DIHYBRID 

Fast Plants Dihybrid Cross 

Purple a pigment known as purple anthocyanin is visible on the hypocotyl. This trait is wildtype (dominant) for anthocyaninless and is referred to as ANL/ANL  

Yellow green this genotype, ygr, when homozygous produces a plant that is lighter green than the normal green Fast Plant

Normal Green this genotype is wildtype (dominant) for yellow green and is referred to as YGR. 

The parents for the production of the F1:
P1: anl/anl, Pan (5), YGR/YGR  anthocyaninless, normal green(left)	P2: ANL/ANL, Pan (8),  YGR/YGR  purple anthocyanin, yellow green (right)

F1: anl/ANL, Pan (5/8), YGR/ygr 
heterozygous for anthocyaninless 
heterozygous for yellow green (middle) 


Expected resullts from this dihybrid cross 


The F2 phenotypes listed above are predicted if the mutant alleles , anl and ygr, are not linked to another trait. Use the F2 segregation data in conjunction with the Chi-squared analysis to estimate the probability that mutant alleles are unlinked or linked. Beyond the Chi-squared analysis the Test Cross is a fundemental criteria for observing possible linkage of alleles. 



The Test Cross (TC) 

The test cross is the essential cross in genetic analyses that provides the most infomative indications of independent assortment or linkage between two traits being tested. In the test cross, F1 progeny are crossed to a stock that is homozygous for the mutant alleles being examined for linkage.

The power of the test cross in linkage mapping is that the combined recombinant frequency (recombinant class count/total) is equal to genetic map units separating the two traits. 

m.u.= recombinant class count/total 

In testing two unlinked recessive mutants the frequency of each parental class and each of the two expected recombinant classes is 0.25. 

Consider recovering the recombinant mutant class from your F2 to be used as a tester or order the tester stock from the CrGC at the same time you obtain your parents.