Fitopatologia
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/173
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Item Explorando o potencial nematicida: avaliação in vitro de extratos e óleo essencial de plantas sobre Meloidogyne paranaensis(Universidade Federal de Viçosa, 2024-02-28) Santana, José Neto Rodrigues; Buonicontro, Dalila Sêni; http://lattes.cnpq.br/8695307942586677Item Diversidade, taxonomia e potencial de fungos micoparasitas de ocorrência natural em Pucciniales no Brasil como agentes de biocontrole da ferrugem asiática da soja(Universidade Federal de Viçosa, 2025-07-31) Dudycz, Ana Rita; Pereira, Olinto Liparini; http://lattes.cnpq.br/2171394596913235Item Análise metabolômica, genômica e potenciais modos de ação de metabólitos secundários de Clonostachys spp. no controle de doenças de plantas(Universidade Federal de Viçosa, 2025-10-08) Almeida, Ana Carolina de; Abreu, Lucas Magalhães de; http://lattes.cnpq.br/7873419398940893O estudo investigou a diversidade metabólica de espécies de Clonostachys e suas aplicações no controle de doenças da parte aérea, como a mancha-alvo (Corynespora cassiicola), a antracnose (Colletotrichum truncatum), a ferrugem- asiática da soja (Phakopsora pachyrhizi) e a pinta-preta (Alternaria grandis). O trabalho foi estruturado em três capítulos interdependentes que integram o screening de extratos orgânicos enriquecidos com metabólitos secundários de Clonostachys spp., análises genômicas e estudos de uma interação extrato-planta-patógeno. No primeiro capítulo, foram avaliados extratos de 59 isolados de diferentes espécies de Clonostachys. Os ensaios in vitro revelaram que isolados de C. chloroleuca e C. rogersoniana apresentaram desempenho superior ao de C. rosea, espécie mais estudada do gênero. Ensaios em soja confirmaram o potencial de determinados extratos no controle da mancha-alvo, especialmente os extratos dos isolados UCBV26 e UCBV116, cuja eficácia foi comparável à de um fungicida comercial. A caracterização química dos extratos bioativos por LC-HRMS apontou predominância de peptaibols. No segundo capítulo, foram investigados os aspectos genômicos e funcionais de dois isolados de C. rogersoniana (UCBV101 e UCBV116), selecionados pela divergência em atividade antifúngicas de seus extratos. Embora apresentem genomas de tamanho e composição semelhantes, as análises revelaram variação nos clusters biossintéticos de metabólitos secundários, incluindo famílias de genes exclusivas de cada isolado. Ensaios biológicos mostraram que ambos possuem atividade antagônica a fungos fitopatogênicos, mas diferem na capacidade de colonização endofítica. No terceiro capítulo, o efeito do extrato de C. rogersoniana (UCBV116) foi avaliado em folhas de soja inoculadas com C. cassiicola. Os resultados indicaram que o extrato atua diretamente na inibição da germinação de conídios do patógeno e influencia em vias associadas à apoptose e autofagia no tecido foliar, tanto na presença quanto na ausência da inoculação. De forma integrada, os resultados evidenciam o potencial dos extratos de Clonostachys como compostos antifúngicos e ampliam o entendimento das interações extrato – patógeno – planta, com implicações práticas para o manejo de doenças foliares. Palavras-chave: extratos fúngicos ; genômica; interação planta-patógeno.Item Histopathological and Molecular insights into the soybean - Aphelenchoides pseudobesseyi interaction(Universidade Federal de Viçosa, 2025-07-23) Honório, Amanda Pereira; Buonicontro, Dalila Seni; http://lattes.cnpq.br/8208384707211515Aphelenchoides pseudobesseyi is considered one of the most harmful plant-parasitic nematodes affecting soybean crops in the north-central region of Brazil. Infected plants commonly exhibit apical necrosis, angular leaf lesions, leaf curling, and a characteristic dark-green tissue coloration, indicative of a stay-green phenotype characterized by delayed senescence. These symptoms severely compromise plant development and hinder mechanical harvesting, underscoring the agronomic importance of this pathogen. However, available information on its interaction with soybean, as well as on the genes and effectors involved in this process, remains limited or even unknown. Therefore, the objectives of this study were: (i) to determine whether A. pseudobesseyi migrates systemically from roots to aerial parts of soybean and to characterize the associated cellular damage, (ii) to characterize the transcriptional profile of soybean plants infected with A. pseudobesseyi and (iii) to identify and annotate specific genes and effectors of A. pseudobesseyi involved in its interaction with soybean, as well as to explore genes and effectors unique to the Aphelenchoides besseyi complex. Histopathological analyses indicated that A. pseudobesseyi migrates externally throughout the plant, as no nematodes were observed in the analyzed tissues (roots, epicotyl and hypocotyl), nor were any cellular alterations associated with their presence detected. Transcriptional analysis of the host plant revealed induction of defense pathways and repression of processes related to photosynthesis and cell growth. Changes in the expression of key genes related to chlorophyll degradation and carbohydrate transport were observed, including members of the stay-green family (D1, D2, SGR3a, SGR3b, and two SGRL isoforms: SGRL1 and SGRL2), as well as red chlorophyll catabolite reductase (RCCR), two pheophytinase isoforms (PPH1 and PPH2), and sucrose-phosphate synthase 2 (SPS2). These results indicate that A. pseudobesseyi infection compromises the flux of assimilates due to nematode feeding and interferes with senescence mechanisms, which may contribute to the manifestation of the stay- green phenotype in infected plants. Regarding the nematode, a set of genes differentially expressed during interaction with soybean was identified, including genes with potential effector functions annotated as hypothetical proteins, as well as genes associated with motility, metabolism, and cuticle structure, such as myosin head, twitchin, cytoplasmic intermediate filament protein, trans-1,2-dihydroxybenzene-1,2-diol dehydrogenase-like, cuticlin-1, and collagen. Among the genes unique to the A. besseyi complex, many lacked functional annotations or contained unknown domains, highlighting the largely unexplored nature of the genome of this group. The annotated genes included domains associated with transcriptional regulation, metabolism, and cellular interaction, such as BTB/POZ, protein kinase, homeodomain, zinc finger, glycoside hydrolase, and major sperm protein. Effector prediction also revealed hypothetical proteins, as well as some with putative functions, such as trehalase and metalloendopeptidase. In conclusion, this study provides novel insights into the interaction between A. pseudobesseyi and soybean, revealing host transcriptional reprogramming and potential effector candidates of the nematode. These findings contribute to a better understanding of the molecular basis of the disease and lay the groundwork for future functional studies aimed at developing sustainable management strategies. Keywords: effectors; foliar nematode; green stem and foliar retention syndrome; histopatology; rna-seqItem Etiology of the stem canker-disease of Coffea canephora: an emerging disease in the states of Espírito Santo and Bahia (Brazil)(Universidade Federal de Viçosa, 2023-12-21) Bracale, Marina Faria; Barreto, Robert Weingart; http://lattes.cnpq.br/6294757846226802Most diseases occurring on coffee in Brazil have been well investigated and their etiology have been fully clarified. A notable exception is that of an emerging disease that is now affecting large areas planted with Coffea canephora (conilon) in the states of Espírito Santo (ES) and Bahia (BA), Brazil. Losses of large stands of adult productive plants are common. The disease symptoms resemble those associated with bark disease – a common, but poorly investigated disease of C. arabica in Africa. Since this disease first appeared in the early 2010s, the search for a pathogen behind it was initiated. The results of the few published studies on the matter are somewhat controversial and even the choice of a common name for the disease was pending, until recently. It has been named (Portuguese name) “cancro dos ramos do cafeeiro – (C. canephora)” or stem canker-disease of conilon (SCC). This is regarded as the worst threat to the conilon plantations in ES and BA, a crop of major relevance for the economy of both states and Brazil too – the second world producer of conilon coffee, behind Vietnam. Many of the elite, highly productive, conilon clones are susceptible. When plants are affected by the disease, particular positions of stems or branches present some intumescence and flaking of the bark. These areas then develop cracks and finally burst to expose the heartwood. In parallel shortening of internodes and branch proliferation together with yellowing of the foliage and complete necrosis, occurs above those damaged areas, similar to the African bark disease of C. arabica. One additional disease symptom appearing since early stages is seen on the leaves of affected portions of the plants. Petioles become twisted and, consequently, the leaves become inverted with the adaxial side facing down and the abaxial becoming upward oriented. Disease progress can be fast and entire rows of susceptible clones are killed leaving entire rows empty in the plantations. What was once thought to be just a localized minor problem for conilon plantations became a widespread problem for this crop in ES and BA. There are two publications that may be regarded as having resolved the issue of the etiology of SCC. These involve: a) a complex of Fusarium spp. and b) Lasiodiplodia iranensis. Nevertheless, the symptomatology of the two cases differs from that of SCC. The former is described as a wilt and the latter is a dieback disease, unlike SCC. In the present study, a detailed description of the SCC is provided, along with results from a metagenomic study aimed at providing an alternative approach to pinpointing an unidentified and elusive pathogen behind SCC. Keywords: coffee; disease; metagenomic.Item Biochemical aspects of a zinc-polyphenolic compound on the maize-Colletotrichum graminicola interaction(Universidade Federal de Viçosa, 2025-07-16) Tibolla, Tiago da Silva; Rodrigues, Fabrício de Avila; http://lattes.cnpq.br/2623138022610743Anthracnose, caused by the hemibiotrophic fungus Colletotrichum graminicola, is one of the major diseases affecting maize production globally. In this context, new alternatives for disease control need to be investigated. In this study, the hypothesis that maize plants sprayed with Semia? [zinc (Zn) (20%) and nitrogen (N) (1%) complexed with a plant-derived pool of polyphenols (10%); referred to as induced resistance (IR) stimulus] could hamper the infection of maize leaves by C. graminicola was investigated. The IR stimulus-sprayed and water-sprayed plants (control) were either non-inoculated or inoculated with C. graminicola. Leaf samples were collected at 2, 4, 6 and 12 days after inoculation for biochemical analysis. Compared to water-sprayed and infected plants, the foliar concentration of Zn, the incubation period and the latent period significantly increased by 159, 136 and 81%, respectively, while the area under anthracnose progress curve significantly decreased by 74% for IR stimulus-sprayed and infected ones. At the biochemical level, increased activities of defense-related (chitinase, ß-1,3-glucanase, phenylalanine ammonia-lyase, polyphenol oxidase and lipoxygenase) and antioxidative (ascorbate peroxidase, catalase, glutathione reductase, peroxidase and superoxide dismutase) enzymes were obtained for IR stimulus-sprayed and infected plants in contrast to water-sprayed and infected ones. These findings highlight the potential of using this IR stimulus for anthracnose management with less dependence on fungicide spray and, consequently, towards a more sustainable agriculture. Keywords: Zea mays ; antioxidative metabolism; host defense reactions; induced resistance; mineral nutritionItem Sensibilidade a fungicidas de isolados de Diaporthe spp. associados à podridão de vagens e grãos da soja(Universidade Federal de Viçosa, 2025-02-27) Rosa, Raphael Barboza; Mizubuti, Eduardo Seiti Gomide; http://lattes.cnpq.br/1584808533887860A podridão de vagens e grãos (PVG) da soja, causada por espécies de Diaporthe, tornou-se um desafio a partir da safra 2019/20. Perdas financeiras de R$ 9,67 bilhões foram estimadas na safra 2021/22 decorrente da epidemia de PVG. Devido aos baixos níveis de resistência das principias variedades de soja à PVG, o uso de fungicidas se torna indispensável. Este estudo avaliou a sensibilidade das espécies D. ueckeri e D. longicolla, agentes causais da PVG, de seis estados brasileiros, a nove fungicidas, com cinco modos de ação diferentes. A sensibilidade dos isolados aos ativos tebuconazol, protioconazol, ipconazol, carbendazim, tiofanato-metílico e tiram + carbendazim foi avaliada com testes de crescimento micelial. Para os ativos picoxistrobina e impirfluxam, a avaliação foi realizada por ensaios de germinação de esporos. O ativo piraclostrobina foi testado com as duas metodologias. Dados de crescimento micelial e germinação de esporos nos testes in vitro foram utilizados para estimar a concentração de cada ingrediente ativo que inibe o crescimento micelial ou germinação de conídios em 50% (CE50). A sensibilidade de Diaporthe aos fungicidas carbendazim, ipconazol, piraclostrobina, tiofanato-metílico e tiram + carbendazim variou dependendo do tecido infectado de origem do isolado (vagem ou haste) e da espécie (D. ueckeri ou D. longicolla). Isolados de D. longicolla foram mais sensíveis aos fungicidas protioconazol e tebuconazol em comparação aos de D. ueckeri. A média da CE50 de tebuconazol e protioconazol para isolados de D. longicolla foi de 0.44 µg/mL e 0.48 µg/mL, enquanto para D. ueckeri foi de 1.23 µg/mL e 0.95 µg/mL, respectivamente. Apenas o fungicida impirfluxam foi eficaz para todos os isolados testados para germinação de conídios, com valores de CE50 variando de 0,4 µg/mL a 2,8 µg/mL. Este estudo estabeleceu a sensibilidade de D. ueckeri e D. longicolla a fungicidas de vários grupos químicos, oferecendo informações importantes para o manejo de doenças causadas por Diaporthe. Palavras-chave: Palavras-chave: Glycine max, Phomopsis, resistência a fungicidas, controle químico, manejo.Item Chrysoporthe wilt in eucalyptus min-stumps: detection, identification of the pathogen, and efficacy of triazole fungicides for disease management(Universidade Federal de Viçosa, 2025-02-13) Andrade, Priscila Raiane Assunção de; Furtado, Gleiber Quintão; http://lattes.cnpq.br/7700162670728263The fungus Chrysoporthe cubensis, in addition to causing canker in trees, has also been reported in eucalyptus mini-stumps to cause wilting that can progress to partial or complete canopy drying of the plants. Considering the limited knowledge about Chrysoporthe wilt in mini-stumps, the objectives of this study were: (1) to confirm the identity of the pathogen through phylogenetic analyses using a larger number of isolates; (2) to determine whether Chrysoporthe sp. occupies an endophytic niche in both asymptomatic rooted cuttings and mini-stumps of eucalyptus; (3) to assess the spread of disease from symptomatic mini-stumps to mini-cuttings and rooted cuttings; (4) to evaluate the sensitivity of the pathogen to triazole fungicides and the efficacy of these molecules in controlling the disease in eucalyptus both preventively and curatively; and (5) to develop a LAMP assay for detecting Chrysoporthe spp. Of the 42 selected isolates obtained from asymptomatic and symptomatic mini-stumps, 41 were identified as C. cubensis, while one isolate, recovered from a symptomatic mini- stump, was identified as Chrysoporthe doradensis. This is the first report of C. doradensis in eucalyptus mini-stump in the world. Disease spread through vegetative propagation in clonal mini-gardens, from mini-stumps to mini-cuttings and to rooted cuttings, was not confirmed. Chrysoporthe sp. could not be recovered from eucalyptus rooted cuttings derived from rooted mini-cuttings collected from symptomatic mini-stumps. The EC50 test showed that C. cubensis isolates are highly sensitive to triazole fungicides at low doses: cyproconazole (0.0770 µg/mL), difenoconazole (0.0065 µg/mL), ipconazole (0.0868 µg/mL), and tebuconazole (0.0376 µg/mL). The fungicides application towards the mini-stumps stem did not result in macroscopic symptoms of phytotoxicity. Curative application of fungicides (72 h after pathogen inoculation) resulted in a 26.94% smaller necrotic lesion in the stem compared to the preventive application (72 h before pathogen inoculation) for all fungicides. The application of the molecules 15 days after pathogen inoculation was ineffective in controlling the disease. However, the fungicides ipconazole and tebuconazole were able to reduce the average number of fruiting bodies on the stem surface by 53.7% and 56.9%, respectively. For the LAMP assay, a primer set (FIP, BIP, B3, and F3) was developed based on the TEF 1a gene. The optimal conditions for amplification were a 2:1 ratio of FIP/BIP to F3/B3 primers, temperatures of 65 and 68°C, and incubation times of 75 and 90 minutes. For positive reaction, the color of the reaction changed from pink to yellow. The primer set was able of detecting C. cubensis and C. doradensis. No amplification of non- target fungi, such as Botrytis sp., Fusarium sp., and Trichoderma sp., was observed, providing evidence of specificity for Chrysoporthe species. This study provides important updates into the detection of Chrysoporthe spp., as well as the etiology and control of Chrysoporthe wilt in eucalyptus mini-stumps, aimed at mitigating the impact of the disease in clonal mini-gardens. Keywords: Chrysoporthe cubensis; Chrysoporthe doradensis; Chemical control; Endophytic niche; Eucalyptus; LAMPItem Yield-loss assessment and development of a high-throughput system for phenotyping maize genotypes for rotten grain(Universidade Federal de Viçosa, 2025-08-28) Gava, Lucas Romão; Machado, Franklin Jackson; http://lattes.cnpq.br/9700881596941344Maize ear rots, including Diplodia Ear Rot (DER), Fusarium Ear Rot (FER), and Gibberella Ear Rot (GER), caused by Stenocarpella macrospora, Fusarium verticillioides, and Fusarium meridionale, respectively, are globally important diseases that can significantly reduce yield and compromise grain quality. To estimate the relationship between disease intensity and yield, two field experiments were conducted in the Triângulo Mineiro region, Minas Gerais, Brazil, during the 2024/25 growing season, with artificial inoculations. General mixed-effect models adjusted for severity, incidence, and rotten grain showed that each 1% increase in disease intensity resulted in yield reductions of -52.83, -48.35, and -42.83 kg ha?¹, respectively. The intercepts of these models, representing the maximum attainable yields in the absence of infection, were estimated at 11,817.6, 13,390.3, and 12,000.0 kg ha?¹. Based on these parameters, relative damage coefficients (Dc) were estimated to range from 0.36% to 0.45%, highlighting the significant impact of ear rots on maize yield. Additionally, the potential of near-infrared (NIR) spectroscopy as a tool to automate the phenotyping of rotten grain incidence was evaluated. Spectra were collected in the 908–1676 nm range, both in the field and in the laboratory, from samples of approximately 500 g. Different pre-processing (SNV, MSC, Savitzky-Golay, and derivatives) were applied, and various regression models were tested, including Partial Least Squares Regression (PLS), Random Forest (RF), and Support Vector Regression (SVR). The best performance was obtained with PLS models, showing accuracies of 0.76–0.79 for field data and 0.75–0.88 for laboratory data, demonstrating good predictive capacity despite relatively high RMSE and RMSEP values. These results reinforce the potential of ear rots to reduce maize yield and indicate that NIR spectroscopy, combined with predictive models, constitutes a promising tool to support field-level phenotyping and guide management strategies. Keywords: maize ear rots; modeling; damage coefficient; near-infrared spectroscopy; phenotypingItem Ferrugem do cafeeiro: comparação de métodos de inoculação e avaliação da resistência de genótipos de Coffea arabica a Hemileia vastatrix(Universidade Federal de Viçosa, 2025-07-30) Vieira, Iago de Carvalho; Machado, Franklin Jackson; http://lattes.cnpq.br/5104104824357743A ferrugem do cafeeiro, causada por Hemileia vastatrix, é uma das principais problemas fitossanitários da cafeicultura. Nesse contexto, o desenvolvimento de cultivares resistentes e a adoção de métodos eficientes de fenotipagem são fundamentais para estratégias sustentáveis de manejo e melhoramento genético. Este estudo teve como objetivos avaliar e otimizar métodos de inoculação quanto à eficiência, reprodutibilidade e preservação do tecido vegetal, bem como caracterizar a resistência de cultivares de Coffea arabica frente às duas raças fisiológicas do patógeno. Compararam-se diferentes técnicas de inoculação, desde a utilização do auxílio do pincel para espalhar os urredosporos sob o tecido foliar e a suspensão de uredosporos, com e sem Tween, em discos de folhas, folhas destacadas e em mudas. Nas inoculações em mudas, em todas as avaliações, a suspensão de esporos foi mais eficiente, apresentando maior frequência de mudas com sintomas e sinais em comparação ao pincel (P < 0,05). Aos 42 DPI, 85,7% das mudas inoculadas por suspensão já exibiam esporulação, enquanto menos da metade das inoculadas com pincel apresentaram sinais do patógeno. Para os ensaios com discos foliares e folhas destacadas, a inoculação com suspensão de uredosporos, contendo Tween, aplicada em discos foliares mostrou-se a mais eficaz, apresentando maior taxa de infecção, esporulação e melhor conservação do tecido, sendo a mais indicada para estudos de fenotipagem em condições controladas. A caracterização da resistência das 38 cultivares frente às raças II e XXXIII, por meio de análise multivariada, foi possível observar o agrupamento das cultivares em quatro categorias: altamente suscetíveis, suscetíveis, moderadamente resistentes e resistentes. A maioria das cultivares foi classificada como resistente à ferrugem, para raça II e XXXIII. Os resultados deste trabalho fornecem subsídios técnico-científicos relevantes para a seleção de genótipos superiores e para a padronização de protocolos experimentais em programas de melhoramento voltados à resistência à ferrugem-do-cafeeiro. Palavras-chave: Coffea arabica; Fenotipagem; Resistência a doenças; Cultivares Resistentes à Ferrugem