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  • 1
    Electronic Resource
    Electronic Resource
    Molecular markers and protein quantities as genetic descriptors in maize. II. Prediction of performance of hybrids for forage traits (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 114 (1995), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: As it is related to the variability in genome expression, variability in protein quantities revealed by two-dimensional electrophoresis was proposed for describing phenotypic diversity. The objective of this study was to compare the predictive power of different genetic distances derived from molecular markers and from protein quantitative variations in a diallel of 210 hybrids among 21 maize inbred lines (Zea mays L.) of various origin. The lines were characterized for: 1. 142 markers resulting from the analysis of enzyme, RFLP, and protein-structure polymorphism; and 2. The variation in relative quantities of 190 proteins. The hybrids were evaluated for six forage traits in four environments. Correlations between the genetic distances computed for 142 marker loci and hybrid performances were moderate to high in diallels using crosses between related lines. Genetic distances based on protein quantities showed, in most cases, similar or lower correlations. Distance measures were not useful as predictors of hybrid performance for crosses between unrelated lines. Protein quantities were better for revealing specific genotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1995.tb00825.x
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  • 2
    Electronic Resource
    Electronic Resource
    Prediction of Maize Hybrid Silage Performance Using Marker Data: Comparison of Several Models for Specific Combining Ability (1998)
    Springer
    Crop science 38 (1998), S. 38-44 
    Details
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 1 maize (Zea mays L.) hybrid performance with some accuracy prior to field evaluation are of particular interest. This study was conducted to evaluate the efficiencies of the conventional additive model based on the general combining ability (GCA) as a control and of three different predictions of the specific combining ability (SCA). The first approach was based on the hypothesis that the degree of SCA expressed by a single-cross is related to the marker distance between its parental lines. The second approach was based on a factorial regression model of interaction, where markers were used by means of principal component analysis to generate covariates for SCA. The third approach was adapted from the best linear unbiased prediction (BLUP) of SCA, where covariances between hybrid SCAs were estimated with marker data. Efficiencies were evaluated by menas of a cross-validation procedure for silage performance of a 21 by 21 half-diallel population among maize inbreds. This procedure was applied to (i) all hybrids and (ii) hybrids between unrelated parents only. In situation (i), introducing a distance term in the model accounted for up to 73.6% of the variation in the hybrid performance observed, whereas the corresponding efficiency of the GCA model was 63.4%. The introduction of a distance term did not modify prediction efficiency in situation (ii) whereas the use of the factorial regression model or the BLUP approach led to moderate improvements. These results suggested that efficient approaches can be proposed to predict hybrid silage yield and that prediction of SCA is mostly justified in situations where coancestry among inbreds is unknown or only suspected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/
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  • 3
    Electronic Resource
    Electronic Resource
    Economic Efficiency of One Cycle of Marker-Assisted Selection (2000)
    Springer
    Crop science 40 (2000), S. 329-337 
    Details
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/
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  • 4
    Electronic Resource
    Electronic Resource
    Relationship between heterosis and heterozygosity at marker loci: a theoretical computation (1991)
    Springer
    Theoretical and applied genetics 81 (1991), S. 571-575 
    Details
    ISSN: 1432-2242
    Keywords: Heterosis ; Heterozygosity ; Markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In this paper we have studied the linear correlation between a genetic distance index between two parent lines (based on marker loci information) and the heterosis observed in the F1 hybrid from the two lines, for a quantitative character (determined by several loci, or QTL). Theoretical computations of the correlation coefficient (ϱ) between the distance index and the heterosis were made, assuming the biallelic model (defined by Fisher). When the alleles at both marker loci and QTL are equally distributed among the whole population of considered lines, the coefficient ϱ is a function of the squares of linkage disequilibria between alleles at marker loci and alleles at QTL. The QTL that are not marked by marker loci and marker loci that do not mark any QTL play symmetrical roles and can decrease ϱ greatly. We conclude that the prediction of F1 hybrid heterosis based on marker loci would be more efficient if these markers were selected for their relationship to the alleles implicated in the heterotic traits considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226720
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  • 5
    Electronic Resource
    Electronic Resource
    Marker-assisted selection with spatial analysis of unreplicated field trials (1999)
    Springer
    Theoretical and applied genetics 98 (1999), S. 234-242 
    Details
    ISSN: 1432-2242
    Keywords: Key words Marker-assisted selection ; Spatial analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Many studies have shown that molecular markers can improve the efficiency of the selection of quantitative traits in plant breeding provided that large population sizes are used. As a way to limit experimental costs it appears that the use of unreplicated trials may be more valuable than the use of replicated plots in one trial. In this particular context of unreplicated large trials, spatial heterogeneity within the field may reduce the efficiency of the selection. The problem of controlling spatial heterogeneity was seldom considered in the case of marker-assisted selection (MAS). Here, we propose an integrated method to predict genetic values considering simultaneously marker information and possible spatial heterogeneity. This method was applied to a population of 300 F3 lines of maize evaluated in 11 unreplicated trials for grain yield. We show that when spatial field heterogeneity is considered through appropriate statistical models the accuracy of genetic value predictions is improved and the same genetic gain can be achieved with a reduced number of trials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051063
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  • 6
    Electronic Resource
    Electronic Resource
    Estimation of the contribution of quantitative trait loci (QTL) to the variance of a quantitative trait by means of genetic markers (1996)
    Springer
    Theoretical and applied genetics 93 (1996), S. 1193-1201 
    Details
    ISSN: 1432-2242
    Keywords: Quantitative trait locus (QTL) ; Genetic markers ; Analysis of variance (ANOVA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The estimation of the contribution of an individual quantitative trait locus (QTL) to the variance of a quantitative trait is considered in the framework of an analysis of variance (ANOVA). ANOVA mean squares expectations which are appropriate to the specific case of QTL mapping experiments are derived. These expectations allow the specificities associated with the limited number of genotypes at a given locus to be taken into account. Discrepancies with classical expectations are particularly important for two-class experiments (backcross, recombinant inbred lines, doubled haploid populations) and F2 populations. The result allows us firstly to reconsider the power of experiments (i.e. the probability of detecting a QTL with a given contribution to the variance of the trait). It illustrates that the use of classical formulae for mean squares expectations leads to a strong underestimation of the power of the experiments. Secondly, from the observed mean squares it is possible to estimate directly the variance associated with a locus and the fraction of the total variance associated to this locus (r l 2 ). When compared to other methods, the values estimated using this method are unbiased. Considering unbiased estimators increases in importance when (1) the experimental size is limited; (2) the number of genotypes at the locus of interest is large; and (3) the fraction of the variation associated with this locus is small. Finally, specific mean squares expectations allows us to propose a simple analytical method by which to estimate the confidence interval of r l 2 . This point is particularly important since results indicate that 95% confidence intervals for r l 2 can be rather wide:2–23% for a 10% estimate and 8–34% for a 20% estimate if 100 individuals are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223450
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  • 7
    Electronic Resource
    Electronic Resource
    Estimation of the contribution of quantitative trait loci (QTL) to the variance of a quantitative trait by means of genetic markers (1996)
    Springer
    Theoretical and applied genetics 93 (1996), S. 1193-1201 
    Details
    ISSN: 1432-2242
    Keywords: Key words Quantitative trait locus (QTL)  ;  Genetic markers  ;  Analysis of variance (ANOVA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The estimation of the contribution of an individual quantitative trait locus (QTL) to the variance of a quantitative trait is considered in the framework of an analysis of variance (ANOVA). ANOVA mean squares expectations which are appropriate to the specific case of QTL mapping experiments are derived. These expectations allow the specificities associated with the limited number of genotypes at a given locus to be taken into account. Discrepancies with classical expectations are particularly important for two-class experiments (backcross, recombinant inbred lines, doubled haploid populations) and populations. The result allows us firstly to reconsider the power of experiments (i.e. the probability of detecting a QTL with a given contribution to the variance of the trait). It illustrates that the use of classical formulae for mean squares expectations leads to a strong underestimation of the power of the experiments. Secondly, from the observed mean squares it is possible to estimate directly the variance associated with a locus and the fraction of the total variance associated to this locus When compared to other methods, the values estimated using this method are unbiased. Considering unbiased estimators increases in importance when (1) the experimental size is limited; (2) the number of genotypes at the locus of interest is large; and (3) the fraction of the variation associated with this locus is small. Finally, specific mean squares expectations allows us to propose a simple analytical method by which to estimate the confidence interval of This point is particularly important since results indicate that 95% confidence intervals for can be rather wide:2–23% for a 10% estimate and 8–34% for a 20% estimate if 100 individuals are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050356
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  • 8
    Electronic Resource
    Electronic Resource
    Comparison of RFLP and morphological distances between maize Zea mays L. inbred lines. Consequences for germplasm protection purposes (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 92-102 
    Details
    ISSN: 1432-2242
    Keywords: Key words RFLP ; Markers ; Genetic distances ; Morphological distances
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A total of 145 maize inbred lines, representative of material released in France, were differentiated using RFLP markers and a set of discriminant morphological traits in order to evaluate the use of molecular markers for large-scale germplasm diversity analysis and determination of distinctness. Several criteria are proposed with respect to choice of probes, which should give reliable results for routine studies and have a known single-locus genetic determinism to avoid redundancy. A method is proposed by which to incorporate the data from different restriction enzymes obtained with the same probe. The precision of the estimation of the genetic distance is given. The relationship between molecular and morphological distances appears to be triangular, molecular divergence behaving as a limiting factor for morphological divergence. This suggested a scheme for incorporating molecular markers in studies of distinctness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050536
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  • 9
    Electronic Resource
    Electronic Resource
    Relationships among maize inbred lines and populations from European and North-American origins as estimated using RFLP markers (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 473-480 
    Details
    ISSN: 1432-2242
    Keywords: Key words RFLP ; Maize ; Lines ; Populations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  RFLP markers have proven to be a reliable and highly informative tool for characterizing genetic diversity in maize. Joint analysis of inbred lines and populations should provide valuable information with respect to (1) a better understanding of the genetic basis of present elite germplasm and (2) the identification of populations that may prove to be useful sources of genetic diversity for breeding programs. Sixty-two inbred lines of known heterotic groups and ten maize populations, some of them significant contributors to the genetic basis of the heterotic groups, were assayed at 28 RFLP loci. Joint data analyses first underlined that the populations displayed a large number of alleles that were absent in the set of inbred lines. Associations among inbreds and populations further proved consistent with pedigree data of the inbreds and provided new information on the genetical basis of heterotic groups. In particular, European flint inbreds were revealed to be as close to the Northeastern U.S. flint population studied as to the typical European populations. These results advocate the analysis of larger sets of populations by means of molecular markers in order to (1) gain insight into the history of maize germplasm and (2) set up appropriate strategies for the use of genetic resources in breeding programs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051259
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  • 10
    Electronic Resource
    Electronic Resource
    The effect of population structure on the relationship between heterosis and heterozygosity at marker loci (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 336-343 
    Details
    ISSN: 1432-2242
    Keywords: Distance ; Markers ; Heterozygosity ; Heterosis ; Specific combining ability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between heterozygosity at neutral marker loci and heterosis of F1 hybrids is investigated using a theoretical model. Results emphasize that linkage disequilibrium between the markers and the loci implicated in heterosis [quantitative trait loci (QTLs) that exhibit dominance effects] is a necessary condition to finding a correlation (ϱ mh ) between heterozygosity at marker loci and the heterosis. The effect of population structure, in which the parental inbred lines of the hybrids belong to different heterotic groups, is considered. ϱ mh is investigated for: (1) hybrids between lines that belong to the same heterotic group (within-group hybrids); (2) hybrids between lines that belong to different groups (between-group hybrids); and (3) all hybrids, both within and between-groups. Within a group, significant values of (ϱ mh ) may arise because of linkage disequilibrium generated by drift. At the between-group level, no correlation is expected since link-age disequilibrium should differ randomly from one group to the other, which is consistent with recent experimental results. Possible ways to achieve prediction of the heterosis in this situation are discussed. When all hybrids are considered simultaneously, divergence of allelic frequencies among groups for the markers and the QTLs produces a correlation between heterosis and heterozygosity at marker loci. This correlation increases with the number of markers that are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225164
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