o| li]1.|Three loci,B, I andF, concerned with the distribution of anthoeyanins in diploid cultivated potatoes, are identified. AllelesBd>Bc>Bb>Ba>b, in order of dominance, are distinguished.
Bd produces in the seed a band of pigment on the node of the hypocotyl of the embryo and, in the mature plant, a band of pigment at each node, a coloured floral abscission layer and a coloured eyebrow on the tuber.
WithBc, a band of pigment at each node of the mature plant is absent, but other effects are like those ofBd.
Bb gives a coloured floral abscission layer and a coloured eyebrow on the tuber. WithBa only the floral abscission layer is coloured.
LocusI in its homozygous recessive phase,ii, inhibits pigment in the tuber.
LocusF in its homozygous recessive phase,ff, gives flecked flowers. li]2.|The three loci are closely linked and probably in the orderB-I-F. li]3.|Bc andI, in coupling, give a positional effect so that the characteristic nodal bands ofBd occur. LocusB appears to be a super-gene. li]4.|The suggestion is made that the proximity of these loci is original and functional. It may facilitate intergenic co-operation in the distribution of pigment.