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Search Results: 1 - 10 of 134121 matches for " Jo?o Bosco dos; "
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Effect of natural selection on common bean (Phaseolus vulgaris) microsatellite alleles
Rodrigues, Taislene Butarello;Santos, Joo Bosco dos;
Genetics and Molecular Biology , 2006, DOI: 10.1590/S1415-47572006000200024
Abstract: the effect of natural selection on microsatellite simple sequence repeat (ssr) alleles was investigated in two distinct common bean (phaseolus vulgaris) generations (f8 and f24) derived from the cross between the p. vulgaris cultivars carioca mg x esal 686. the f2 segregant population was propagated by the bulk method and 107 plants were sampled in two generations (f8 and f24). each plant generated one family which was replicated by the bulk method to f8:11 and f24:27 families from which dna was extracted. thirty pairs of microsatellite primers were polymorphic for the parents and the bulk of the f24:27 families. out of 30 loci selected by natural selection, 29 microsatellite alleles came from the carioca mg parent and one allele came from the esal 686 parent. natural selection affected all the generations and its intensity was specific for each locus and generation. therefore all the alleles selected at each locus must be important for adaptation in a breeding program.
Identification of resistant genotypes considering polygenic systems in host-pathogen interaction
Melo, Leonardo Cunha;Santos, Joo Bosco dos;
Genetics and Molecular Biology , 1999, DOI: 10.1590/S1415-47571999000400022
Abstract: plant resistance to pathogens is the most efficient form of disease control. however, identification of resistant genotypes is often difficult, especially when the genetic basis for the host-pathogen relationship is unknown. this study was carried out to test a methodology capable of providing, in a simple way, information about host vertical and horizontal resistance as well as pathogen virulence. a simulation using twenty, ten, and five pathogen races and twenty hosts was carried out. host reaction was controlled by ten genes with two alleles each. eight genes had little effects, one had medium and the other strong effects. genetic control of pathogenicity was identical to that of the host. only homozygous genotypes were used for pathogens and hosts in this simulation, with no epistatic effects. simulation was based on the expected disease severity with the inoculation of twenty hosts with twenty pathogen races, according to additive and interactive models proposed by parlevliet and zadoks (euphytica 26: 5-21, 1977). data were analyzed by model iv of griffing, using a partial diallel scheme. a high correlation was found between general reaction ability (gra) and potential host resistance, which proved to be an indicator of horizontal resistance. a high correlation between general aggressivity ability (gaa) and potential pathogenicity of the race also proved to be an aggressivity indicator. specific interaction ability (sia) is an indicator of host vertical resistance and pathogen virulence. simulation with a lower number of races (ten and five) showed similar results. sia was significant in both the interactive and additive models.
Identification of resistant genotypes considering polygenic systems in host-pathogen interaction
Melo Leonardo Cunha,Santos Joo Bosco dos
Genetics and Molecular Biology , 1999,
Abstract: Plant resistance to pathogens is the most efficient form of disease control. However, identification of resistant genotypes is often difficult, especially when the genetic basis for the host-pathogen relationship is unknown. This study was carried out to test a methodology capable of providing, in a simple way, information about host vertical and horizontal resistance as well as pathogen virulence. A simulation using twenty, ten, and five pathogen races and twenty hosts was carried out. Host reaction was controlled by ten genes with two alleles each. Eight genes had little effects, one had medium and the other strong effects. Genetic control of pathogenicity was identical to that of the host. Only homozygous genotypes were used for pathogens and hosts in this simulation, with no epistatic effects. Simulation was based on the expected disease severity with the inoculation of twenty hosts with twenty pathogen races, according to additive and interactive models proposed by Parlevliet and Zadoks (Euphytica 26: 5-21, 1977). Data were analyzed by model IV of Griffing, using a partial diallel scheme. A high correlation was found between general reaction ability (GRA) and potential host resistance, which proved to be an indicator of horizontal resistance. A high correlation between general aggressivity ability (GAA) and potential pathogenicity of the race also proved to be an aggressivity indicator. Specific interaction ability (SIA) is an indicator of host vertical resistance and pathogen virulence. Simulation with a lower number of races (ten and five) showed similar results. SIA was significant in both the interactive and additive models.
Effect of self-pollination monitored by microsatellite markers on maize kernel weight
Marcio Balestre,Joo Candido de Souza,Joo Bosco dos Santos,Reginaldo Roberto Luders
Crop Breeding and Applied Biotechnology , 2007,
Abstract: The objective of this study was to evaluate the effect of fertilization by autopollen on maize kernel weight. Fivesingle cross hybrids (30F90. A2555, DKB333B, 2223, and 2324) were planted and hybrid leaf samples taken for DNAextraction. The crosses 2223XDKB333B; 2223XA2555; 2324XDKB333B and 2324XP30F90 were performed. Ten kernels ofeach ear of each cross were separated, sown in a greenhouse and the DNA of the respective seedlings was extracted, to identifythe kernel origin. The results obtained here demonstrated that allopollen increased the mean kernel weight by 16.5mg (gainof 4.65%). The proportion of sampled allopollen to self pollen was statistically equal, according to the c2 test, demonstratingthat there were no significant differences between the proportion of fertilized and sampled allopollen and autopollen in the ear.It was concluded that compared to autopollen, allopollen increases the mean weight of fertilized grain.
Natural selection in common bean microsatellite alleles and identification of QTLs for grain yield
Leite,Monik Evelin; Santos,Joo Bosco dos; Carneiro,Flávia Fernandes; Couto,Karla Rodrigues;
Electronic Journal of Biotechnology , 2011,
Abstract: natural selection acts to select better adapted individuals or alleles in segregating population and help plant breeding. the objective of this work was to verify the effect of natural selection on microsatellite alleles as indicators of better adaptation and identification of quantitative trait loci (qtls) for grain yield. this study evaluated 107 progenies from the f8 and 107 from the f24 generation derived from crossing carioca mg and esal 686 lines, carried out by the bulk method, and evaluated in three different seasons: winter 2001; rainy 2001 and dry 2002. it was utilized 22 polymorphic markers and the natural selection acted in all of them. the frequency of the alleles of the parent carioca mg, the most adapted, was increased in all of the 22 loci in f8 and 19 loci in f24. selection affected each locus with different intensities in different generations. all of the selected alleles can be important for breeding program. qtls were identified in generation f8 and f24 at varied magnitudes. the best marker pvttc002 explained 11.76% of variation in grain yield. however, an elevated interaction between qtls and the environments was observed, showing the great difficulty in assisted selection.
Natural selection for efficiency in the use of nitrogen in common bean identified by analysis of microsatellites and grain yield
Leite,Monik Evelin; Lima,Igor Almeida; Pereira,Dyanna Rangel; Santos,Joo Bosco dos;
Electronic Journal of Biotechnology , 2012, DOI: 10.2225/vol15-issue6-fulltext-6
Abstract: this study was carried out in order to verify whether natural selection acts on segregating common bean populations grown in the presence and absence of n, and to verify that natural selection affects the frequency of microsatellite alleles specifically, and in order to identify those that can assist in selection. four populations from the crosses ouro negro x ci-107 and vc-5 x iapar-81 were carried forward in bulk to f8 at both levels of n. ouro negro and vc-5 are considered stress tolerant to nitrogen and iapar-81 and ci-107 responsive. one hundred progenies were obtained from each cross and grown in the presence and absence of n. dna was extracted from 400 progenies, of which 194 were evaluated in the rainy season and 79 in the winter crop for grain yield. these progenies were evaluated in two separate experiments with and without n, in a 14 x 14 lattice design during rainy season and 9 x 9 in the winter season. we selected 35 pairs of polymorphic primers from the parents, with 20 being common from the two crosses. using dna of the 400 progenies, it was found that natural selection acted in 33 loci, in at least one environment and cross, and that alleles of the four parents were favoured by natural selection. qtls were identified for the response rate of n and for grain yield and the linked markers are potential for assisted selection, especially the two most stable; bmd-20, in response to the use of n and pvbr-93 for grain yield.
Marker-assisted backcrossing using microsatellites and validation of SCAR Phs marker for resistance to white mold in common bean
Carneiro,Flávia Fernandes; Santos,Joo Bosco dos; Leite,Monik Evelin;
Electronic Journal of Biotechnology , 2010,
Abstract: molecular markers may accelerate selection through the identification of plants with higher proportion of recurrent parent genome, as well as identifying those plants bearing target alleles like quantitative traits loci (qtls) for white mold resistance. the objectives of this work were: 1) to employ microsatellite markers (ssr) in order to accelerate the recovery of recurrent parent genome 2) to validate sequence characterized amplified region (scar) phs associated with a qtl that confers resistance to white mold, as previously identified in bean populations. lines g122 and m20 were crossed, which generated 267 f1 plants from backcross (bc) bc1 and 113 plants from backcross bc2.ssr polymorphic markers were adopted. the relationship between bc plants and the recurrent parent was estimated based on the recurrent genome proportion (pr) in each bc plant, and the sorensen-dice genetic similarity (sgir). to determine how much the phenotypic variation is explained by scar phs, 56 f1:2bc1 progenies were evaluated on the field following a random block design with two replications through the straw test method. ssr markers are efficient in identifying individuals with a greater proportion of the recurrent genome. scar phs was not efficient for the indirect selection of common beans for white mold resistance.
Identification of SSR and RAPD markers linked to a resistance allele for angular leaf spot in the common bean (Phaseolus vulgaris) line ESAL 550
Silva, Gilvan Ferreira da;Santos, Joo Bosco dos;Ramalho, Magno Antonio Patto;
Genetics and Molecular Biology , 2003, DOI: 10.1590/S1415-47572003000400009
Abstract: the objective of this study was to identify rapd and ssr markers associated with a resistant allele for angular leaf spot (phaeoisariopsis griseola) from the line 'esal 550', derived from the andean 'jalo eep 558' cultivar, to assist selection of resistant genotypes. the resistant line 'esal 550' and the susceptible cultivar 'carioca mg' were crossed to generate f1 and f2 populations. one hundred and twenty f2:3 families were evaluated. the dna of the 12 most resistant families was bulked and the same was done with the dna of the 10 most susceptible, generating two contrasting bulks. one rapd and one ssr marker was found to be linked in coupling phase to the resistant allele. the ssr marker was amplified by the primer pv-atct001282c, and its distance from the resistant allele was 7.6 cm. this is the most useful marker for indirect selection of resistant plants in segregating populations. the rapd marker was amplified by the primer opp07857c linked in coupling phase to the resistant allele, and distant 24.4 cm. therefore, this rapd marker is not so useful in assisting selection because it is too far from the resistant allele.
Comparison of similarity coefficients based on RAPD markers in the common bean
Duarte, Jair Moura;Santos, Joo Bosco dos;Melo, Leonardo Cunha;
Genetics and Molecular Biology , 1999, DOI: 10.1590/S1415-47571999000300024
Abstract: the alterations caused by eight different similarity coefficients were evaluated in the clustering and ordination of 27 common bean (phaseolus vulgaris l.) cultivars analyzed by rapd markers. the anderberg, simple matching, rogers and tanimoto, russel and rao, ochiai, jaccard, sorensen-dice, and ochiai ii's coefficients were tested. comparisons among the coefficients were made through correlation analysis of genetic distances obtained by the complement of these coefficients, dendrogram evaluation (visual inspection and consensus fork index - cic), projection efficiency in a two-dimensional space, and groups formed by tocher's optimization procedure. the employment of different similarity coefficients caused few alterations in cultivar classification, since correlations among genetic distances were larger than 0.86. nevertheless, the different similarity coefficients altered the projection efficiency in a two-dimensional space and formed different numbers of groups by tocher's optimization procedure. among these coefficients, russel and rao's was the most discordant and the sorensen-dice was considered the most adequate due to a higher projection efficiency in a two-dimensional space. even though few structural changes were suggested in the most different groups, these coefficients altered some relationships between cultivars with high genetic similarity.
Prediction of seed-yield potential of common bean populations
Abreu, ?ngela de Fátima Barbosa;Ramalho, Magno Antonio Patto;Santos, Joo Bosco dos;
Genetics and Molecular Biology , 2002, DOI: 10.1590/S1415-47572002000300013
Abstract: earliest possible prediction of seed-yield potential of autogamous crop populations increases breeding program efficiency by saving time and resources. alternatives for obtaining seed-yield predictions were compared by evaluating four common-bean populations in f1 and f2 generations together with the parents. mean components (m + a' and d) and variances were estimated. the potential of each population was predicted by using both these and the jinks and pooni (1976) procedure, which allows probability estimation of each population of originating lines surpassing a determined standard. estimate efficiency was determined by evaluating performances of 62 f5:7 families from each population. mean component m + a' estimates obtained for the f1 and f2 generations proved efficient in predicting seed yield of f7 generation lines as did d for estimate variance among f7 generation families. in addition, the jinks and pooni (1976) procedure proved efficient in early prediction of common bean population genetic potentials, especially when using the m + a' estimate.
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