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19 result(s)
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Abstract

An interesting example of symbiotic association is the mutualism between ants in the tribe Attini and fungi they grow for food. Fungi in the genus Escovopsis are parasites of the fungal partner cultivated by these insects. The parasite is specialized to certain mutualistic fungi, although occasional host switches occurred during the evolution of this association. Recently, our research group described Escovopsis trichodermoides from lower attine ant colonies. There is a lack of knowledge regarding its specificity and parasitic mechanisms towards the mutualistic fungi cultivated by lower attine ants. In this study we will attempt to answer the question: Does E. trichodermoides present similar parasite-host specificity that naturally occurs in other Escovopsis species? In vitro dual-culture assays will be performed to evaluate whether these strains inhibit the growth of the mutualistic fungi. In addition, experiments will be carried out to evaluate the preference of E. trichodermoides strains to different mutualistic fungi of lower attine ants. Then, we will also verify the possible mechanisms used by E. trichodermoides to affect their host. In this case, we will perform growth assays of the mutualistic fungi against the metabolites produced by E. trichodermoides, in addition to scanning electron microscopy experiments to investigate the physical interaction with its host. Our results will determine whether E. trichodermoides is in fact a parasite of the fungi cultivated by lower attine ants. Moreover, our results will demonstrate the generalist or specialist behavior of this parasite against its host. Therefore, this project will contribute to the understanding of the evolution process of Escovopsis parasitism associated with lower attine ants, describing the role of E. trichodermoides in colonies of these insects. (AU)

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)

Abstract

Ants in tribe Attini cultivate fungi for food, establishing a mutualistic relationship with their partner. These insects develop the fungiculture in the fungus gardens. It is known that fungus garden have high concentrations of simple sugars, resultant of degradation the plant substrate by the ants' mutualistic fungi. The genus Escovopsis comprises fungi considered mycoparasites of the ants' fungal cultivars. Although previous works have explored several aspects of this parasite-host interaction, the nutritional mechanisms of Escovopsis are still poorly known. Here, we aim to investigate whether Escovopsis benefits from the sugars present in the fungus garden matrix and if these nutrients influence the infectivity towards its host. We will perform in vitro bioassays to evaluate the assimilation of different carbon sources by Escovopsis in the presence and absence of the host. In addition, we intent to observe the parasite-host interaction using confocal laser scanning microscopy applying specific fluorescent dyes to examine cellular viability and cell wall integrity. We hope to understand the mechanisms which Escovopsis parasitize its host. Our goal is to determine whether the host degradation is initiated either before or after the physical contact with Escovopsis hyphae. The approach and techniques we intent to use have never been employed in this parasite-host system. Thus, the present study will gather original information to fill the gaps about the biology of this important parasitic fungus. Such knowledge will boost the research using this fungus as a biological control agent. (AU)

Abstract

Attine ants maintain a mutualistic relationship with fungi grown for food. Parasitic fungi from the genus Escovopsis threaten the ant mutualistic partner. Despite the importance of this genus in the biological control of leaf-cutting ants (higher-attines), few studies focused in the taxonomy and systematics of Escovopsis. Recent results from our research group (Young Research Award FAPESP grant # 2011/16765-0 and 2013/25748-8) suggest the parasite has an increased diversity as well as high morphological variability with adaptations to parasitize the mutualistic fungus. However, little is known about the Escovopsis that occur in non-leaf-cutting attine ant colonies (lower-attines). Here, we aim to carry out a comprehensive study considering Escovopsis from several ant species from different geographical regions to answer the following questions: I) What is the diversity of the genus Escovopsis?, II) Is this diversity similar among higher and lower-attines? and (III) What is the morphological variability of the genus? We will investigate a comprehensive collection of Escovopsis (about 400 strains) obtained over the years by our research group and by the laboratory of Dr. Ulrich G. Mueller (UTexas, Austin, USA) as well as additional strains collected in the present proposal. All strains will be sequenced for three molecular markers (ITS, tef1 and LSU) for phylogenetic analyses and a detailed analysis of the morphological structures will also be performed. This work will unravel the genetic and morphological diversity of the genus Escovopsis, likely resulting in new species descriptions and creating a taxonomic basis for studies involved in the biological control work of attine ants. (AU)

Abstract

Fungus-growing ants in the tribe Attini maintain mutualistic association with fungi that are cultivated for food. Fungus gardens of these insects harbors a complex microbiome, including yeasts, filamentous fungi and bacteria. Several lines of evidence suggest that the bacterial community found in the fungus garden perform physiological functions for the colony, such as nitrogen fixation, plant biomass degradation, nutrient biosynthesis and antimicrobial defenses. Our main goal is to compare the metabolic potential of the bacterial microbiome from the fungiculture practiced by Atta sexdens rubropilosa (leaf-cutter fungiculture in which fresh leaves are used as substrate for fungus cultivation) and Mycocepurus goeldii (lower fungiculture in which dry parts of plants, seeds and others substrates are used for fungus cultivation). From a bacterial enrichment of fungus gardens of these ants, the total DNA of the bacterial community was extracted and sequenced. Here, we aim to perform the assembly and analysis of the metabolic potential of our dataset, using specific softwares. Such analyses are fundamental to support the data processing and will be carried out in Dr. Cameron Robert Currie's lab (Department of Bacteriology, University of Wisconsin-Madison, EUA). This lab present a wide experience in studies regarding ecology and evolution of the attine ants-microbial association. Along the past years, Dr. Curie and his team unraveled several aspects of the microbial diversity in this environment, revealing various functions performed by micro-organisms in this microbiome. Since this lab harbors the required specialists and tools to explore the two metagenomes generated, the analyses to be carried out in the Currie Lab are essential for the development of the master project in which this proposal is attached. (AU)

Abstract

Pressmud is a material derived from sugarcane juice filtrate. Around 26 to 40 kg of this residue are produced per ton of sugarcane. This residue is mainly used as fertilizer in crops either with or without processing such as composting. Because pressmud presents high amounts of phosphorus, nitrogen and carbon it is an ideal habitat for microbial growth. In previous studies we unraveled the diversity of fungi in fresh pressmud and processed pressmud in a composting system by 454 pyrossequencing; in addition we characterized the enzymatic potential of heat-tolerant fungi isolated from these substrates. We obtained isolates of Thermomucor indicae-seudaticae, a thermophilic fungus able to produce biomass-degrading enzymes such as cellulase, pectinase and xylanase. Although many genomes from fungal species have been studied, the genome of T. indicae-seudaticae remains unexplored. Thus, we aim to look at genes encoding for relevant enzymes for biotechnological applications (cellulase, pectinase, xylanase and protease) in the genome of this fungus. In addition, we aim to study another under explored group of extremophiles, the osmophlilic fungi. We isolated 27 fungal strains from fresh pressmud and we will identify these isolates whereas previous studies have shown their potential for industrial application. By exploring the enzymatic repertoire in the genome of T. indicae-seudaticae as well as the diversity of osmophilic fungi we expect to shed the light onthe diversity and biotechnological potential of extremophilic fungi found in pressmud. (AU)

Abstract

Fungus-growing ants in the tribe Attini maintain a mutualistic relationship with fungi cultivated for food, in a structure named "fungus garden". This substrate harbors a complex microbiome, involving bacteria, yeasts and filamentous fungi. Like other microbiomes, the interaction between microorganisms and the environmental pressure determine the diversity of chemical compounds produced by microorganisms involved in the consortium, including secondary metabolites with therapeutic properties. Here, we aim to compare the metabolic potential in fungus garden microbiomes of two fungiculture systems practiced by fungus-growing ants. Through metagenomics profiling, we will compare the functional aspects of microbiomes associated with fungus garden in the lower and the leafcutter ant fungicultures. This study will allow the determination of genes involved in natural products of therapeutic interest. In addition, the results will build knowledge of the ant-fungus symbiosis, through the bacterial community role in the different fungiculture systems. (AU)

Abstract

Ants in the tribe Attini share the ability to cultive fungi for food. In this association, the fungus provides nutrients for the colony. In turn, ants provide protection and dispersion of the fungal partner. Fungi in the genus Escovopsis are specific parasites of the fungus cultivated by attine ants. Previous studies have focused on Escovopsis strains infecting the fungus cultivated by leaf-cutting ants, the most derived group within the tribe Attini. However, few studies evaluated the interactions of Escovopsis towards the fungus cultivated by the lower attines. Our research group described the first species of Escovopsis (E. kreiselii) from colonies of lower attine ants, however, the pathogenicity and virulence of E. kreiselii remain unknown. Using in vitro bioassays, we will investigate the specificity and pathogenicity of E. kreiselii and other Escovopsis strains isolated from lower attine colonies. The results of the present study will gather novel information regarding the biology of these important fungi in order to build knowledge about the interaction of Escovopsis and the fungus cultivated by the lower attine ants. (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)

Abstract

Endophytic fungi live within plant tissues without causing any apparent symptoms of disease. Such fungi stimulate plant defenses against pathogenic micro-organisms through production of chemical compounds; thus, they are considered a promising source for the discovery of new bioactive compounds. Using culture dependent methods and polyphasic taxonomy, here we aim to evaluate the diversity of endophytic fungi associated with Begonia sp., a plant not explored for the associate endophytes. Begonia sp. occur both in the continental zone of the State of São Paulo and at the archipelago of Alcatrazes; this constitutes an ideal scenario to assess the diversity of endophytes present in this plant and the putative factors that modulate the diversity of such fungi. Leaves of five specimens of Begonia sp. will be sampled in each locality and used for fungal isolation. In addition, we aim to assess the potential of endophytes in inhibiting the growth of plant pathogens in in vitro bioassays. From the point of view of prospection, unexplored environments, such as the Alcatrazes Island, provide a unique opportunity for searching relevant endophytic fungi for biotechnology. Overall, the results of this proposal will contribute to two aspects of the endophytic fungi associated with Begonia sp.: (i) increase knowledge of the factors that influence the communities of endophytic fungi associated with plants in different locations (and the possible discovery of new undescribed species) and (ii) the discovery of fungi that produce bioactive compounds of interest for controlling plant pathogens. (AU)

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