杀线虫真菌Sr18发酵液对松材线虫超微结构的影响

Sr18真菌是一株自主分离获得的具有广谱杀线虫活性的生防菌。为探明该菌的杀线虫作用机理，以松材线虫为靶标，借助场发射高分辨扫描电镜及透射电镜，对1/2浓度的Sr18发酵液小分子活性组分处理后的线虫及未处理的正常线虫进行了超微观察。高分辨率扫描电镜观察结果表明，小分子物质对松材线虫头部、体壁和尾部均有损伤，并观察到内容物外溢的现象。透射电镜观察结果显示，线虫表皮和体腔分离，细胞核受损严重，形状不规则，粗面内质网核糖体聚集，线粒体空泡样变，肌纤维受损。这些现象从形态结构角度证实了该发酵液小分子活性成分对线虫的损伤是整体性的毒杀作用，排除了表面触杀的机制。这为进一步揭示Sr18的杀线虫机理以及线虫生防制剂的开发提供了重要理论依据。 

Effects of nematicidal filamentous fungus Sr18 metabolites on the ultrastructure of Bursaphelenchus xylophilus

Filamentous fungus Sr18 is a documented bio-control fungus against nematodes with broad-spectrum nematocidal activity. In present research, high resolution field emission scanning electron microscopy ( SEM) and transmission electron microscopy ( TEM) were used to observe the micro-structure surface as well as internal cellular ultrastructure of Bursaphelenchus xylophilus. The results of SEM indicated that small molecular active products damaged the B. xylophilus' heads, body wall and tail. The dissolved substance inside the cell flowed out was observed by SEM. The results of TEM indicated that nematodes' cuticle and coelom were separated, and cell nucleus were seriously damaged, and became irregular. The ribosomes on rough endoplasmic reticulum became aggregated. The mitochondria appeared vacuolated. The muscle cells were also damaged. The above phenomena demonstrated that the nematocidal mechanism of small molecular active products was poisoned holistically rather than surface contact action. The research provides scientific evidence for further revealing the nematocidal mechanism of Sr18 as well as the development of biological pesticide controlling nematodes.