Navegando por Autor "Barros, E. G. de"
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Item Allelism tests between the rust resistance gene present in common bean cultivar Ouro Negro and genes Ur-5 and Ur-11(Journal of Phytopathology, 2003-11-04) Alzate-Marin, A. L.; Souza, T. L. P. O. de; Ragagnin, V. A.; Moreira, M. A.; Barros, E. G. deThe pathogenic variability of the fungus Uromyces appendiculatus is an obstacle for the creation of rust‐resistant common bean (Phaseolus vulgaris L.) varieties. Gene pyramiding is an alternative strategy for the development of varieties with durable resistance. However, to reach this goal it is important to identify different genes with ample resistance spectra. Cultivars Ouro Negro, Mexico 309 and Belmidak RR‐3 have been shown to be resistant to several rust races identified in the state of Minas Gerais, Brazil. Ouro Negro is the only rust resistance source being used in the BIOAGRO/Universidade Federal de Viçosa (UFV) breeding programme, which aims at pyramiding resistance genes in the ‘carioca‐type’ cultivar Rudá. It would be also interesting to use Mexico 309 (Ur‐5) and Belmidak RR‐3 (Ur‐11) in the breeding programme. However, there is no available information on the possible allelic relationships between the Ouro Negro resistance gene and Ur‐5 and Ur‐11. This work aimed at: (1) determining the allelic relationship between the Ouro Negro resistance gene and Ur‐5 and Ur‐11; and (2) evaluating a random amplified polymorphic DNA (RAPD) marker previously reported as being linked to Ur‐11, in populations from crosses between Belmidak RR‐3 and Rudá. The allelism tests confirmed that the Ouro Negro rust resistance gene is distinct from Ur‐5 and Ur‐11 and the molecular analyses confirmed that the RAPD marker can be used in our breeding programme to develop ‘carioca‐type’ cultivars with the Ur‐11 gene.Item Analysis of genetic diversity of Fusarium oxysporum f. sp. phaseoli isolates, pathogenic and non-pathogenic to common bean (Phaseolus vulgaris L.)(Journal of Phytopathology, 2006-09) Zanotti, M. G. S.; Queiroz, M. V. de; Santos, J. K. dos; Rocha, R. B.; Barros, E. G. de; Araújo, E. F.Twenty isolates of Fusarium oxysporum from Brazil, pathogenic and non-pathogenic to common bean, were analysed using random amplified polymorphic DNA (RAPDs) to study the genetic diversity. RAPD analysis using 23 oligonucleotides resulted in the amplification of 229 polymorphic and 7 monomorphic DNA fragments ranging from 234 to 2590 bp. High genetic variability was observed among the isolates, with the distances varying between 8% and 76% among pathogenic, 2% and 63% among the non-pathogenic and 45% and 76% between pathogenic and non-pathogenic isolates. The analysis of genetic distance data showed that the pathogenic isolates tended to group in one group and the non-pathogenic in another. The genetic distance values of 30% among the pathogenic isolates in cluster A are compatible with the genetic distance values observed within the physiological races, but the distance values among the pathogenic isolates in clusters B and G are not compatible with the distance values observed within the race. Although our results are preliminary, it was not possible to exclude the existence of more than one race of this fungus in Brazil.Item Cloning and characterization of a gene encoding the endopolygalacturonase of Penicillium griseoroseum(Biotechnology Letters, 1999-05) Ribon, A. O. B.; Coelho, J. L. C.; Barros, E. G. de; Araújo, E. F.A conserved region of a polygalacturonase (PG) gene from Penicillium griseoroseum was PCR amplified and used to screen a genomic library from this fungus. The nucleotide sequence of the isolated clone (pggI) consisted of 1497 bp, including a coding region of 1251 bp. This region potentially encodes a protein of 376 amino acids, and is interrupted by two introns. Extensive homology was observed between this protein and several fungal endopolygalacturonases. DNA hybridization analyses revealed that there is a low copy number of pggI in the P. griseoroseum genome, probably one or two copies.Item Development and agronomic performance of common bean lines simultaneously resistant to anthracnose, angular leaf spot and rust(Plant Breeding, 2009-04-01) Ragagnin, V. A.; Souza, T. L. P. O. de; Sanglard, D. A.; Arruda, K. M. A.; Costa, M. R.; Alzate‐ Marin, A. L.; Carneiro, J. E. de S.; Moreira, M. A.; Barros, E. G. deThe common bean is affected by several pathogens that can cause severe yield losses. Here we report the introgression of resistance genes to anthracnose, angular leaf spot and rust in the ‘carioca‐type’ bean cultivar ‘Rudá’. Initially, four backcross (BC) lines were obtained using ‘TO’, ‘AB 136′, ‘Ouro Negro’ and ‘AND 277’ as donor parents. Molecular fingerprinting was used to select the lines genetically closer to the recurrent parent. The relative genetic distances between ‘Rudá’ and the BC lines varied between 0.0% and 1.99%. The BC lines were intercrossed and molecular markers linked to the resistance genes were used to identify the plants containing the genes of interest. These plants were selfed to obtain the F2, F3 and F4 plants which were selected based on the presence of the molecular markers mentioned and resistance was confirmed in the F4 generation by inoculation. Four F4:7 pyramid lines with all the resistance genes showed resistance spectra equivalent to those of their respective donor parents. Yield tests showed that these lines are as productive as the best ‘carioca‐type’ cultivars.Item Sequence characterized amplified regions linked to rust resistance genes in the common bean(Crop Science, 2000-05) Corrêa, Ronan Xavier; Costa, M. R.; Good- God, P. I.; Ragagnin, V. A.; Faleiro, F. G.; Moreira, M. A.; Barros, E. G. deUromyces appendiculatus (Pers.) Unger, the causative fungus of rust in common beans (Phaseolus vulgaris L.), consists of many pathotypes or pathogenic races. Cultivar Ouro Negro is resistant to most pathotypes detected in Brazil in the last few decades. We attempted to identify molecular markers linked to a rust resistance gene block present in Ouro Negro. DNA samples extracted from homozygous near isogenic BC3F2:3 lines derived from a cross between susceptible cultivar US Pinto 111 and Ouro Negro were grouped, following greenhouse inoculations, into two contrasting bulks, one containing only resistant and the other only susceptible plants. The bulks were amplified with 605 random primers and two of them amplified bands which were heteromorphic between the two bulks. These random amplified polymorphic DNA (RAPD) bands were transformed into sequence characterized amplified regions (SCARs) SCARBA08 and SCARF10. The rust resistance–susceptibility phenotypes and the molecular genotypes with the two SCAR markers of 303 F2:3 families from US Pinto 111 × Ouro Negro were determined. SCARBA08 and SCARF10 were determined to be 4.3 ± 1.2 and 6.0 ± 1.3 centimorgans (cM) from the rust resistance locus, respectively. These markers are being used in combination with other markers for resistance to rust, anthracnose, and angular leaf spot previously identified in our laboratory to aid the indirect selection of desirable plants in segregating populations in which Ouro Negro has been used as donor parent.