Óleos essenciais e extratos vegetais no controle de fitopatógenos de grãos de soja.

A utilização de sementes sadias é um importante método para diminuir a ocorrência de doenças desde o inicio de seu cultivo. Uma das alternativas ao uso de agrotóxicos é a utilização de óleos essenciais e extratos de plantas que possuam propriedades tóxicas aos fitopatógenos. O objetivo deste trabalho foi avaliar o efeito de óleos essenciais e extratos hidroalcoólicos de plantas medicinais na sanidade e germinação de sementes de soja. Os óleos essenciais e os extratos hidroalcoólicos foram diluídos em água destilada, na concentração de 2 mg/mL para os extratos e 20% para os óleos essenciais. Em seguida, as sementes foram pulverizadas com os tratamentos e secas a sombra durante 4 horas em temperatura ambiente (25ºC). Os tratamentos utilizados foram: T1=testemunha (água destilada); T2 = óleo essencial de gengibre; T3 = óleo essencial de limão Taiti; T4 = extrato de pariparoba e T5 = extrato de penicilina. Os testes de germinação e sanidade foram realizados segundo as Regras para Análises de Sementes (RAS). Os resultados obtidos no teste de germinação demonstraram que o percentual de germinação inicial das sementes não tratadas (4%) encontrava-se muito abaixo dos níveis recomendados pelas RAS (80%), não tendo como avaliar a interferência dos tratamentos na germinação. Em função deste resultado, foi realizado o teste de sanidade visando o tratamento de grãos. O óleo essencial de gengibre apresentou uma redução da incidência de 75% de Cladosporium sp; Rhizopus sp.; Fusarium spp. quando comparado à testemunha. Pode-se concluir que o óleo essencial de gengibre na concentração de 20% apresenta atividade positiva no controle de Cladosporium sp, Rhizopus sp e Fusarium spp em grãos de soja.

Fungal endophytic communities associated to the phyllosphere of grapevine cultivars under different types of management

Fungal endophytes present in different asymptomatic grapevine plants (Vitis vinifera L.) located in different vineyards within Alentejo, a highly important viticulture region in Portugal, were identified in this study. Sampled grapevine plants included the three most representative cultivars in the region, Syrah, Cabernet Sauvignon, and Aragonez, growing under two different modes of management, conventional and biological. Sixteen fungal taxa were identified through sequencing of the internal transcribed spacer region. Total number of endophytic fungi isolated showed significant differences both in management mode and in cultivars, with higher numbers in grapevines under conventional mode and from Syrah cultivar. The composition of fungal endophytic communities did not show significant differences among cultivars, but differences were observed between fungal communities isolated from grapevines under biological or conventional modes. The most fungal taxa isolated from grapevines cultivated under biological mode were Alternaria alternata, Cladosporium sp., and Nigrospora oryzae, and under conventional mode Botrytis cinerea, Epicoccum nigrum, and Epicoccum sp. These differences suggest that the different products used in grapevine production have impacts in fungal endophytic composition. Further investigation of the identified fungi with respect to their antagonistic characteristics and potential use in plant protection to ensure food safety is now in course.

DETECTION OF SPORES AND HYPHAE OF ARTWORKS’ BIODETERIOGENIC FILAMENTOUS FUNGI BY RNA-FISH

Filamentous fungi are a threat to the conservation of Cultural Heritage. Thus, detection and identification of viable filamentous fungi are crucial for applying adequate Safeguard measures. RNA-FISH protocols have been previously applied with this aim in Cultural Heritage samples. However, only hyphae detection was reported in the literature, even if spores and conidia are not only a potential risk to Cultural Heritage but can also be harmful for the health of visitors, curators and restorers. Thus, the aim of this work was to evaluate various permeabilizing strategies for their application in the detection of spores/conidia and hyphae of artworks’ biodeteriogenic filamentous fungi by RNA-FISH. Besides of this, the influence of cell aging on the success of the technique and on the development of fungal autofluorescence (that could hamper the RNA-FISH signal detection) were also investigated. Five common biodeteriogenic filamentous fungi species isolated from biodegradated artworks were used as biological model: Aspergillus niger, Cladosporium sp, Fusarium sp, Penicillium sp. and Exophialia sp. Fungal autofluorescence was only detected in cells harvested from Fusarium sp, and Exophialia sp. old cultures, being aging-dependent. However, it was weak enough to allow autofluorescence/RNA-FISH signals distinction. Thus, autofluorescence was not a limitation for the application of RNA-FISH for detection of the taxa investigated. All the permeabilization strategies tested allowed to detect fungal cells from young cultures by RNA-FISH. However, only the combination of paraformaldehyde with Triton X-100 allowed the detection of conidia/spores and hyphae of old filamentous fungi. All the permeabilization strategies failed in the Aspergillus niger conidia/spores staining, which are known to be particularly difficult to permeabilize. But, even in spite of this, the application of this permeabilization method increased the analytical potential of RNA FISH in Cultural Heritage biodeterioration. Whereas much work is required to validate this RNA-FISH approach for its application in real samples from Cultural Heritage it could represent an important advance for the detection, not only of hyphae but also of spores and conidia of various filamentous fungi taxa by RNA-FISH.