), creatinine kinase (CK), alanine transaminase (ALT), and aspartate transaminase (AST) levels; reduced nitric oxide (NO) production, hydrogen peroxide (H₂O₂), and lipid peroxide (LPO); and increased the total antioxidant content (T-AOC), glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD) activities compared with the model group. In addition, dose-dependent trans-nerolol significantly increased the Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase levels. Moreover, trans-nerolol markedly reduced the endogenous and external apoptotic pathways; downregulated the protein expression of Cytc, apoptotic protease activating factor-1 (Apaf1), Fibroblast-associated (Fas), Cysteine-aspartate protease 3 (Caspase3), Cysteine-aspartate protease 8 (Caspase8), and Cysteine-aspartate protease 9 (Caspase9); and upregulated the expression of Heat shock protein 70 (Hsp70) and B-cell lymphoma-2 (Bcl-2). These data indicate that trans-nerolol exerts protective effects against myocardial ischemia (MI), and its mechanism is associated with the suppression of the Cytc- and caspase-signaling pathways. Trans-nerolol has a therapeutic effect on MI, and its mechanism of action is related to its anti-apoptotic effect. These results suggest that Dalbergia odorifera has a potential role to be developed as an MI-promoting therapeutic agent.