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Search Results: 1 - 10 of 45 matches for " Niday AN;Boiteux "
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Resposta à mosca-branca (Bemisia tabaci) e ao Tomato severe rugose virus de acessos de Solanum subgênero Leptostemonum
Michereff-Filho, Miguel;Machini, Wesley DB;Mendon?a, José L;Fonseca, Maria Esther de N;Fernandes-Acioli, Niday AN;Boiteux, Leonardo S;
Horticultura Brasileira , 2012, DOI: 10.1590/S0102-05362012000300014
Abstract: the whitefly (bemisia tabaci) and the infection by begomovirus species are two major problems affecting yield and quality of the tomato (solanum lycopersicum) crop as well as other solanaceae species of economic importance. the present work was conducted aiming to characterize the reaction of 36 accessions of the genus solanum subgenus leptostemonum (= spiny solanum species) and closely related species to tomato severe rugose virus (tosrv) and b. tabaci. seedlings of the accessions (43 days after sowing) were exposed under greenhouse conditions to viruliferous whiteflies (b. tabaci biotype b) carrying an isolate of tosrv. two susceptible tomato cultivars were used as susceptible controls. reaction to the virus was evaluated using a symptom severity scale and the systemic tosrv infection was evaluated via pcr with universal begomovirus primers. a group of accessions from s. stramonifolium, s. asperolanatum, and s. jamaiscense displayed mild symptoms and low virus accumulation. the accession s. mammosum 'cnph 035', even though tolerant, was the only one displaying clear tosrv symptoms and conspicuous systemic spread of the virus. the remaining accessions were found to be free of tosrv symptoms and with no indication of systemic infection. this germplasm collection was also evaluated to b. tabaci in a free-choice assay under greenhouse conditions. significant differences were observed for the number of eggs and number of 4th instar nymphs. a group of ten accessions from s. asperolanatum, s. stramonifolium, s. paniculatum, and s. syssimbrifolium displayed no signs of whitefly infestation. therefore, accessions of the subgenus leptostemonum might represent potential sources of resistance genes to both b. tabaci and tosrv. this genetic diversity might be transferred to other solanum species via conventional and/or transgenic approaches. our results also indicated that these spiny solanum species might have minor importance either as reservoirs of begomovirus or as alterna
Outbreak of Fusarium oxysporum f. sp. lycopersici race 3 in commercial fresh-market tomato fields in Rio de Janeiro State, Brazil
Reis, Ailton;Boiteux, Leonardo S;
Horticultura Brasileira , 2007, DOI: 10.1590/S0102-05362007000300025
Abstract: fusarium wilt, caused by three races of fusarium oxysporum f. sp. lycopersici, is one of the most important tomato diseases. in brazil, all three races were reported, however, race 3 has been so far restricted only to espírito santo state. in the present work, seven f. oxysporum isolates obtained from wilted plants of the race 1 and 2-resistant tomato hybrids 'giovana', 'carmen' and 'alambra' in s?o josé de ubá and itaocara (rio de janeiro state, brazil) were characterized at race level. virulence assays were performed using a set of race differential cultivars: 'ponderosa' (susceptible to all races), 'ipa-5' (resistant to race 1), 'floradade' (resistant to races 1 and 2), 'bhrs-2,3' (resistant to all three races). two wild tomato accessions (solanum pennellii 'la 716' e s. chilense 'la 1967') previously reported as resistant to all brazilian isolates of f. oxysporum f. sp. lycopersici were also evaluated. isolates from s?o josé de ubá and itaocara were highly virulent to 'ponderosa', 'ipa-5' and 'floradade'. they were also able to infect a few plants of 'bhrs-2,3', inducing vascular browning and wilt symptoms. solanum pennellii and s. chilense accessions displayed an extreme (immune-like) resistant response. these results indicated that all seven isolates could be classified as f. oxysporum f. sp. lycopersici race 3, expanding the geographical distribution of this pathogen within brazil. the hypothesis of transmission via contaminated seeds is reinforced after the present report, which confirms the almost simultaneous outbreak of race 3 in two geographically isolated tomato-growing areas in brazil (espirito santo and rio de janeiro). evaluation of commercial seed lots imported into brazil for contamination with the pathogen would be necessary in order to avoid nation-wide spread of this serious disease.
Photodynamic DNA damage induced by phycocyanin and its repair in Saccharomyces cerevisiae
Pádula, M.;Boiteux, S.;
Brazilian Journal of Medical and Biological Research , 1999, DOI: 10.1590/S0100-879X1999000900002
Abstract: in the present study, we analyzed dna damage induced by phycocyanin (phy) in the presence of visible light (vl) using a set of repair endonucleases purified from escherichia coli. we demonstrated that the profile of dna damage induced by phy is clearly different from that induced by molecules that exert deleterious effects on dna involving solely singlet oxygen as reactive species. most of phy-induced lesions are single strand breaks and, to a lesser extent, base oxidized sites, which are recognized by nth, nfo and fpg enzymes. high pressure liquid chromatography coupled to electrochemical detection revealed that phy photosensitization did not induce 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodguo) at detectable levels. dna repair after phy photosensitization was also investigated. plasmid dna damaged by phy photosensitization was used to transform a series of saccharomyces cerevisiae dna repair mutants. the results revealed that plasmid survival was greatly reduced in rad14 mutants, while the ogg1 mutation did not modify the plasmid survival when compared to that in the wild type. furthermore, plasmid survival in the ogg1 rad14 double mutant was not different from that in the rad14 single mutant. the results reported here indicate that lethal lesions induced by phy plus vl are repaired differently by prokaryotic and eukaryotic cells. morever, nucleotide excision repair seems to play a major role in the recognition and repair of these lesions in saccharomyces cerevisiae.
Fran a: choque de culturas
Boiteux, Bayard,Werner, Maurício
PASOS : Revista de Turismo y Patrimonio Cultural , 2006,
Abstract: Opiniones y ensayos
Photodynamic DNA damage induced by phycocyanin and its repair in Saccharomyces cerevisiae
Pádula M.,Boiteux S.
Brazilian Journal of Medical and Biological Research , 1999,
Abstract: In the present study, we analyzed DNA damage induced by phycocyanin (PHY) in the presence of visible light (VL) using a set of repair endonucleases purified from Escherichia coli. We demonstrated that the profile of DNA damage induced by PHY is clearly different from that induced by molecules that exert deleterious effects on DNA involving solely singlet oxygen as reactive species. Most of PHY-induced lesions are single strand breaks and, to a lesser extent, base oxidized sites, which are recognized by Nth, Nfo and Fpg enzymes. High pressure liquid chromatography coupled to electrochemical detection revealed that PHY photosensitization did not induce 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) at detectable levels. DNA repair after PHY photosensitization was also investigated. Plasmid DNA damaged by PHY photosensitization was used to transform a series of Saccharomyces cerevisiae DNA repair mutants. The results revealed that plasmid survival was greatly reduced in rad14 mutants, while the ogg1 mutation did not modify the plasmid survival when compared to that in the wild type. Furthermore, plasmid survival in the ogg1 rad14 double mutant was not different from that in the rad14 single mutant. The results reported here indicate that lethal lesions induced by PHY plus VL are repaired differently by prokaryotic and eukaryotic cells. Morever, nucleotide excision repair seems to play a major role in the recognition and repair of these lesions in Saccharomyces cerevisiae.
Estimativa da diversidade genética de germoplasma de cebola via descritores morfológicos, agron?micos e bioquímicos
Buzar, Anne Giselle R;Oliveira, Valter R;Boiteux, Leonardo S;
Horticultura Brasileira , 2007, DOI: 10.1590/S0102-05362007000400007
Abstract: the genetic diversity of 64 tropical and subtropical onion accessions (allium cepa l.) belonging to the embrapa hortali?as collection was estimated using 23 morphological, agronomic, and biochemical descriptors. methods of multivariate statistical analysis (mahalanobis' d2 distances, tocher's cluster analysis and nearest-neighbor method) were employed in order to obtain the average genetic distances among accessions and to perform the clustering. the onion germplasm displayed a relatively large genetic base. cultivars ex 3000 and régia were the two most similar accessions. the highest mean genetic distance was observed between cultivars val 14 and beta cristal. the tocher's optimization method revealed the formation of 13 groups, whereas the nearest-neighbor method revealed the formation of 12 groups (cutting point of 43% of dissimilarity. the majority of the accessions belonging to grano and granex cultivars (agronomically classified as short-day and early-maturing types) clustered together in the same group. the white bulb accessions for processing (beta cristal; dehydrator # 8; dehydrator # 6; primero and white creole), with the exception of tampico white, displayed a small genetic divergence. the accessions tx 24, baia periforme super precoce, ex 3001, excel, red creole, h 688, franciscana ipa 10 and roxa ipa 3 displayed a large genetic divergence. the descriptors total sugar content, bulb length, number of days from planting to harvesting (i.e. plant cycle), percentage of bulbs with transversal diameter between 70 and 90 mm, and average bulb weight were responsible for 58% of the genetic variability present among accessions. studies of divergence among accessions are important to choose divergent parentals but complementary genetic materials would allow the development of useful segregating populations with wide genetic basis for tropical onion breeding programs.
Genetic parameter and correlation estimates of processing traits in half-sib progenies of tropical-adapted carrot germplasm
Vieira, Jairo V;Silva, Giovani Olegario da;Boiteux, Leonardo S;
Horticultura Brasileira , 2012, DOI: 10.1590/S0102-05362012000100002
Abstract: the estimate of the genetic parameters associated with processing (fresh-cut) traits, including root length (rl), is crucial for carrot breeding programs in tropical areas. the cultivar alvorada is an important germplasm due to its resistance to nematodes, leaf blight, heat-tolerance, and high carotenoid content. seventy-four 'alvorada' half-sib progenies were evaluated during the summer of 2005 in the federal district, brazil, in a randomized complete block design with three replications. thirteen competitive plants in each block were randomly selected and evaluated and/or classified for rl and for number of leaves (nl), leaf length (ll), root tip type (rt), root mass (rw), crown shape (cs), root diameter (rd), and xylem diameter (xd). the pearson's correlation coefficients and the heritability values were estimated for all traits. the path analysis was also used considering the rl trait as dependent variable. the heritability for rl ranged from 12 to 44%. for the other traits, the values ranged from 3% (rd) to 79% (ll). phenotypic and genotypic correlations among all traits were low to intermediate. path analysis indicated positive direct relationship between rl and rw, whereas rd and xd displayed negative direct effect on rl. longer roots had narrow diameter and narrow xd. recurrent selection based upon either half-sib or s1 families would be more effective than mass phenotypic recurrent selection in increasing rl and to develop populations expressing multiple desirable processing traits in tropical-adapted carrot germplasm.
Identifica??o de genótipos do gênero Solanum (sec??o Lycopersicon) com resistência a Stemphylium solani e S. lycopersici
Miranda, Bruno Eduardo C de;Boiteux, Leonardo S;Reis, Ailton;
Horticultura Brasileira , 2010, DOI: 10.1590/S0102-05362010000200007
Abstract: the gray leaf spot disease, caused by the fungi stemphylium solani and s. lycopersici, has been considered as a minor tomato disease in brazil due to the use of varieties with genetic resistance in combination with fungicide sprays. however, recent reports of severe epidemics of the gray leaf spot in the various tomato-producing areas of the country suggest that the employment of resistant cultivars should be re-implemented as a control strategy. in the present study, 109 cultivated and wild solanum (section lycopersicon) accessions were evaluated to isolates of both s. solani and s. lycopersici. in the first assay, spore suspension (adjusted to 104 conidia/ml) of the isolates 'eh-1740' (s. solani) and 'eh-1749' (s. lycopersici) were employed to inoculate seedlings transplanted 15 days after sowing and kept in a greenhouse. plants were inoculated 18 days after transplanting and evaluated 15 days after inoculation. fifty-eight promising accessions identified in the first assay were evaluated again with the same isolates in a second experiment. the reaction of the accessions to the pathogens was evaluated every two days using as assessment criteria the incubation period, the severity of gray leaf spot, and the disease index. disease severity values over time were used to calculate the area under the disease progress curve. promising sources of resistance to both pathogens were identified in accessions of s. lycopersicum, s. habrochaites, s. peruvianum and s. pimpinellifolium. the resistant sources identified in s. pimpinellifolium and s. lycopersicum accessions probably have the gene sm. however, s. habrochaites and s. peruvianum might be potential new sources of gene/alleles that confer resistance to both fungi. this diversity of stemphylium resistance genes might be useful for tomato breeding programs in the future as well as in integrated management systems of the disease.
Resistance to Septoria lycopersici in Solanum (section Lycopersicon) species and in progenies of S. lycopersicum × S. peruvianum
Satelis, Jaqueson Ferreira;Boiteux, Leonardo Silva;Reis, Ailton;
Scientia Agricola , 2010, DOI: 10.1590/S0103-90162010000300012
Abstract: septoria leaf spot (septoria lycopersici) is one of the major fungal diseases of tomatoes (solanum lycopersicum) in tropical and subtropical regions with humid climates and/or in areas cultivated under sprinkler irrigation systems. sources of resistance have been found in accessions of solanum (section lycopersicon) species. however, many of the described sources are not effective under brazilian conditions. the objective of this work was to evaluate wild and cultivated solanum (section lycopersicon) germplasm to s. lycopersici isolates. a collection of 124 accessions was initially evaluated under greenhouse conditions. ten accessions were highly resistance (hr), whereas 33 were classified as having a resistant (r) response to s. lycopersici isolates. field evaluation was also conducted with a sub-set of accessions identified as either hr or r in the greenhouse experiment. this field evaluation confirmed greenhouse tests and indicated the presence of some potential sources of rate-reducing resistance. one highly resistant and eight resistant s. habrochaites accessions were identified as being resistant under both conditions, confirming that this wild species is one of the most promising sources of resistance to s. lycopersici. five new sources with high levels of resistance were found in s. peruvianum accessions (pi-306811, cnph-1036, la-1910, la-1984 and la-2744). one accession derived from an interspecific cross between s. lycopersicum and s. peruvianum was also found to be highly resistant and might be useful to introgress resistance factors from this wild species into cultivated tomato germplasm. however, additional breeding efforts will be necessary to introgress into the cultivated tomato the resistance factors identified in other s. peruvianum accessions due to the presence of natural crossing barriers between the two species.
Powdery mildew of ornamental species caused by Oidiopsis haplophylli in Brazil
Reis, Ailton;Boiteux, Leonardo Silva;Paz-Lima, Milton Luiz;
Summa Phytopathologica , 2007, DOI: 10.1590/S0100-54052007000400015
Abstract: oidiopsis haplophylli (syn. oidiopsis sicula) was identified as the causal agent of powdery mildew diseases occurring on five ornamental species in brazil. this disease was observed in plastic house-grown lisianthus (eustoma grandiflorum: gentianaceae), in nasturtium (tropaeolum majus: tropaeolaceae) cultivated under open field conditions and in greenhouse-grown calla lily (zantedeschia aethiopica: araceae), impatiens (impatiens balsamina: balsaminaceae) and balloon plant (asclepias physocarpa: asclepiadaceae). typical disease symptoms consisted of chlorotic areas on the upper leaf surface corresponding to a fungal colony in the abaxial surface. with the disease progression, these chlorotic areas eventually turned to necrotic (brown) lesions. fungi morphology on all hosts was similar to that described for the imperfect stage of leveillula taurica (o. haplophylli). the koch's postulates were fulfilled by inoculating symptom-free plants via leaf-to-leaf contact with fungal colonies. additional inoculations using an isolate of o. haplophylli from sweet pepper (capsicum annuum) demonstrated that it is pathogenic to all five species belonging to distinct botanical families, indicating lack of host specialization. this is the first formal report of a powdery mildew disease on lisianthus, calla lilly, impatiens and nasturtium in brazil. it is, to our knowledge, the first report of o. haplophyllii infecting a. physocarpa, extending the host range of this atypical powdery mildew-inducing fungus. this disease might become important on these ornamental crops especially in protected cultivation and also under field conditions in hot and dry areas of brazil.
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