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Plant genetics and Oregon Wolfe Barley
The OWB population is a useful and engaging tool for addressing key
issues in plant genetics including genetic diversity; segregation,
independent assortment, and linkage; epistasis; and qualitative
vs. quantitative inheritance.
Dr. Wolfe’s ingenious idea of developing dominant and recessive
multiple marker stocks led to the development of one of the most
genetically diverse mapping populations available. The OWB-D and
OWB-R parents not only contrast for morphological traits, they also
show a very high level of genetic diversity at DNA-based marker loci,
such RFLP's, SSR's, and Dsts.
- Diversity
in morphology: 2-row vs. 6-row and white striped vs. green
leaves.
- Diversity at the DNA level
- RFLPs: ABG462
- SSR's: BMAG0353
- Dst's: DST1
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Segregation, Independent assortment and linkage
Segregation, independent assortment, and linkage are fundamental genetic
principles that are a consequence of events in meiosis. Each OWB plant
is a unique genotype due to the number and location of crossovers that
occurred in meiosis leading to the gamete from which the plant originated.
Because the OWB's are a doubled haploid population, all individuals are
homozygous and each reflects a specific meiotic configuration.
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Linkage maps
A linkage map is built based on the number and location of crossovers
that occurred in each OWB plant. Based on the order and distance of
loci estimated from the entire population, graphical genotypes can be
created for each OWB plant that reveal which portions of its chromosomes
trace to the OWB-D parent and which trace to the OWB-R parent.
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Allelic Variation
The allelic variants used for map construction show a range of intra- and
inter-locus interactions.
- Intra-locus interactions include complete dominance (Vrs1 vs. vsr1)
and codominance (ABG462, BMAG0353, and DST1).
- The hooded vs. non-hooded phenotype is an example of epistasis
(inter-locus allelic interaction).
Allelic variation may lead to phenotypic variation. Phenotypic variation,
in turn, may be qualitative (e.g. 2-row vs. 6-row) or quantitative (e.g.
spike length).
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