Answer
For functional analysis, ap3 mutants (lacking AP3 function) were transformed with either the functional AP3 gene or the functional gene minus its C terminus. The former construct restored function/petal formation, showing the AP3's function is to cause petals to form, and the version without the C terminus failed to to do this, showing that, for petal formation, the critical part of AP3 protein is the C terminus.
Work Step by Step
Functional analysis involves demonstrating gene function, usually by working with mutants that lack function and by restoring function in whole and in part using transgenes.