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18 result(s)
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Abstract

Ants in the tribe Attini (the "attines") live with symbiotic fungi they cultivate for food. Escovopsis fungi are parasites of the attine ants' fungal partner, characterizing a tripartite association (ants, mutualistic and parasitic fungi). Previous studies by our laboratory (FAPESP grants 2014/24298-1 and 2011/16765-0) allowed us to gather a collection of Escovopsis and mutualistic fungi strains from various attine ant species across several biomes in Brazil. We demonstrated that a high diversification of Escovopsis strains occurred over the evolutionary time. Similar parasite strains were found in colonies of different attine ant species. Whether these strains are capable to infect different mutualistic fungi remains elusive. To understand the parasite specificity towards its host, we pose the following questions: (i) in higher-attines: can Escovopsis strains found in leaf-cutter ant colonies infect fungi cultivated by non-leaf-cutter ants? (ii) in lower-attines: is E. trichodermoides a generalist parasite? (iii) what are the mechanisms the parasite use to kill its host? (iv) can Escovopsis consume the cellular contents of its host? To provide answers for the first two questions we will carry out in vitro assays presenting different mutualistic fungi strains to Escovopsis to evaluate its specificity. In addition, dual-culture assays will be carried out to determine magnitude of the interaction towards different hosts. To answer the third question, we will use confocal laser scanning microscopy to evaluate whether specialized structures of the parasite are necessary to interact with its host. The forth question will be pursued by enriching the fungal cultivar with nitrogen isotopes and follow their patch to the fungal parasite, confirming the parasitic nature of Escovopsis (i.e. by direct absorbing cellular contents from its host). Together, data from specificity experiments and the mechanisms of action are fundamental to understand the biology of Escovopsis parasitism and open new avenues to apply this microorganism as a potential control agent of leaf-cutter ants, well-known agriculture pests in Brazil. (AU)

Phylogeny of fungal parasites in gardens of attine ants

Grant number:14/24298-1
Support type:Regular Research Grants
Duration: March 01, 2015 - July 31, 2017
Field of knowledge:Biological Sciences - Microbiology
Principal Investigator:André Rodrigues
Grantee:
Home Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro, SP, Brazil
Assoc. researchers:

Christian Rabeling ; Fernando Carlos Pagnocca ; Heraldo Luis de Vasconcelos ; Mauricio Bacci Junior

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)

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