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Search Results: 1 - 10 of 116773 matches for " Antonio W;Quezado-Duval "
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Estabilidade da resistência de 'Ohio 8245' e 'Heinz 9553' à mancha bacteriana do tomateiro
Pontes, Nadson de C;Moita, Antonio W;Quezado-Duval, Alice Maria;
Horticultura Brasileira , 2012, DOI: 10.1590/S0102-05362012000100017
Abstract: bacterial spot is one of the major diseases of both processed and fresh-market tomato crops. the disease causes defoliation, which decreases yield and exposes fruits to sunscald. in this work, resistance levels of 'ohio 8245' and 'heinz 9553' to the four bacterial spot xanthomonads are reported in order to evaluate these cultivars as patterns and/or sources of resistance. the trial was carried out in greenhouse conditions, in a split-plot completely randomized block design with three replications. the main plot was "isolate", whereas the subplot was "cultivar". three isolates of each species were inoculated at the seedling stage. incubation period and severity (leaf diseased area percentage, lda%, and area under disease progress curve, audpc) were evaluated. interaction was detected among factors for all variables. no differences in the incubation period among cultivars were detected, except for the isolate cnph 142-t of x. vesicatoria, which was less for the cultivars 'ohio 8245' and 'heinz 9553'. differences among isolates were detected only in 'heinz 9553', with the least values for isolates of x. vesicatoria and x. perforans. for the majority of isolates, less lda% was observed for cultivars ohio 8245 and heinz 9553. on the other hand, for audpc, 'ohio 8245' had the least value followed by 'heinz 9553'. it is suggested that these both cultivars have broad spectrum quantitative resistance which can be used for breeding studies.
Ra?as de Xanthomonas spp. associadas à mancha-bacteriana em tomate para processamento industrial no Brasil
Quezado-Duval, Alice Maria;Camargo, Luis Eduardo A.;
Horticultura Brasileira , 2004, DOI: 10.1590/S0102-05362004000100016
Abstract: the great genetic diversity of the causal agents of bacterial spot is the main problem to the development of tomato and pepper varieties with durable resistance. seventy two strains of xanthomonas spp. collected from commercial fields of processing tomatoes in the states of goiás, minas gerais, pernambuco, and bahia were classified in races according to their reactions on differential genotypes of tomato (walter, hawaii 7998 and nil 216) and capsicum [ecw (early calwonder), ecw-10r, ecw-20r, ecw-30r and pi 235047]. bacterial suspensions (5 ′ 108 ufc/ml) were infiltrated in the abaxial leaf face of the plants at the three to five true-leaf stage. the plants were then kept in a growth chamber at 28oc and a 12-h light/dark photoperiod. the response reactions were observed up to 36 hours after inoculation, depending on the genotype. races t1p2, t1p8 and t3 were identified in x. axonopodis pv. vesicatoria; race t2 in x. vesicatoria; and races t2p7 e t2p8 in 'x. gardneri'. the presence of genes avrrxv and avrxv3 was confirmed by polymerase chain reaction (pcr) with specific primers in strains that produced hypersensitive reaction on 'hawaii 7998' (races t1) and 'nil 216' (race t3), respectively. this is the first report of races t3, t1p8, t2p7 and t2p8 in brazil.
Desempenho de cultivares de batata em solo infestado com Ralstonia solanacearum, ra?a 1
Quezado-Duval, Alice Maria;Lopes, Carlos Alberto;
Horticultura Brasileira , 1999, DOI: 10.1590/S0102-05361999000300015
Abstract: twenty-eight potato cultivars were evaluated for resistance to bacterial wilt caused by ralstonia solanacearum, race 1, biovar i, from may to august, 1998, at embrapa hortali?as. the trial was carried out in a naturally infested field in a randomised complete block design with three replications and six plants per plot of 2.4 m2. 'cruza 148' and 'achat' (resistant), and 'bintje' (susceptible) were used as controls. disease incidence was assessed for eight weeks starting 22 days after planting, when the first symptoms were observed. the areas under the disease progress curves (audpc) were calculated and the cluster analysis performed using the unweighted pair-group method by arithmetic averages (upgma) and simple euclidian distance coefficient. five clusters of resistance/susceptibility levels were defined. 'cruza 148', 'cruza 148 mutant', 'araucaria' and 'granola' had the lowest levels of disease and belonged to cluster 1 (audpc values from 0.00 up to 256.90). these cultivars also had the highest commercial (tubers >50mm diameter) and total yields (13.3 and 25.1 t/ha; 10.4 and 21.9 t/ha; 11.4 and 18.8 t/ha, and 14.6 and 16.4 t/ha, respectively). negative significant correlations (p<0.01) were found between audpc and commercial yield (r = - 0.76) and audpc and total yield (r = - 0.83).
Sensibilidade a cobre, estreptomicina e oxitetraciclina em Xanthomonas spp. associadas à mancha-bacteriana do tomate para processamento industrial
Quezado-Duval, Alice Maria;Gazzoto Filho, Ademir;Leite Júnior, Rui P.;Camargo, Luis Eduardo A.;
Horticultura Brasileira , 2003, DOI: 10.1590/S0102-05362003000400020
Abstract: copper fungicides and antibiotics are frequently used to control bacterial pathogens in processing tomatoes in brazil. however, failure of control is common and can be caused by the presence of resistant strains. in vitro tests were carried out to evaluate the sensitivity to copper, streptomycin and oxitetracyclin of 389 xanthomonads strains isolated from tomato plants with bacterial spot symptoms: 92 of x. axonopodis pv. vesicatoria (60 strains group a /race t1 and 32 group c /race t3), 93 of x. vesicatoria (group b/race t2) and 204 of x. gardneri (group d/race t2). the strains were obtained from commercial fields in the states of goiás, minas gerais, pernambuco, and bahia from 1995 to 1998 and in 2000. bacterial suspension aliquots of 5 ml were deposited on nutrient-agar medium amended with copper sulfate (at concentrations of 50 and 200 μg/ml), streptomycin sulfate (25 and 200 μg/ml) or oxitetracyclin hydrocloridrate (25 μg/ml). none of the strains was resistant to oxitetracyclin or to copper at 200 μg/ml of copper sulphate. however, strains differed in their sensitivity to 50 μg/ml copper and to streptomycin sulfates (both concentrations used). the frequencies of x. gardneri, x. axonopodis pv. vesicatoria (groups "a" and "c") and x. vesicatoria resistant strains to streptomycin (25 μg/ml of streptomycin sulphate) were, respectively, 98%, 38% and 2%, whereas to copper the frequencies were 48%, 4% and 74%, respectively. all strains of group c/race t3 were sensitive to streptomycin and 97% sensitive to copper. ninety eight percent of 'x. gardneri' strains, 38% of x. axonopodis pv. vesicatoria and only 2% of x. vesicatoria were resistant to streptomycin (25 μg/ml of the product used) whereas the frequencies of copper resistant strains were 48%, 4% and 74%, respectively for the three species of xanthomonas.
Sensibilidade a cobre, estreptomicina e oxitetraciclina em Xanthomonas spp. associadas à mancha-bacteriana do tomate para processamento industrial
Quezado-Duval Alice Maria,Gazzoto Filho Ademir,Leite Júnior Rui P.,Camargo Luis Eduardo A.
Horticultura Brasileira , 2003,
Abstract: Apesar de amplamente empregados em lavouras de tomate para processamento industrial no Brasil, fungicidas cúpricos e antibióticos registrados para uso agrícola nem sempre resultam em controle eficiente das bacterioses que afetam a cultura. O aparecimento de estirpes resistentes é uma das causas dessa baixa eficiência. Avaliou-se, in vitro, a sensibilidade a cobre, estreptomicina e oxitetraciclina de 389 isolados de Xanthomonas spp. associadas à mancha-bacteriana do tomateiro, sendo 92 de X. axonopodis pv. vesicatoria (60 do grupo "A"/ra a T1 e 32 do "C"/ra a T3), 93 de X. vesicatoria (grupo "B"/ra a T2) e 204 de X. gardneri (grupo "D"/ra a T2). Os isolados foram obtidos de plantas doentes em campos comerciais de tomate para processamento industrial nos estados de Goiás, Minas Gerais, Pernambuco e Bahia, nos anos de 1995 a 1998 e em 2000. Alíquotas de 5 ml de suspens es bacterianas foram depositadas em meio Nutriente-ágar suplementado com sulfato de cobre, nas concentra es de 50 e 200 μg/ml; sulfato de estreptomicina, a 25 e 200 μg/ml e cloridrato de oxitetraciclina, a 25 μg/ml. Nenhum isolado foi resistente a oxitetraciclina, como também nenhum foi resistente ao cobre na concentra o de 200 μg/ml do sulfato de cobre. No entanto, houve diferen a entre isolados quanto à sensibilidade ao sulfato de cobre na concentra o de 50 μg/ml e ao sulfato de estreptomicina nas duas concentra es empregadas. As freqüências de isolados de X. gardneri, X. axonopodis pv. vesicatoria (grupos "A" e "C") e X. vesicatoria resistentes à estreptomicina (25 μg/ml do produto usado) foram, respectivamente, 98%, 38% e 2%, ao passo que, ao cobre, foram, respectivamente, 48%, 4% e 74%. Todos os isolados do grupo "C" foram sensíveis à estreptomicina e 97% sensíveis ao cobre.
Natural variability in Arabidopsis thaliana germplasm response to Xanthomonas campestris pv. campestris
Carmo, Lílian S.T.;Candido, Elizabete S.;Campos, Pollyanna F.;Quezado-Duval, Alice Maria;Leonardecz, Eduardo;Lopes, Carlos A.;Quirino, Betania F.;
Fitopatologia Brasileira , 2007, DOI: 10.1590/S0100-41582007000200001
Abstract: this work aimed to study the interaction between the model plant arabidopsis thaliana and xanthomonas campestris pv. campestris (xcc), the pathogen responsible for black rot of crucifers. the response of 32 accessions of a. thaliana to the brazilian isolate of xcc cnph 17 was evaluated. no immunity-like response was observed. "cs1308", "cs1566" and "cs1643" grown in continuous light were among the accessions that showed strongest resistance when inoculated with 5 x 106 cfu/ml. in contrast, "cs1194" and "cs1492" were among the most susceptible accessions. similar results were obtained when plants were grown under short-day conditions. to quantify the differences in disease symptoms, total chlorophyll was extracted from contrasting accessions at different time points after inoculation. chlorophyll levels from controls and xcc inoculated plants showed a similar reduction in resistant accessions, whereas xcc-inoculated susceptible accessions showed a greater reduction compared to controls. to test the specificity of resistance, accessions cs1308, cs1566, cs1643 and cs1438 (which showed partial resistance to cnph 17), were inoculated with a more aggressive isolate of xcc (cnph 77) and ralstonia solanacearum. among the accessions tested, "cs1566" was the most resistant to xcc cnph 77 and also displayed resistance to r. solanacearum. accessions cs1308, cs1566 and cs1643 were also inoculated with a high titer of xcc cnph 17 (5 x 108 cfu/ml). no collapse of tissue was observed up to 48 h after inoculation, indicating that a hypersensitive response is not involved in the resistance displayed by these accessions.
Ocorrência e caracteriza??o do complexo de espécies causadoras da mancha bacteriana do tomateiro no Alto Vale do Rio do Peixe, SC
Costa, Josineide R.;Araújo, Edivanio R.;Becker, Walter F.;Ferreira, Marisa A.S.V.;Quezado-Duval, Alice Maria;
Tropical Plant Pathology , 2012, DOI: 10.1590/S1982-56762012000200009
Abstract: the aim of this study was to identify at the species level xanthomonas strains causing tomato bacterial spot in the region of "alto vale do rio do peixe", state of santa catarina, brazil, as well as to determine their in vitro sensitivity to copper. species were determined by similarity analysis of genomic profiles generated by box-pcr and sensitivity to copper was established using the cye medium supplemented with copper sulfate at concentrations of 50, 100 and 200 μg/ml. of the 44 isolates, 80% were identified as x. gardneri, 11% as x. perforans and 9% as x. vesicatoria. according to the response to copper, the isolates were divided into four classes (s, sensitive; ms, moderately sensitive; mi, moderately insensitive; i, insensitive). regarding the sensitivity to copper, 98% of all isolates were sensitive at 200 μg/ml, suggesting that the recommended dosage of copper-based products registered for the crop may still provide effective control of the different bacterial species.
'BRS Tospodoro': a high lycopene processing tomato cultivar adapted to organic cropping systems and with multiple resistance to pathogens
Giordano, Leonardo de B;Boiteux, Leonardo S;Quezado-Duval, Alice M;Fonseca, Maria Esther de N;Resende, Francisco V;Reis, Ailton;González, Matías;Nascimento, Warley Marcos;Mendon?a, José L;
Horticultura Brasileira , 2010, DOI: 10.1590/S0102-05362010000200019
Abstract: 'brs tospodoro' is a high lycopene tomato cultivar, which combines multiple disease resistance genes and desirable processing traits. this cultivar was found to be suitable for both conventional and organic crop systems. 'brs tospodoro' was obtained via backcross breeding using 'viradoro' as recurrent parent and the inbred line 'cnph 1306' as the donor of the pto gene (resistance to pseudomonas syringae pv. tomato race 0). 'brs tospodoro' has the mi1-2 gene that controls resistance to root-knot nematodes (meloidogyne incognita, m. javanica, and m. arenaria) as well as tolerance to populations of the aphid macrosiphum euphorbiae (vector of potyvirus species), and to whiteflies (bemisia tabaci). 'brs tospodoro' has also the sw-5b gene, which controls resistance to major tospovirus species (groundnut ringspotirus, tomato chlorotic spot virus, chrysanthemum stem necrosis virus, and tomato spotted wilt virus). this cultivar is also resistant to stemphylium solani and s. lycopersici (sm gene), fusarium oxysporum f. sp. lycopersici race 1 (i-1 gene) and verticillium dahlie race 1 (ve gene). 'brs tospodoro' presents uniform fruit ripening, with the first harvest being done around 110 to 120 days after plant emergence. the fruits are firm, square-shaped, with an average weight of 46 g (in organic cropping) to above 70 g (in conventional cropping). the soluble solids content is in the range between 4.6 and 4.8 obrix. the external fruit color is uniform (gene u) and bright red (l* = 44.1; a* = 33.9; b* = 20.4). the average lycopene content of mature fruits is 104 μg/g. this cultivar has the jointless locus (j2), which facilitates both manual and mechanical harvesting. 'brs tospodoro' has determinate growth habit (locus sp) with vigorous foliage, which provides good fruit protection from sunscald. 'brs tospodoro' can be cultivated in all the traditional processing tomato-producing areas of brazil without the need of any technical adjustment. 'brs tospodoro' displayed very good
A Study of Chinese Reverse Mergers in United States Capital Markets
Charles W. DuVal, Will Quilliam
GSTF Journal on Business Review , 2015, DOI: 10.5176/2010-4804_4.1.361
Abstract: This article examines Chinese reverse mergers (RMs), historically a popular method for Chinese companies to enter the United States capital markets. The authors develop a regression model to identify the characteristics associated with successful Chinese RM companies and compare their long term performance to other benchmarks, to include U.S. reverse mergers, Chinese cross-listed firms and the Russell 2000.
New hosts of Myrothecium spp. in Brazil and a preliminary in vitro assay of fungicides
Quezado Duval, A.M.;Henz, G.P.;Paz-Lima, M.L.;Medeiros, A.R.;Miranda, B.E.C.;Pfenning, L.H.;Reis, A;
Brazilian Journal of Microbiology , 2010, DOI: 10.1590/S1517-83822010000100034
Abstract: myrothecium roridum and m. verrucaria are two plant pathogenic species causing foliar spots in a large number of cultivated plants. this paper aims to study the causal agents of foliar spots in vegetable crops (sweet pepper, tomato and cucumber), ornamental plants (spathiphyllum wallisii, solidago canadensis, anthurium andreanum, dieffenbachia amoena) and a solanaceous weed plant (nicandra physaloides). most of the isolates were identified as m. roridum; only the isolate 'myr-02' from s. canadensis was identified as m. verrucaria. all the isolates were pathogenic to their original plant hosts and also to some other plants. some fungicides were tested in vitro against an isolate of m. roridum and the mycelial growth recorded after seven days. fungicides with quartenary ammonium, tebuconazole and copper were highly effective in inhibiting the mycelial growth of m. roridum. this paper confirms the first record of m. roridum causing leaf spots in sweet pepper, tomato, spathiphyllum, anthurium, dieffenbachia and n. physaloides in brazil. we also report m. roridum as causal agent of cucumber fruit rot and m. verrucaria as a pathogen of tango plants.
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