> a naturally-occurring mutation which is artificially selected-for by a grower

Actually plant breeders use radioactive radiation, and certain mutagenic poisons, to increase to mutation rate way above normal, in order to get more mutated offspring to work with.

What you write about "transgenically-inserted genes are mitochondrial" and "not part of a regulatory chain, and may produce arbitrary metabolites" is total bollocks and I have no idea where you got that particular misinformation from.

https://en.wikipedia.org/wiki/Mutation_breeding