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Host-specificity and mechanisms of action of Escovopsis parasites found in the gardens of attine ants

Grant number: 17/12689-4
Support type:Regular Research Grants
Duration: September 01, 2017 - August 31, 2019
Field of knowledge:Biological Sciences - Microbiology
Principal Investigator:André Rodrigues
Grantee:André Rodrigues
Home Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro, SP, Brazil
Assoc. researchers:Mauricio Bacci Junior ; Priscila Cintra Socolowski
Associated grant(s):18/50019-3 - Parasites in ant gardens: exploring host parasite interactions in fungus farming ants, AP.R

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)