Volume 8 Issue 4
The Sesquiterpene Biosynthesis and Vessel-Occlusion Formation in Stems of Aquilaria sinensis (Lour.) Gilg Trees Induced by Wounding Treatments without Variation of Microbial Communities
Zheng Zhang, Jianhe Wei, Xiaomin Han, Liang Liang, Yun Yang, Hui Meng, Yanhong Xu and Zhihui Gao
1National Engineering Laboratory for Breeding of Endangered Medicinal Materials, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100193, China
2Hainan Provincial Key Laboratory of Resources Conservation and Development of Southern Medicine, Hainan Branch of the Institute of Medicinal Plant Development, Chinese Academy of Medicinal Sciences and Peking Union Medical College, Wanning 571533, China
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Abstract
As widely recognized, agarwood formation in Aquilaria trees is induced by external wounding. Because agarwood usually harbors specific microbes, the function of microbes in agarwood formation has been debated for almost a century. In this study, two wounding methods, the burning-chisel-drilling method (BCD) and the whole-tree agarwood-inducing method (Agar-Wit), were used under the non-contamination of environmental microorganisms. After pyrosequencing the small rRNA subunits of the wounds induced by the BCD and Agar-Wit, no substantial variation was observed either in fungal and bacterial enrichment and diversity or in the relative abundances of taxa. By contrast, significant variations in fungal and bacterial communities were detected following the partial tree pruning (PTP)-wounding. The wound-induced sesquiterpene biosynthesis and vessel-occlusion formation, however, were found to be similar in all types of wounded trunks. We thus infer that wounding in the absence of variations in microbial communities may induce agarwood formation. This result does not support the long-standing notion that agarwood formation depends on microbes.
Keywords:Aquilaria sinensis; wound; microbe; vessel occlusion; sesquiterpene; plant defense response