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Variation in submergence tolerance. http://www.a2mediagroup.com/data/images/news/categories/riceplant.jpg. Linkage mapping (quantitative). intolerant. tolerant. Fine-mapping. Finding the causative variant. Transgenic test. http://www.plantsci.cam.ac.uk/Haseloff/SITEGRAPHICS/Agrotrans.GIF.
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Variation in submergence tolerance http://www.a2mediagroup.com/data/images/news/categories/riceplant.jpg
Linkage mapping (quantitative) intolerant tolerant
Transgenic test http://www.plantsci.cam.ac.uk/Haseloff/SITEGRAPHICS/Agrotrans.GIF
Coding variants http://homepages.strath.ac.uk/~dfs99109/BB310/CFTRgene.jpg Fig. 2B
Single-locus: AA x BB AB (F1) AB x AB AA AB BA BB (F2)
1 locus, incomplete dominance AB BA AA BB “Effect of having a B” 25% 50% 25% AB BA AA BB
Two loci long chrom short chrom locus 2 locus 1
Two loci long chrom short chrom Parent A A A A A locus 2 locus 1
Two loci long chrom long chrom short chrom short chrom Parent A Parent B A A B B A A B B locus 2 locus 2 locus 1 locus 1
Two loci long chrom long chrom short chrom short chrom Parent A AA/AA x BB/BB Parent B A A B B A A B B locus 2 locus 2 locus 1 locus 1
Two loci long chrom long chrom short chrom short chrom Parent A AA/AA x BB/BB Parent B A A B B A A B B locus 2 locus 2 locus 1 locus 1 AB/AB (F1)
Two loci long chrom long chrom short chrom short chrom Parent A AA/AA x BB/BB Parent B A A B B A A B B locus 2 locus 2 locus 1 locus 1 AB/AB (F1) Locus1/Locus 2
Two loci long chrom long chrom short chrom short chrom Parent A AA/AA x BB/BB Parent B A A B B A A B B locus 2 locus 2 locus 1 locus 1 AB/AB (F1) Locus1/Locus 2 AB/AB x AB/AB 16 possibilities (F2)
Two loci, incomplete dominance or BA or BA
Two loci, incomplete dominance How many squares of the Punnett square are represented here? or BA or BA
Two loci, incomplete dominance Effect of B at locus 2
Two loci, incomplete dominance Effect of B at locus 2
0 0.5 1.0 1.5 Phenotype Two loci, incomplete dominance
0 0.5 1.0 1.5 Phenotype Two loci, incomplete dominance * What is the genotype? AA/AA AB/AA BB/AA AA/AB
0 0.5 1.0 1.5 Phenotype Two loci, incomplete dominance * What is the genotype? AA/AB BB/AB AB/AB AA/BB
0 0.5 1.0 1.5 Phenotype Two loci, incomplete dominance * How many F2’s have this genotype? 1/16 2/16 3/16 4/16
Two loci, incomplete dominance Notation is different, trait is qualitative; math is the same. Fig. 3.17
2-locus interaction Junglefowl Leghorn http://www.projects.roslin.ac.uk/chickmap/organism.html
Two loci long chrom long chrom short chrom short chrom Parent J JJ/JJ x LL/LL Parent L J J L L J J L L locus 2 locus 2 locus 1 locus 1 JL/JL (F1) Locus1/Locus 2 JL/JL x JL/JL 16 possibilities (F2)
2-locus interaction Effect of J at locus 2
2-locus interaction Effect of J at locus 2
2-locus interaction Effect of J at locus 2 Effect of variation at locus 2 depends on genotype at locus 1: non-additive
2-locus interaction For example: locus 1 is polymorphism in a transcription factor gene that affects protein binding affinity, locus 2 is in a binding site Effect of J at locus 2 Effect of variation at locus 2 depends on genotype at locus 1: non-additive
2-locus interaction Effect of J at locus 2 Locus 2 is epistatic to locus 1: effects of locus 1 are masked in individuals with JJ or JL,LJ at locus 2 Locus 2 follows a dominance model: JJ and JL,LJ have the same phenotype, LL differs “The dominant allele of locus 2 does the masking”
Pathogenic yeast How did YJM145 gain the ability to grow at body temperature?
A model quantitative trait Lab parent
A model quantitative trait Lab parent Pathogenic parent
A model quantitative trait 100 progeny ≥ pathogenic parent Lab parent Pathogenic parent
NO progeny as extreme as diploid hybrid Diploid hybrid Lab parent Pathogenic parent
Did the mapping… Significant linkage to yeast chrom XIV and chrom XVI.
Did the fine-mapping… Which gene is causative?
Tested in hybrid diploids Pathogenic Pathogenic Lab Lab
Tested in hybrid diploids Pathogenic Pathogenic Lab Lab