Chapter 4, Problem 2QSDC

In oats, the color of the chaff is determined by a two-gene interaction. When a true-breeding black chaff plant was crossed to a true-breeding white chaff plant, the ${\text{F}}_{\text{1}}$ generation was composed of all black chaff plants. When the ${\text{F}}_{\text{1}}$ offspring were crossed to each other, the ratio produced was 12 black to 3 gray to 1 white. First, construct a Punnett square that accounts for this pattern of inheritance. Which genotypes produce the gray chaff phenotype? Second, at the level of protein function, how would you explain this type of inheritance?