College of Life Sciences, Beijing Normal University, Beijing, China.
Chinese Academy of Inspection and Quarantine, Beijing, China.
PLoS One. 2019 Aug 19;14(8):e0221099. doi: 10.1371/journal.pone.0221099. eCollection 2019.
The pinewood nematode (PWN), Bursaphelenchus xylophilus, is an important plant-parasitic nematode that can cause severe mortality of pine trees. This PWN-induced harm to plants may be closely related to the abundance and diversity of the symbiotic microorganisms of the parasitic nematode. In this study, nematodes were divided into untreated and antibiotic-treated groups. Nematodes were treated by fumigation with different amounts of α-pinene, and the resultant mortality rates were analyzed statistically. Concentrations of symbiotic bacteria were calculated as colony-forming units per nematode. High-throughput sequencing was used to investigate the bacterial community structure. The results showed that the mortality of nematodes increased slightly with an increasing concentration of α-pinene, and nematodes untreated with antibiotics were more sensitive to α-pinene than those treated with antibiotics. The highest abundance of symbiotic bacteria was obtained via medium and low levels of α-pinene, but for which community diversity was the lowest (Shannon and Simpson indexes). The proportion of Pseudomonas spp. in the symbiotic bacteria of nematodes without antibiotics was relatively high (more than 70%), while that of Stenotrophomonas spp. was low (6%-20%). However, the proportion of Stenotrophomonas spp. was larger than that of Pseudomonas spp in the symbiotic bacteria associated with the antibiotic-treated nematodes. Pseudomonas sp. increased after pinene treatment, whereas Stenotrophomonas spp. decreased. These results indicate that although α-pinene has low toxicity to PWNs over a short time period, α-pinene ultimately influences the abundance and community diversity of the symbiotic bacteria of these nematodes; this influence may potentially disturb the development and reproduction of nematodes in the process of infecting pine trees.
松材线虫（Bursaphelenchus xylophilus）是一种重要的植物寄生线虫，可导致松树严重死亡。这种松材线虫对植物的危害可能与寄生线虫共生微生物的丰度和多样性密切相关。在本研究中，将线虫分为未处理和抗生素处理组。用不同量的α-蒎烯对线虫进行熏蒸处理，并统计分析死亡率。通过计算每只线虫的菌落形成单位来计算共生细菌的浓度。使用高通量测序来研究细菌群落结构。结果表明，线虫的死亡率随着α-蒎烯浓度的增加而略有增加，未用抗生素处理的线虫比用抗生素处理的线虫对α-蒎烯更敏感。共生细菌的丰度在中低浓度的α-蒎烯下获得最高，但群落多样性最低（香农和辛普森指数）。在未用抗生素处理的线虫共生细菌中，假单胞菌属的比例相对较高（超过 70%），而 Stenotrophomonas 属的比例较低（6%-20%）。然而，在与抗生素处理的线虫相关的共生细菌中， Stenotrophomonas 属的比例大于假单胞菌属。在α-蒎烯处理后，假单胞菌属增加，而 Stenotrophomonas 属减少。这些结果表明，尽管α-蒎烯在短时间内对松材线虫的毒性较低，但α-蒎烯最终会影响这些线虫共生细菌的丰度和群落多样性；这种影响可能会干扰线虫在感染松树过程中的发育和繁殖。
