Dynamic analysis of gene expression and determination of chemicals in agarwood in Aquilaria sinensis

Abstract

Agarwood is the resinous heartwood of Aquilaria species. However, low yields and high costs of existing stimulation methods have led to the need for new techniques to produce agarwood rapidly and effectively. We developed a biological agarwood-inducing technique (Agar-Bit) that produces high yields and quality within 6 months. To better understand agarwood formation by Agar-Bit, dynamic gene expressions of key synthetases pathways of sesquiterpenes and chalcone-related enzymes at different times were determined after both Agar-Bit and the traditional burning chisel drilling (BCD) stimulation on Aquilaria sinensis trees. The qRT-PCR results show that some characteristic synthase genes were expressed at greatly different levels and times compared with the controls. For the Agar-Bit technology, main changes were after the 3rd or 5th month, while BCD expression clearly changed at the 5th month. Essential oils and total chromone contents were simultaneously determined. In the Agar-Bit group, both were higher and similar to natural levels. The Agar-Bit methodology is a new option for producing agarwood as demonstrated by genetic and chemical aspects. The differences in gene expression within 6 months for both groups indicates that the mechanisms of the two methods are different. These findings provide information on genetic variation during the process of agarwood formation.

Effects of various artificial agarwood-induction techniques on the metabolome of Aquilaria sinensis

“…In spite of the fact that agarwood-producing plants such as A. sinensis take a long time to develop and the agarwood-formation process takes an equivalent amount of time, the demand for agarwood and its derivatives is on the rise [ 4 , 13 , 28 ]. To overcome this, A. sinensis is intentionally wounded to produce agarwood [ 11 , 13 , 37 – 39 , 44 ].…”

“…Cold treatment with or without brine induced six 2-(2-phenylethyl) chromones and derivatives which is contrary to the report of Naziz et al [ 54 ]. These 2-(2-phenylethyl) chromones and derivatives have received much attention in recent years due their role in influencing quality of agarwood [ 57 ], chemical isolation [ 5 , 58 – 60 ], pharmacological effects [ 61 – 63 ] and their biosynthesis pathways [ 19 , 28 ]. In all, nine 2-(2-phenylethyl) chromones and derivatives were detected in F while four, six and one were detected in FS, D and DS, respectively (Fig.…”

“…Additionally, Agar-Wit creates a larger wound because the inducer is carried through plant vascular tissue by transpiration. The preloaded inducer in a transfusion set is spread through plant transpiration, resulting in a greater coverage area of agarwood but with more destroyed tissues [ 27 , 28 ]. Specifically, Liu et al [ 27 ] used a combination of methods, including a partially-pruned tree, a burning chisel-drilling tree, and fungi inoculation tree, to induce resin formation in Aquilaria sinensis .…”

“…They discovered that the agarwood derived from the Agar-Wit induction method was of higher quality than agarwood derived from the existing methods. Similarly, the Agar-bit procedure distributes the inducing reagent through plant transpiration, with the exception that the reagents are injected directly into the tree’s stems [ 28 ], which results in a more uniform distribution of the reagent.…”

Transcriptome and Chemical Analysis of Healthy and Infected Stems of Aquilaria Malaccensis

“…The production of agarwood is unable to meet the demand of the growing market. Agarwood formation took at least 3 to 4 years to meet the general quality standard while high grade agarwood took more than 10 years and limited in yield (Zhang et al 2010, Wu et al 2017, Chhipa & Kaushik 2017. Agarwood price is determined by its grade (Nor- Azah et al 2013).…”