Quote:
Originally Posted by quiltergal
In order for alba to display in the parents then they must each have a pair of alba genes IF the alba gene is recessive. If that is the case then two alba parents will always throw alba offspring since they only carry recessive genes.
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That would be true IF there was just one type of "alba gene". But mutations in several different genes could make the plant unable to produce the normal pigmentation. One to make a precursor molecule, and another to convert it to the visible pigment, for instance. Almost every metabolic pathway has many steps, and you can get an alba by disrupting any step in the process that produces the pigment. If the 2 parents have recessive non-functioning genes at different steps in the process, then the offspring gets a functioning dominant gene for each step also, from opposite parents, and normal non-alba pigmentation.