Agarwood ( Aquilaria spp.) fragrance and its origin in stress make it probably the most suitable model to study stress-induced aroma. Production being confined only to certain small pockets of South and Southeast Asia, agarwood is arguably the costliest wood in the world. Formation of fragrant agarwood resin is the outcome of complex biotic, abiotic, and physical stress on the Aquilaria trees. The intricate mechanism by which some 150 odd fragrant molecules that constitute agarwood aroma is formed is still not clearly understood. The present review therefore aims to bring to focus this less known but highly valuable stress-induced aroma from Asia. Discussions on agarwood species, occurrence, distribution, formation, and products have been included as foundation. Although global trade in agarwood and its products is estimated at US$6 billion to US$8 billion, no reliable data are readily available in literature. Therefore, an effort has been made to review the current status of agarwood trade. The element of stress and its correlation to agarwood aroma is discussed in the subsequent sections. Natural agarwood formation as well as technologies and interventions in agarwood induction are stress-based (natural and artificial injury, insect and fungal attack, chemical induction). The molecular triggers are gradually coming to light as new studies are implicating jasmonate, LOX signaling, and other stress reaction routes as the source of agarwood aroma. This review therefore has strived to compile the information that is scattered across scientific as well as other authentic literature and update the reader on the current status. More information about the specific roles of other vital stressors like insects, abiotic, and genetic factors is eagerly awaited from ongoing and future research to further understand the unique fragrance of agarwood.

Fragrant agarwood, arguably the costliest wood in the world, is formed by plant-fungal interactions in Aquilaria spp. However, very little is known about this fragrant outcome of interaction. Therefore, mimicking the ancient traditions of agarwood production in Assam (Northeast India), a chemometric assessment of the agarwood-fungus interaction was made by chemical profiling (GC-MS) coupled with statistical analysis (principal component, correlation network analysis) across three platforms, viz. callus, juvenile plants and resinous wood-chips with an associated Fusarium. In the study of callus-fungus interaction, increased accumulation of key aroma compounds such as pentatriacontane {fold change (log2FC) = 3.47)}, 17-pentatriacontene (log2FC = 2.95), tetradecane, 2-methyl- (log2FC = 1.10) over callus and activation of pathways related to defense and secondary metabolism indicated links to aroma production. Study on fungal interactions in juvenile plants and resinous wood-chips indicated formation of terpenoid precursors (e.g. farnesol, geranylgeraniol acetate) and agarwood sesquiterpenes (e.g. agarospirol, γ-eudesmol). Correlation network analysis revealed the possible regulation of sesquiterpene biosynthesis involving squalene. Also a direct role of fungus in aroma (e.g. dodecane, 4-methyl-, tetracosane) was highlighted. Appearance of fragrant molecules unknown to agarwood during interaction featured as a new possibility for future research.

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Investigate the protein-ligand binding affinity and evaluate the receptor binding abilities of different classes of ligands for APOE4 through molecular docking studies. The polymorphic nature of human Apo E gene encodes one of 3 common epsilon (ε) alleles (ε2, ε3, and ε4), reported to influence the risk of cardiovascular diseases. Structural basis of APOE4 involvement in CAD suggests that the intramolecular domain interactions to be a suitable target for therapeutic intervention. Identification of APOE4 modulators, targeted towards therapeutic candidates in CAD using Molecular Docking studies. Various classes of ligands including known drugs used in the treatment of CAD, fragment-based stabilizers and their similar structures and molecules with known bioactivity against APOE4 were screened for their binding affinity and further investigated for their interactions with APOE4. Computational studies show the benzyl amide derived structures to be useful candidates in modulation of APOE4. The protein-ligand binding affinities predicted in the study indicated receptor binding abilities of APOE4 that can lead to have interesting insights on structural conformity of APOE4 and its correlated functional aspects. Understanding modulation of APOE4 can pave ways to use it as biomarker for CAD as well as for its therapeutics. Further analysis of the variation of the docked protein structure, molecular dynamic simulation can be performed to generate a dynamic structure for binding analysis.

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Plant Tissue Cult. & Biotech. 23(1): 115?120, 2013 (June)DOI: http://dx.doi.org/10.3329/ptcb.v23i1.15568

Agarwood is the resinous infected wood obtained from Aquilaria species, which is a highly priced product in the flavour and fragrance market. Its formation is a complex process of interaction between the plant, insect, and microorganisms. Multiple studies concerning the interaction of microorganisms with the Aquilaria tree have been reported. However, the significant interaction between the insect Zeuzera conferta Walker (Lepidoptera: Cossidae) with Aquilaria has been overlooked, and only exiguous studies have been accomplished. Considering the dearth of available literature on this interesting phenomenon a review has been attempted. The taxonomical and morphological descriptions proffered by researchers and the insect life cycle are discussed. The review lays emphasis on the chemical ecology of the interaction between Z. conferta, Aquilaria and associating microorganisms as a possible continuum operating in the form of complex chemical signalling via release and sensing of Volatile Organic Compounds (VOCs), Herbivore Induced Plant Volatiles (HIPVs) and Microbial Volatile Organic Compounds (MVOCs). The review also scrutinizes the future perspectives of understanding the interaction in devising suitable management strategies to prevent uncontrolled infestation and, simultaneously, develop artificial rearing technology for the insect Z. conferta as a strategy for ensuring sustainable livelihood of farmers dependent on agarwood production.

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