Blp normal phenotype (dominant)	blp mutant phenotype (recessive)

Description:
Black pigmentation of the lemma and pericarp develops slightly before maturation of the spike. Pigmented organs may include all parts of the spike, awns, the upper portion of the stem, and upper leaves. The intensity of pigmentation associated with each of the dominant alleles at the Blp locus is characteristic of that allele, and is relatively stable over environments. Black seed is produced by melanin-like pigment in the pericarp. Woodward reports that the dominance ranking of alleles at the Blp locus is related to the intensity of black pigmentation they confer, with the Blp1.b (B) allele conferring extreme black pigmentation. The Blp1.mb (B^mb^) allele is associated with medium black and a reduced distribution pattern; and the Blp1.g (B^g^) allele is associated with light black or gray coloration.
Description courtesy of the Barley Genetics Stocks AceDB Database
Note: The spike on the right in each photo show the Blp gene expression in the Zeo semi-dominant dwarf phenotype.

Links:
Barley Genetics Stocks AceDB Database
GrainGenes Gene Record

References:
J.D. Franckowiak, U. Lundqvist, and T. Konishi (1997) New and revised names for barley genes.  Barley Genetics Newsletter. Volume 26

Barley Genetic Stock Description: Stock number: BGS 203