The present invention provides a method for controlling undesired vegetation at a plant cultivation site, the method comprising the steps of providing a plant that comprises at least one nucleic acid comprising a nucleotide sequence encoding a wild-type or a mutated protoporphyrinogen oxidase (PPO) which is resistant or tolerant to a PPO-inhibiting herbicide by applying to said site an effective amount of said herbicide. The invention also provides plants comprising wild-type or mutated PPO enzymes, and methods of obtaining such plants.
