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Doctoral Thesis
DOI
https://doi.org/10.11606/T.87.2016.tde-26092016-121015
Document
Author
Full name
Raíssa Mesquita Braga
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2016
Supervisor
Committee
Araujo, Welington Luiz de (President)
Araújo, Francisca Diana da Silva
Maldonado, Gabriel Padilla
Ribeiro, Manuella Nóbrega Dourado
Silva, Luiziana Ferreira da
Title in Portuguese
Identificação de genes possivelmente envolvidos na biossíntese da epicolactona em Epicoccum nigrum.
Keywords in Portuguese
Epicoccum nigrum
Biossíntese
Endófito
Epicolactona
Policetídeo
Policetídeo sintase
Abstract in Portuguese
Epicoccum nigrum é um fungo ubíquo conhecido por sua capacidade de produzir vários metabólitos secundários bioativos e pelo seu uso potencial como agente de biocontrole contra vários fitopatógenos. Entre os compostos produzidos por E. nigrum, epicolactona é um policetídeo com uma estrutura bastante complexa. O objetivo desta tese foi identificar e caracterizar genes relacionados à biossíntese da epicolactona em E. nigrum. Três mutantes defectivos para a produção de epicolactona anteriormente gerados por mutagênese aleatória foram analisados. Entretanto, os resultados mostraram que o T-DNA provavelmente estava inserido em regiões regulatórias. Usando ferramentas de bioinformática, seis genes de PKSs foram selecionados para deleção. A deleção do gene PKSi12 mostrou que os seus produtos estão relacionados à atividade antagonista. A análise química permitiu a identificação putativa dos preditos precursores da epicolactona, os quais tiveram sua produção afetada no mutante ΔPKSi12. Uma possível via de biossíntese de epicoccona B e epicoccina por E. nigrum foi proposta.
Title in English
Identification of candidate genes contributing to epicolactone biosynthesis in Epicoccum nigrum.
Keywords in English
Epicoccum nigrum
Biosynthesis
Endophyte
Epicolactone
Polyketide
Polyketide synthase
Abstract in English
Epicoccum nigrum is a ubiquitous fungus mainly known for its ability to produce many bioactive secondary metabolites and for its potential use as a biocontrol agent against many phytopathogens. Among the compounds produced by E. nigrum, epicolactone is a polyketide with a very complex structure. The aim of this thesis was to identify and characterize genes related to epicolactone biosynthesis in E. nigrum. Three defective epicolactone mutants previously generated by random mutagenesis were analyzed. However, the results showed that the T-DNA was probably inserted in regulatory regions. Using a genome mining approach, six PKS genes were selected for deletion. The deletion of PKSi12 gene showed that its products are related to E. nigrum antagonistic activity against fungal phytopathogens. The chemical analysis allowed a putative identification of the previously proposed epicolactone precursors, which production was affected in the ΔPKSi12 mutant. A proposed biosynthesis of epicoccone B and epicoccine by E. nigrum was suggested.
 
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Release Date
2020-09-26
Publishing Date
2016-09-26
 
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