Seeds that have all dominant factors for anthocyanin pigmentation in the aleurone sometimes do not form pigment if the plant also carries certain B and Pl alleles. The basal portion of these "shaded" ears does not develop pigment in the aleurone. The progeny in one family (E125) of E. H. Coe's material that segregated several ears with the "shaded" expression were tabulated. Of 5 B-w Pl (weak purple) plants, one showed a "shaded" phenotype; of 23 B Pl plants, 11 showed this expression; none of the 5 B' Pl plants or the 6 B pl plants show this phenotype. The tendency for plants with colored husks to show this phenotype is consistent with the hypothesis that some amount of light is required to induce pigmentation even in seeds with all dominant factors for aleurone pigment present. Possibly several layers of purple husks can screen the transmitted light so that the basal portion of the ear does not receive this required light. When colorless seeds from the basal portion of a B Pl "shaded" ear were germinated in the dark for 48 hours only a diffuse pale pigment developed; germination under light was required for development of full purple pigment in these seeds. The explanation for the "shaded" ears phenotype cannot be as simple as this, however, because many B Pl plants do not have "shaded" ears. Furthermore, plants with green husks that are wrapped in 2 layers of aluminum foil to exclude light can still develop purple pigment in the aleurone.
Return to the MNL 53 On-Line Index
Return to the Maize Newsletter Index
Return to the Maize Genome Database Page