Lunden (1932) summarised the colour of potato flowers are follows:
There are two groups:
A number of workers have found that white flowers are recessive to coloured. But sometimes white x white gives coloured forms.
D, a basic gene, which, when alone, produces no colour.
R, a red gene, which only works if D is present.
P, a third gene, giving purple, which only works if R and D are present.
This would give:
PRD = purple
pRD = red
PRd = tinged white
other combinations = white
Salaman states that this is an oversimplification and that other genes must be involved. For example, Salad Blue has pure blue flowers...-N.D.
It now seems clear that pigmentation is governed by three main types of gene:
1. a basic gene.
2. a red-producing gene.
3. a blue-producing gene.
To this may be added an anthocyanin (plant pigment) inhibitor.
There is strong evidence for different but simiilar versions of the basic, red- producing and blue-producing genes, since one does not always get the expected result from crossing apparently identical material.
Pictures (click on small images for detail):
Nigel Deacon / Diversity website
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