For example, in 1992 Tim Croughan discovered a single rice (Oryza sativa) plant that had survived (what should have been a lethal dose of) an imidazolinone-based herbicide, due to a (mutated) gene in its DNA that made it resistant to imidazolinones. That plant was then propagated via straightforward breeding to yield seeds still sown today.

Many years ago, some other crops similarly were given new traits (e.g., herbicide tolerance, compositional improvements, etc.) via MUTATION BREEDING (i.e., soaking seeds or pollen in mutation-causing chemicals such as colchicine, or bombardment of seeds by ionizing radiation to cause random genetic mutations, followed by grow-out and selection of the particular mutation desired such as herbicide tolerance-- as described above).

Other crops were given new traits via crossing them with related wild plants; which occasionally resulted in extremely high levels of natural toxicants in those plants/seeds (e.g., solanine, psoralene, etc.).

Still others were given new traits via wide-crossing them with other domesticated species (e.g., the tangelo is a hybrid of the grapefruit and the tangerine).

The United States' Food and Drug Administration (FDA) regulates all new crop plants similarly (e.g., also requires testing of plants produced via "traditional breeding methods" for the potential presence of introduced or increased natural toxicants).