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Autor: search.filters.author.Guimarães, Sarah da Silva CostaData inicial: 2020

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Agora exibindo 1 - 3 de 3
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    Pseudomonas coronafaciens pv. garcae and P. amygdali pv. tabaci isolated from coffee plants cause diseases in different species
    (Editora UFLA, 2025-06-16) Raimundi, Melina Korres; Souza, Ricardo Magela de; Guimarães, Sarah da Silva Costa; Alvarenga, Ariane de Souza; Ribeiro, Daniel Henrique; Resende, Mário Lúcio Vilela
    Bacterial halo blight and bacterial leaf spot have similar symptoms in coffee plants, and the etiological agents Pseudomonas coronafaciens pv. garcae (Pcg) and P. amygdali pv. tabaci (Pat) have very similar colony morphologies and biochemical characterizations, which makes it difficult to provide a correct diagnosis. To date, Coffea arabica is the only known natural host of Pcg, while Pat affects a wide range of host plants. However, no studies have yet been conducted to test the pathogenicity of Pcg strains in Pat hosts or Pat strains from different hosts in coffee plants. The objectives of this study were to evaluate the virulence level among Pcg strains and to perform cross-inoculation tests to confirm the hosts specificity for Pcg and Pat. In the virulence tests, there was variation in aggressiveness among Pcg strains. The reference isolate (CFBP 1634) and seven Pcg strains considered more aggressive were selected for cross-inoculation testing on different Pat hosts. All the Pat strains, regardless of the host of origin, caused disease in the coffee seedlings and Pcg strains caused disease in Phaseolus vulgaris, Cucumis sativus, Carica papaya, Aster sp., Coffea arabica, Celosia plumosa and Desmodium incanum. Therefore, there is no host specificity for Pcg and Pat, using artificial inoculation. These results are important for the beginning of the knowledge of the host range of Pcg and may contribute to the development of strategies to manage the disease.
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    Total phenolic content and antioxidant capacity in Muscodor spp. inoculated seedlings of coffee cultivars of Brazil
    (Editora UFLA, 2025-06-04) Mourão, Bárbara; Bertolucci, Suzan Kelly Vilela; Guimarães, Sarah da Silva Costa; Coelho, Adriane Duarte; Rocha, João Pedro Miranda; Carvalho, Júlia Helena Gomes de; Pedroso, Márcio Pozzobon; Cardoso, Patrícia Gomes
    Fungi of the genus Muscodor have received considerable attention for producing volatile and non-volatile organic compounds with biological activity. The objective of this study was to determine the total phenolic content and antioxidant capacity in two coffee cultivars (Catuaí Vermelho and Topázio) inoculated with the endophytic fungi Muscodor coffeanum and Muscodor sp. and in fungal extracts, as well as to characterize the phenolic compounds and trigonelline produced by isolates of Muscodor. Seeds of Coffea arabica (Catuaí Vermelho and Topázio cultivars) were inoculated with twelve fungal isolates and grown in a greenhouse for 24 months. The results showed that the cultivars inoculated with M. coffeanum (CML 4019) had the highest production of total phenolic content and antioxidant capacity. The presence of total phenolic content showed a direct correlation with antioxidant activity. Total phenolic content and antioxidant capacity varied among different Muscodor isolates. The phenolic profile of Muscodor extract determined by HPLCDAD showed the production of catechin, vanillin, and the caffeic, chlorogenic, ferulic, gallic, o-coumaric, p-coumaric, and syringic acids and the alkaloid trigonelline. These endophyte fungi associated with the coffee fruit can improve the quality of the beverage.
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    Diagnosis of leaf bacterial diseases of coffee reveals the prevalence of halo blight
    (Editora UFLA, 2021) Raimundi, Melina Korres; Souza, Ricardo Magela de; Figueira, Antônia dos Reis; Silva, Gustavo Matheus; Santos, Ana Carolina de Paula; Guimarães, Sarah da Silva Costa
    The diagnosis of foliar bacterial diseases in coffee (Coffea arabica), such as halo blight (Pseudomonas syringae pv. garcae), bacterial leaf spot (P. syringae pv. tabaci), bacterial blight (P. cichorii), and dark leaf spot (Robbsia andropogonis), is considered a challenge for plant pathologists. The misidentification has been occurring when the diagnosis is solely based on symptoms and biochemical properties. Thus, the objective of this study was to identify and differentiate species and pathovars of Pseudomonas pathogenic to coffee plants, enabling a survey of the occurrence of these bacteria in the main producing regions of Minas Gerais state, Brazil. Firstly, the pathogenicity of the isolates was confirmed by inoculation in C. arabica cv. Catuaí Vermelho IAC 99. Then, biochemical analyses, combined with, repetitive element-polymerase chain reaction (rep-PCR) and phylogeny based on rpoD gene sequences were used to characterize 84 Pseudomonas isolates from coffee crops and nurseries. Based on rpoD-phylogeny, 73 isolates were identified as P. syringae pv. garcae, five as P. syringae pv. tabaci and six as P. cichorii. The rep-PCR results suggest a high genetic variability in populations of Pseudomonas syringae pv. Garcae and P. cichorii. This is the first report of the occurrence of bacterial leaf spot (P. syringae pv. tabaci) in the coffee-producing filed in Minas Gerais State. The findings confirmed the prevalence of P. syringae pv. garcae in coffee production fields in the State and the generated knowledge will contribute for the development of species-specific primers for the identification and detection of this pathogen.