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Open Access Highly Accessed Research article

Identification of genes related to agarwood formation: transcriptome analysis of healthy and wounded tissues of Aquilaria sinensis

Yanhong Xu1, Zheng Zhang12, Mengxi Wang3, Jianhe Wei12*, Hongjiang Chen2, Zhihui Gao1, Chun Sui1, Hongmei Luo1, Xingli Zhang1, Yun Yang2, Hui Meng2 and Wenlan Li3

  • * Corresponding author: Jianhe Wei wjianh@263.net

  • † Equal contributors

Author Affiliations

1 Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing, 100193, China

2 Hainan Branch Institute of Medicinal Plant (Hainan Provincial Key Laboratory of Resources Conservation and Development of Southern Medicine), Chinese Academy of Medical Sciences & Peking Union Medical College, Wanning, 571533, China

3 Research Center on Life Sciences and Environmental Sciences, Harbin University of Commerce, Harbin, 150076, China

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BMC Genomics 2013, 14:227  doi:10.1186/1471-2164-14-227

Published: 8 April 2013

Abstract

Background

Agarwood is an expensive resinous heartwood derived from Aquilaria plants 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 all Aquilaria spp. being endangered and listed in the Appendix II of the CITES (http://www.cites.org webcite). 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 wounded A. 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 in Escherichia 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 of ASS was significantly induced by MJ, and the production of sesquiterpenes was elevated accordingly. The expression of some transcription factors and protein kinases, especially MYB4, WRKY4, MPKK2 and MAPK2, was also induced by MJ and coordinated with ASS expression, suggesting they maybe positive regulators of ASS.

Conclusions

This study provides extensive transcriptome information for Aquilaria spp. and valuable clues for elucidating the mechanism of wound-induced agarwood sesquiterpenes biosynthesis and their regulation.

Keywords:
Agarwood; Aquilaria sinensis; GC-MS; Sesquiterpenes; Transcriptome; Wound signal transduction