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In recent years, illegal felling of and damage to the incense tree Aquilaria sinensis (Lour.) Spreng. have been reported in Hong Kong. Their native populations are under increasingly severe threat. Therefore, the development of a standard and efficient method to classify and document wounds on vulnerable trees is urgently needed for conservation purposes. In this study, photogrammetry was used to document wounds in A. sinensis through 3D modeling. A total of 752 wound records from 484 individual A. sinensis trees from Hong Kong were included to establish a new wound classification system. Our major findings include a novel standardized procedure for photogrammetric documentation and a wound classification system. The results of this study will facilitate A. sinensis conservation, by enhancing wound documentation and information transfer to law enforcement and education. [ABSTRACT FROM AUTHOR]

Abstract In recent years, illegal felling of and damage to the incense tree Aquilaria sinensis (Lour.) Spreng. have been reported in Hong Kong. Their native populations are under increasingly severe threat. Therefore, the development of a standard and efficient method to classify and document wounds on vulnerable trees is urgently needed for conservation purposes. In this study, photogrammetry was used to document wounds in A. sinensis through 3D modeling. A total of 752 wound records from 484 individual A. sinensis trees from Hong Kong were included to establish a new wound classification system. Our major findings include a novel standardized procedure for photogrammetric documentation and a wound classification system. The results of this study will facilitate A. sinensis conservation, by enhancing wound documentation and information transfer to law enforcement and education.

The plastid is an essential organelle for its role in photosynthesis and energy production and its genomic information is always employed as important evolutionary markers to explore the relationship among species. Agarwood (Aquilaria), prized for its aromatic blend, finds extensive use in various cultures as incense and perfume. Despite its high economic importance, the phylogenetic status among Aquilaria based on plastomes remains ambiguous due to the lack of available plastomic resources. To bridge this knowledge gap, 22 Aquilaria plastomes were newly sequenced, similar variation patterns in this genus were determined, including a shared 16 bp extension of the rps19 gene and seven highly variable regions. The analysis highlighted the highest prevalence of the A/T motif among simple sequence repeats in these plastomes. Further phylogenetic analysis revealed Aquilaria's phylogenetic implications with an expanded dataset. This comprehensive plastomic resource not only enhances our understanding of Aquilaria evolution but also presents potential molecular markers for DNA barcoding.

Respiratory burst oxidase homolog (Rboh) generates reactive oxygen species (ROS) as a defense response during biotic and abiotic stress. In Aquilaria plants, wounding and fungal infection result in biosynthesis and deposition of secondary metabolites as defense responses, which later form constituents of fragrant resinous agarwood. During injury and fungal invasion, Aquilaria tree generates ROS species via the Rboh enzymes. Despite the implication of Rboh genes in agarwood formation, no comprehensive genomic-level study of the Rboh gene family in Aquilaria is present. A systematic illustration of their role during stress and involvement in initiating signal cascades for agarwood metabolite biosynthesis is missing. In this study, 14 Rboh genes were retrieved from genomes of two Aquilaria species, A. agallocha and A. sinensis, and were classified into five groups. The promoter regions of the genes had abundant of stress-responsive elements. Protein-protein network and in silico expression analysis suggested their functional association with MAPK proteins and transcription factors such as WRKY and MYC2. The study further explored the expression profiles of Rboh genes and found them to be differentially regulated in stress-induced callus and stem tissue, suggesting their involvement in ROS generation during stress in Aquilaria. Overall, the study provides in-depth insight into two Rboh genes, AaRbohC and AaRbohA, highlighting their role in defense against fungal and abiotic stress, and likely during initiation of agarwood formation through modulation of genes involved in secondary metabolites biosynthesis. The findings presented here offer valuable information about Rboh family members, which can be leveraged for further investigations into ROS-mediated regulation of agarwood formation in Aquilaria species. [ABSTRACT FROM AUTHOR]

Respiratory burst oxidase homolog (Rboh) generates reactive oxygen species (ROS) as a defense response during biotic and abiotic stress. In Aquilaria plants, wounding and fungal infection result in biosynthesis and deposition of secondary metabolites as defense responses, which later form constituents of fragrant resinous agarwood. During injury and fungal invasion, Aquilaria tree generates ROS species via the Rboh enzymes. Despite the implication of Rboh genes in agarwood formation, no comprehensive genomic-level study of the Rboh gene family in Aquilaria is present. A systematic illustration of their role during stress and involvement in initiating signal cascades for agarwood metabolite biosynthesis is missing. In this study, 14 Rboh genes were retrieved from genomes of two Aquilaria species, A. agallocha and A. sinensis, and were classified into five groups. The promoter regions of the genes had abundant of stress-responsive elements. Protein–protein network and in silico expression analysis suggested their functional association with MAPK proteins and transcription factors such as WRKY and MYC2. The study further explored the expression profiles of Rboh genes and found them to be differentially regulated in stress-induced callus and stem tissue, suggesting their involvement in ROS generation during stress in Aquilaria. Overall, the study provides in-depth insight into two Rboh genes, AaRbohC and AaRbohA, highlighting their role in defense against fungal and abiotic stress, and likely during initiation of agarwood formation through modulation of genes involved in secondary metabolites biosynthesis. The findings presented here offer valuable information about Rboh family members, which can be leveraged for further investigations into ROS-mediated regulation of agarwood formation in Aquilaria species.

Agarwood, also known as Oud in perfumery, is a wood modified through contact with microorganisms. It emits a sweet and heady fragrance that is rare and precious. It derives its rarity from its very existence, from the trees of the genus Aquilaria. Indeed, agarwood arises from an interaction between the wood of those trees and associated microorganisms, which, after the trunk has been wounded, induce a reaction leading to the production of secondary compounds that give the wood its typical black coloration after oxidation. The compounds involved are mainly chromones and oxygenated sesquiterpenes, such as eudesmol, agarospirol, jinkoh-eremol and valerianol. Demand for agarwood on the international market has increased considerably over the last ten years or so. Its derivatives, including the essential oil extracted from it, are therefore expensive. Agarwood essential oil fetches US$ 5,000 to US$ 10,000 per kg, and is the most expensive oil on the market. That explains why this product is coveted by the owners of the trees, who attempt to compensate for its rarity by practising various agarwood induction methods. The methods, such as making holes or hammering nails into the trunks of the trees, or inoculating mixtures of biochemical products, are often harmful to the trees and detrimental to the composition of the essential oil extracted from them. Consequently, a consortium of farmers in French Guiana and scientists from CIRAD (French Agricultural Research Centre for International Development) is implementing the Aquil@Guyane project, designed to grow Aquilaria trees originating from Southeast Asia in French Guiana, with a view to producing agarwood with a controlled chemical composition that respects the biology and the ecology of the trees, while helping to conserve the genus Aquilaria, which is classed as being under threat of extinction (in CITES annex II) in its natural range. To that end, a biological induction trial was launched. Two induction methods were tested: a way of inducing black wood by environmental microorganisms, achieved by making wounds in the trunk, contaminated or not with soil from the plantation, and a second way of inducing black wood by fungal strains grown in the form of pure strains, selected for their wood-decay trait and because they are common fungi in French Guiana. For the second method, experiments were carried out specifically with brown-rot and whiterot fungi. In order to compare the two methods, we studied the area of inoculation propagation, the volatile compounds making up the essential oils extracted from the blackened wood, and essential oil yields. We were thus able to show that the second black wood induction method was effective in producing agarwood with a controlled chemical composition and a yield that seemed to be better that the usual commercial yield. It should be noted that white-rot fungi, especially Ganoderma resinaceum, Gloeophyllum trabeum and Pycnoporus sanguineus, proved to be the most effective for induction, for the quality of the chemical composition, and for essential oil yields. [ABSTRACT FROM AUTHOR]

Agarwood is originated from the resinous part of Aquilaria and Gyrinops plants and has been a precious biomaterial for applications in traditional medicine, perfumery, cosmetics, and religious purposes all over the world. In the wild, the formation of agarwood is related to the defense mechanism of the tree in response to physical damage that allows further microbial infestation into its wood, while having the whole tree covered with agarwood would take up a long time, and it rarely happens. For Aquilaria and Gyrinops, the presence of endophytes is mainly found derived from the tree. The isolated endophytes could be important sources of natural products, while some could contribute to the formation of agarwood in the tree, which is safe for the environment and human health. This review summarized the biodiversity of fungal endophytes recorded in Aquilaria and Gyrinops and their potential effects on host trees. Till now, 67 endophytic genera have been isolated from Aquilaria and Gyrinops, and 18 ones were found responsible for the promotion of agarwood formation. Additionally, 92 compounds have been reported to be produced by the agarwood endophytes, and 52 ones displayed biological activities, most of which have anti-inflammatory, anti-bacterial, and anti-cancer activities. Nevertheless, fungal endophytes are promising agents that deserved to be further studied and scaled up to a commercial level for the production of agarwood oil, but the role of endophytes in the agarwood host trees needs to be furtherly investigated in future studies.

The current study for the first time showed that agarwood resin formation in Aquilaria species could be induced by the mycotoxin-containing aqueous extracts of certain fungi. Volumes of 25, 50, and 100 mL of mycotoxin-containing extracts from the ASP-U strain of Aspergillus niger and the FUS-U strain of Fusarium solani were inoculated into Aquilaria crassna trees at 1 m intervals with three replicates. Resin production due to the extracts of ASP-U and FUS-U strains was restricted to ± 20 cm and ± 60 cm, respectively from the inoculation point after seven months and the color of the resinous agarwood varied from yellowishbrown to black. The differences in resin content formation due to the different inoculant volumes of ASP-U and FUS-U were statistically significant and the average resin contents varied from 0.89%4.44% and 1.24%9.20%, respectively. GC-MS analysis of the resin extracts detected 27 constituents responsible for the characteristic aroma of agarwood resin. Among them were phenyl butanone, agarofuran, agarospirol, ß-caryophyllene, alloaromadendrene oxide and (-) guaiene-1(10),11-diene-15-ol were found in all extracts. These compounds were common in commercially available agarwood induced by live fungal species. Hence, the study demonstrated that mycotoxin extracts from specific fungal strains could be used for agarwood production in Aquilaria. [ABSTRACT FROM AUTHOR]

Agarwood, popularly known as oudh or gaharu, is a fragrant resinous wood of high commercial value, traded worldwide and primarily used for its distinctive fragrance in incense, perfumes, and medicine. This fragrant wood is created when Aquilaria trees are wounded and infected by fungi, producing resin as a defense mechanism. The depletion of natural agarwood caused by overharvesting amidst increasing demand has caused this fragrant defensive resin of endangered Aquilaria to become a rare and valuable commodity. Given that instances of natural infection are quite low, artificial induction, including biological inoculation, is being conducted to induce agarwood formation. A long-term investigation could unravel insights contributing toward Aquilaria being sustainably cultivated. This review will look at the different methods of induction, including physical, chemical, and biological, and compare the production, yield, and quality of such treatments with naturally formed agarwood. Pharmaceutical properties and medicinal benefits of fragrance-associated compounds such as chromones and terpenoids are also discussed. [ABSTRACT FROM AUTHOR]

Agarwood, resin produced by wounded Aquilaria plants, is widely used in perfume and medicine. In this study, artificial agarwood induced by physical injury, chemical stimulation, fungal infection, and comprehensive stimulation, which are the common induction methods, was collected. After gas chromatography–mass spectrometry (GC–MS) analysis, the total ion chromatogram/mass ion chromatogram (TIC/MIC) and qualitative peak data from artificial agarwood were used as training sets in discriminant analysis to examine the formation modes of natural agarwood by a random forest model which was shown to be superior to discriminate the formation of natural agarwood. The results implied that natural agarwood is likely formed through four formation modes. The discriminant result from random forest model showed that 17.1% of natural agarwood samples were formed by physical injury, 22.9% by chemical stimulation, 2.9% by fungal infection, and 57.1% by comprehensive stimulation. 2-Butanone-4-phenyl-, benzenepropanoic acid, guaiol, baimuxinal, and 2-(2-phenylethyl) chromone were the main chemical markers of the agarwood. The apparent abundance from the GC–MS fingerprints was used to distinguish agarwood formed by different formation processes. [ABSTRACT FROM AUTHOR]

The incense culture in the Japanese archipelago dates back almost one and a half millennia in terms of its development since the discovery of the agarwood bar in 595 off the coast of Awaji Island. In a relatively short period of time, aromatic wood has gone from an exotic phenomenon of mainland culture into becoming one of Japan’s most important items of trade and economic relations with the countries of East Asia. The value of karamono (“things from China”) goods, which, among other things, included incense and tools for its burning, can hardly be overestimated: these were not merely “luxury goods” accessible to the privileged social classes, but rather full-fledged vehicles of continental culture influence. Aromatic wood was used in medicine, religious practices, and in everyday life. Over time, under the influence of Buddhism and the principles of aristocratic and samurai ideology, the use of incense turned not only into a traditional art, but also into a symbol of the national culture of Japan. Based on the analysis of written and artistic Japanese sources, as well as field studies, this article explores the classification of aromatic wood species of the agarwood tree (aquilaria), which played a key role in Japanese culture in the Middle Ages and the Modern Period. These classifications are still being used in assessing the quality of wood and wood products. Medieval Japanese masters invented ways of encoding aromas of fragrant wood through the characteristics of tastes and the place of growth of aromatic trees, as well as through the figurative, symbolic, and metaphorical meaning of each name.

Agarwood from Aquilaria plants, also known as Chen Xiang (沉香), is traditionally used for the treatment of abdominal pain and as a sedative. Because of the great demand and the rareness of agarwood, extensive harvesting of Aquilaria plants has nearly led to the extinction of the species. To fully utilize this resource, the use of different parts of Aquilaria needs to be investigated. This article will focus on the pharmacological properties and the mechanism of action of different parts of Aquilaria plants. [ABSTRACT FROM AUTHOR]

Agarwood, popularly known as oudh or gaharu, is a fragrant resinous wood of high commercial value, traded worldwide and primarily used for its distinctive fragrance in incense, perfumes, and medicine. This fragrant wood is created when Aquilaria trees are wounded and infected by fungi, producing resin as a defense mechanism. The depletion of natural agarwood caused by overharvesting amidst increasing demand has caused this fragrant defensive resin of endangered Aquilaria to become a rare and valuable commodity. Given that instances of natural infection are quite low, artificial induction, including biological inoculation, is being conducted to induce agarwood formation. A long-term investigation could unravel insights contributing toward Aquilaria being sustainably cultivated. This review will look at the different methods of induction, including physical, chemical, and biological, and compare the production, yield, and quality of such treatments with naturally formed agarwood. Pharmaceutical properties and medicinal benefits of fragrance-associated compounds such as chromones and terpenoids are also discussed.

In the current review article, the studies conducted to investigate the anti-inflammatory activity of Aquilaria species are compiled and summarized. Since inflammation is the underlying cause of many diseases, the encounter of effective and safe biomedical anti-inflammatory compounds has become the focus of recent researches. Aquilaria species were known to possess a wide spectrum of pharmacological activities, among which anti-inflammatory activity has been reported in many in vitro and in vivo studies. Chromones, sesquiterpenoids, flavonoids, benzophenones and phorbol esters were the major anti-inflammatory compounds isolated from Aquilaria species. The objective of this review paper is to extend researches on the anti-inflammatory activity of different parts of Aquilaria species and support their future use in natural pharmaceutical preparations for the treatment of inflammation-associated conditions. [ABSTRACT FROM AUTHOR]

Trees in the genus Aquilaria (Thymelaeaceae) are known as lign aloes, and are native to the forests of southeast Asia. Lign aloes produce agarwood as an antimicrobial defence. Agarwood has a long history of cultural and medicinal use, and is of considerable commercial value. However, due to habitat destruction and over collection, lign aloes are threatened in the wild. We present a chromosomal‐level assembly for Aquilaria sinensis, a lign aloe endemic to China known as the incense tree, based on Illumina short‐read, 10X Genomics linked‐read, and Hi‐C sequencing data. Our 783.8 Mbp A. sinensis genome assembly is of high physical contiguity, with a scaffold N50 of 87.6 Mbp, and high completeness, with a 95.8% BUSCO score for eudicotyledon genes. We include 17 transcriptomes from various plant tissues, providing a total of 35,965 gene models. We reveal the first complete set of genes involved in sesquiterpenoid production, plant defence, and agarwood production for the genus Aquilaria, including genes involved in the biosynthesis of sesquiterpenoids via the mevalonic acid (MVA), 1‐deoxy‐D‐xylulose‐5‐phosphate (DXP), and methylerythritol phosphate (MEP) pathways. We perform a detailed repeat content analysis, revealing that transposable elements account for ~61% of the genome, with major contributions from gypsy‐like and copia‐like LTR retroelements. We also provide a comparative analysis of repeat content across sequenced species in the order Malvales. Our study reveals the first chromosomal‐level genome assembly for a tree in the genus Aquilaria and provides an unprecedented opportunity to address a variety of applied, genomic and evolutionary questions in the Thymelaeaceae more widely. [ABSTRACT FROM AUTHOR]

Agarwood has been used as an incense and in traditional medicines as aphrodisiac, sedative, cardiotonic, and carminative. In this study, five new 2-(2-phenylethyl)chromones (2, 13–16) and eleven known compounds (1, 3–12) were isolated from the agarwood. The structures of the new compounds were determined by 1H-, 13C-, and two-dimensional NMR together with electronic circular dichroism (ECD) spectroscopy. All isolated compounds were evaluated for the phosphodiesterase (PDE) 3A and 5A1 inhibitory activity by the fluorescence polarization method. Dimeric 2-(2-phenylehyl)chromones (13, 14, 16) had potent inhibitory activity to PDE 5A1 with IC50 values of micro molar range (13: 4.2 μM, 14: 7.9 μM, 16: 4.3 μM), whereas they had weak activity to PDE 3A. In contrast, compound (15), which has a phenylpropionic acid moiety instead of the 2-(2-phenylethyl)chromone moiety in the dimers, showed moderate inhibition of both PDE 3A (IC50: 42.6 μM) and PDE 5A1 (IC50: 15.1 μM). [ABSTRACT FROM AUTHOR]

Agarwood is a type of resinous wood found in the trunks of Aquilaria and some other genera. It is widely used as an herbal medicine for sedation, detoxification, and treatment of stomachaches, as well as for incense sticks. However, the number of source plants is decreasing, and in 2005, they were added to Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). To identify source species of agarwood, we previously developed a DNA-barcoding method using resin deposition sites. In this study, to identify additional agarwood source species, the barcoding method was applied to source plants and commercial agarwood samples collected from Sumbawa, Lombok, Sulawesi, and Kalimantan in Indonesia, a major agarwood-producing country. In addition, the method was also applied to incense stick samples labeled as agarwood. As a result, several samples were identified as Gyrinops, which is not currently listed as an agarwood source plant in the Japanese standards for non-Pharmacopoeial crude drugs 2018 (Non-JPS 2018). From the viewpoint of securing future resources, these findings suggest that Gyrinops species should, therefore, be added to the list of agarwood source species. [ABSTRACT FROM AUTHOR]

Agarwood is a resinous part of the non-timber Aquilaria tree, which is a highly valuable product for medicine and fragrance purposes. To protect the endangered Aquilaria species, mass plantation of Aquilaria trees has become a sustainable way in Asian countries to obtain the highly valuable agarwood. As only physiologically triggered Aquilaria tree can produce agarwood, effective induction methods are long sought in the agarwood industry. In this paper, we attempt to provide an overview for the past efforts toward the understanding of agarwood formation, the evolvement of induction methods and their further development prospects by integrating it with high-throughput omics approaches.

Agarwood is a resinous part of the non-timber Aquilaria tree, which is a highly valuable product for medicine and fragrance purposes. To protect the endangered Aquilaria species, mass plantation of Aquilaria trees has become a sustainable way in Asian countries to obtain the highly valuable agarwood. As only physiologically triggered Aquilaria tree can produce agarwood, effective induction methods are long sought in the agarwood industry. In this paper, we attempt to provide an overview for the past efforts toward the understanding of agarwood formation, the evolvement of induction methods and their further development prospects by integrating it with high-throughput omics approaches. [ABSTRACT FROM AUTHOR]

Agarwood, the resinous product of Aquilaria spp. (Thymelaeaceae), is highly valued for medicinal and fragrant purposes. Unsustainable forest harvesting contributes to the declining population in the wild, threatening their existence. As a protection effort, cultivation occurred in range countries, mainly in Asia, effectively establishing mass plantations. The success of domesticating Aquilaria relies heavily on technological advancement in agarwood induction, without which the entire thriving industry will collapse. In this paper, we describe efforts since 1929 and current progress and variation in induction as practiced in Asia. The methods include traditional practices and artificial induction via inoculum and chemical inducer, experimented and patented or otherwise. Artificial induction methods are being developed to intensify agarwood production in terms of yield and quality. While traditional methods are commonly applied by rural planters, artificial methods with the use of specific agents/chemicals are seen as more appealing for inducing agarwood, and have a higher demand from entrepreneurs and plantation owners. Several issues related to induction technology faced by stakeholders in agarwood cultivation are presented, such as safety levels, cost, yields, and quality. We conclude by highlighting remaining challenges in induction methods and their associated technologies. [ABSTRACT FROM AUTHOR]

Aquilaria is a tree species belonging to the Thymeleaceae family. When Aquilaria sp. is injured, it can produce agarwood. Agarwood is characterized by a darker wood colour than the healthy one and by a strong perfume that is much esteemed by perfumers and some oriental religious communities. The production of agarwood is presumed to depend on environmental factors, among them fungi. The aim of this work is to obtain an overview of fungi present in Aquilaria sp. from different countries. Aquilaria sp. is endemic to South East Asia including notably Cambodia, Laos and Thailand, where it is cultivated to produce agarwood. In French Guiana, farmers would like to locally produce agarwood in their field. That's why we wonder if fungal communities naturally present in French Guiana present characteristics making it compatible with the induction of agarwood. In this study, NGS was used to characterize fungal communities associated with agarwood: 693,961 sequences that cover ITS2 estimated about 250bp have been obtained. These sequences have been grouped into 535 OTUs, displaying 100% identity. In this study, 87% were Ascomycetes and 10.5% were Basidiomycetes. These results show also differences in fungal communities between aboveground and belowground parts of the tree. Likewise, differences between countries within fungal communities were also observed. [ABSTRACT FROM AUTHOR]

Aromatics originating from the resin-infused infected wood of the Aquilaria and Gyrinops genera have distinct and valued fragrances. Resin formation occurs as a response to internal injury and/or infections in the stems of the agarwood tree. The incenses and perfumes that are produced from agarwood have been valued for centuries and used by many cultures for spiritual, opulent, and aphrodisiac purposes. Agarwood is highly revered in the seminal texts of Hinduism, Christianity, Buddhism, and Islam. As early as 1400 B.C.E., agarwood was described as a fragrant product in Sanskrit texts, and in 65 B.C.E., Dioscorides detailed several medical applications for agarwood. Knowledge of human-induced agarwood formation was recorded in China as early as 300 C.E., where it was known that cutting into a tree would lead to a color change in its internal tissues within a year of the injury as a consequence of resin development. There is historical evidence of international trade in agarwood between the producing (tropical southeastern Asia) and consuming (Middle East, India, China, and Japan) regions of the world. Agarwood has been consumed primarily as incense with the burning of wood chips directly or as an important ingredient for powdered incense blends. The aromatic qualities of agarwood are influenced by the species and variety of the two genera, geographic location, its branch, trunk and root origin, length of time since infection, and methods of harvesting and processing. The subtle but numerous variations in agarwood properties led to the development of systems for product classification and description in several consumer countries. This paper reviews the uses and trade of agarwood and its social, political, and economic significance in human history. [ABSTRACT FROM AUTHOR]

Agarwood, a highly precious non-timber fragrant wood of Aquilaria spp. (Thymelaeaceae), has been widely used in traditional medicine, religious rites, and cultural activities. Due to the inflated demanding and depleted natural resources, the yields of agarwood collected from the wild are shrinking, and the price is constantly rising, which restricts agarwood scientific research and wide application. With the sustainable planting and management of agarwood applied, and especially the artificial-inducing methods being used in China and Southeast Asian countries, agarwood yields are increasing, and the price is becoming more reasonable. Under this condition, illuminating the scientific nature of traditional agarwood application and developing new products and drugs from agarwood have become vitally important. Recently, the phytochemical investigations have achieved fruitful results, and more than 300 compounds have been isolated, including numerous new compounds that might be the characteristic constituents with physiological action. However, no one has focused on the new compounds and presented a summary until now. Alongside phytochemical advances, bioactivity screening and pharmacological investigation have also made a certain progress. Therefore, this review discussed the new compounds isolated after 2010, and summarized the pharmacological progress on agarwood and Aquilaria plants. [ABSTRACT FROM AUTHOR]

The structure and development of interxylary phloem (IP) and external phloem in Aquilaria sinensis were investigated using light and scanning electron microscopy. Complete IP strands were isolated, measuring 14 ± 4 mm in length and 417 ± 124 µm in width. The outer margin of IP was composed of two to three layers of fusiform parenchyma cells. The development of IP can be divided into five stages: 1) Locally IP starts its differentiation within a small segment of a broad cambial zone, at the cost of xylem differentiation. 2) Inward growth of IP advances, and fibres and sieve tubes differentiate. 3) IP is constricted by the encroachment of immature xylem cells between cambium and immature IP. 4) IP is isolated from the cambium and surrounded by immature, non-lignified xylem tissue. 5) IP is surrounded by lignified xylem tissue, and the fibres within IP become lignified. In all the phloem islands in a ten-year-old stem, sieve elements showed positive staining of callose with aniline blue. However, no staining of callose was observed in the external secondary phloem of agarwood trees collected from two different sites. No sieve tubes or sieve pores were detected by SEM observation of numerous serial cross and radial sections of the external phloem. We therefore conclude that sieve tubes are absent from the external phloem or extremely rare and that the transport of photosynthetic products in the stem of A. sinensis takes place in the interxylary phloem. [ABSTRACT FROM AUTHOR]

Six previously undescribed uncommon ester-bonded dimeric compounds (aquilacrassnins A–F) containing a sesquiterpenoid and a 5,6,7,8-tetrahydroxy-2-(2-phenylethyl)-5,6,7,8-tetrahydro -4 H -chromone units were isolated from the EtOAc extract of agarwood originating from Aquilaria crassna . Their structures were elucidated by spectroscopic (NMR, UV, IR, MS, and ECD) methods. All the compounds were tested for AChE inhibitory activity and cytotoxicity against K562, BEL-7402, SGC-7901, Hela, and A549 tumor cell lines. The results showed that aquilacrassnin A, B, and E exhibited weak cytotoxicity against the five tested cell lines, whereas all the compounds were inactive against AChE. [ABSTRACT FROM AUTHOR]

Sesquiterpenes are one of the most important defensive secondary metabolite components of agarwood. Agarwood, which is a product of the Aquilaria sinensis response to external damage, is a fragrant and resinous wood that is widely used in traditional medicines, incense and perfume. We previously reported that jasmonic acid (JA) plays an important role in promoting agarwood sesquiterpene biosynthesis and induces expression of the sesquiterpene synthase ASS1, which is a key enzyme that is responsible for the biosynthesis of agarwood sesquiterpenes in A. sinensis. However, little is known about this molecular regulation mechanism. Here, we characterized a basic helix-loop-helix transcription factor, AsMYC2, from A. sinensis as an activator of ASS1 expression. AsMYC2 is an immediate-early jasmonate-responsive gene and is co-induced with ASS1. Using a combination of yeast one-hybrid assays and chromatin immunoprecipitation analyses, we showed that AsMYC2 bound the promoter of ASS1 containing a G-box motif. AsMYC2 activated expression of ASS1 in tobacco epidermis cells and up-regulated expression of sesquiterpene synthase genes (TPS21 and TPS11) in Arabidopsis, which was also promoted by methyl jasmonate. Our results suggest that AsMYC2 participates in the regulation of agarwood sesquiterpene biosynthesis in A. sinensis by controlling the expression of ASS1 through the JA signaling pathway. [ABSTRACT FROM AUTHOR]

Agarwood, the resinous heartwood produced by some Aquilaria species such as Aquilaria crassna , Aquilaria malaccensis and Aquilaria sinensis , has been traditionally and widely used in medicine, incenses and especially perfumes. However, up to now, the authentication of agarwood has been largely based on morphological characteristics, a method which is prone to errors and lacks reproducibility. Hence, in this study, we applied metabolomics and a genetic approach to the authentication of two common agarwood chips, those produced by Aquilaria crassna and Aquilaria malaccensis . Primary metabolites, secondary metabolites and DNA markers of agarwood were authenticated by 1 H NMR metabolomics, GC–MS metabolomics and DNA-based techniques, respectively. The results indicated that agarwood chips could be classified accurately by all the methods illustrated in this study. Additionally, the pros and cons of each method are also discussed. To the best of our knowledge, our research is the first study detailing all the differences in the primary and secondary metabolites, as well as the DNA markers between the agarwood produced by these two species. [ABSTRACT FROM AUTHOR]

Agarwood is a resin wood, which formed in the stem of Aquilaria and may represent the most prized non-timber forest product, which can be used in fragrances, incense, medicines, aromatherapy, and religious ceremonies. Aquilaria is an endangered genus due to the excessive exploitation of its precious agarwood, while not all Aquilaria species can produce agarwood effectively or different Aquilaria species produce agarwood with distinctive fragrances and price. Therefore, it is an important task to improve the identification methods of Aquilaria species. In order to identify the Aquilaria species, the leaf anatomical structures of selected Aquilaria species were compared in this study. The mature leaves of the six Aquilaria species (Thymelaeaceae) were studied with light microscopy and paraffin sectioning, and twelve quantitative traits of the leaves were measured and analyzed. The result showed that the leaf structures of six Aquilaria species were similar. All leaves showed the xerophytic feature. All leaves were typical bifacial type and were composed of epidermis, mesophyll and vein. The epidermis consisted of single layer epidermal cells. The upper epidermis were much thicker than the lower epidermis. The sunken stomata existed only in lower epidermis which was sporadically covered by hairs. The stomata were of anomocytic type. The mesophyll was well developed which were composed of palisade parenchyma, spongy parenchyma and lithocyst. The palisade parenchyma was composed of 1-2 layers of cylindrical cells, in which many rectangular lithocyst arranged perpendicularly to the epidermis. The hypodermis was located in spongy parenchyma, which was composed of idioblasts. The micrib belonging to bicollateral bundle was well developed. The bundle sheath and pith both contain a number of idioblasts. ANOVA analysis showed that the eleven quantitative traits were significantly different among six species, except for ratio of palisade to spongy tissue. Clustering analysis showed that six species were clustered into three main groups. Group 1 consisted of A. sinensis, A. crassna and A. banaensis; Group 2 consisted of A. baillonii and A. malaccensis; Group 3 only consisted of A. yunnanensis. The results provides some new information for the species identification, but also is of great significance for the conservation and utilization of Aquilaria spp. [ABSTRACT FROM AUTHOR]