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Advisor(s)
Abstract(s)
A castanha europeia (fruto de Castanea sativa Mill.) é um alimento muito nutritivo, e em
Trás-os-Montes, Portugal, este fruto é amplamente produzido, consumido e
comercializado. Devido as características nutricionais e de humidade, as castanhas são
altamente propícias ao desenvolvimento de fungos deteriorantes, que resultam em
grandes perdas na qualidade dos frutos, sendo este o principal problema pós-colheita
associado à castanha armazenada. Na última década, o fungo Gnomoniopsis smithogilvyi
tem emergido preocupantemente em diversos países produtores de castanha como agente
causal da podridão castanha, e atualmente é considerado um dos principais agentes
fúngicos causadores de podridão. O presente estudo é pioneiro na caracterização e
identificação deste agente fúngico e da respectiva doença, em Portugal e em variedades
de castanha portuguesas. Este conhecimento é de maior importância e urgência para os
produtores, comerciantes e indústrias do setor deste fruto, para otimizar a prevenção e o
controle deste problema. Os objetivos desse trabalho foram: i) Caracterizar morfológica,
ecofisiológica e molecularmente os isolados portugueses de G. smithogilvyi; ii)
Caracterizar a doença causada por este agente e determinar a patogenicidade e a virulência
deste fungo em três variedades portuguesas de castanha (Judia, Longal e Martaínha); iii)
Estudar a efetividade do uso de Trichoderma viridescens como um agente de biocontrole
contra o patógeno G. smithogilvyi. As variedades de castanha portuguesas não mostraram
resistência ou tolerância a infeção por este fungo, entre si, sendo altamente suscetíveis
quando previamente feridas e inoculadas artificialmente, com 100% de infeção e
apodrecimento. Porém quando os frutos estavam sadios e bem formados, sua casca foi
eficiente no combate a infeção pelo patógeno externo. Confirmou-se a existência de G.
smithogilvyi endofítico nas castanhas portuguesas, distribuído aparentemente de forma
igual entre as variedades. Verificou-se que os isolados portugueses de G. smithogilvyi
apresentam elevada semelhança morfológica, ecofisiológica e molecular com os isolados
do fungo de outros países. G. smithogilvyi sofreu redução de crescimento significativa
nos testes de biocontrole feitos com T. viridescens em meio PDA, comparado aos
controles sem o uso de T. viridescens. No entanto, esse efeito não foi significativo em
meio à base de castanha, verificando-se assim uma grande adaptação do fungo ao
substrato castanha, o que deixa antever que a redução ou eliminação da podridão castanha
será difícil de obter.
Sweet chestnut (the fruit of Castanea sativa Mill.) is a nutritious food of great importance in Trás-os-Montes, Portugal. Given its nutritional and water contents, chestnuts are highly prone to the development of spoilage fungi, which result in great quality losses, being this the major post-harvest problem associated with stored chestnut. In the last decade, the fungus Gnomoniopsis smithogilvyi has emerged in several chestnut-producing countries at worrying levels as the causal agent of brown rot, and is currently considered one of the major chestnut rot-causing agents. This study aimed at identifying and characterizing, for the first time in Portugal, this agent in Portuguese chestnut varieties. This acknowledgement is of the utmost significance por the chestnut producers, the industry and the sellers, as a first step towards the mitigation of this disease. Under this framework, the objectives of the study were: i) characterize at the morphological, ecophisiological and molecular levels the Portuguese isolates of G. smithogilvyi; ii) characterize the disease caused by this fungus in terms of pathogenicity and virulence in three Portuguese chestnut varieties (Judia, Longal and Martaínha); iii) study the effectiveness of Trichoderma viridescens as a potential biocontrol agent against G. smithogilvyi. The Portuguese chestnut varieties did not show any resistence or tolerance against G. smithogilvyi, and were highly susceptible (100% rotten) to the fungus when previously wounded and artificially inoculated. However, in apparently healthy and intact fruits, the fungus was unable to infect the fruit, showing the efficiency of the peel in retaining the disease. It was also confirmed that the fungus is present endophitically in the three chestnut varieties. In terms of the fungus characterization, it was shown that the Portuguese isolates of G. smithogilvyi are highly similar to the ones isolated in other countries at all studied levels. When tested against T. viridescens, G. smithogilvyi showed growth reduction in the medium PDA, but not in chestnut-based medium, which leads to the conclusion that the fungus is highly adapted to chestnut, and its reduction or elimination from the fruit will be difficult to achieve.
Sweet chestnut (the fruit of Castanea sativa Mill.) is a nutritious food of great importance in Trás-os-Montes, Portugal. Given its nutritional and water contents, chestnuts are highly prone to the development of spoilage fungi, which result in great quality losses, being this the major post-harvest problem associated with stored chestnut. In the last decade, the fungus Gnomoniopsis smithogilvyi has emerged in several chestnut-producing countries at worrying levels as the causal agent of brown rot, and is currently considered one of the major chestnut rot-causing agents. This study aimed at identifying and characterizing, for the first time in Portugal, this agent in Portuguese chestnut varieties. This acknowledgement is of the utmost significance por the chestnut producers, the industry and the sellers, as a first step towards the mitigation of this disease. Under this framework, the objectives of the study were: i) characterize at the morphological, ecophisiological and molecular levels the Portuguese isolates of G. smithogilvyi; ii) characterize the disease caused by this fungus in terms of pathogenicity and virulence in three Portuguese chestnut varieties (Judia, Longal and Martaínha); iii) study the effectiveness of Trichoderma viridescens as a potential biocontrol agent against G. smithogilvyi. The Portuguese chestnut varieties did not show any resistence or tolerance against G. smithogilvyi, and were highly susceptible (100% rotten) to the fungus when previously wounded and artificially inoculated. However, in apparently healthy and intact fruits, the fungus was unable to infect the fruit, showing the efficiency of the peel in retaining the disease. It was also confirmed that the fungus is present endophitically in the three chestnut varieties. In terms of the fungus characterization, it was shown that the Portuguese isolates of G. smithogilvyi are highly similar to the ones isolated in other countries at all studied levels. When tested against T. viridescens, G. smithogilvyi showed growth reduction in the medium PDA, but not in chestnut-based medium, which leads to the conclusion that the fungus is highly adapted to chestnut, and its reduction or elimination from the fruit will be difficult to achieve.
Description
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Keywords
Podridão castanha Gnomoniopsis smithogilvyi Castanea sativa Biocontrole Trichoderma viridescens Fungos