In many situations, the different versions of the genes
(alleles) that control a grain quality trait
will have a lack of dominance.
This means that heterozygous
individuals will have a phenotype
that is different from (normally in between) either of the homozygous genotypes
. If an intermediate type is not expressing the grain quality trait to an acceptable level, the seed
producer will be required to produce homozygous seed for the producer to grow. This is not an issue for a self-pollinated crop but it would be a concern for someone like Dr. Russell in developing corn hybrids
with low seed phosphorous (P) levels. If the alleles
that control low seed P have a dominant
effect, only one low P parent line
would need to be developed. The understanding the plant breeder develops as they work with these traits will thus be critical in helping the seed producer make the right decisions.