Analysis of Gene Expression and Quality Of

Abstract

Agarwood, precious resinous trunks or branches derived from Aquilaria plants, is widely used in incense and perfume. However, due to its low yield and high production cost, a novel stimulating method is required to produce agarwood rapidly and effectively. We studied the biologically agarwood-inducing technique (Agar-Bit) that achieved high yield and qualified production. In this study the gene expressions and chemical compositions in agarwood obtained from Aquilaria sinensis trees using Agar-Bit were characterised. Mechanically-stimulated agarwood was used as control. Some characteristic synthase genes expressed degrees and times differently compared with control. For Agar-Bit group expressions of biological synthase genes were upregulated in 12 hours, then downregulated except CHS1 (chalcone synthase genes) after stimulation. For mechanically-stimulated agarwood they were upregulated in 24 hours, then downregulated except HMGR (3-hydroxy-3-mythlglutaryl-CoA reductase). The chemical compositions of agarwood by Agar-Bit and control were investigated by total chromone and essential oil contents. Therefore, we concluded that Agar-Bit can markedly motivate some characteristic synthase gene expressions and produce unique and identical chromone chemicals in agarwood. These findings may supplement information on agarwood formation theories and provide genetic varieties during the process.

Agarwood Induction: Current Developments and Future Perspectives

“…Naturally, agarwood formation is often linked to the physical wounding or damage of Aquilaria trees caused by thunder strike, animal grazing, pest and disease infestations (Rasool and Mohamed, 2016; Wu et al, 2017). These events expose the inner part of the trees toward pathogenic microbes, which elicit the defense mechanism of Aquilaria to initiate the resin production.…”

“…Instead of relying on external stimuli to trigger plant responses, either by mechanical wounding or biological inoculum, some induction approaches have been developed to introduce signaling molecules directly and specifically into Aquilaria trees to initiate agarwood resin biosynthesis pathways (Liu Y. et al, 2013; Wu et al, 2017). Chemical inducers normally comprise of phytohormones, salts, minerals and biological-derived substances (Zhang et al, 2012; Liu Y. et al, 2013; Van Thanh et al, 2015).…”

“…Through this method, a larger agarwood coverage area can be achieved, but unfortunately produces more decayed tissues. Similarly, Agar-bit method adopts the idea of distributing the inducing reagent by plant transpiration, except that the reagents are injected directly into the stems of the tree (Wu et al, 2017).…”

“…The integration of systems biology and omics approaches, covering genomics, transcriptomics, proteomics, metabolomics and functional analysis; provide a potential solution to comprehend the multigenic nature of resin biosynthesis in Aquilaria . On the basis of large number of previously conducted agarwood induction experiments, transcriptomic and metabolites studies (Naef, 2011; Gao X. et al, 2014; Ye et al, 2016; Wu et al, 2017), integrated omics analysis can indeed serve as a platform to build a more comprehensive picture of agarwood resin biosynthetic mechanism that involve different omics layers. The development of high-throughput mass spectrometry (MS), microarray and sequencing technologies (DNA and RNA) have made it possible to integrate such data into a system biological framework via integrated-omics which would help to predict gene-gene interactions, identify driver genes and the molecular signatures of agarwood formation (Figure 5).…”

The Scent of Stress: Evidence From the Unique Fragrance of Agarwood

“…Similarly, another new technique for agarwood induction is known as biologically agarwood-inducing technique (Agar-Bit), which yields better quality and quantity of agarwood. It was found that the Agar-Bit method upregulated the expression of some biological synthase genes (farnesyldiphosphate synthase, sesquiterpene synthase, and chalcone synthase) compared to the mechanically stimulated agarwood (Wu et al, 2017; Tan et al, 2019). Subsequently, Subasinghe et al (2018) carried out an artificial induction by Aspergillus niger and F. solani for agarwood resin formation in Gyrinops walla trees.…”