Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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Item Carfentrazone-ethyl and glyphosate drift inhibits uredinial formation of Austropuccinia psidii on Eucalyptus grandis leaves(Pest Management Science, 2019-01) Santos, Samuel Alves dos; Tuffi-Santos, Leonardo David; Tanaka, Francisco André Ossamu; Sant’Anna-Santos, Bruno Francisco; Rodrigues, Fabrício de Ávila; Alfenas, Acelino CoutoThe response to infection of Austropuccinia psidii in resistant (CLR‐383) and susceptible (CLR‐384) Eucalyptus grandis clones, exposed to herbicide drift of carfentrazone‐ethyl, glyphosate and a mixture of these two herbicides, was evaluated at microscopic and physiological levels.Plants of the two clones showed symptoms of phytotoxicity caused by herbicide drift. However, net CO2 assimilation rate, height and shoot dry matter were lower in CLR‐384 than in CLR‐383. At the ultrastructure level, the leaves of both clones exposed to the herbicides showed thylakoid disorganization and accumulation of starch grains in the chloroplasts. Only plants of CLR‐384 were infected by A. psidii, but when exposed to herbicide drift, rust severity was lower than in control plants. Six days after inoculation (dai), plants of this clone exposed to the herbicides had smaller uredinia than control plants. At 12 dai, non‐herbicide treated plants showed normal uredinia, containing abundant urediniospores. By contrast, plants exposed to the herbicides were less colonized by the fungus, and the uredinia were smaller with reduced production of urediniospores, which were sometimes not even detected. Glyphosate and carfentrazone‐ethyl herbicide drift reduce infection and uredinial formation of A. psidii and to some extent induce basal resistance in a susceptible clone of E. grandis.Item Xanthomonas axonopodis pv. eucalyptorum pv. nov. causing bacterial leaf blight on eucalypt in Brazil(The Plant Pathology Journal, 2018-08) Ferraz, Hélvio Gledson Maciel; Badel, Jorge Luis; Guimarães, Lúcio Mauro da Silva; Reis, Bruna Paolinelli; Tótola, Marcos Rogério; Gonçalves, Rivadalve Coelho; Alfenas, Acelino CoutoBacterial leaf blight is a major disease of eucalypt, especially under nursery conditions. Different bacterial species have been associated with the disease in several countries, and despite its importance worldwide, it is not clear to date whether similar disease symptoms are caused by the same or by different etiological agents. In this study, 43 bacterial strains were isolated from blighted eucalypt leaves collected in different geographic areas of Brazil and inoculated onto a susceptible eucalypt clone. Polyphasic taxonomy, including morphological, physiological, biochemical, molecular, and pathogenicity tests showed that only certain strains of Xanthomonas axonopodis caused symptoms of the disease. Strains varied in their aggressiveness, but no correlation with geographic origin was observed. MLSA-based phylogenetic analysis using concatenated dnaK, fyuA, gyrB and rpoD gene sequences allocated the strains in a well-defined clade, corresponding to Rade-marker’s group RG 9.6. Inoculation of nineteen plant species belonging to seven botanical families with representative strain LPF 602 showed it to be pathogenic only on Eucalyptus spp, and Corymbia spp. Based on distinct biochemical and pathogenic characteristics that differentiate the eucalypt strains from other pathovars of the X. axonopodis species, here we propose their allocation into the new pathovar X. axonopodis pv. eucalyptorum pv. nov.Item Virulence and impact of brazilian strains of Puccinia psidii on hawaiian ‘Ōhi‘a (Metrosideros polymorpha)(Pacific Science, 2014-01) Silva, André Costa da; Andrade, Pedro Magno Teixeira de; Alfenas, Acelino Couto; Graça, Rodrigo Neves; Cannon, Phil; Hauff, Rob; Ferreira, Diego Cristiano; Mori, SylviaA single strain of Puccinia psidii, the causal agent of rust disease on Myrtaceae, was recently reported on multiple myrtaceous hosts in Hawai‘i, but this strain has caused only mild levels of damage to the state’s predominantn ative forest tree, ‘öhi‘a ( etrosideros polymorpha). Multiple other strains of Puc Mcinia psidii have been identified from Brazil and characterized via extensive sampling and microsatellite analyses. Potential effects of other Brazilian P. psidii strains on Hawai‘i’s ‘öhi‘a were investigated with two inoculation experiments conducted in Brazil. The first, a split-plot experiment, was conducted to deter- mine pathological impact of five Brazilian P. psidii strains on ‘öhi‘a seedlings and to assess variation in susceptibility of seedlings from six different open- ollinatedp ‘öhi‘a parent trees to each P. psidii strain. The second experiment was conducted to determine influence of the rust disease on growth and survival of ‘öhi‘a seedlings. Three of the five P. psidii strains were highly virulent on most of the inoculated ‘öhi‘a seedlings (93% 00% infection rates), and none of the ‘öhi‘a–1 families used in this test showed significant resistance. The other two strains tested were much less virulent. Infection by the highly virulent strains of P. psidii resulted, on average, in a 69% reduction in height growth and 27% increase in mortality of ‘öhi‘a seedlings at 6 months postinfection. These results have immediate implications for designing Hawai‘i’s quarantine barriers.Item Genetic mapping and validation of QTLs associated with resistance to Calonectria leaf blight caused by Calonectria pteridis in Eucalyptus(Tree Genetics & Genomes, 2014-11-15) Zarpelon, Talyta Gafassi; Guimarães, Lúcio Mauro da Silva; Faria, Danielle Assis; Coutinho, Marcelo Magalhães; Cápua Neto, Braz; Teixeira, Ramon Ubirajara; Grattapaglia, Dario; Alfenas, Acelino CoutoCalonectria leaf blight (CLB) caused by Calonectria pteridis is one of the main leaf diseases in Brazilian Eucalyptus plantations in warm climates with prolonged periods of rain. The main symptoms are leaf spots followed by intense defoliation in highly susceptible plants. Exploiting the existing inter- and intraspecific variability for defoliation is the best option to control this disease. Nevertheless, nothing is known about the genetic architecture of resistance to CLB in Eucalyptus. We built microsatellite-based genetic maps for E. urophylla × E. camaldulensis (EU11 × EC06) F1 family of 89 plants. Four or five clonal replicates per individual offspring were clonally propagated, totalling 445 plants which were phenotyped for defoliation in the basal third of the branches at 30 days following controlled inoculation with a single-spore isolate. Genetic mapping was performed using a pseudo-testcross, and QTLs detected using composite interval mapping. Five QTLs were detected for resistance to CLB; of them, only one could be validated in two unrelated pedigrees, and its effect was conservatively estimated as controlling between 5 and 10 % of the phenotypic variation when the bias derived from the limited size of the mapping population was taken into account. This work provides a starting point for future studies of the genetics of resistance to CLB, and adds further evidence to the challenge of ascertaining the effects of QTLs detected in a single biparental background across unrelated families.Item Cloning and characterization of gene-resistant analogs (RGAs) involved in rust (Puccinia psidii) resistance in Eucalyptus grandis(Journal of Forestry Research, 2015-09) Alfenas, Acelino Couto; Laia, Marcelo Luiz; Brommonschenkel, Sergio Hermínio; Oda, Shinitiro; Melo, Eduardo José de; Silva, Inaê Mariê de Araújo; Gonçalves, Janaína Fernandes; Marques, AriadneDisease-resistant genes play an important role in defending against a variety of pathogens and insect pests in plants. Most of the disease-resistant genes encode proteins with conserved leucine rich repeat and nucleotide binding site domains. In this study, we cloned and characterized gene-resistant analogs (RGAs) from Eucalyptus grandis using degenerate PCR, with primers specifically targeting these two domains. The amplified fragments were cloned into the pGEM-T vector and transformed into Escherichia coli. Among the 90 clones obtained, 13 were sequenced and compared with each other and with previously identified gene-resistant diseases. A BLASTX search in GenBank revealed high similarities among the conserved domains of these cloned genes with RGA genes. Some clones, however, showed no significant similarity with DNA sequences in GenBank. Southern blotting analysis identified several polymorphic RFLP loci between distinct genotypes. However, none of them co-segregated with the Puccinia psidii Winter resistance gene 1 (Ppr1) in a population study.Item Genetic control of resistance on Mangifera indica to Ceratocystis wilt(Scientia Horticulturae, 2016-11-01) Arriel, Daniele Aparecida Alvarenga; Guimarães, Lúcio Mauro da Silva; Resende, Marcos Deon Vilela de; Silva, Daniella Flávia Said Heid Schettini; Siqueira, Dalmo Lopes de; Alfenas, Acelino Couto; Lima Neto, Francisco PinheiroCeratocystis wilt, caused by Ceratocystis fimbriata is one of the most serious limiting factors for mango production in Brazil. Despite efforts in the selection and the identification of mango cultivars resistant to Ceratocystis wilt, the genetic basis of the resistance remains unknown. Therefore, the objective of this study was to understand the inheritance of resistance to C. fimbriata by artificial inoculations of the pathogen in progenies of six commercial varieties of mango using “Tommy Atkins” as the male parent. The cultivars “Keitt”, “Palmer”, “Tommy Atkins” and “Van Dyke” were confirmed as moderately resistant, whereas “Coquinho”, “Espada” and “Haden” were susceptible. The results of the inoculation on the progenies of these cultivars revealed that the resistance in mango is polygenic with a prevalence of genes expressing the effects of dominance and epistasis. The genetic gain with the selection of the 10 more resistant plants was 46%, which indicated a 46% reduction in disease severity. In general, a low frequency of the alleles favorable to disease resistance was observed in the population studied, which suggests the need for the introduction of new sources of genetic materials carrying the genes responsible for resistance.Item Eucalypt plants are physiologically and metabolically affected by infection with Ceratocystis fimbriata(Plant Physiology and Biochemistry, 2017-12-02) Silva, André Costa da; Silva, Franklin Magnum de Oliveira; Milagre, Jocimar Caiafa; Omena-Garcia, Rebeca Patricia; Abreu, Mário Castro; Mafia, Reginaldo Gonçalves; Nunes-Nesi, Adriano; Alfenas, Acelino CoutoCeratocystis wilt, caused by Ceratocystis fimbriata, is currently one of the most important disease in eucalypt plantations. Plants infected by C. fimbriata have lower volumetric growth, lower pulp yields and reduced timber values. The physiological bases of infection induced by this pathogen in eucalypt plant are not known. Therefore, this study aims to assess the physiological and metabolic changes in eucalypt clones that are resistant and susceptible to C. fimbriata. Once, we evaluated in detail their leaf gas exchange, chlorophyll a fluorescence, water potential, metabolite profiling and growth-related parameters. When inoculated, the susceptible clone displayed reduced water potential, CO2 assimilation rate, stomatal conductance, transpiration rate, photochemical quenching coefficient, electron transport rate, and root biomass. Inoculated resistant and susceptible clones both presented higher respiration rates than healthy plants. Many compounds of primary and secondary metabolism were significantly altered after fungal infection in both clones. These results suggest that, C. fimbriata interferes in the primary and secondary metabolism of plants that may be linked to the induction of defense mechanisms and that, due to water restrictions caused by the fungus in susceptible plants, there is a partial closure of the stomata to prevent water loss and a consequent reduction in photosynthesis and the transpiration rate, which in turn, leads to a decrease in the plant's growth-related. These results combined, allowed for a better understanding of the physiological and metabolic changes following the infectious process of C. fimbriata, which limit eucalypt plant growth.Item Resistance of Eucalyptus pellita to rust (Puccinia psidii)(Crop Breeding and Applied Biotechnology, 2014-09-15) Santos, Marisângela Rodrigues; Guimarães, Lúcio Mauro da Silva; Resende, Marcos Deon Vilela de; Rosse, Leonardo Novaes; Zamprogno, Karina Carnielli; Alfenas, Acelino CoutoEucalypts rust (Puccinia psidii) is currently one of the major diseases in commercial eucalypt plantations in Brazil. The primary method of disease control is the use of resistant genotypes, and, among the different species of Eucalyptus, E. pellita is indicated as a promising source of resistance. In this work, the genetic control of rust resistance in E. pellita through inoculations under controlled conditions of 441 plants from four full-sibling families was studied. Inoculations were performed using the monopostular isolate UFV-2, race 1. All families tested segregated for rust resistance, and the number of resistant plants was higher than susceptible in all crosses. Inheritance models based on few genes did not fully explain the observed segregation patterns, and the narrow-sense heritability of rust resistance was estimated between 32.7% and 37.3%. The results suggested that rust resistance in E. pellita is complex and is controlled by major- and minor-effect genes.Item Primeiro registro de Cylindrocladium parasiticum em plantas de teca no Pará(Summa Phytopathologica, 2004-06-06) Alfenas, Rafael Ferreira; Alfenas, Acelino Couto; Poltronieri, Luiz Sebastião; Verzignassi, Jaqueline Rosemeire; Benchimol, Ruth Linda; Poltronieri, Tathianne Pastana de SousaTectona grandis Linn. F., popularmente conhecida como teca, é uma árvore de grande porte, nativa das florestas tropicais. No sul da Ásia, a cultura de teca é tradicional, sendo cultivada em grande escala. Atualmente, a área mundial plantada excede os 3 milhões de hectares, incluindo, além dos asiáticos, que são os maiores produtores, outros países tropicais, como o Togo, Camarões, Zaire, Nigéria, Trinidad, Honduras e Brasil. Apesar de poder ser cultivada apenas em regiões tropicais, a madeira de teca é muito procurada, principalmente no continente europeu, onde o preço por metro cúbico supera o do mogno. Em outubro de 2008 folhas de teca, oriundas de plantio comercial localizado no município de Igarapé-Açu (PA), apresentando manchas de coloração marrom clara, que coalesciam e atingiam grande extensão do limbo foliar foram encaminhadas ao Laboratório de Fitopatologia da Embrapa Amazônia Oriental. Um fungo do gênero Cylindrocladium foi isolado em agar-água e multiplicado para meio de cultura batata-dextrose-ágar (BDA). A partir do teste de patogenicidade, realizado em mudas sadias de teca com dois meses de idade, os mesmos sintomas observados em campo foram novamente verificados e o fungo reisolado das plantas inoculadas, confirmando a espécie de Cylindrocladium como o agente causal da doença. Verificou-se, sobre as lesões e meio de cultura, o desenvolvimento de conidióforos penicilióides, contendo vesículas globosas a subglobosas e conídios cilíndricos, hialinos, com um a três septos, medindo 54-78x4, 5-5, 9ìm, típicos de Cylindrocladium parasiticum Crous, Wingfield & Alfenas (Crous et al., Mycol. Res. 97:889-896, 1993), teleomorfo: Calonectria ilicicola Boedijn & Reitsma. Este é o primeiro registro deste fungo em plantas de teca no Estado do Pará e, aparentemente, no BrasilItem Leaf blight and defoliation of Eugenia spp. caused by Cylindrocladium candelabrum and C. spathiphylli in Brazil(Summa Phytopathologica, 2010-11-06) Alfenas, Rafael Ferreira; Alfenas, Acelino Couto; Poltronieri, Luiz Sebastião; Verzignassi, Jaqueline Rosemeire; Benchimol, Ruth Linda; Poltronieri, Tathianne Pastana de SousaLeaf blight and defoliation of Eugenia stipitata Mc Vaugh and Eugenia patrisii Vahl, caused respectively by Cylindrocladium candelabrum (Calonectria scoparia) and C. spathiphylli (Calonectria spathiphylli) are reported in the state of Pará, Brazil. On both host species, the disease is characterized by dark brown lesions of different sizes and shapes. A whitish bright sporulation, resembling Cylindrocladium is observed on the necrotic lesions by using a stereomycroscope or a pocket lense (10-20 X). Under favorable conditions and depending on the level of infection, intense premature tree defoliation may also be found.Although the conidial germination and mycelial growth were higher at 25ºC for both species, C. candelabrum was more sensitive to the variation of temperature (10, 20, 30 and 40 ºC) than C. spathiphylli. This is the first report of C. candelabrum and C. spathiphylli on Eugenia stipitata (araçá-boi) and on Eugenia patrisii (ubaia-da-amazônia), respectively in Brazil.
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