Comparative Transcriptome Analysis of the Pinewood Nematode Bursaphelenchus xylophilus Reveals the Molecular Mechanism Underlying Its Defense Response to Host-Derived α-pinene.

Yongxia Li,Long Pan,Yuqian Feng,Xun Deng,Fanli Meng,Wei Zhang,Xingyao Zhang,Xuan Wang

doi:10.3390/ijms20040911

Abstract

Bursaphelenchus xylophilus is fatal to the pine trees around the world. The production of the pine tree secondary metabolite gradually increases in response to a B. xylophilus infestation, via a stress reaction mechanism(s). α-pinene is needed to combat the early stages of B. xylophilus infection and colonization, and to counter its pathogenesis. Therefore, research is needed to characterize the underlying molecular response(s) of B. xylophilus to resist α-pinene. We examined the effects of different concentrations of α-pinene on the mortality and reproduction rate of B. xylophilus in vitro. The molecular response by which B. xylophilus resists α-pinene was examined via comparative transcriptomics of the nematode. Notably, B. xylophilus genes involved in detoxification, transport, and receptor activities were differentially expressed in response to two different concentrations of α-pinene compared with control. Our results contribute to our understanding of the molecular mechanisms by which B. xylophilus responds to monoterpenes in general, and the pathogenesis of B. xylophilus.

Highlights

Pine wilt disease (PWD) is caused by the pine wood nematode (PWN), Bursaphelenchus xylophilus, [1] and is an extremely destructive disease
The toxicity of α-pinene on B. xylophilus was determined by the cotton ball assay, with the results showing that the B. xylophilus mortality rate was significantly different compared with the control (p < 0.05), and that mortality increased with increasing concentrations of α-pinene
We examined the effects of different concentrations of α-pinene on the mortality and reproduction rate of B. xylophilus in vitro

Summary

Introduction

Pine wilt disease (PWD) is caused by the pine wood nematode (PWN), Bursaphelenchus xylophilus, [1] and is an extremely destructive disease. PWD has caused major losses of forests in European [2,3,4,5] and Asian [6,7,8] countries, especially in Japan, China, South Korea, Portugal, and Spain. It was first identified in Nanjing, Jiangsu Province, China in 1982 [9]. Monochamus spp. beetles [13,14] are the major vectors for B. xylophilus infection, as they feed on more than one pine tree during the course of their lives and, thereby, introduce the nematodes into multiple trees through the open sores caused by feeding. Despite many studies concerning PWD and PWNs, the pathogenic mechanism of B. xylophilus has not been completely elucidated

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