Sami Jorge Michereff
Universidade Federal Rural de Pernambuco
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Featured researches published by Sami Jorge Michereff.
Fungal Diversity | 2013
Nelson B. Lima; Marcus V.A. Batista; Marcos Antonio de Morais; Maria Angélica Guimarães Barbosa; Sami Jorge Michereff; Kevin D. Hyde; Marcos Paz Saraiva Câmara
Colletotrichum species are the most important and widespread form of decay affecting mango fruit worldwide. In this study, Colletotrichum species associated with fruit anthracnose isolated from mango in northeastern Brazil were subject to molecular and morphological analyses. The partial sequences of the glyceraldehyde-3-phosphate dehydrogenase gene of 143 Colletotrichum isolates was amplified, as an initial measure of genetic diversity. A subset of 47 isolates, selected to represent the range of genetic diversity and geographic origin, were further sequenced using the partial actin, β-tubulin, calmodulin, glutamine synthetase genes and rDNA-ITS region. The multilocus sequence analysis, together with a critical examination of the phenotypic characters, revealed four previously described species (Colletotrichum asianum, Colletotrichum fructicola, Colletotrichum tropicale and Colletotrichum karstii) and one new species. The new species is introduced as Colletotrichum dianesei and formally described, illustrated and compared with similar taxa. Only C. asianum and C. karstii have previously been reported from mango, while the other species represent the first report associated with the mango fruits worldwide. All species are reported for the first time associated with the mango fruits in Brazil.
European Journal of Plant Pathology | 2010
Valéria Sandra Oliveira Costa; Sami Jorge Michereff; Ricardo Brainer Martins; Carlos Alberto Tuão Gava; Eduardo S. G. Mizubuti; Marcos Paz Saraiva Câmara
The aim of the present study was to assess diversity in the Botryosphaeriaceae on trees and fruit of mango (Mangifera indica L.) in a semi-arid region in northeastern Brazil in which most exported fruit in the country are produced. Using morphological characteristics and DNA sequence data (ITS-1, ITS-2 and 5.8S rDNA) we confirmed the presence of Lasiodiplodia theobromae in the region, and for the first time report Fusicoccum aesculi and Neofusicoccum parvum. L. theobromae was prevalent in the Assú Valley and F. aesculi and N. parvum were in the São Francisco Valley. In fruit inoculations, L. theobromae and N. parvum were more virulent than F. aesculi.
Fungal Diversity | 2014
Willie Anderson dos Santos Vieira; Sami Jorge Michereff; Marcos Antonio de Morais; Kevin D. Hyde; Marcos Paz Saraiva Câmara
Endophytic species of Colletotrichum associated with Mangifera indica (mango) are poorly understood. In this study, Colletotrichum species were isolated from mango in Pernambuco State, Brazil. There were significant differences in isolation frequencies of Colletotrichum species among sites and plant tissues. Mature leaf blades were colonized by most Colletotrichum isolates at the majority of sites. Partial sequences of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of 97 Colletotrichum isolates were amplified as an initial measure of genetic diversity. Phylogenetic analysis with a subset of 22 isolates were performed based on a multi-locus dataset (ACT, TUB2, CAL, CHS-1, GAPDH, ITS) followed by Apn2/MAT IGS sequence-analysis for isolates within the C. gloeosporioides species complex. Molecular analysis associated with phenotypic characteristics revealed six previously described species [C. asianum, C. cliviae, C. dianesei (syn. C. melanocaulon), C. fructicola, C. karstii and C. tropicale] and one new species. This new species is introduced as C. endomangiferae. All species isolated were pathogenic on mango fruits but varied in their virulence. There was no distribution pattern of species among sites and plant tissues, although C. asianum was the most prevalent species at all sites and in all plant tissues studied. Five previously reported Colletotrichum species causing anthracnose in mango fruits in northeastern Brazil were also recovered as endophytes.
Fungal Diversity | 2014
Mariote dos Santos Brito Netto; Iraildes P. Assunção; Gaus Silvestre de Andrade Lima; Marília W. Marques; Waléria Guerreiro Lima; Jean Herllington Araújo Monteiro; Valdir de Queiroz Balbino; Sami Jorge Michereff; Alan J. L. Phillips; Marcos Paz Saraiva Câmara
This study aims to identify and characterize species of Lasiodiplodia associated with stem-end rot of papaya in six different populations in the Northeast of Brazil. Fungal identifications were made using a combination of morphology together with a phylogenetic analysis based on partial translation elongation factor 1-α sequence (EF-1α) and internal transcribed spacers (ITS). Five species of Lasiodiplodia were identified: Lasiodiplodia brasiliense sp. nov., L. hormozganensis, L. marypalme sp. nov., L. pseudotheobromae and L. theobromae. Only L. theobromae had previously been reported in papaya, while all the other species are reported for the first time in association with this host in Brazil and worldwide. Lasiodiplodia theobromae was the most prevalent species. All species of Lasiodiplodia were pathogenic on papaya fruit, with L. hormozganensis being the most virulent.
Fitopatologia Brasileira | 2003
Suzana Alencar Freire Dantas; Sônia Maria Alves de Oliveira; Sami Jorge Michereff; Luciana Cordeiro Nascimento; Luciana Melo Sartori Gurgel; Wagner Rogério Leocádio Soares Pessoa
Fungal diseases constitute one of the main causes of losses during commercialization of tropical fruits. Papaya (Carica papaya) and orange (Citrus spp.) fruits were analyzed in relation to the disease incidence and frequency of the pathogenic species for six months, in the Distribution Centre of the city of Recife, Pernambuco, Brazil. Forty fruits of each species were evaluated monthly at five commercialization points, for a total of 200 fruits/month/species. A great diversity of diseases occurred in papaya fruits, where incidences ranged from 39,71% to 0,07%, with the higher level for stem-end rot. In orange fruits the disease incidence was 11,85% and 0,87%, for Lasiodiplodia stem-end rot and antracnose, respectively. The pathogens that presented higher frequencies were Colletotrichum gloeosporioides (44,95%) in papaya and Lasiodiplodia theobromae (11,85%) in orange. The diversity of diseases verified in this study suggests a need for more effective control measures during the production and postharvest phases of papaya and orange, seeking to propitiate reduction of the losses.
Microbial Ecology | 1994
Sami Jorge Michereff; N. S. S. Silveira; Ailton Reis; Rosa de Lima Ramos Mariano
Curvularia eragrostidis yam leaf spot is a serious concern among the northeast Brazilian yam growing areas. In order to study its biocontrol, bacterial isolates from the yam phylloplane were tested against the pathogen. They were evaluated with respect to the following parameters: (1) inhibition of C. eragrostidis mycelial growth by using paired culture and cellophane membrane methods, (2) inhibition of conidium germination by using a paired suspension test, (3) reduction of disease severity and, (4) persistence of antagonistic action, on plants under greenhouse conditions. From a total of 162 bacterial isolates, 39 showed antagonism to the pathogen in paired culture. The bacteria produced extracellular, nonvolatile, and diffusible metabolites in the membrane cellophane test. Seventeen isolates resulted in more than 75% inhibition of C. eragrostidis mycelial growth. Among them, IF-26 showed the greatest antagonism. The isolates IF-82, IF-88, and IF-109 inhibited pathogen conidial germination, with average inhibition levels of 99.2, 98.2 and 96.2%, respectively. Under greenhouse conditions the antagonists were applied at three different time intervals relative to C. eragrostidis inoculation: 3 days before, at the same time, and 3 days after. IF-82 and IF-88 applied at the same time as pathogen inoculation both reduced disease severity 75%. IF-82 showed the best persistence of antagonistic action, with an average of 96.3%. IF-82, identified as Bacillus subtilis, was the best biocontrol agent for the yam leaf spot disease in this study.
Mycopathologia | 1995
Sami Jorge Michereff; N. S. S. Silveira; Ailton Reis; Rosa de Lima Ramos Mariano
TenTrichoderma isolates were studied under greenhouse conditions as potential agents for biocontrol of yam leaf spot, caused byCurvularia eragrostidis. TheTrichoderma isolates demonstrated high efficiency of disease control. Application of the antagonists on the same day asC. eragrostidis inoculation showed the best results. One isolate achieved 75 percent disease severity reduction. The survival of theTrichoderma isolates decreased after its application on the phylloplane with values of 57 and 41 percent at the 49th day, in the absence and presence of the phytopathogen respectively. The antagonism persisted well againstC. eragrostidis, the TN1 isolate praises 89 percent.
Summa Phytopathologica | 2006
Sami Jorge Michereff; Marissônia A. Noronha; Domingos Eduardo Guimarães Tavares de Andrade; Elaine Passos de Oliveira; Maria Santina Xavier Filha; Priscilla Anunciada Alves Moreira
Cercospora leaf spot of sweet pepper caused by the fungus Cercospora capsici is an important disease occurring in tropical conditions. Due to the inexistence of standard methods to quantify this disease in field conditions, a diagrammatic key including the levels 1.5, 3.5, 8.0,16.5, 31.0 and 50.0% of diseased leaf area was elaborated and tested for accuracy, precision and reproducibility to estimate Cercospora leaf spot severity without and with using the key. The diagrammatic key was validated by 13 raters with and without using the key, using 50 leaves with different levels of severity previously measured by the software AutoCAD®. Two evaluations were performed with the key at 7-day intervals when the same raters visually estimated different sequences of the same leaves. The accuracy and precision of each rater were determined by simple linear regression between actual and estimated severity. Without the key, eight raters overestimated disease severity. With the key raters obtained better levels of accuracy and precision, however four of them tended to overestimate the severity with absolute errors concentrated below 10%. Raters had good repeatability and high reproducibility in estimating disease severity by using the key when it was not used. The proposed diagrammatic key is suitable for evaluation of sweet pepper Cercospora leaf spot severity.
Summa Phytopathologica | 2006
Maria Angélica G. Barbosa; Sami Jorge Michereff; Gustavo Mora-Aguilera
A ferrugem branca, causada pelo fungo Puccinia horiana, e considerada a principal doenca do crisântemo no Brasil, induzindo severas perdas aos produtores. Apesar da importância, inexistem estudos epidemiologicos no pais, e para que estes estudos sejam realizados, e necessario o desenvolvimento de metodos padronizados de quantificacao da severidade da doenca no campo. Visando atender a essa demanda, foi elaborada uma escala diagramatica com os niveis de 1, 3, 6, 10, 18 e 30% de area foliar lesionada, testando-se a acuracia, a precisao e a reprodutibilidade das estimativas de severidade da ferrugem branca com e sem a sua utilizacao. Na validacao da escala diagramatica, 50 folhas com diferentes niveis de severidade da doenca, mensurados previamente com o programa AutoCADâ, foram avaliadas por 10 pessoas sem e com a utilizacao da escala diagramatica. Foram realizadas duas avaliacoes com a utilizacao da escala, com intervalo de sete dias, onde sequencias diferentes das mesmas folhas foram estimadas visualmente pelos mesmos avaliadores. A acuracia e a precisao de cada avaliador foi determinada por regressao linear simples, entre a severidade real e a estimada. Sem o auxilio da escala, todos os avaliadores superestimaram consistentemente a severidade, indicando a presenca de desvios positivos constantes para todos os niveis de severidade da doenca. As avaliacoes realizadas com a escala diagramatica foram mais acuradas nas estimativas da maioria dos avaliadores e mais precisas para todos os avaliadores, alem de proporcionar boa repetibilidade e elevada reprodutibilidade entre avaliacoes de diferentes avaliadores. A escala diagramatica mostrou-se adequada para avaliacao da severidade da ferrugem branca do crisântemo.
Plant Disease | 2010
R. J. Nascimento; Eduardo S. G. Mizubuti; M. P. S. Câmara; M. F. Ferreira; M. Maymon; S. Freeman; Sami Jorge Michereff
Species of the genus Colletotrichum are commonly reported as pathogens of fruits in tropical regions. Papaya fruits (Carica papaya L.), cv. Golden, with typical lesions of anthracnose, chocolate spot, and/or stem-end rot were collected from 18 papaya-producing areas of northeast Brazil in 2007. One hundred and fifty-five isolates of Colletotrichum spp. were obtained from the fruit lesions and cultured on potato dextrose agar. Pathogenicity tests were conducted by placing a 20-μl drop of 105 conidia ml-1 suspension on a wounded area of two healthy fruits of cv Golden at the climacteric stage. Inoculated fruits were placed in a moist chamber at 26°C (±2) for 48 h. After this period, the plastic covers of the trays used to form the moist chamber were removed and the trays were kept at 26°C (±2) for 98 h when symptoms were assessed. The causal agents of fruit rot were recovered from inoculated fruits showing symptoms of anthracnose and chocolate spot. Conidia from fresh lesions were collected and measured. Conidia dimensions were 13.49 × 3.80 μm, length/width ratio = 3.55 μm. Conidia were predominantly cylindrical to bluntly rounded ends and slightly flattened. All isolates were morphologically similar to Colletotrichum gloeosporioides Penz (1). Molecular analyses of the isolates were carried out with taxon-specific primers for C. acutatum J.H Simmonds and C. gloeosporioides (3). Only one amplicon was detected for eight isolates with the C. gloeosporioides primer. All isolates were genotyped using inter-simple sequence repeat (ISSR) primers. Three groups of isolates were found, one containing the eight C. gloeosporioides isolates, a second group comprised of 141 isolates, and a third contained six isolates. The second and third groups were more similar to each other than to the first C. gloeosporioides group. Thirty two representative isolates of the three ISSR groups were sequenced for the internal transcribed spacer (ITS) and glutamine synthetase (GS) (GenBank Nos. HM163181 and HM015847) regions. With molecular phylogenetic analyses, two well-supported clades were formed, one with the C. gloeosporioides isolates and the other with sequences highly similar (99% similarity) to the two ITS sequences available in GenBank (DQ003310 and GU358453) and the GS region of G. magna Jenkins & Winstead (DQ792873). The latter was reported in the United States and Taiwan (2,4). Isolates of C. magna and C. gloeosporioides are morphologically similar and identification needs to be based on molecular analyses. To our knowledge, this is the first report of C. magna causing rot of papaya fruit in Brazil. References: (1) P. F. Cannon et al. Mycotaxon 104:189, 2008. (2) M. Z. Du et al. Mycologia 97:641, 2005. (3) P. Talhinhas et al. Appl. Environ. Microbiol. 71:2987, 2005. (4) J. G. Tsay et al. Plant Dis. 94:787, 2010.