Prelecionista: Priscila Raiane Assunção de Andrade
Orientador: Gleiber Quintão Furtado
Data: 08/04/2025, às 16h, online
Local: Online, via Google Meet*

Resumo: The genus Chrysoporthe includes important pathogens that affect trees in the families Melastomataceae and Myrtaceae, among which Chrysoporthe cubensis stands out as the main fungal species associated with eucalyptus canker. This disease gained prominence in Brazil during the 1970s due to its substantial qualitative and quantitative impact on commercial eucalyptus plantations. Recently, C. cubensis has also been reported in eucalyptus mini-stumps, causing wilting that can progress to partial or complete canopy drying. Due to the limited understanding of Chrysoporthe wilt dissemination and management in mini-stumps, this study aimed to (1) investigate the occupation of endophytic niches by Chrysoporthe spp. in eucalyptus mini-stumps and seedlings, assess the potential role of vegetative propagation in disease transmission, and confirm the identity of Chrysoporthe species associated with symptomatic and asymptomatic eucalyptus mini-stumps using phylogenetic analyses; (2) to evaluate the sensitivity of C. cubensis isolates to four triazole fungicides and their efficacy in controlling Chrysoporthe wilt through preventive and curative applications; and (3) to design primers and develop a colorimetric molecular assay based on loop-mediated isothermal amplification (LAMP) for the rapid and specific detection of Chrysoporthe spp. Of the 42 isolates obtained from mini-stumps, 41 were identified as C. cubensis, while one isolate, obtained from a symptomatic mini-stump, was identified as Chrysoporthe doradensis — which is the first report of this species in eucalyptus mini-stumps. Although Chrysoporthe sp. was recovered from asymptomatic eucalyptus mini-stumps, indicating its presence in endophytic niches during part of its life cycle, the transmission of the disease through vegetative propagation—from mini-stumps to mini-cuttings and seedlings in clonal mini-gardens—was not confirmed. The study also revealed that C. cubensis isolates are highly sensitive to the fungicides cyproconazole, difenoconazole, ipconazole and tebuconazole. Curative application of these fungicides resulted in smaller necrotic lesions compared to preventive treatment. However, application of the fungicides at 15 days post inoculation failed to control the disease; nevertheless, ipconazole and tebuconazole reduced the formation of fruiting bodies on eucalyptus bark. Finally, a set of primers targeting the TEF-1α gene was designed for LAMP-based detection of Chrysoporthe spp. These findings contribute to the understanding and control of Chrysoporthe wilt in eucalyptus mini-stumps, helping to mitigate its impact on clonal mini-gardens.

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