Thread: Genetics Math
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Old January 24, 2013   #3
Darren Abbey
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Join Date: Jun 2012
Location: Minnesota
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TGRC is a good source for information on the various known genes:
http://tgrc.ucdavis.edu/Genes.html
Another page with some overlap to above:
http://kdcomm.net/~tomato/Tomato/mutant.html
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The green fleshed trait is probably caused by the recessive 'gf'... so both are 'gf/gf'. The green striped trait is caused by the recessive 'gs'... so both are 'gs/gs'. All their offspring should be green fleshed, with green stripes.

'Abg' produces dark antho fruit shoulder in one copy, but lethal in two copies. 'Aft' produces dark antho coloring in two copies and a lighter color in one copy. 'atv' produces antho coloring in stems/leaves when in two copies. BGZ is a stable for the fruit color, so it is 'Aft/Aft'. FHGTC doesn't have the antho coloring, so it is 'Aft-/Aft-' 25% of your F2s should have the dark antho color, while another 50% should have some antho color.

This paper has some good discussion about tomato fruit shape genetics: http://www.plantphysiol.org/content/156/1/275.full.pdf. There are a number of genes involved in shape, but I suspect the 'sun' gene is responsible for the elongation and pointed shape in BGZ. FHGTC will have the dominant wild type allele only ('Sun/Sun'). 25% of your F2s should have the elongated trait.
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To get all three traits, multiple the probability of each separately: (gf/gf)(gs/gs)(Aft/Aft)(sun/sun) = (1.00)(1.00)(0.25)(0.25) = 0.0625

To calculate the number of plants you would expect to have to grow before you found one like you were looking for, invert the probability: 1/0.0625 = 16
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