Varanda-Haifig Sadala Schmidt, Albarici Tatiane Regina, Nunes Pablo Henrique, Haifig Ives, Vieira Paulo Cezar, Rodrigues Andre
Departamento de Bioquímica e Microbiologia, Universidade Estadual Paulista (UNESP), Av. 24A, 1515, Bela Vista, Rio Claro, SP, 13506-900, Brazil.
Departamento de Química, Universidade Federal de São Carlos, Rodovia Washington Luís, km 235, São Carlos, SP, 13565-905, Brazil.
Antonie Van Leeuwenhoek. 2017 Apr;110(4):593-605. doi: 10.1007/s10482-016-0826-y. Epub 2016 Dec 31.
Leaf-cutter ants cultivate and feed on the mutualistic fungus, Leucoagaricus gongylophorus, which is threatened by parasitic fungi of the genus Escovopsis. The mechanism of Escovopsis parasitism is poorly understood. Here, we assessed the nature of the antagonism of different Escovopsis species against its host. We also evaluated the potential antagonism of Escovopsioides, a recently described fungal genus from the attine ant environment whose role in the colonies of these insects is unknown. We performed dual-culture assays to assess the interactions between L. gongylophorus and both fungi. We also evaluated the antifungal activity of compounds secreted by the latter on L. gongylophorus growth using crude extracts of Escovopsis spp. and Escovopsioides nivea obtained either in (1) absence or (2) presence of the mutualistic fungus. The physical interaction between these fungi and the mutualistic fungus was examined under scanning electron microscopy (SEM). Escovopsis spp. and E. nivea negatively affected the growth of L. gongylophorus, which was also significantly inhibited by both types of crude extract. These results indicate that Escovopsis spp. and E. nivea produce antifungal metabolites against the mutualistic fungus. SEM showed that Escovopsis spp. and E. nivea maintained physical contact with the mutualistic fungus, though no specialised structures related to mycoparasitism were observed. These results showed that Escovopsis is a destructive mycoparasite that needs physical contact for the death of the mutualistic fungus to occur. Also, our findings suggest that E. nivea is an antagonist of the ant fungal cultivar.
切叶蚁培育并以互利共生真菌——球囊白鬼伞为食，而球囊白鬼伞受到埃斯科沃普氏菌属寄生真菌的威胁。人们对埃斯科沃普氏菌的寄生机制了解甚少。在此，我们评估了不同埃斯科沃普氏菌物种对其宿主的拮抗性质。我们还评估了埃斯科沃普氏菌属的潜在拮抗作用，该属是最近在阿蒂纳蚁环境中发现的真菌属，其在这些昆虫群落中的作用尚不清楚。我们进行了共培养试验，以评估球囊白鬼伞与这两种真菌之间的相互作用。我们还使用从埃斯科沃普氏菌属物种和雪白埃斯科沃普氏菌中获得的粗提物，评估了后者分泌的化合物在有无互利共生真菌的情况下对球囊白鬼伞生长的抗真菌活性。在扫描电子显微镜（SEM）下检查了这些真菌与互利共生真菌之间的物理相互作用。埃斯科沃普氏菌属物种和雪白埃斯科沃普氏菌对球囊白鬼伞的生长产生负面影响，两种类型的粗提物也显著抑制了球囊白鬼伞的生长。这些结果表明，埃斯科沃普氏菌属物种和雪白埃斯科沃普氏菌会产生针对互利共生真菌的抗真菌代谢物。扫描电子显微镜显示，埃斯科沃普氏菌属物种和雪白埃斯科沃普氏菌与互利共生真菌保持物理接触，尽管未观察到与真菌寄生相关的特殊结构。这些结果表明，埃斯科沃普氏菌是一种具有破坏性的真菌寄生物，需要物理接触才能导致互利共生真菌死亡。此外，我们的研究结果表明，雪白埃斯科沃普氏菌是蚂蚁真菌培养物的拮抗剂。
