Finding beneficial fungi antagonistic toward nematodes is important for developing more sustainable agricultural practices. We isolated abundant fungi from cysts of the beet cyst nematode Heterodera schachtii and tested their interaction with nematodes and sugar beet. By molecular screening of fungal communities colonizing five field populations of H. schachtii using DGGE and Sanger sequencing, three strains identified as Exophiala sp., Pochonia chlamydosporia and Pyrenochaeta sp. were frequently found in infected cysts and then specifically isolated (in pure culture). The three isolates were able to re-infect the cysts and colonize the eggs of H. schachtii in vitro fulfilling Koch’s postulates. In greenhouse trials, the root weight of sugar beet plants grown in substrates inoculated with nematodes and the fungal isolates was significantly higher compared to plants inoculated with nematodes only. The number of cysts propagated on roots was lower in substrates inoculated with Pyrenochaeta sp. than those in substrates inoculated with the other two fungi. However, cyst numbers did not significantly differ from the control because the propagation rate of the nematode increased with the root weight. The proportion of infected eggs per cyst was higher under the fungal treatments than the control, and it increased with the number of propagated cysts. The results showed that the here-studied strains of Exophiala sp., Pochonia chlamydosporia and Pyrenochaeta sp. were frequently found colonizing the nematode cysts of different populations of H. schachtii and were efficient in parasitizing the eggs of the nematode.

寻找对线虫有益的真菌对开发更具可持续性的农业实践非常重要。我们从甜菜囊肿线虫Heterodera schachtii的囊肿中分离了丰富的真菌，并测试了它们与线虫和甜菜的相互作用。通过使用DGGE和Sanger测序对在五个沙特氏菌田间种群中定居的真菌群落进行分子筛选，鉴定出三种菌株，分别为Exophiala sp。，Pochonia chlamydosporia和Pyrenochaeta sp。通常在感染的囊肿中发现，然后专门分离（在纯培养物中）。这三个分离株能够重新感染囊肿并在Schachtii的卵中定殖在体外满足科赫的假设。在温室试验中，与仅接种线虫的植物相比，在接种了线虫和真菌分离物的基质中生长的甜菜植株的根重明显更高。接种Pyrenochaeta sp的基质中，在根部繁殖的囊肿数量较少。比接种另外两种真菌的底物要高。但是，由于线虫的繁殖率随根重的增加而增加，因此囊肿的数量与对照组没有显着差异。在真菌处理下，每个囊肿受感染卵的比例高于对照组，并且随繁殖的囊肿数量的增加而增加。结果表明，这里研究的Exophiala sp。，Pochonia chlamydosporia和Pyrenochaeta sp。经常发现它们定居在沙特氏菌的不同种群的线虫囊中，并能有效地寄生线虫卵。