Lab. of Forest Pathogen Integrated Biology, Research Institute of Forestry New Technology, Chinese Academy of Forestry, Beijingl00091, China.
Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing210037, China.
Parasitology. 2020 Jan;147(1):50-57. doi: 10.1017/S0031182019001264. Epub 2019 Sep 17.
Pinewood nematode, Bursaphelenchus xylophilus, a pine parasitic nematode, poses a serious threat to its host pine forests globally. When dispersal-stage larvae 4 (dauer, DL4) of B. xylophilus enters the new pine, it moults into propagative adult (dauer recovery) and reproduces quickly to kill the host pine. Here, we found pine chemical volatiles, rather than the common dauer recovery factors of nematodes (e.g. suitable temperatures, nutrient availability or density), promote B. xylophilus dauer recovery. The results showed that volatilization of chemicals in host pines could attract DL4 and promote DL4 recovery. To identify which chemicals promote this process, we determined the stimulated activity of the main volatiles of pines including six monoterpenes and two sesquiterpenes. Results showed that all the six monoterpenes promoted dauer recovery, especially β-pinene and β-myrcene, but the two sesquiterpenes have no effect on the transformation. Furthermore, β-pinene performed gradient effects on dauer recovery. We hypothesized that when DL4 infect pine trees, the pine volatiles released from the feeding wounds are used as chemical signals for DL4 transformation to adult to reproduce and rapidly kill the pines. Our study identified the B. xylophilus dauer recovery chemical signal and may contribute to preventing pine wilt disease.
松材线虫，穴居柄尾线虫，一种寄生在松树上的线虫，对全球的宿主松林构成了严重威胁。当穴居柄尾线虫的分散阶段幼虫 4（持久幼虫，DL4）进入新的松树时，它会蜕皮为繁殖成虫（持久幼虫恢复）并迅速繁殖，杀死宿主松树。在这里，我们发现了松树的化学挥发物，而不是线虫常见的持久幼虫恢复因子（例如，适宜的温度、营养供应或密度），促进了穴居柄尾线虫的持久幼虫恢复。结果表明，宿主松树上化学物质的挥发可以吸引 DL4 并促进 DL4 的恢复。为了确定哪些化学物质促进了这一过程，我们确定了包括六种单萜和两种倍半萜在内的主要松树挥发物的刺激活性。结果表明，所有六种单萜都促进了持久幼虫的恢复，尤其是β-蒎烯和β-月桂烯，但两种倍半萜对转化没有影响。此外，β-蒎烯对持久幼虫的恢复表现出梯度效应。我们假设当 DL4 感染松树时，从取食伤口释放的松树挥发物被用作 DL4 向成虫转化的化学信号，以繁殖并迅速杀死松树。我们的研究确定了穴居柄尾线虫持久幼虫恢复的化学信号，可能有助于预防松材线虫病。
