Peroxidase Isoenzyme Variation in Interspecific Elm Hybrids

1972 ◽  
Vol 2 (3) ◽  
pp. 264-270 ◽  
Author(s):  
Peter P. Feret
Keyword(s):  
Segregation Distortion ◽  
Close Correlation ◽  
Crossing Over ◽  
Peroxidase Isoenzymes ◽  
Mendelian Segregation ◽  
Peroxidase Isoenzyme ◽  
Segregation Ratios ◽  
Isoenzyme Variation

Analysis of peroxidase isoenzymes in interspecific elm hybrids indicated that a close correlation exists between parental isoenzymes and those of the progeny. In some crosses, isoenzymes undergo mendelian segregation while in others segregation distortion is evident. Mechanisms proposed to account for the disturbed segregation ratios and unexpected phenotypes include crossing over between peroxidase loci, accumulation of lethal genetic deficiencies, and dominance of some peroxidase genes.

Molecular Mapping of Segregation Distortion Loci in Aegilops tauschii

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 319-327 ◽  
Author(s):  
J D Faris ◽  
B Laddomada ◽  
B S Gill
Keyword(s):  
Segregation Distortion ◽  
Molecular Mapping ◽  
Aegilops Tauschii ◽  
Distorted Segregation ◽  
F2 Population ◽  
Male Gametes ◽  
Skewed Segregation ◽  
Segregation Ratios ◽  
Backcross Populations ◽  
Intraspecific Hybrids

Abstract Distorted segregation ratios of genetic markers are often observed in progeny of inter- and intraspecific hybrids and may result from competition among gametes or from abortion of the gamete or zygote. In this study, 194 markers mapped in an Aegilops tauschii F2 population were surveyed for distorted segregation ratios. Region(s) with skewed segregation ratios were detected on chromosomes 1D, 3D, 4D, and 7D. These distorter loci are designated as QSd.ksu-1D, QSd.ksu-3D, QSd.ksu-4D, and QSd.ksu-7D. Three regions of segregation distortion identified on chromosome 5D were analyzed in two sets of reciprocal backcross populations to analyze the effect of sex and cytoplasm on segregation distortion. Extreme distortion of marker segregation ratios was observed in populations in which the F1 was used as the male parent, and ratios were skewed in favor of TA1691 alleles. There was some evidence of differential transmission caused by nucleo-cytoplasmic interactions. Our results agree with other studies stating that loci affecting gametophyte competition in male gametes are located on 5DL. The distorter loci on 5DL are designated as QSd.ksu-5D.1, QSd.ksu-5D.2, and QSd.ksu-5D.3.

scholarly journals Experiments on the physiology and genetics of the smut fungi. Cultural characters. Part II. - The effect of certain external conditions on their segregation

1931 ◽  
Vol 108 (758) ◽  
pp. 395-423 ◽  
Keyword(s):  
Higher Plants ◽  
Smut Fungi ◽  
Mendelian Segregation ◽  
Segregation Ratios ◽  
External Conditions

The researches, which are described under the above general heading, were begun in 1925. Their object was to find out if the inheritance of the characters in the smut fungi was similar to that in the higher plants and animals. The evidence presented, and to hand, was in the previous paper (1928) considered sufficient to justify the conclusion that, in their segragation, these fungi did obey the laws of meendel. In that paper certain of the cultural characters were shown to be segregated in ratios of 2 : 3, 3 : 1 and 4: 0 in those cells which were deduced to be the immediate progeny of the reduction divisions. The anomalous ratio of 3 : 1 was at that time the only difficulty, and this was, it seemed, probably due to the interaction of a number of Mendelian factors. Since that time segregation ratios of 2 : 1 : 1 (or 1 : 1: 2) and 1 : 2 :1 have been recognised. It is thought that the conclusion that the segregation in these fungi is along Mendelian lines is fully justified by the experiments described in this paper. In the fungi generally, as Brierley has stated (1929), "local peculiarities" may be expected, but, so far, in the smut fungi I find typical haploid inheritance with one possible exception. If the factor gender (sex) only is considered, the evidence is overwhelmingly in favour of strict Mendelian segregation, both in that the factors are segregated in pairs and, as demonstrated in the present paper, that segregation under normal circumstances is haphazard. Also when the cultural characters are considered, the evidence is conclusive expect that in one character this peculiar 3 : 1 ratio is found.

A basic peroxidase isoenzyme from the grape pedicel is induced by gibberellic acid

1999 ◽  
Vol 26 (4) ◽  
pp. 387 ◽  
Author(s):  
Francisco J. Pérez ◽  
Verónica Morales
Keyword(s):  
Ascorbic Acid ◽  
Gibberellic Acid ◽  
Peroxidase Activity ◽  
Hormone Treatment ◽  
Table Grape ◽  
Guaiacol Peroxidase ◽  
Peroxidase Isoenzymes ◽  
Peroxidase Isoenzyme ◽  
Soluble Peroxidase

Soluble peroxidase activity from pedicels of seedless table grape cv. Sultana was highly stimulated by post-bloom applications of gibberellic acid (GA3) to vines. The increase in peroxidase activity was mainly due to the induction of a basic peroxidase isoenzyme (pI > 9; BPrx-HpI). The activity of two other peroxidase isoenzymes of pI 6.5 and 3.2 was not altered by the hormone treatment. BPrx-HpI was induced by GA3 in pedicels and rachis but not in berries, although in berries peroxidase activity was also stimulated by post-bloom GA3 applications. BPrx-HpI oxidised guaiacol and ortho-phenylenediamine (o-PDA), while the others peroxidases found in the pedicel and in the berry oxidised only o-PDA. Hence, BPrx-HpI was characterised as a guaiacol-peroxidase showing no activity towards ascorbic acid (ASC). The possible role of BPrx-HpI in pedicel lignification and berry-drop caused by GA3 applications to cv. Sultana vines is discussed.

scholarly journals The effect of suppressing crossing-over on the response to selection in Drosophila melanogaster

1970 ◽  
Vol 16 (1) ◽  
pp. 1-16 ◽  
Author(s):  
C. P. McPhee ◽  
Alan Robertson
Keyword(s):  
Drosophila Melanogaster ◽  
Dominant Gene ◽  
Crossing Over ◽  
Linkage Equilibrium ◽  
Selection Experiment ◽  
Base Population ◽  
Response To Selection ◽  
Wild Type ◽  
Segregation Ratios

SUMMARYA selection experiment for sternopleural bristles in Drosophila melanogaster was undertaken to measure the effect of suppressing crossing-over on chromosomes II and III using the inversions Curly and Moiré marked with a dominant gene, which severely reduce crossing-over. In one set of lines selected wild-type males were mated to selected females, heterozygous for Cy and Mé, and in a parallel set selected males carrying the inversions were mated to selected wild-type females. Because there is no crossing-over in the males in this species, crossing-over is much reduced in the first set and is at its usual level in the second. The effect of the selection was measured on flies which did not carry the inversions. The suppression of crossing-over reduced the advance at the limit by 28 ± 8% for selection upwards and by 22 ± 7% for selection downwards. The segregation ratios of the inversions were observed throughout the experiment. At the end, the proportion of wild-type flies emerging was not different in the two sets of lines. The results are consistent with an assumption of initial linkage equilibrium between loci affecting sternopleural bristles in the base population.

Why Mendelian segregation?

2006 ◽  
Vol 34 (4) ◽  
pp. 566-568 ◽  
Author(s):  
F. Úbeda
Keyword(s):  
Natural Selection ◽  
Segregation Distortion ◽  
New Paradigm ◽  
Mendelian Segregation ◽  
New Model ◽  
Unrealistic Assumption

The discovery of alleles that are able to distort segregation during meiosis in their favour raises the question of why Mendelian segregation is the rule and segregation distortion the exception. Previous research on this topic was limited by an unrealistic assumption: equal segregation in the two sexes. Úbeda and Haig [(2005) Genetics 170, 1345–1357] provide a new model allowing sex-specific segregation distortion. This model shows that natural selection favours departure from Mendelian expectations. The evolutionary instability of Mendelian segregation under more realistic assumptions requires a new paradigm that explains its ubiquity.

scholarly journals Single-Locus Inheritance in the Tetraploid Treefrog Hyla versicolor With an Analysis of Expected Progeny Ratios in Tetraploid Organisms

Genetics ◽  
1987 ◽  
Vol 116 (2) ◽  
pp. 299-311
Author(s):  
J Ellen Marsden ◽  
Steven J Schwager ◽  
Bernie May
Keyword(s):  
Null Allele ◽  
Hyla Versicolor ◽  
Crossing Over ◽  
Tetraploid Species ◽  
Double Reduction ◽  
Adequate Knowledge ◽  
Disomic Inheritance ◽  
Segregation Ratios ◽  
Minimum Number ◽  
Species Being

ABSTRACT The recently evolved autotetraploid frog, Hyla versicolor, was examined electrophoretically for evidence of genomic restructuring leading to diploidization. Loci were tested against the progeny ratios expected if inheritance was disomic vs. tetrasomic. Two loci (Mpi and Sod-2) appeared to be inherited tetrasomically, one (Mdh-2) appeared to be inherited disomically, and one (Tpi) appeared to be inherited disomically in one family and tetrasomically in another family, when tested conventionally against 1:2:1 and 1:4:1 segregation ratios. The minimum number of progeny required for this type of analysis for codominant alleles is shown to be 92. Progeny resulting from double reduction were observed, and the occurrence of a null allele class at Mpi was noted. A reexamination of expected progeny ratios in tetraploid organisms reveals that tetrasomic inheritance patterns cannot be predicted without adequate knowledge of the amount of crossing-over, the proportion of tetravalents vs. random bivalents that are formed, and the ratio and types of centromere segregation (alternate and adjacent) that occur from tetravalents in the species being studied. However, disomic inheritance can be unambiguously confirmed only by the production of all heteroallelic gametes from homobivalent, symmetrically heterozygous individuals. In addition, a method is described for estimating genecentromere distances using the ratio of progeny genotypes in certain crosses in tetraploid species.

scholarly journals Segregation and Linkage Relationships of Allozymes in Pinus Brutia Ten

2006 ◽  
Vol 55 (1-6) ◽  
pp. 155-160
Author(s):  
Nuray Kaya ◽  
K. Isik
Keyword(s):  
Seed Orchard ◽  
Mendelian Inheritance ◽  
Recombination Fraction ◽  
Starch Gel Electrophoresis ◽  
Mendelian Segregation ◽  
Pinus Brutia ◽  
Segregation Ratios ◽  
Starch Gel ◽  
Allozyme Loci ◽  
Linkage Relationships

Abstract Female gametophytes of Pinus brutia Ten. were analyzed to study Mendelian segregation and linkage among allozyme loci in a seed orchard composed of 28 clones. Isozyme variants of nine enzyme systems encoding 14 loci from megagametophytes were assayed by starch gel electrophoresis. While six of the 14 loci were monomorphic, the remaining eight were polymorphic. Analysis of observed segregation ratios of all polymorphic loci except for Sdh1, showed a good fit to the 1:1 ratios expected for Mendelian inheritance. Linkage relationships of the eight polymorphic allozyme loci were analyzed by testing 23 of the 28 possible two-locus combinations. Two-locus segregations in three pairs (Got2- Mdh1, Got2-Pgi2 and Pgd3-Sdh1) were significantly heterogeneous (P ≤ 0.05). Relatively weak linkage was observed between only one pair of genes (Adh2:Got2). Recombination fraction for Adh2:Got2 was found to be 0.24 (± 0.06).

scholarly journals Mapping Quantitative Trait Loci Using Distorted Markers

2009 ◽  
Vol 2009 ◽  
pp. 1-11 ◽  
Author(s):  
Shizhong Xu ◽  
Zhiqiu Hu
Keyword(s):  
Qtl Mapping ◽  
Segregation Distortion ◽  
Quantitative Trait ◽  
Expectation Maximization Algorithm ◽  
Real Life ◽  
Segregation Ratio ◽  
Joint Analysis ◽  
Mendelian Segregation ◽  
Real Life Data ◽  
Trait Locus

Quantitative trait locus (QTL) mapping is usually performed using markers that follow a Mendelian segregation ratio. We developed a new method of QTL mapping that can use markers with segregation distortion (non-Mendelian markers). An EM (expectation-maximization) algorithm is used to estimate QTL and SDL (segregation distortion loci) parameters. The joint analysis of QTL and SDL is particularly useful for selective genotyping. Application of the joint analysis is demonstrated using a real life data from a wheat QTL mapping experiment.

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