The obligatory mutualism of Attini ants with their cultivated fungus is an example of symbiosis shaped by millions years of coevolution. Attini ants cultivate basidiomycetes fungi (Basidiomycota; Agaricales: Lepiotaceae e Pterulaceae) as enzymes and food source in specialized gardens. Acromyrmex and Atta genera (Attini tribe) are commonly known as leaf-cutting ants, because they forage leaves and fresh flowers used as substrate for the growth of the symbiotic fungus.Besides the mutualistic relationship with basidiomycetes fungi, Attini ants are involved in a symbiotic association with actinomycetes of the Pseudonocardia genus, which produce antibiotics to inhibit the growth of Escovopsis, a specialized parasitic fungus of fungus gardens. Over the 120 years of research on the relationship of the Attini ants with their cultivated fungus, initiated by the work of Möller (1893), many findings have been made due to technological advances. Thus, the understanding about the symbiosis has been modified and today there are many reports of bacteria, yeasts and filamentous fungi in Attini ants exoskeleton and fungal gardens.Among these reports, new yeast species have been described, Cryptococcus haglerorum, Blastobotrys attinorum e Trichosporon chiarellii, contributing to the knowledge of currently known yeasts. On the other hand, interesting associations were also found, as in the case of black yeasts classified as a fifth symbiont in the complex interaction among Attini ants - cultivated fungus - Pseudonocardia - Escovopsis. Black fungi of Chaetothyriales (e.g. Cladophialophora, Phialophora, Exophiala) and Capnodiales (e.g. Cladosporium, Penidiella) orders were also observed in the exoskeleton of leaf-cutting ants (Atta genus). The presence of these fungi in the ants has been considered extremely important, since they are micro-organisms not commonly isolated from the environment and whose niche in nature is still unknown for many species.The role of many black fungi found in the fungal gardens and exoskeleton of Attini ants is still unclear and additional studies are needed to better understand the network of interactions involved in the symbiosis of Attini ants with different micro-organisms. In this context resides the basis of this research.
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