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Updated: Jul 4, 2026
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Environmentally Induced Heritable Changes in Flax
Published on: January 26, 2011
Segregation distortion in Lolium: evidence for genetic effects.
U C M Anhalt1, P J S Heslop-Harrison, S Byrne
1Teagasc Crops Research Centre, Oak Park, Carlow, Co. Carlow, Ireland.
Summary
Segregation distortion (SD) is a common genetic phenomenon. This study found genetic effects, not population structure, cause SD, with one mapping population showing significantly less distortion.
Area of Science:
- Genetics
- Plant Breeding
- Genomics
Background:
- Segregation distortion (SD) deviates genetic ratios from Mendelian expectations, a frequent observation in genetic mapping.
- Understanding SD is crucial for accurate genetic map construction and identifying genes influencing trait inheritance.
Purpose of the Study:
- To construct and analyze genetic maps in two Lolium perenne populations to investigate segregation distortion.
- To compare the extent of SD between an F(2) and an F(1) derived mapping population.
- To explore potential causes of SD, including genetic effects and population structure.
Main Methods:
- Development of two Lolium perenne mapping populations: an F(2) biomass population (360 genotypes) and an F(1) late flowering population (182 genotypes).
- Construction of genetic maps for both populations and parental lines.
- Detection and quantification of segregation distortion using marker loci and associated p-values.
- Application of genomic in situ hybridization (GISH) to analyze chromosomal composition.
Main Results:
- Significant segregation distortion was detected in both mapping populations.
- The F(1) late flowering population exhibited approximately half the extent of SD (32%) compared to the F(2) biomass population (63%).
- GISH analysis revealed non-recombined Fescue chromosome segments in parental lines, suggesting a genetic basis for observed distortions.
Conclusions:
- Segregation distortion in these Lolium perenne populations is primarily attributed to genetic effects rather than population structure or marker type.
- The study introduces two novel L. perenne mapping populations and their associated genetic maps, with one being the largest reported for Lolium.
- The findings provide valuable insights into the genetic architecture influencing segregation patterns in ryegrass.
Related Concept Videos
01:18Dihybrid Crosses
Overview
01:49Law of Segregation
When crossing pea plants, Mendel noticed that one of the parental traits would sometimes disappear in the first generation of offspring, called the F1 generation, and could reappear in the next generation (F2). He concluded that one of the traits must be dominant over the other, thereby causing masking of one trait in the F1 generation. When he crossed the F1 plants, he found that 75% of the offspring in the F2 generation had the dominant phenotype, while 25% had the recessive phenotype.
02:03Law of Independent Assortment
While Mendel’s Law of Segregation states that the two alleles for one gene are separated into different gametes, a different question of how different genes are inherited remains. For example, is the gene for tall plants inherited with the gene for green peas? Mendel asked this question by experimenting with a dihybrid cross; a cross in which both parents are homozygous for two distinct traits resulting in an F1 generation that are heterozygous for both traits.
02:03Law of Independent Assortment
While Mendel’s Law of Segregation states that the two alleles for one gene are separated into different gametes, a different question of how different genes are inherited remains. For example, is the gene for tall plants inherited with the gene for green peas? Mendel asked this question by experimenting with a dihybrid cross; a cross in which both parents are homozygous for two distinct traits resulting in an F1 generation that are heterozygous for both traits.
01:21Frequency-dependent Selection
When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.Positive Frequency-Dependent SelectionIn positive...
02:46Chi-square Analysis
The chi-square test is a statistical hypothesis test. It is used to check whether there is a significant difference between an expected value and an observed value. In the context of genetics, it enables us to either accept or reject a hypothesis, based on how much the observed values deviate from the expected values.
The chi-square test was developed by Pearson in 1990.
The first step of performing a Chi-square analysis is to establish a null hypothesis, which assumes that there is no real...
The chi-square test was developed by Pearson in 1990.
The first step of performing a Chi-square analysis is to establish a null hypothesis, which assumes that there is no real...