Phylogeny of fungal parasites in gardens of attine ants

Abstract

Ants in the tribe Attini maintain a mutualism with fungi cultivated for food. The fungal cultivar is the target of a specialized fungal parasite in the genus Escovopsis. Previous work carried out by our research group (FAPESP-JP grant # 2011/16765-0 and 2013/25748-8) unraveled the diversity of this parasite that infects gardens of leaf-cutting ants, as well as the high degree of shared infections among leafcutters and higher-attine ants. Additionally, we also observed striking morphological characteristics (i.e. presence of a vesicle in the reproductive asexual structures) that differentiate strains of the parasite that infects higher-attine and lower-attine gardens. In this proposal, we intend to study Escovopsis infecting fungus gardens of Apterostigma ants. Such parasites are of particular interest because they are a transition group in the evolution of Escovopsis that infects gardens of higher and lower-attine ants. Given this scenario of evolutionary transition, we propose to answer the following questions: (i) Escovopsis strains that infect gardens of higher-attine ants also infect Apterostigma gardens? And: (ii) Are the morphological markers from Escovopsis infecting gardens from higher attines also present in Escovopsis infecting Apterostigma gardens? To answer these questions we intend to sample parasites that infect gardens of these ants, to analyze the morphological characteristics (presence or absence of vesicles) and sequence three molecular markers (ITS, LSU and TEF1) to develop a multilocus phylogeny of the parasite. The results of this proposal will help to understand the dynamics of the parasite and its switches between phylogenetically unrelated attine ants (higher and lower attines). Furthermore, assessing the morphology of these fungi will possibly verify if vesicles is a unique morphological adaptation of Escovopsis infecting gardens of higher-attine ants. Such adaptation can be related to the type of fungiculture practiced by these attines, including the leaf-cuting ants, considered a major agricultural pest in our country. Understanding the nature of this adaptation may help to unravel the mechanisms of Escovopsis parasitism. (AU)