In Corn, Red Kernels (PP)are Typically Dominant to White Kernels

In corn, red kernels (PP)are typically dominant to white kernels (pp).A red plant was crossed to a white plant to produce a Pp heterozygote with red kernels.However, a partially white kernel appeared unexpectedly.This kernel was grown into an adult plant, and for several generations of crosses, all the offspring of this original kernel had a mix of partially red and partially white kernels.However, when the seeds were grown in the presence of a demethylating drug, all of the resulting plants had red kernels.Explain why the mixed color kernel appeared, why the offspring of this kernel also had the mixed color phenotype, and why the demethylating drug had its effect.