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Quantitative genetics of autogamous F2
1Institute of Molecular Biosciences, Massey University, and Donach Plant Breeding Academy, Palmerston North, New Zealand. genovir@donach.ac.nz
Hereditas
|February 9, 2002
Summary
This study derives general quantitative genetic properties for self-fertilized F2 generations, revealing distinct genetic variances and higher selection potential compared to traditional F2 populations. These findings offer new insights into breeding strategies.
Area of Science:
- Quantitative Genetics
- Plant Breeding
- Population Genetics
Background:
- Previous knowledge on the quantitative genetic properties of F2 generations derived from self-fertilization of hybrids (F1) was limited.
- Understanding these properties is crucial for optimizing breeding programs and predicting genetic outcomes.
Purpose of the Study:
- To derive general quantitative genetic properties for the F2 generation resulting from self-fertilization of F1 hybrids.
- To extend and generalize existing knowledge on F2 populations, particularly focusing on autogamous (self-pollinating) systems.
- To investigate the relationships between inbreeding, genetic variances, and selection potential in selfed F2 populations.
Main Methods:
- Derivation of new equations for genotype and allele frequencies.
- Calculation of inbreeding coefficient, genic (additive-genetic) and dominance variances.
- Estimation of broadsense and narrowsense heritabilities and selection potential.
Main Results:
- The bulk mean of the selfed F2 is generally lower, while genotypic variance is higher, compared to F1 and allogamous (cross-pollinating) F2.
- Genic and dominance variances in the selfed F2 differ significantly from classical counterparts and exhibit complex relationships with inbreeding.
- Inbreeding level is constant regardless of parental combinations, unlike in allogamous F2 populations.
Conclusions:
- The selfed F2 generation exhibits unique quantitative genetic properties, including high selection potential and potentially greater genetic advance than allogamous F2 under specific selection conditions.
- Selfing in spatially separated F2 swarms can enhance natural selection.
- These findings provide a more elaborate understanding of inbreeding effects and genetic variation in autogamous breeding systems.
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.
02:27Trihybrid Crosses
Trihybrid Crosses
Some of Mendel’s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A trihybrid cross is a combination of three individual monohybrid crosses. For example, plant height (tall vs. short), seed shape (round vs. wrinkled), and seed color (yellow vs. green).
The F1 generation plants of a trihybrid cross are heterozygous for all three traits and produce eight gametes. Upon self-fertilization, these gametes have an equal chance to...
Some of Mendel’s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A trihybrid cross is a combination of three individual monohybrid crosses. For example, plant height (tall vs. short), seed shape (round vs. wrinkled), and seed color (yellow vs. green).
The F1 generation plants of a trihybrid cross are heterozygous for all three traits and produce eight gametes. Upon self-fertilization, these gametes have an equal chance to...
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.
01:43Incomplete Dominance
Gregor Mendel's work (1822 - 1884) was primarily focused on pea plants. Through his initial experiments, he determined that every gene in a diploid cell has two variants called alleles inherited from each parent. He suggested that amongst these two alleles, one allele is dominant in character and the other recessive. The combination of alleles determines the phenotype of a gene in an organism.