Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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Item Atividade de enzimas associadas ao estado de indução em mudas de cacaueiro expostas a dois actinomicetos residentes de filoplano(Summa Phytopathologica, 2008-01) Romeiro, Reginaldo da Silva; Baracat-Pereira, Maria Cristina; Lanna-Filho, Roberto; Batista, Gisele Sales; Pomella, Alan Willian Vilela; Macagnan, DirceuDois antagonistas selecionados para o biocontrole da vassoura-de-bruxa do cacaueiro foram avaliados quanto à capacidade em ativar mecanismos de defesa de plantas contra patógenos. Para tanto, mudas seminais de cacaueiro "comum" foram cultivadas em casa-de-vegetação por 30 dias e expostas aos antagonistas aplicados a mudas de cacaueiro por atomização, individualmente e em associação. O primeiro par de folhas das mudas dos diferentes tratamentos foi coletado aos dois, quatro, 12 e 24 dias após a exposição aos antagonistas. Foi quantificada a atividade de peroxidases, polifenoloxidases, quitinases e b-1,3-glucanases no material coletado. Observou-se um aumento na atividade de peroxidases e polifenoloxidases nos primeiros dias após a exposição das mudas, especialmente ao isolado Ac26. Não foi observado efeito aditivo ou sinergístico nas mudas expostas aos dois isolados simultaneamente.Item Induction of systemic resistance in tomato by the autochthonous phylloplane resident Bacillus cereus(Pesquisa Agropecuária Brasileira, 2006-08) Halfeld-Vieira, Bernardo de Almeida; Vieira Júnior, José Roberto; Romeiro, Reginaldo da Silva; Silva, Harllen Sandro Alves; Baracat-Pereira, Maria CristinaThe objective of this work was to verify if the induced resistance mechanism is responsible for the capacity of a phylloplane resident bacteria (Bacillus cereus), isolated from healthy tomato plants, to control several diseases of this crop. A strain of Pseudomonas syringae pv. tomato was used as the challenging pathogen. The absence of direct antibiosis of the antagonist against the pathogen, the significant increase in peroxidases activity in tomato plants exposed to the antagonist and then inoculated with the challenging pathogen, as well as the character of the protection, are evidences wich suggest that biocontrol efficiency presented by the antagonist in previous works might be due to induced systemic resistance (ISR).Item Seleção de bactérias endofíticas de tomateiro como potenciais agentes de biocontrole e de promoção de crescimento(Ciência e Agrotecnologia, 2009) Romeiro, Reginaldo da Silva; Barretti, Patrícia Baston; Mizubuti, Eduardo Seiti Gomide; Souza, Jorge Teodoro deQuarenta isolados bacterianos endofíticos de plantas sadias de tomateiro foram avaliados quanto à sua potencialidade como agentes de biocontrole de doenças do tomateiro. Foi realizada, em casa de vegetação, uma seleção massal utilizando-se Pseudomonas syringae pv. tomato e Alternaria solani, como patógenos desafiantes. Com base na média do número de lesões por planta, quatro isolados foram selecionados como potenciais agentes de biocontrole dessas enfermidades fúngica e bacteriana do tomateiro. Esses isolados foram identificados, por meio do sequenciamento do gene 16S do DNA ribossômico, como Acinetobacter johnsonii (UFV-E05), Serratia marcescens (UFV-E13), Sinorhizobium sp. (UFV-E25) e Bacillus megaterium (UFV-E26). Os mesmos isolados selecionados para o biocontrole também foram avaliados quanto à sua capacidade de promover o crescimento em plantas e somente S. marcescens (UFV-E13) proporcionou aumento na altura das plantas.Item Biocontrol of tomato late blight with the combination of epiphytic antagonists and rhizobacteria(Biological Control, 2006-09) Lourenço Júnior, Valdir; Maffia, Luiz A.; Romeiro, Reginaldo da Silva; Mizubuti, Eduardo S. G.Control of tomato late blight (LB) in Brazil is heavily based on chemicals. However, reduction in fungicide usage is required in both conventional and organic production systems. Assuming that biological control is an alternative for LB management, 208 epiphytic microorganisms and 23 rhizobacteria (RB) were isolated from conventional and organically grown tomato plants and tested for antagonistic activity against Phytophthora infestans. Based on in vitro inhibition of sporangia germination and detached leaflet bioassays, four EP microorganisms (Aspergillus sp., Cellulomonas flavigena, Candida sp., and Cryptococcus sp.) were selected. These microorganisms were applied either singly or combined on tomato plants treated or not with the RB Bacillus cereus. On control plants, LB progress rate (r), area under disease progress curve, and final disease severity were high. Lowest values of final severity were recorded on plants colonized by B. cereus and treated with C. flavigena, Candida sp. and Cryptococcus sp. There was no reduction on disease severity in plants treated only with RB. Biological control of LB resulted in low values of r and final severity. Integration of biological control with fungicides, cultural practices, and other measures can contribute to manage LB on tomato production systems.Item A new bacterial disease of tomato in Viçosa, Minas Gerais state(Revista Ceres, 1995-05) Oliveira, José Rogério de; Miguel, Dulândula Silva; Romeiro, Reginaldo da SilvaIn 1991 it was observed a new disease of tomato in commercial plantations at the region of Viçosa, Minas Gerais State, Brazil. The disease shows up as necrotic lesions in leaves, either irregularly round or along leaf borders, initially small and increasing in size with age. These lesions are usually surrounded by a chlorotic halo. Drop exsudate tests indicated a bacterial etiology for the disease. From such lesions, it was consistently isolated a bacterium that gives rise to clear, opaque, regular, elevated and shinning colonies. Inoculations tests rendered HR in leaves of coffee, tobacco, bean and passion fruit as well as typical disease symptoms in tomato leaves. The bacterium is a single, regular, straight, Gram-negative, strictly aerobic rod, unable to use asparagine as sole C and N source, unable to produ-ce xanthomonadins, does not induce hipertrOphic growth in the host, produces a blue fluorescent pigment, grows easily in routine culture media and was positioned in the genus Pseudomonas, fluorescent group. Biochemical, staining and biological tests indicate the pathogen belongs to the species Pseudomonas syríngae pv. tomato,Item Atividade bacteriocinogênica entre isolamentos de Xanthomonas campestris pv. Arracaciae(Revista Ceres, 1999-01) Siqueira, Marita Francisca de; Romeiro, Reginaldo da SilvaTwenty four isolates of Xanthomonas campestris pv. arracaciae were tested against each other for production and sensibility of bacteriocins, Only five isolates behaved as producers and two did work as indicators. This is the first report on bacteriocin production by the pathovar.Item Isolamento e seleção massal de actinomicetos antagônicos a Agrobacterium tumefaciens(Revista Ceres, 2001-05) Silva, Harllen Sandro Alves; Romeiro, Reginaldo da SilvaDe amostras de solo, coletadas em diferentes locais, procedeu-se ao isolamento, em meio extrato de solo-ágar, de 321 culturas de actinomicetos, Todos foram individualmente testados para verificar a atividade de antibiose “in vim)” contra Agrobacterium tumefaciens e a eficiência em proteger folhas destacadas de Kalanchoe tubiflora contra o patógeno. Combinando-se os resultados destes dois testes, foi possível selecionar 33 actinomicetos come potenciais antagonistas. A repetição dos teste I"in vitro” e “in viva" permitiu estreitar o número de isolamentos de antagonistas promissores para 14, e esses estão sendo testados, em casa de vegetação, para o controle biológico da galha bacteriana da roseira (A. tumefaciens).Item Sensibilidade de fitobactérias às substâncias com propriedades antimicrobianas presentes em extratos de folhas de fumo inoculadas do patógeno incompatível Pseudomonas syringae pv. pisi(Revista Ceres, 1990-05) Silva, Talmir Duarte da; Romeiro, Reginaldo da SilvaPlantas de fumo (Nicotiana tabacum cv. 'Turkish' foram inoculadas de uma suspensão de células do patógeno incompatível Pseudomonas syringae pv. pisi. Vinte e quatro horas após, porções do limbo foliar, com sintomas típicos de reação de hipersensibilidade, foram submetidas à extração, pelo método de difusão facilitada (17), em etanol, a 40%. O extrato etanólico, concentrado, a vácuo, foi fracionado com acetato de etila. A fração acetato de etila revelou conter substâncias com propriedades antimicrobianas. Fitobactérias patogênicas para o fumo revelaram-se insensíveis à atividade presente no extrato, ao passo que as não-patogênicas para o fumo tiveram sua mutiplicação inibida.Item Queima bacteriana (Xanthomonas campestris) do alho-poró (Allium porrum) em Minas Gerais, Brasil(Revista Ceres, 1999-01) Moura, Andréa Bittencourt; Romeiro, Reginaldo da SilvaA leek disease found in Vicosa, Minas Gerais, showed pale apical lesions progressing downward from the leaf apex which later became necrotic. These leaves are completely taken up by the infection, dry up and fall off, while the plant remains alive. One bacterium producing medium yellow, shining, regularly edged, elevated colonies was isolated in a standard culture medium. It was unable to induce HR in beans, coffee, passion fruit, tobacco and tomato but induced the same observed leaf symptoms when reinoculated into healthy leek plants. The isolated bacteria are straight, regular, rod-shaped, Gram-negative cells, unable to use asparagine, strict aerobes, xanthomonadin-producers, non tumorogenic and can be positioned in Xanthomonas. Biochemical tests identified X. campestris as the species. The disease may be seed transmitted.Item Bacterial blight (Xanthomonas campestris) of suflower (Helianthus annuus), a new disease(Revista Ceres, 1998-05) Romeiro, Reginaldo da Silva; Moura, Andréa BittencourtIn Vicosa, Minas Gerais, Brazil, a disease in sunflower (Helianthus annuus) was observed, whose symptoms show up as necrotic lesions, always surrounded by chlorotic haloes, predominately located at the leaf margin and, less frequently, dispersed in the leaf limb. The same lesion patterns were also visualized in stem and flower parts. Lesion fragments mounted in water and observed under the lowest microscope magnification showed cepious bacterial streams indicating a bacterial etiology for the disease. From lesions a bacterium was isolated that produces yellow, shining, regular edges, elevated colonies in standard culture media, able to induce HR in bean leaves and to reproduce original symptoms if inoculated in the host. Isolates are straight, regular, rod-shaped cells, Gram-negative, unable to use asparagine a sole Carbon and/or Nitrogen source, strict aerobes, xanhomonadines producers, are not tumorogenic and can be positioned in the genus Xanthomonas. Biological, biochemical and staining tests lead to the identification of the pathogen as Xanthomonas campestris. Its is not known the way by which the pathogen was introduced in the region but it might be through botanical seeds, Losses to the pathogen are very severe in spite of that fact that plant death was not observed or suppression of flower production. A preposition for creation of a new pathovar "Silvia", being, as a consequence, the name of the pathogen Xanthomonas campestris pv. silvia has been made.